# That's a pretty cheap boat heater!



## cjmcfall (May 30, 2007)

I haven't tried this yet but seems like an interesting idea. Has anyone given this a go? Did it work?

I may try it next time I'm at the boat and before the real cold sets in. And to be clear - the boat is on the hard.

How to Heat Your Room for 15 Cents a Day | REALfarmacy.com | Healthy News and Information


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## deniseO30 (Nov 27, 2006)

LOL... good way to burn the boat to the waterline too!


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## cjmcfall (May 30, 2007)

Ha! You're probably right, but it's got to be safer than a "burn-o-matic" pressurized alcohol stove! Once I almost turned me and the boat into a bbq - not cool.


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## newhaul (Feb 19, 2010)

It does work but I will still use my two bit a day propane force ten bulkhead heater


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## Barquito (Dec 5, 2007)

I find that if I bring my 300 watt work light, and am pretty active trying to fix something in the cabin, that I stay warm-ish. Anyone have any idea what percent of the 300 watts ends up as light versus heat?


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## smackdaddy (Aug 13, 2008)

Hey! That's our own Dylan Winter!

Brilliant solution Dylan! I've gotta try that one.


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## flyingwelshman (Aug 5, 2007)

That's our old friend Dylan Winter of Keep Turning Left - a great series of on-line videos from around (literally) England. Check it out!

He used to post here quite frequently but I haven't seen him for a while.

Dylan did stir up a bit of debate over the idea of cooking canned goods in their cans. Somehow or other canned Haggis became the focus.

Here's a link to that funny thread.


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## flyingwelshman (Aug 5, 2007)

smackdaddy said:


> Hey! That's our own Dylan Winter!
> 
> Brilliant solution Dylan! I've gotta try that one.


Beat me! That's what happens when you spend too much time re-reading classic threads!


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## Minnesail (Feb 19, 2013)

Barquito said:


> I find that if I bring my 300 watt work light, and am pretty active trying to fix something in the cabin, that I stay warm-ish. Anyone have any idea what percent of the 300 watts ends up as light versus heat?


All of it.

Incandescent light bulbs are only about 10% efficient, the other 90% is released as heat. But the light they emit gets absorbed by whatever it hits and warms them, so a 300 watt bulb is effectively the same as a 300 watt space heater.


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## jwing (Jun 20, 2013)

Barquito said:


> I find that if I bring my 300 watt work light, and am pretty active trying to fix something in the cabin, that I stay warm-ish. Anyone have any idea what percent of the 300 watts ends up as light versus heat?


How much light (lumen) a particular bulb (lamp) produces compared to how much power it requires (watts) is called "luminous efficacy." Web search the term for more details, but efficacy is different for each type of lamp.

100% of the electricity that goes into any lamp is eventually converted into heat, regardless of its efficacy. So, for heating a room, a 300-watt lamp is the same as a 300-watt space heater.

Also a bare candle puts out the same amount of heat as a candle surrounded by a clay pot. I'll take the light bulb.


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## weinie (Jun 21, 2008)

Im calling bs on this one. A candle only puts out so much energy. You cannot simply increase this output by channelling it into a terra cotta pot. It would be the same heat energy if you had left the pots off.


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## Omatako (Sep 14, 2003)

I haven't tried it but I have been told that the same ceramic pot over a burner on the gas stove set to the lowest setting will actually get the pot to glow and the heat emitted is substantial.

Yes, I know the gas stove will suffocate everyone within a square mile and the glowing pot will burn the boat to the waterline but seemingly it has been done many times and quite successfully. You just don't want to be doing this in a heavy, lumpy sea - catching the pot as it falls off the stove could smart a little.

Also, the concept of "a candle only puts out so much heat" - well yes that is true but a candle freely burning dissipates the heat very quickly whereas captured under a ceramic pot gathers the heat and absorbs it into the pot. I'm not saying it works effectively because I haven't tried it but it isn't the same thing.

As a parallel concept, I'll bet that the flame in the Force Ten bulkhead heater if left to burn free outside of the heater would have little effect on the heat in the cabin. If it had the same effect away from the heater, why would anyone buy the heater?


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## fiatracer163 (Oct 21, 2011)

physics - Is this tealight-flowerpot heater more efficient than just tealights? - Skeptics Stack Exchange

His computer puts off more heat than the candles.


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## deniseO30 (Nov 27, 2006)

a candle is about 3,600 btu an hour. Electric, convert watts x 3.415 = btuhs


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## pdqaltair (Nov 14, 2008)

Exactly, Jwing and Minnesail have it. I remember and engineer exam, way back when; the question included all of the physical properties of the refrigerant, compression ratios and on-and-on, as well as the amp draw of the motor. We were to calculate the warming of the room. Kids toiled away, when all they needed was the amp draw and a few unit conversion factors.

I've even tried the flower pot method on a kitchen stove, because I was bored. Perhaps it would do something worthwhile in terms of radiant heat; not much. It did increase CO emissions until the pot got up to temperature. Bad.

Until someone finds a clay pot that generates it's own heat this will be nothing more than a durable urban legend. A dangerous one.


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## newhaul (Feb 19, 2010)

I does work fine for what it is BTW I first saw the idea in mother earth news about 25 years ago listed as emergency heating for under 200 sq ft I rather think the people huddled round it gave off more heat in the original article.ss


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## weinie (Jun 21, 2008)

Omatako said:


> Also, the concept of "a candle only puts out so much heat" - well yes that is true but a candle freely burning dissipates the heat very quickly whereas captured under a ceramic pot gathers the heat and absorbs it into the pot. I'm not saying it works effectively because I haven't tried it but it isn't the same thing.


Where does the candle dissipate the heat to? Could it be the room... the same place the pots do?


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## Omatako (Sep 14, 2003)

weinie said:


> Where does the candle dissipate the heat to? Could it be the room... the same place the pots do?


OK so this gets interestinger and interestinger. 

Going back to my earlier corollary, if the flame in the Force Ten burner was left to burn quietly in the corner, would it produce the same heat as the Force Ten heater? Maybe it does. I have no idea.

See, if I look at this thingy below (Oh, it's a Force 10 heater), it appears to have a burner under the bulk of the body. If heating up the bulk of the body is not what creates the heat in the cabin, then why would one want the bulk of the body in the boat taking up space? Why not have just the burner? One (or at least I) must make the assumption that the burner (or candle) heats the body (or clay pot) which heats the space around it.










I'm not saying that I have done this flower pot thing or that I believe it works. I live in a part of the world where heating boats is unnecessary. But my question above begs an answer - What is it about the body (clay pot) above the burner (candle) that turns an ordinary flame into a cabin heater? I don't know the answer - seemingly you do.


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## tdw (Oct 2, 2006)

You live in bloody New Zealand ffs .... what do you mean you don't need a heater ?  Just another fair weather sailor. No wonder the Kiwis couldn't beat the Australian in the AC ....


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## deniseO30 (Nov 27, 2006)

The inner pot has "thermal mass" the outer pot would cause convection air currents around the inner. The candle flame would not get hot enough to begin catalytic action of the combustion gases.. leastwise I don't think so.


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## jwing (Jun 20, 2013)

deniseO30 said:


> a candle is about 3,600 btu an hour. Electric, convert watts x 3.415 = btuhs


How big would a candle have to be to put out 3600 Btuh? That's more heat than ten 100-watt incandescent light bulbs!


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## deniseO30 (Nov 27, 2006)

wax burns about 125,000 btuh Oil, in just about all it's forms burns about 140,000 btuh


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## Omatako (Sep 14, 2003)

tdw said:


> You live in bloody New Zealand ffs .... what do you mean you don't need a heater ?  Just another fair weather sailor. No wonder the Kiwis couldn't beat the Australian in the AC ....


We're tough over on this side of the ditch - no "Sunshine Coast" for us!! Besides when I want to get warm on the boat, I use something that lives, breathes, has just two legs and no wool :laugher

As far as the Cup goes . . . . let the record show . . . .



I only see one Union Jack . . . .

Oh and we (NZ) at least got to defend the cup more than once.


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## PaulinVictoria (Aug 23, 2009)

> Besides when I want to get warm on the boat, I use something that lives, breathes, has just two legs and no wool


You set fire to a seagull? Wouldn't that smell a bit?


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## jwing (Jun 20, 2013)

The difference between a bare flame and a Force 10 heater is the heat transfer mechanism. Both impart the exact same amount of heat into a room. The heater converts a bunch of the heat into radiant heat, which is a more efficient way to heat distant objects that cannot tolerate high temperatures, such as skin. Therefore it feels warmer to a person. Think of sunshine on a cool day or a campfire on a chilly night.
By the way, a shaded thermometer, not being affected by radiation, will show that the thermally massive heaters are slower to raise air temperature. Conversely, radiant heating systems keep people warm at lower air temperatures than air heaters, and therefore are more fuel efficient.


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## davidpm (Oct 22, 2007)

I found that if I replace the wax tea lights with the battery powered LED lights it will last for a couple days and I'm just as warm as with the wax ones long as I put on my base layer.

The gentle glow is warmly comforting.


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## guyfromiowa (Jan 28, 2010)

Wait. Canned haggis? Food? Just asking. Carry on.


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## Delezynski (Sep 27, 2013)

I have seen a number of people use the flower pot over a burner. On boat is smallish (27 foot) and very well insulated, so it does not take a lot to keep it warm inside. It also has a solid fuel heater (called a fireplace  ). It sure works GREAT for us. When there was snow on the dock, seems all foot prints lead to our boat.

For a time, I used coal in it. I would load a few brown sandwich bags and know that each one lasted for about 4 hours.

I have come up with a better idea now. I put an oil lamp in there. I can control the flame and position of the lamp so I have a high and low setting. And, it will last all night now. 










Greg


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## bfloyd4445 (Sep 29, 2013)

deniseO30 said:


> LOL... good way to burn the boat to the waterline too!


but just think if that happens then you could use the floating hull as a pan and light a few hundred of them things then put two giant pots on top and heat up the whole marina


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## smackdaddy (Aug 13, 2008)

Omatako said:


> We're tough over on this side of the ditch - no "Sunshine Coast" for us!! Besides when I want to get warm on the boat, I use something that lives, breathes, has just two legs and no wool :laugher
> 
> As far as the Cup goes . . . . let the record show . . . .
> 
> ...


Bam!


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## smackdaddy (Aug 13, 2008)

jwing said:


> The difference between a bare flame and a Force 10 heater is the heat transfer mechanism. Both impart the exact same amount of heat into a room. The heater converts a bunch of the heat into radiant heat, which is a more efficient way to heat distant objects that cannot tolerate high temperatures, such as skin. Therefore it feels warmer to a person. Think of sunshine on a cool day or a campfire on a chilly night.
> By the way, a shaded thermometer, not being affected by radiation, will show that the thermally massive heaters are slower to raise air temperature. Conversely, radiant heating systems keep people warm at lower air temperatures than air heaters, and therefore are more fuel efficient.


Yes. But what about a flower pot?


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## ltgoshen (Jan 5, 2009)

cjmcfall said:


> Ha! You're probably right, but it's got to be safer than a "burn-o-matic" pressurized alcohol stove! Once I almost turned me and the boat into a bbq - not cool.


Hey,hey!! I have a pressurized alcohol stove. I have burnt nothing but chicken and only did that once. They are a good stove if you respect them and learn how to use them.


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## Multihullgirl (Dec 2, 2010)

physics - Is this tealight-flowerpot heater more efficient than just tealights? - Skeptics Stack Exchange


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## baboon (Aug 7, 2008)

jwing said:


> The difference between a bare flame and a Force 10 heater is the heat transfer mechanism. Both impart the exact same amount of heat into a room. The heater converts a bunch of the heat into radiant heat, which is a more efficient way to heat distant objects that cannot tolerate high temperatures, such as skin. Therefore it feels warmer to a person. Think of sunshine on a cool day or a campfire on a chilly night.
> By the way, a shaded thermometer, not being affected by radiation, will show that the thermally massive heaters are slower to raise air temperature. Conversely, radiant heating systems keep people warm at lower air temperatures than air heaters, and therefore are more fuel efficient.


In practice the force 10 heater will put out less total heat than the bare burner alone since a portion of the heat heads up the chimney. The loss is a small price to pay for getting the moisture out of the boat.


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## TomMaine (Dec 21, 2010)

Whatever radiant heater you use, the lower it is to the sole, the better(preferably, just above your toes).


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## tdw (Oct 2, 2006)

All I can add is that generations of sailors in southern Australia (aka Tasmania ... the cold bit of Oz) have been using the pot method with supposedly some success. 

Obviously they are deluded. As for the safety angle, they are seemingly capable of leaving a hatch open when an open flame is alight down below. 

Now it must be admitted that even if it is the coldest part of mainland(ish) Australia, by e.g Canadian standards it is not exactly frigid. So yon earthenware pot may well be more effective in cold but still above freezing temps.


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## newhaul (Feb 19, 2010)

baboon said:


> In practice the force 10 heater will put out less total heat than the bare burner alone since a portion of the heat heads up the chimney. The loss is a small price to pay for getting the moisture out of the boat.


Not to mention the carbon monoxide


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## jwing (Jun 20, 2013)

baboon said:


> In practice the force 10 heater will put out less total heat than the bare burner alone since a portion of the heat heads up the chimney. The loss is a small price to pay for getting the moisture out of the boat.


Oops; I didn't know that Force 10 is a vented heater. You are right, some of the heat goes out the flue and you are right again, it's worth the loss to get the products of combustion (including water vapor) out of the cabin.


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## Brent Swain (Jan 16, 2012)

Breathing paraffin fumes sounds like no fun.


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## Maine Sail (Jan 6, 2003)

jwing said:


> Oops; I didn't know that Force 10 is a vented heater. You are right, some of the heat goes out the flue and you are right again, it's worth the loss to get the products of combustion (including water vapor) out of the cabin.


Sadly those LPG Force 10's only make the cabin wetter, not drier. They also really perform very poorly as heaters. We owned three of them, installed by PO's, on three different boats, and found them to be an utter waste of space and money. The Dickenson's actually do something not so much for the Force 10, or a flower pot, on any decent sized boat here in Maine


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## TakeFive (Oct 22, 2009)

smackdaddy said:


> Hey! That's our own Dylan Winter!
> 
> Brilliant solution Dylan! I've gotta try that one.


I'm surprised that nobody commented how precariously the flower pots were balanced on the pan. I'm not surprised he demoed it on land and not on a boat - one wake and the whole thing would be headed for the cabin sole.

I saw on another website that a typical candle puts out 77±9 W of heat. No more than a typical light bulb.

Also, I would be concerned about CO output from restricting the air flow. Maye after the whole things heats up there's a sufficient draft through the pots, but until then it could be dangerous.

When I'm on the boat I use a $15 WalMart space heater. I got one with a three-level knob for 500-1000-1500 watts. I run it on 1000 max, since 1500 blows my 10A circuit breaker. It circulates a lot of air, so the heater itself stays cool, which I prefer. An oil type heater would be best, but they are bulky and mine is very compact, which is good for a small boat like I have.


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## jfdubu (Jul 18, 2002)

There are a few things about this that make it a viable option for some boaters.
1) the candles don't use electricity, the heat source is the flame.
2) candles are a great way of drying a damp boat
3) by channeling the heat into the pots a much more efficient conductor stores the heat. True the candles generate the same amount of energy, pots or not, but by absorbing the heat into the pots a heat battery of sorts is created.

Bottom line, under sail, bad item. Tied to a dock or mooring without shore power, pretty effective.


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## aeventyr60 (Jun 29, 2011)

A trawler kero lantern works pretty well at putting out a bit of heat.


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## newhaul (Feb 19, 2010)

My force ten served well last winter on the hook never had a moisture problem


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## deniseO30 (Nov 27, 2006)

I'd like to see an old Aladdin kerosene mantle burner (not the wick type.) under something like a clay pot. would get quite hot is my guess.


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## TakeFive (Oct 22, 2009)

My family used to have an Aladdin kerosene heater (wick type) on our un-insulated aluminum motor boat (34' KingsCraft houseboat - really cool design as houseboats go). Aluminum has the highest thermal conductivity of all metals, and the boat had huge single-pane slider windows, so that boat leaked heat like a sieve. I can only imagine how much CO2 (and maybe CO) built up inside that thing when we cranked the heat up. This was the early '70s, before CO detectors, etc.

I think the biggest questions about any unvented flame in a boat are fire hazard and oxygen depletion leading to CO. It's a significant risk.

The whole clay pot thing is a red herring. The flame is going to put out heat roughly proportional to the number of carbon and hydrogen atoms that are oxidized. Whether the heat is distributed via natural convection, forced convection, or radiance will affect how localized the heat is, but the total amount of heat in the boat is just related to the rate the fuel burns. There's no "magic bullet" that makes the thing put out more heat than is contained in the fuel.


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## deniseO30 (Nov 27, 2006)

Rick. yes and.. not necessarily. There is engineering involved with combustion.. but it's not really applied to candles. For figuring.. wax is close although lower then fuel oil in btu content.

In true combustion chambers, interesting things happen with flame and refractory materials, air, draft, etc. A heater will make heat better then a device made for light.

Nothing really new, even a fireplace has a "smoke shelf" and wood stoves have something similar . Also when surfaces like fire brick, ceramic, stone, metals, get at a certain temp they improve combustion. On our cars we have catalytic converters.. on jets.. after burners. So.. there is allot of combustion engineering going on in may places.

Combustion Efficiency and Excess Air


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## weinie (Jun 21, 2008)

I was hoping Mainesail would have done rigorous testing and quantitative evaluations on video of candle/flower pot heating systems by now!


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## Maine Sail (Jan 6, 2003)

TakeFive said:


> *There's no "magic bullet" that makes the thing put out more heat than is contained in the fuel.*


Bingo!!!! Someone paid attention in physics class!!!!! If we could magically do that our energy needs would have been solved long ago.....


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## Steve in Idaho (Jun 22, 2012)

deniseO30 said:


> I'd like to see an old Aladdin kerosene mantle burner (not the wick type.) under something like a clay pot. would get quite hot is my guess.


No need for a pot. They put out a lot of heat as they come. We have three of them. With a properly trimmed wick and adjusted not-too-high, they burn cleaner than a flat wick - and one will heat a small room pretty well.

The Aladdin mantle lamp takes full advantage of convection. Convection doesn't "create heat", but it does feed combustion - making it more complete (enhanced oxygen supply). Just blow on a hot coal to see what I mean.

I don't know about this candle and flowerpot thing, but if it sets up good airflow through convection (unlike what is portrayed in the diagram on the link someone posted), it might increase the heat output some (along with enhancing distribution). Our home's wood stove has a ceramic-based catalytic burner in the gallery leading to the flue. I don't completely understand the process (it's chemical?) but it boosts the heat output by causing combustion of waste gasses in the wood smoke (up to well over 2000 degrees with a very small fire, if you let it have too much oxygen - enough to start self-destructing). It does raise efficiency and reduce fuel use. 
So, if there is some sort of catalytic action taking place with the flower pots (which I doubt) then it may have some merit.


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## TakeFive (Oct 22, 2009)

Steve in Idaho said:


> ...I don't know about this candle and flowerpot thing, but if it sets up good airflow through convection (unlike what is portrayed in the diagram on the link someone posted), it might increase the heat output some (along with enhancing distribution)....So, if there is some sort of catalytic action taking place with the flower pots (which I doubt) then it may have some merit.


Good point about enhanced airflow making the fuel burn faster. That would increase heat a bit without violating the laws of physics.

Maybe someone should try sputtering some platinum onto a couple clay pots and see if it boosts output. :laugher


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## Maine Sail (Jan 6, 2003)

TakeFive said:


> Good point about enhanced airflow making the fuel burn faster. That would increase heat a bit without violating the laws of physics.
> 
> Maybe someone should try sputtering some platinum onto a couple clay pots and see if it boosts output. :laugher


Making them burn faster does not change the BTU content of the candles only accelerates how fast the heat is put into the cabin.


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## TakeFive (Oct 22, 2009)

Maine Sail said:


> Making them burn faster does not change the BTU content of the candles only accelerates how fast the heat is put into the cabin.


Agreed, you'd have to replace them sooner.


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## weinie (Jun 21, 2008)

Maine Sail said:


> Making them burn faster does not change the BTU content of the candles only accelerates how fast the heat is put into the cabin.


Well, that WOULD heat the cabin faster, however the guy in the video says one one set of candles lasts all day and one set all night. Also, I'm not sure that you CAN make a candle burn any faster without changing the wick or wax properties.


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## Maine Sail (Jan 6, 2003)

weinie said:


> Well, that WOULD heat the cabin faster, however the guy in the video says one one set of candles lasts all day and one set all night. Also, I'm not sure that you CAN make a candle burn any faster without changing the wick or wax properties.


He did say the candles last for "and each one burns for about 4 hours" he then says "so four in the morning and four in the afternoon". It appears he is talking about an 8 hour work day..?

I suspect by "day" he is not referring to a 24 hour day because that would require 6 changes of the tea lights per 24 hour period....... Still the flower pot adds nothing about the BTU put into the room, it only changes how it is radiated. I don't recall that he ever claimed the pots made the candles throw off any more BTU, just comments about air flow changes.


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## SJ34 (Jul 30, 2008)

Excellent job Dylan. Six pages in a single day discussing how hot a tealight burns and you aren't even the OP. Keep up the good work.


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## dylanwinter1 (Jan 15, 2010)

SJ34 said:


> Excellent job Dylan. Six pages in a single day discussing how hot a tealight burns and you aren't even the OP. Keep up the good work.


Sorry to have missed the party. I have been doing some winter sailing this week on the Firth of Forth - and jolly nice it was too. Katie L steers herself on a remarkable number of different points of sail so I have spent a fair amount of time standing in the companionway by the origo making tea and toast while watching the local fauna - includuing dolphins for the first time

Never seen them before - five decades of sailing and never seen them with the number 1 eyeball.

The film has now had over 3 million hits - it is my sixth viral (assuming a viral is over a million) and that one took me by surprise. It has been up for over a year - initially getting around 8,000 hits from fans of the two ronnies who think the mention of four candles is highly amusing






then last month it escaped onto facebook.

one day it got half a million hits

shame I got kicked out of adsense as 3 million hits are worth $3,000

however, to flower pots.

I do a lot of winter sailing and the cabin of the boat is only the size of a telephone box on its side - so not a massive challenge to heat

I cook slow meals - often boiling cans - I use tealights candles on a metal pie dish. My other main source of warmth is two sleeping bags, a wooly hat and a slug or two of cheap whisky. I am a red headed celt so I am genetically cold tolerant.

But this last year or so I have been getting cold in the house - during the winter I move the office up to the smallest room in the house. When I had two large CRT monitors they more or less heated the room - just with the occasional use of a convection heater.

now that I have flat screens the system is using much less power

128 watts per monitor in the past against 38 watts for the flat ones

I found that I was getting cold so I tried a plate of tealights as I use on the boat. Each one gives off around 80 watts - so 320 watts or a third of a bar. 
it did not seem to help so I bunged a flower pot on top - and it got bloody hot but not much airflow

so instead of doing my work I experimented a bit and came up with the double pot with the inner one blocked. That seemed to increase the air flow in the most wonderful way - I assume that the inner pot, which gets too hot to touch heats the air between the two and draws cold air over its surface. Using the pots does not seem to increase burn time. But it does move the heat around a bit and stir the air. Placing it close to the desk and down low also gave me a bit of radiant heat.

no more cold ankles and cold hands.

On the assumption that there are lots of people around like me who work from home but are too tight/environmentally aware to put the heating on in the whole house and who might have chucked out their old CRTs then this might have helped.

It has been a most entertaining month or so - watching the film spread around the world - and I have been contacted by several radio stations to do short interviews. Last winter 30,000 extra old people died - like me they are frightened to put on the heating because of the guaging barstewards who run our power companies in the UK.

reading the inane comments on the film has been most illuminating - seeing the me too videos on youtube

some are pretty funny - try typing flower pot heater into youtube.

You have to admire people for seeing something and then trying something different. A few nirks saw the film and decided that if four candles are good then 12 is better - one bloke put a metal plate over the top of his 12 candles and set light to his workbench - well duh

One bloke had three units side by side - it failed to set off his CO alarm but he said the room smelt of candles - well duh 2

One bloke pointed out that it had no impact on his 24 x 15 foot fron room - he was a canuck - well duh 3

The understanding of science is pretty darned thin in some areas - and the inability of people to listen to the words is also amazing.

People seem to think that I am claiming that it will heat the whole house, or that the flower pots conjures heat out of thin air.

Some people refuse to believe that the pots have any impact at all - one bloke put one in his bathroom came back an hour later and pointed a remote thermometer at the tiles on the wall - unsurprisingly, being cemented to a thick wall the tiles did not warm up much.

So chaps - the flower pots just move the heat around more efficiently - they do not produce more heat than a candle. Yes naked flames can be dangerous - but I cook over a naked flame.

I often run with scizzors just for the raw thrisll of it.

although it is, as I understand it , extremely hard to kill yourself by carbon monoxide poisoning or suffocate yourself with four candles - otherwise people would be expiring by the dozen in their candle lit bathrooms or while having a candle lit shag of a night.

The flower pot idea has been used in chicken coops, greenhouses, in outside dunnies and in Anderson shelters for longer than any of us have been on the planet.

I just tweaked the design a little

The good thing is that it is the sort of experiment any of us can do

you can now buy kits on ebay - and that is a wonderful thing.

now then.... back to outboard wells in Westerly Centaurs.


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## Brewgyver (Dec 31, 2011)

deniseO30 said:


> a candle is about 3,600 btu an hour. Electric, convert watts x 3.415 = btuhs


Wow, that must be some other kind of candle. Where id you get that 3,600 BTUH figure? That would be 60 BTU/Minute, which would reheat a 12 ounce cup of coffee from 60 F to 140 F in one minute, (theoretical, with zero losses). Even if you assume only a 50% efficiency in heat transfer, it would do it in two minutes.


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## deniseO30 (Nov 27, 2006)

Brewgyver said:


> Wow, that must be some other kind of candle. Where id you get that 3,600 BTUH figure? That would be 60 BTU/Minute, which would reheat a 12 ounce cup of coffee from 60 F to 140 F in one minute, (theoretical, with zero losses). Even if you assume only a 50% efficiency in heat transfer, it would do it in two minutes.


I used something called the internet and did a "search" this is the "link" it's what we do to find something of interest on the thing called the internet
https://www.google.com/search?q=BTU+of+a+candle&ie=utf-8&oe=utf-8&aq=t&rls=com.yahoo:en-USfficial&client=firefox&channel=fflb
Wow
I can do a thing called "copy and paste" too. So, depending on which site, the BTU of a candle is all over the place. No one seems to have actually come up with the actual btu content. Some convert it to lumens then watts, others used the fuel and it's btu content. 3600 seems high to me, on another site one person has it at 250 btuh. which seems way low. 
Anyways... you are of course welcome to do your own research since you seem to need a way to question my way of coming up with answers.

Yes, I have noticed how none of the guys ever question the information given from another guy! :laugher


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## deniseO30 (Nov 27, 2006)

Someone is marketing them LOL Notice.. they don't have the BTUH listed.
How To Heat Up Your Room Using Just a Candle: Kandle Heeter! - The Green Optimistic


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## Brewgyver (Dec 31, 2011)

deniseO30 said:


> I used something called the internet and did a "search" this is the "link" it's what we do to find something of interest on the thing called the internet
> https://www.google.com/search?q=BTU+of+a+candle&ie=utf-8&oe=utf-8&aq=t&rls=com.yahoo:en-USfficial&client=firefox&channel=fflb
> Wow


Yes, I searched and read quite a few results. I read several that had a basis in fact, rather than the totally unsubstantiated claim in the first hit (1 btu/sec).

There are a few variables, but the concensus is that the actual number is 80 to 100 watts, or a max of about 341 BTU/Hr.


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## deniseO30 (Nov 27, 2006)

PDF BTUH content of many types of things that get burned This list has wax burning at 18,621 btuh (you would need to find out how much wax your candle burns an hour. ) then find out how much heat is actually used.. it would be less then 40% is my guess

http://www.balboa-pacific.com/WasteToEnergy/BTU_Values.pdf


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## Brewgyver (Dec 31, 2011)

deniseO30 said:


> Someone is marketing them LOL Notice.. they don't have the BTUH listed.
> How To Heat Up Your Room Using Just a Candle: Kandle Heeter! - The Green Optimistic


Does on this page, quoting the "developer" of the heater"
3″ dia. by 3″ 'dollar store' candle will yield about 50 BTUs an hour"


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## deniseO30 (Nov 27, 2006)

What is this need you have to prove me wrong? 50 btuh sounds way low btw. 
from another site

http://boards.straightdope.com/sdmb/showthread.php?t=117206
Guest 
Join Date: Oct 2000
Quote:
(12.6 lumens/W) * (1 W/ 0.1 lumen) = 126 W
126 W X 3.4 (B.t.u/H)/W = 428.4 Btu/hour per candle.
428.4 Btu/hour X 6 candles = 2570.4 Btu/hour.
(250 W per candle is too high an estimate, as a 250 watt light bulb, unlike a candle, will melt a lot of wax)

A typical gas stove burner puts out ~12,000 Btu/H, so we're not talking a lot of heat. On the other hand, a standard small window air conditioner is good for 5000 BTU/hour. Six candles would use up half its cooling capacity.

If we look at it in terms of people:
A person using 2500 Calories (Kcal) a day puts out 2500/24 = 104 Kcal/hour
104Kcal/hour X 3.98 Btu/Kcal = 414.5 Btu/hour per person.
So lighting 6 candles would have about the same effect as asking 6 more people into the room.
(1 person = ~1 candle)
That's not likely to be a problem when its 56 degrees outside.
.........

I'm retired, have lots of time, you want to continue this??


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## Brewgyver (Dec 31, 2011)

deniseO30 said:


> PDF BTUH content of many types of things that get burned This list has wax burning at 18,621 btuh (you would need to find out how much wax your candle burns an hour. ) then find out how much heat is actually used.. it would be less then 40% is my guess
> 
> http://www.balboa-pacific.com/WasteToEnergy/BTU_Values.pdf


Yes, that is 18,621 BTU/Hr for one pound of parafin/wax. Estimated burn time of a one pound candle from several candlemaker's (example)web pages? Based on the small wick type used in the "heater", from 112 to 144 hours, which would bl 129 to 166 BTU/Hr.


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## Brewgyver (Dec 31, 2011)

deniseO30 said:


> What is this need you have to prove me wrong?


I don't have ANY need to prove you wrong. Honest.



deniseO30 said:


> Yes, I have noticed how none of the guys ever question the information given from another guy!


I'm not sure how to respond to that, except that if you read all my posts, you would see that I do, indeed, question information from another guy, if I believe the information is not accurate. I seldom question anybody about actual sailing issues, as I am a beginner, which is of course the main reason I'm on SN in the first place. But I can occasionally voice an opinion in issues related to my work and general experience.

Your initial claim that a candle gives off 3,600 BTU/Hr of heat was SO outlandish that I had to point it out, asking you where you got such a figure. Your (somewhat sarcastic) reply said that you got it from an internet search, from which you apparently picked a number quoted by some guy with no citation at all to back up such a ridiculous number.

Going back to what you said first:


deniseO30 said:


> a candle is about 3,600 btu an hour. Electric, convert watts x 3.415 = btuhs


All you have to do is divide 3,600 by 3.412 (the actual conversion factor) to see that the 3,500 number would have one candle equivalent to a 1KW electric heater.

Anyway, you don't have to take it so personally, we're all just talking here. You're retired, I'm at work with nothing to do, so I'm just killing some time, as well. I sincerely hope you have a Happy Thanksgiving!


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## Steve in Idaho (Jun 22, 2012)

dylanwinter1 said:


> ....So chaps - the flower pots just move the heat around more efficiently - they do not produce more heat than a candle....


As I suspected. And thanks for the interesting read!



> How To Heat Up Your Room Using Just a Candle: Kandle Heeter! - The Green Optimistic
> http://i0.wp.com/www.greenoptimistic.com/wp-content/uploads/2008/11/kh-group.jpg?resize=284,300


To add to the amusement. Unlike the subject o f the OP, this product doesn't even have the appearance of providing the mechanics to do anything but separate silly people from their money. Making a "working model" would actually be cheaper and easier. Could it be that actually allowing heat to be concentrated into the output of a flower pot with a hole in the bottom would be too much of a liability for such a commercial product? Oh well....put something together that we can sell without getting sued - even if it doesn't do anything but look cute.

Gotta love gullible people('s money).


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## deltaten (Oct 10, 2012)

Denise;
Jumping in late, so's I don't know if I missed it...

The Alladin's require the tall, glass chimney to burn properly. I don't believe that a clay pot over 'em would work so well. They throw as much (more?) heat than light, it seems  Two will heat my kitchen.Near twice cubic vol.of my 27ftr's interior, so........


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## Steve in Idaho (Jun 22, 2012)

So - this thread has attracted me because I have been wondering about heat. Having never yet owned boat with a cabin (our latest has a cuddy w/dodger), I have no idea what is commonly used for heat while cruising. As a landlubber, I have a lot of experience with flameless catalytic heaters and have been very happy with them. Does anybody use this kind of heat source in their sailboat? So far I have seen references to wood stoves (where do y'all put the wood pile?) and propane flame heat - but no reference to cat-burners.

Forgive the question please - I'm just a landlocked spud, so don't have cruisers to reference locally. But would a small portable catalytic be a good option for killing the chill in our simple little cabin?


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## deniseO30 (Nov 27, 2006)

deltaten said:


> Denise;
> Jumping in late, so's I don't know if I missed it...
> 
> The Alladin's require the tall, glass chimney to burn properly. I don't believe that a clay pot over 'em would work so well. They throw as much (more?) heat than light, it seems  Two will heat my kitchen.Near twice cubic vol.of my 27ftr's interior, so........


Not sure.. not sure I'd bother to try either. I like mantle light. don't know how Abe Lincoln managed with a candle, because candle light is feeble! On sailing trips we would use the coleman lantern if it was cool enough outside to not over heat the inside of the boat.

This whole thing about how much heat a candle makes is all over the net and there are many many answers by people way more knowledgeable then me. but when I write something people seem to think it's written in stone LOL

Then I can start the whole thing going again by asking;

*How much useable heat can we get out of a candle?*


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## SloopJonB (Jun 6, 2011)

a 3" candle puts out about 50 BTU's according to reliable sources (the web). 

You'd have to have the interior of your boat looking like a palm readers consulting room to get enough heat from candles.


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## SJ34 (Jul 30, 2008)

deniseO30 said:


> Then I can start the whole thing going again by asking;
> 
> *How much useable heat can we get out of a candle?*


Devious Denise


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## dylanwinter1 (Jan 15, 2010)

SloopJonB said:


> a 3" candle puts out about 50 BTU's according to reliable sources (the web).
> 
> You'd have to have the interior of your boat looking like a palm readers consulting room to get enough heat from candles.


Bumma

so I just imagined I was warm

suddenly my carrieage and fine white horses have turned into a pumpkin and four white mice

D


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## deniseO30 (Nov 27, 2006)

sj34 said:


> devious denise


 "who, meeee?


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## deniseO30 (Nov 27, 2006)

OK all.. on the cool side of things.. how many BTU does your marine refrigeration compressor move? 300 btuh comes to mind no I'm not going to research it.. I'm going eat turkey and have quiet day with friends and family LOL


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## pdqaltair (Nov 14, 2008)

deniseO30 said:


> OK all.. on the cool side of things.. how many BTU does your marine refrigeration compressor move? 300 btuh comes to mind no I'm not going to research it.. I'm going eat turkey and have quiet day with friends and family LOL


In the winter? Zero. We put the perishables in a box in the cockpit.


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## deniseO30 (Nov 27, 2006)

pdqaltair said:


> In the winter? Zero. We put the perishables in a box in the cockpit.


 cop out!  Have a great thanks giving!


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## SloopJonB (Jun 6, 2011)

deniseO30 said:


> OK all.. on the cool side of things.. how many BTU does your marine refrigeration compressor move? 300 btuh comes to mind no I'm not going to research it.. I'm going eat turkey and have quiet day with friends and family LOL


I would think 3000 would be more likely. Marine heaters put out 4K BTU on up to 40K and more.


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## tdw (Oct 2, 2006)

dylanwinter1 said:


> Bumma.so I just imagined I was warm
> suddenly my carrieage and fine white horses have turned into a pumpkin and four white mice
> D


So very deluded, sad to see. Still and all I did hear about a wildy eccentric Brit who is supposedly sailing a trailor sailor around Britain. Have you ever heard of such nonsense ? The man is obviously barking. Probably still boils cans without piercing them first.



aeventyr60 said:


> A trawler kero lantern works pretty well at putting out a bit of heat.


We used kero lanterns for years on previous boats. They are remarkably effective. Maybe just a tadge safer than candles ?



deniseO30 said:


> I'd like to see an old Aladdin kerosene mantle burner (not the wick type.) under something like a clay pot. would get quite hot is my guess.


Tried one of those but I found the hissing noise somewhat offputting.

Overall .... I've always lusted after a fireplace but haven't ever got there. Storing the firewood seems a slight problem.

Given that DW was the fella who spurred the OP to post I'm wondering if a lot of this debate centres around the question of "just how hot do you need to be ? ". I'm sure this is true of many Brits and Australians of my generation in that we consider comfortably warm in the dead of winter to be a somewhat cooler temp that those weaned on reverse cycle air con and central heating. We don't see the need to ponce about in t-shirts and shorts (not to mention black flip flops) as the temperature plummets.

Use heating device to take the chill off, that's all you really need. If you are still cold ..... that's why god gave us wool. (I nearly said sheep but felt that could be misconstrued .... especially by those damned Kiwis. )


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## aeventyr60 (Jun 29, 2011)

A good shag helps warm things up.


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## Kielanders (Dec 8, 2011)

Is anyone aware of heat loss studies for sailboats?

With so many variables, it would be difficult. But it seems that there should be a general way based on length and beam, insulated/non insulated, boat material type, etc - say, giving one a result on average, of a 100 BTUH loss per foot, or some such rule of thumb.

How are the Force 10s sized and sold, via interior cabin volume?


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## deniseO30 (Nov 27, 2006)

Kielanders said:


> Is anyone aware of heat loss studies for sailboats?
> 
> With so many variables, it would be difficult. But it seems that there should be a general way based on length and beam, insulated/non insulated, boat material type, etc - say, giving one a result on average, of a 100 BTUH loss per foot, or some such rule of thumb.
> 
> How are the Force 10s sized and sold, via interior cabin volume?


It's been years and years since I've used this; http://www.eminnetonka.com/community_development/permits/documents/heat_loss_calculation.PDF and now everyone uses software to do the same. My guess would be to find equivalent materials on the list and calc based on that. Heat loads on a boat or sailboat would be extreme for cooling (sun load) and heating,(infiltration) since most don't have any insulation. However, most boats are pretty small compared to land based structures so the loads are manageable. Kind of like heating a cave, garage, basement. Even RVs are insulated more then boats.


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## Steve in Idaho (Jun 22, 2012)

tdw said:


> > Originally Posted by deniseO30
> > I'd like to see an old Aladdin kerosene mantle burner (not the wick type.) under something like a clay pot. would get quite hot is my guess.
> >
> >
> > ...


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## Maine Sail (Jan 6, 2003)

Kielanders said:


> Is anyone aware of heat loss studies for sailboats?
> 
> With so many variables, it would be difficult. But it seems that there should be a general way based on length and beam, insulated/non insulated, boat material type, etc - say, giving one a result on average, of a 100 BTUH loss per foot, or some such rule of thumb.
> 
> How are the Force 10s sized and sold, via interior cabin volume?


I did a heat loss calc for our CS-36T using the old school IBR technique. A lot of it was guess work to figure transmission values. I sized it for 15F as my coldest temp. At 15F our 8000 BTU forced air diesel heater needs to run nearly continuously to maintain 72F inside the boat so my sizing was near spot on.. At 30F -35F I estimate we need about 5500 - 6500 BTU... Our spring/fall overnight temps often drop to the low to mid 30's and for these temps the sizing came out very, very close....

Four or even six candles is not even noticeable on our 36 footer in fall or spring, heck for that matter neither was the Force 10 because we had to open so many hatches to keep it drier that it defeated the purpose of the heater to begin with. Some heat went straight out the stack........


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## jwing (Jun 20, 2013)

Maine Sail said:


> I did a heat loss calc for our CS-36T using the old school IBR technique. A lot of it was guess work to figure transmission values. I sized it for 15F as my coldest temp. At 15F our 8000 BTU forced air diesel heater needs to run nearly continuously to maintain 72F inside the boat so my sizing was near spot on.. At 30F -35F I estimate we need about 5500 - 6500 BTU... Our spring/fall overnight temps often drop to the low to mid 30's and for these temps the sizing came out very, very close....


What is the IBR technique? Does it consider the heat loss to the water? I imagine that in some boats, heat loss to water is greater than heat loss to air, making building load calculation spreadsheets not applicable.


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## deniseO30 (Nov 27, 2006)

Maine Sail said:


> I did a heat loss calc for our CS-36T using the old school IBR technique. A lot of it was guess work to figure transmission values. I sized it for 15F as my coldest temp. At 15F our 8000 BTU forced air diesel heater needs to run nearly continuously to maintain 72F inside the boat so my sizing was near spot on.. At 30F -35F I estimate we need about 5500 - 6500 BTU... Our spring/fall overnight temps often drop to the low to mid 30's and for these temps the sizing came out very, very close....
> 
> Four or even six candles is not even noticeable on our 36 footer in fall or spring, heck for that matter neither was the Force 10 because we had to open so many hatches to keep it drier that it defeated the purpose of the heater to begin with. Some heat went straight out the stack........


Actually allot of heat goes up the stack in such equipment MS. then quite quite some time ago condensing type of equipment hit the the old schoolers. Flue gases so cool it only needs pvc pipe to carry it outside.

I've a client that has steam boiler fired around 400,000 with a 10" flue pipe..


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## Maine Sail (Jan 6, 2003)

jwing said:


> What is the IBR technique? Does it consider the heat loss to the water? I imagine that in some boats, heat loss to water is greater than heat loss to air, making building load calculation spreadsheets not applicable.


IBR or I=B=R or the Hydronics Institute is the old Institute of Boiler and Radiator Manufacturers. I used to be a manufacturers rep may years ago in the hydronics and HVAC industry and sold boilers, furnaces and radiant products among others...

I believe the IBR does not exist any longer and they are now part of or were absorbed into GAMA (gas appliance manufacturers association)..

As I said a lot of translating heat loss to boats is guess work but it can be done. Seeing as heat rises and cabin soles usually have a layer of dead air between hull and cabin I was minimally concerned with serious changes to the floor loss calcs but I did lower my floor temps IIRC.

I ran mine out old school on paper but I understand now there are a few IBR based calculators out there that are much easier, almost plug and play but you do need to understand some basic concepts of sizing...

Back when I was sizing hydronic, air & radiant systems the IBR heat loss calcs were by far the most accurate.. The IBR did some great work and pioneering in that field....


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## Maine Sail (Jan 6, 2003)

deniseO30 said:


> Actually allot of heat goes up the stack in such equipment MS. then quite quite some time ago condensing type of equipment hit the the old schoolers. Flue gases so cool it only needs pvc pipe to carry it outside.
> 
> I've a client that has steam boiler fired around 400,000 with a 10" flue pipe..


Yep it is called stack loss...... This is why DV boilers & gas appliances are now so popular and outdoor temperature compensating controls are also becoming very popular.

I have had an outdoor temp sensed boiler control since 1989 and yet today the vast majority of hydronic heated homes, like 98%, still don't have or use one and they throw $$$ up the chimney every day.....

The European style multi-pass boilers, Viessmann, Buderus etc.. scrub more heat out than the old pin type straight castings thus lower stack temps for oil fired hydronic boilers....

System efficiency is what matters most but sadly many installers and home owners get hung up on only combustion efficiency. You can have GREAT combustion efficiency but lousy system efficiency if it is not properly installed or sized.. Years ago many installers in the North East were sizing for -35 to -40 below zero. Can it happen? Sure, and when it does throw on a sweater otherwise your system is grossly over-sized for the majority of the year..... Changing the mind set of the installer was painful.

Heck last winter my neighbor was quoted a tankless coil pin type boiler and was told "It's 88% efficient." (yeah, combustion efficiency)... What a load of BS... I hooked her up with a _good_ contractor and she now has a truly efficient oil heating system. To quote someone that type of boiler in 2013 is utterly offensive but it happens every day....


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## Kielanders (Dec 8, 2011)

Maine Sail said:


> Yep it is called stack loss...... This is why DV boilers & gas appliances are now so popular and outdoor temperature compensating controls are also becoming very popular.
> 
> I have had an outdoor temp sensed boiler control since 1989 and yet today the vast majority of hydronic heated homes, like 98%, still don't have or use one and they throw $$$ up the chimney every day.....
> 
> ...


Now if Viessmann made a condensing unit for sailboats, I'd like to see the price tag on that. Any idea what a condensate spill in the bilge would do to the glass?

Does anyone on here use a Dickson stove for heat? I was thinking of their smallest unit for my boat, but was wondering about the efficiency.


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## tdw (Oct 2, 2006)

aeventyr60 said:


> A good shag helps warm things up.


Indeed but the shagging of artiodactyla is still to be frowned upon. 

(and yes I did have to google sheep to find that they are of the genus "artiodactyla" )


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## pdqaltair (Nov 14, 2008)

Kielanders said:


> Is anyone aware of heat loss studies for sailboats?
> 
> With so many variables, it would be difficult. But it seems that there should be a general way based on length and beam, insulated/non insulated, boat material type, etc - say, giving one a result on average, of a 100 BTUH loss per foot, or some such rule of thumb.
> 
> How are the Force 10s sized and sold, via interior cabin volume?


They teach us those calculations in engineering school, but there is an easier way. Engineers like simple experiments and scale-up.

A 1500 watt space heater delivers 5100 BTUs/hr. Bring one from home.

* Allow to reach steady state (several hours). Record the temperature differential.
* Determine the max temperature differential you desire, adding something for wind, if the test day was calm.

BTUs required = 5100 x (delta T test)/(delta T required)

Add a little extra if you want a quicker warm up.

This post speaks to the thermal efficiency of one installation.
Sail Delmarva: Let There be Heat!


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## deniseO30 (Nov 27, 2006)

Kielanders said:


> Now if Viessmann made a condensing unit for sailboats, I'd like to see the price tag on that. Any idea what a condensate spill in the bilge would do to the glass?
> 
> Does anyone on here use a Dickson stove for heat? I was thinking of their smallest unit for my boat, but was wondering about the efficiency.


There are on demand units small enough for boats but they all need electric to operate. Then also there's the marine "code" that most if any don't qualify for.

Atmospheric combustion, draft to fire and chimney to carry off the combustion gases. (like the Dickson) are not very. Probably around 68-80% Do they even have an afue rating?


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## Delezynski (Sep 27, 2013)

Kielanders said:


> ..........
> 
> Does anyone on here use a Dickson stove for heat? I was thinking of their smallest unit for my boat, but was wondering about the efficiency.


Are you talking about this?










As I said in an old message in this thread, I now put an oil lamp in it for heat, or a nice effect.

Not only can I adjust the flame height for more or less heat, but I can also move the lamp in the fireplace forward or back. If the lamp is directly under the flew, I get less heat, more goes up the chimney. If I move it under the top (back) I get more heat. We also put a stainless steel cup of water on top of the stove that helps.

Greg


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## pdqaltair (Nov 14, 2008)

deniseO30 said:


> There are on demand units small enough for boats but they all need electric to operate. Then also there's the marine "code" that most if any don't qualify for.
> 
> Atmospheric combustion, draft to fire and chimney to carry off the combustion gases. (like the Dickson) are not very. Probably around 68-80% Do they even have an afue rating?


The Dixon P9000 is sealed and has concentric flue and comb air pipes. Quite efficient, more so if a fan is dirrected at the flue.


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## deniseO30 (Nov 27, 2006)

pdqaltair said:


> The Dixon P9000 is sealed and has concentric flue and comb air pipes. Quite efficient, more so if a fan is directed at the flue.


Yes, but I've not seen actual AFUE ratings on "marine" heating units yet. Not that I'm loosing sleep over it 

Propane afue (general)
Conventional 55-65%
Mid-efficiency 79-85%
Condensing 88-95%


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## Kielanders (Dec 8, 2011)

Delezynski said:


> Are you talking about this?
> 
> 
> 
> ...


I was actually thinking of their smallest cook stove, and using it as a cabin heater as well.

DickinsonMarine.com - Marine Stoves


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## pdqaltair (Nov 14, 2008)

pdqaltair said:


> They teach us those calculations in engineering school, but there is an easier way. Engineers like simple experiments and scale-up.
> 
> A 1500 watt space heater delivers 5100 BTUs/hr. Bring one from home.
> 
> ...


a. No one commented that I have the ratio, above, inverted. Obviously.

b. A valid way to calculate efficiency is from stack conditions (temp and excess oxygen). I did this for a Dickson 9000 and got ~ 82% efficiency at at full load with a fan blowing across it (I operate it that way to spread the heat, but it certainly increases output and efficiency). It helps that it has combustion air preheating, is fully sealed (combustion air comes in through a pipe), and unit losses go into the cabin. Other fired heater types? I haven't a clue but I will test those I come across and post something. It's easy... if you can borrow a gas analyzer.


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## hellosailor (Apr 11, 2006)

Befuddled memory that the flowerpots have something to do with taking the ephemeral heated combustion gasses, which would normally go up to the ceiling and then lose their heat to the outside, and converting the heat into radiation (instead of convection?) which is then more effectively transferred back into the portion of the room where you need it.

Twenty years ago it was normal and accepted to put clay flowerpots on your stove or alcohol burner, to make them more efficient at heating the cabin. Same thing, except over the last 20 years my memory fails to recall the physics of it. IS THERE A PHYSICIST OR A COMBUSTION ENGINEER IN THE HOUSE?

Like wizards they are never around when you need one.

But tea candles, really. Better to learn yogi and raise your metabolism and body temperature. Animals, including humans, really CAN do that with practice.

Although pyramidal flowerpots are cheaper and faster and that magic pyramid power makes the tea candles almost as effective as samovars.


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## dylanwinter1 (Jan 15, 2010)

hellosailor said:


> Befuddled memory that the flowerpots have something to do with taking the ephemeral heated combustion gasses, which would normally go up to the ceiling and then lose their heat to the outside, and converting the heat into radiation (instead of convection?) which is then more effectively transferred back into the portion of the room where you need it.
> 
> Twenty years ago it was normal and accepted to put clay flowerpots on your stove or alcohol burner, to make them more efficient at heating the cabin. Same thing, except over the last 20 years my memory fails to recall the physics of it. IS THERE A PHYSICIST OR A COMBUSTION ENGINEER IN THE HOUSE?
> 
> ...


you might be surprised - should you try it

- sadly it is the sort of experiment that is way too complex,expensive and potentially dangerous for ordinary people to try for themselves.

Far better just to dismiss the idea out of hand without trying it first.


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## Kielanders (Dec 8, 2011)

pdqaltair said:


> a. No one commented that I have the ratio, above, inverted. Obviously.
> 
> b. A valid way to calculate efficiency is from stack conditions (temp and excess oxygen). I did this for a Dickson 9000 and got ~ 82% efficiency at at full load with a fan blowing across it (I operate it that way to spread the heat, but it certainly increases output and efficiency). It helps that it has combustion air preheating, is fully sealed (combustion air comes in through a pipe), and unit losses go into the cabin. Other fired heater types? I haven't a clue but I will test those I come across and post something. It's easy... if you can borrow a gas analyzer.


Borrow a gas analyzer? No, this is just an excuse to buy a gas analyzer - I'll tell the Admiral 'it could kill us if we don't'.

I have a friend from school who's an HVAC Engineer who I'll get to walk me through your equation, but I think I understood your point about calculating the differential between indoor and outdoor design temperatures on the Delta T's.

I really liked your thoughts on keeping it simple, practical - take a couple of electric space heaters out there, and do some measurements - good solid real world advice. Thank you.

Any thoughts on insulating a glass boat? I know Brent uses spray foam on his steel hulls for both insulation and condensation management. A lot of people up here use the mylar bubble wrap - to what effect, I'm not sure. I have my interior removed, so I'm in a good position to consider any option.

I still have a question as to whether or not, for my calcs, more heat will be removed from the cabin underwater through conduction in the normally 38 degree water, or from convection above the exposed cabin under a -5 wind chill. It's going to be chilly no matter what, but dry chilly is better than wet chilly - so if the heat does nothing more than dry the cabin, it's a win.

By the way, I'm not trying to hijack the thread - I'm still open to candles.



Thanks.


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## deniseO30 (Nov 27, 2006)

hellosailor said:


> Befuddled memory that the flowerpots have something to do with taking the ephemeral heated combustion gasses, which would normally go up to the ceiling and then lose their heat to the outside, and converting the heat into radiation (instead of convection?) which is then more effectively transferred back into the portion of the room where you need it.
> 
> Twenty years ago it was normal and accepted to put clay flowerpots on your stove or alcohol burner, to make them more efficient at heating the cabin. Same thing, except over the last 20 years my memory fails to recall the physics of it. IS THERE A PHYSICIST OR A COMBUSTION ENGINEER IN THE HOUSE?
> 
> ...


Now I feel insulted! lol


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## ottos (Aug 12, 2008)

Kielanders said:


> Any thoughts on insulating a glass boat? I know Brent uses spray foam on his steel hulls for both insulation and condensation management. A lot of people up here use the mylar bubble wrap - to what effect, I'm not sure. I have my interior removed, so I'm in a good position to consider any option.


Here's some insulation thoughts.... The Frugal Mariner: Insulating your boat


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## Delezynski (Sep 27, 2013)

ottos said:


> Here's some insulation thoughts.... The Frugal Mariner: Insulating your boat


Close to that, I did a short (7 min) Youtube video on how we insulated our boat. It's at;





Ours is a 27 foot, but if it's not freezing outside, the heat of the 2 of us and one oil lamp keeps us nice and warm. 

** NOTE; it's in 3D, but you can turn that off by clicking on the gear symbol at the bottom right and selecting off.


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## Kielanders (Dec 8, 2011)

Delezynski said:


> Close to that, I did a short (7 min) Youtube video on how we insulated our boat. It's at;
> Hull Insulation - YouTube
> 
> Ours is a 27 foot, but if it's not freezing outside, the heat of the 2 of us and one oil lamp keeps us nice and warm.
> ...


Thanks for the video. I saw that you'd posted it about a year ago. How do you feel about the insulation, now having lived with it for a bit?


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## Delezynski (Sep 27, 2013)

Kielanders said:


> Thanks for the video. I saw that you'd posted it about a year ago. How do you feel about the insulation, now having lived with it for a bit?


It's working very well Kielanders.

We finished up a trip to the San Francisco Bay area and it helped a LOT! We were COLD there from March to June. We used the oil lamp for light and DID use a bit of lamp oil in the oil lamp in the fireplace. Also, had a hard time finding lamp oil! SO when I did find some I got a gallon. 










Greg


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## hellosailor (Apr 11, 2006)

Greg-
FWIW the 3D does not turn off in MSIE 10. At least here, "Off" just gives the picture big red and green stripes on edges of things.

Dylan, you are right. Experimenting with pyramidal flowerpots and high thermal fluxes is what destroyed the Egyptian dynasties and banished their gods from this earth. But the regular flowerpots, like I said, were standard equipment not so long ago.


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## Delezynski (Sep 27, 2013)

hellosailor said:


> Greg-
> FWIW the 3D does not turn off in MSIE 10. At least here, "Off" just gives the picture big red and green stripes on edges of things.
> 
> ... SNIP ........


hello,

Sorry about that.  It works in Firefox and Chrome, at least for me.

I think it must be a Youtube thing. Once I upload it I don't have further control over it.

Greg


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## pdqaltair (Nov 14, 2008)

deniseO30 said:


> Yes, but I've not seen actual AFUE ratings on "marine" heating units yet. Not that I'm loosing sleep over it
> 
> Propane afue (general)
> Conventional 55-65%
> ...


Here you go, at least for mine (Dickson). 84.5% estimated AFUE. Given the stack temperature is below boiling, not unexpected (I believe condensing starts at about 135F, depending on excess air and fuel choice).

Sail Delmarva: Heater Efficiency


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