# Bilge pump non return valve.



## H and E

Someone recommended that I install a non return valve on my automatic bilge pump. As a result I ordered one and installed it. BIG MISTAKE. The first time I tested it the valve stuck and would not allow the water to pump out. Its now gone. After I pumped the bilge there was no flow back through the pump back into the bilge.


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## Maine Sail

H and E said:


> Someone recommended that I install a non return valve on my automatic bilge pump. As a result I ordered one and installed it. BIG MISTAKE. The first time I tested it the valve stuck and would not allow the water to pump out. Its now gone. After I pumped the bilge there was no flow back through the pump back into the bilge.


Yep.... Big mistakes on centrifugal type pumps....


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## Sabreman

As Maine Sail says, it's a mistake to install a check valve in line with a centrifugal bilge pump (e.g., Rule pumps). The pump can move a lot of water but doesn't have much power. Think of it as high voltage, low amperage. Use a Vented Loop instead. 

The PO of our boat installed a check valve and the bilge pump never really worked. I fussed with it for the first few months of ownership until the bilge filled and the battery drained when the pump ran in a vain attempt to move the water. I installed a vented loop and haven't thought of it in 7 years.


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## Brewgyver

It's not quite as simple as no check valve on centrifugal pumps. A great many centrifugal pumps MAY use a check valve (or foot valve, as they are called when installed directly into the pump outlet. Most sump pump and condensate pump installations use a check or foot valve.

It's just that the typical 12 volt bilge pump for small boats has very low head capacity. The tradeoff is between flow and head, as it is on all centrifugal pumps. Higher head = lower flow, and vice versa.


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## Maine Sail

These valves quite often stick shut especially if the bilge pump does not cycle often. The biggest draw back is the added head pressure that the pump can not overcome. This additional head is caused by the standing water in the discharge hose, and thus, a centrifugal pump will simply cavitate and do nothing but make some neat little bubbles in the bilge.

For boats stored in-water during cold weather the water in the bilge hose above bilge level can freeze when the bilge water is not frozen. This present an impossible situation to pump into.

Fill a grain silo with corn and then try to push a door open into it...... Pretty tough. The check valve creates the same type of resistance to the bilge pump, Centrifugal pumps deal horribly with any added head pressure..

Check valves on rotary vane pumps or diaphragm pumps do not suffer the issues they do on centrifugal Rule style pumps. I have seen everything from ruined interior cabinetry, cabin soles and engines due to stuck check valves. I have also seen boats that sank because of a stuck check valve..

The largest maker of centrifugal bilge pumps, Rule, specifically recommends not to use them.

They can be a danger if used on a system with centrifugal bilge pump. Bilge pumps are safety items anything that can prevent the pump from pumping becomes a potential danger.

Rule Pump Instructions


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## Classic30

Maine Sail said:


> These valves quite often stick shut especially if the bilge pump does not cycle often. The biggest draw back is the added head pressure that the pump can not overcome. This additional head is caused by the standing water in the discharge hose, and thus, a centrifugal pump will simply cavitate and do nothing but make some neat little bubbles in the bilge.
> 
> For boats stored in-water during cold weather the water in the bilge hose above bilge level can freeze when the bilge water is not frozen. This present an impossible situation to pump into.
> 
> Fill a grain silo with corn and then try to push a door open into it...... Pretty tough. The check valve creates the same type of resistance to the bilge pump, Centrifugal pumps deal horribly with any added head pressure..
> 
> Check valves on rotary vane pumps or diaphragm pumps do not suffer the issues they do on centrifugal Rule style pumps. I have seen everything from ruined interior cabinetry, cabin soles and engines due to stuck check valves. I have also seen boats that sank because of a stuck check valve..
> 
> The largest maker of centrifugal bilge pumps, Rule, specifically recommends not to use them.
> 
> They can be a danger if used on a system with centrifugal bilge pump. Bilge pumps are safety items anything that can prevent the pump from pumping becomes a potential danger.


Maine, there *are* instances where you might need to install a check valve (I needed to) and ways to do so that doesn't give rise to the "standing water in the discharge hose" you mention (install it high up near the discharge point - not in the bilge with the pump itself).. I guess exactly what you do depends on the specific circumstances and the type of boat.

I've known check valves to fail *open* (bits of rubbish preventing the flap closing), but I've never heard of one sticking closed.. but then we don't get the freezing weather you get. I've known of boats that sank because there was no check valve fitted when they needed one..

IMHO, the bottom line is: Don't install a check valve unless your particular installation means you have no other alternative.

BTW, the other thing that can prevent the pump pumping is lack of a strum box.. make sure you use one.


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## Ajax_MD

Sabreman said:


> As Maine Sail says, it's a mistake to install a check valve in line with a centrifugal bilge pump (e.g., Rule pumps). The pump can move a lot of water but doesn't have much power. Think of it as high voltage, low amperage. Use a Vented Loop instead.
> 
> The PO of our boat installed a check valve and the bilge pump never really worked. I fussed with it for the first few months of ownership until the bilge filled and the battery drained when the pump ran in a vain attempt to move the water. I installed a vented loop and haven't thought of it in 7 years.


If I install a vented loop in my discharge line, should be closer to the pump, or to the point of discharge?


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## Maine Sail

Hartley18 said:


> Maine, there *are* instances where you might need to install a check valve (I needed to) and ways to do so that doesn't give rise to the "standing water in the discharge hose" you mention (install it high up near the discharge point - not in the bilge with the pump itself).. I guess exactly what you do depends on the specific circumstances and the type of boat.
> 
> I've known check valves to fail *open* (bits of rubbish preventing the flap closing), but I've never heard of one sticking closed.. but then we don't get the freezing weather you get. I've known of boats that sank because there was no check valve fitted when they needed one..
> 
> IMHO, the bottom line is: Don't install a check valve unless your particular installation means you have no other alternative.
> 
> BTW, the other thing that can prevent the pump pumping is lack of a strum box.. make sure you use one.


If you want to use a two pump system a "nuisance pump" and a "primary" pump then a check valve can be fitted to the lower nuisance water pump. they still stick and kill batteries though... I would NEVER, and I don't use the word never often, recommend a check valve on a single pump installation when a centrifugal pump is being used. If you want a check valve please use a rotary vane or diaphragm pump that has the ability to deal with the head pressure of the standing water and to push open a sticky check valve... Centrifugal pumps often just make neat little bubbles and the water remains in the bilge.

It is your boat, you can do as you wish, but check valves on centrifugal pumps are a danger waiting to happen. You would be horrified at the number of "check valves" I see that fail to open. I am the guy replacing the batteries that the bilge pump killed when the check valve stuck and the float switch remained ON.........


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## MastUndSchotbruch

Maine Sail said:


> ... Centrifugal pumps often just make neat little bubbles and the water remains in the bilge...


I experimented a bit with a check valve (NOT on a boat, actually, long story...). My experience was exactly what you describe, it got stuck in the 'closed' state at the drop of a hat.

BUT: I had never thought of doing what Hartley suggests:

"install it high up near the discharge point - not in the bilge with the pump itself"

In that case, you do NOT have the water column keeping the valve stuck in closed. That seems to me the smart way to do it (why didn't I think of that?).

Next time I have a chance, I will try that on my installation.


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## Maine Sail

MastUndSchotbruch said:


> I experimented a bit with a check valve (NOT on a boat, actually, long story...). My experience was exactly what you describe, it got stuck in the 'closed' state at the drop of a hat.
> 
> BUT: I had never thought of doing what Hartley suggests:
> 
> "install it high up near the discharge point - not in the bilge with the pump itself"
> 
> In that case, you do NOT have the water column keeping the valve stuck in closed. That seems to me the smart way to do it (why didn't I think of that?).
> 
> Next time I have a chance, I will try that on my installation.


But that pretty much defeats the entire purpose of the check valve. A siphon break is still a choice that won't stick closed. If you are not preventing hose drain back then there is little point for a check valve...... Bilge pump hoses should always be installed to prevent back siphoning which includes a high loop and a siphon break....


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## MysticGringo

MastUndSchotbruch said:


> BUT: I had never thought of doing what Hartley suggests:
> 
> "install it high up near the discharge point - not in the bilge with the pump itself"
> 
> In that case, you do NOT have the water column keeping the valve stuck in closed. That seems to me the smart way to do it (why didn't I think of that?).
> 
> Next time I have a chance, I will try that on my installation.


Won't that still keep the column of water in the hose as the valve will create vacuum as the water tries to drain out of the hose?

I have check valves on my lines, but I use two pumps with impellers and they have enough force to push the column of water out. Still, after this thread I am going to replace them with vented loops as I want better reliability.

My plan is to as close to the pump as possible, and try to get the loop as high as I can. My outlets are right below the hull/deck joint, and I'm not entirely sure I can get the vented loops that high... is that going to be an issue?


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## MastUndSchotbruch

Maine Sail said:


> But that pretty much defeats the entire purpose of the check valve. A siphon break is still a choice that won't stick closed. If you are not preventing hose drain back then there is little point for a check valve...... Bilge pump hoses should always be installed to prevent back siphoning which includes a high loop and a siphon break....


Of course you are entirely right, as far as boats and bilges are concerned.

I know I may be a bit off-topic here, this being sailnet, but as I mentioned, my application is not on a boat. I need to pump some water uphill but in my case there is no possibility that a siphoning situation develops. My problem is only that the hose is long, and the water that runs back will cycle the pump again. If I can prevent the hose emptying (or at least slow it down significantly), that will solve the cycling problem.

Seems to me that for my particular situation, a check valve close to the top end might solve the problem. Glad I read this thread, I never had thought about it.


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## Classic30

Maine Sail said:


> But that pretty much defeats the entire purpose of the check valve. A siphon break is still a choice that won't stick closed. If you are not preventing hose drain back then there is little point for a check valve...... Bilge pump hoses should always be installed to prevent back siphoning which includes a high loop and a siphon break....


Agreed, you need to prevent back siphoning which includes a high loop and a siphon break.. but you're *quite wrong *about having the check valve up high defeating the purpose. Hose drain back is irrelevant - it's, what, 1 litre of water max?

Think about what happens when you put the gunnel under on a flush-deck boat with the bilge pump exit out of the side just above the waterline - even with a high loop and a siphon break. 

Boats have sunk because of that.


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## Maine Sail

Hartley18 said:


> Agreed, you need to prevent back siphoning which includes a high loop and a siphon break.. but you're *quite wrong *about having the check valve up high defeating the purpose. Hose drain back is irrelevant - it's, what, 1 litre of water max?
> 
> Think about what happens when you put the gunnel under on a flush-deck boat with the bilge pump exit out of the side just above the waterline - even with a high loop and a siphon break.
> 
> Boats have sunk because of that.


What is *"quite wrong"* is an installation like you state.. Sorry but I can't fix an improperly designed bilge pump system. As I said and was discussing in a "PROPERLY" designed bilge pumping system, which on sailboats does NOT include placing the exit where it will go under water under heel and can't be protected by a siphon break, there is no need for a check valve.

Sorry but if you have a boat designed like this to rely on a $0.50 piece of rubber flapper is just crazy. The US ABYC recognizes this and specifically prohibits check valves used for this purpose. This is a situation that requires surgery, don't put a Band-Aid on it.

An installation such as that does not meet even the basic safety standards.

ABYC:
*22.8.6 The discharge location shall be above the
maximum heeled waterline, or

22.8.7 the discharge may be located below the
maximum heeled waterline if the discharge line is provided
with both of the following:

22.8.7.1 a seacock installed in accordance with the
requirements of ABYC H-27, Seacocks, Thru-Hull
Connections, and Drain Plugs, and

22.8.7.2 a vented loop or other means to prevent
siphoning into the boat. A check valve shall not be used for
this purpose.*


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## Classic30

So, in your opinion, out the stern is the *only* suitable location for a bilge pump exit?

..or do you have some other system in mind??


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## tdw

Just to clarify ... we only talking electric pumps here ? 

Our manual emergency pump (Henderson type) has been unused for many years and I suspect that its rubber flappy thing has perished. Yes there is a seacock on the through hull. 

I'm about ready to rebuild the thing but what of adding a check valve into the line as back up ? Is this OK ? Is this stupid ? Is this simply not necessary ?


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## Maine Sail

Hartley18 said:


> So, in your opinion, out the stern is the *only* suitable location for a bilge pump exit?
> 
> ..or do you have some other system in mind??


No, I have seen perfectly suitable stern quarter outlets, bow and even side discharges with a center-line siphon break and a shut off seacock... I do prefer the stern though as do many builders who try and do it right..

Side discharges are my least favorite and I would personally avoid them at all costs on a sailboat. The proper installation of the siphon break gets difficult and can leave exposed hose visible in the cabin, to do a "safe" install for a side discharge..

Bilge pumps to me are not an "after thought" they can be a safety item and one that should be taken seriously. Having had a thru-hull fitting snap, another story for another day, I do take bilge pumps and proper installation techniques seriously.

My main objection is using a check valve to keep your vessel afloat. But I am not alone on this and the ABYC concurs.. My only beef is the use of check valves on a primary bilge pump when that pump is also a centrifugal/Rule type.

I have less issues with them on rotary vane or diaphragm pumps because they CAN open them where the centrifugal often won't...


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## Maine Sail

tdw said:


> Just to clarify ... we only talking electric pumps here ?
> 
> Our manual emergency pump (Henderson type) has been unused for many years and I suspect that its rubber flappy thing has perished. Yes there is a seacock on the through hull.
> 
> I'm about ready to rebuild the thing but what of adding a check valve into the line as back up ? Is this OK ? Is this stupid ? Is this simply not necessary ?


Those Henderson pumps can suck Bigfoots turds through a straw. No issues with a check valve on those but do use an intake screen on the pick up..

Again the real concern is with a "Rule" type centrifugal pump and the use of a check valve. These pumps have very little ability to deal with restricted or increased head pressure before they just sit there and make tiny bubbles and kill your bank..


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## tdw

Well then I'll keep well clear of Bigfoot country ..... 

Intake screen already in place. 

Thanks MS.


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## Classic30

Maine Sail said:


> No, I have seen perfectly suitable stern quarter outlets, bow and even side discharges with a center-line siphon break and a shut off seacock... I do prefer the stern though as do many builders who try and do it right..
> 
> Side discharges are my least favorite and I would personally avoid them at all costs on a sailboat. The proper installation of the siphon break gets difficult and can leave exposed hose visible in the cabin, to do a "safe" install for a side discharge..


I totally agree - but in an older boat there is not always a choice. If you hadn't guessed already, my suggested use of the check valve for a side discharge is to act as a 'flapper' to keep water coming back into the boat when heeled and the bilge pump is not running.. you still need the loop and siphon break.

Since the valve spends most of it's life above the water-line, there is no columns of water either side to hold it closed and the biggest risk is it perishing and failing open. Believe me, it's far better than having the boat threaten to sink under you.

Discharge into the cockpit is looking better all the time! 



Maine Sail said:


> Bilge pumps to me are not an "after thought" they can be a safety item and one that should be taken seriously. Having had a thru-hull fitting snap, another story for another day, I do take bilge pumps and proper installation techniques seriously.
> 
> My main objection is using a check valve to keep your vessel afloat. But I am not alone on this and the ABYC concurs.. My only beef is the use of check valves on a primary bilge pump when that pump is also a centrifugal/Rule type.


I wouldn't like to suggest anyone relying on a check valve to keep your vessel afloat. For that reason, installation down in the bilge (as a 'foot valve') is a really bad idea!



Maine Sail said:


> I have less issues with them on rotary vane or diaphragm pumps because they CAN open them where the centrifugal often won't...


In my experience rotary vane or diaphragm pumps are more likely to blow the hose-end off the check valve if it fails to open... but if you are going to use them just make sure your piping can handle the output pressure, 'tis all.


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## H and E

Lots of information here. The factory manual bilge exits out the stern. I installed the automatic electric bilge and placed the discharge high in the cockpit so I could see if there was a problem causing the pump to run. If water gets in the discharge hose I have much bigger issues. I test it occasionally to insure it works properly. During a test is when I discovered that the check valve was malfunctioning.


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## Brewgyver

MastUndSchotbruch said:


> Of course you are entirely right, as far as boats and bilges are concerned.
> 
> I know I may be a bit off-topic here, this being sailnet, but as I mentioned, my application is not on a boat. I need to pump some water uphill but in my case there is no possibility that a siphoning situation develops. My problem is only that the hose is long, and the water that runs back will cycle the pump again. If I can prevent the hose emptying (or at least slow it down significantly), that will solve the cycling problem.
> 
> Seems to me that for my particular situation, a check valve close to the top end might solve the problem. Glad I read this thread, I never had thought about it.


Mast, you should install a check valve at or close to the pump. This is the kind of application I mentioned in my earlier post. This is a typical sump pump installation. This one threads directly into the outlet of a Little Gian sump pump:









Another very common example is a condensation pump on an air handler in a location that has no path for a gravity drain line.


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## MastUndSchotbruch

Brewgyver said:


> Mast, you should install a check valve at or close to the pump. This is the kind of application I mentioned in my earlier post. This is a typical sump pump installation. This one threads directly into the outlet of a Little Gian sump pump:


Well, I tried that. And what happened is exactly what MaineSail and other have predicted: the small Rule (centrifugal) pump could not open the valve against the water column. Probably some crud played a role there too since it actually worked when I cleaned everything nicely and wiggled the flap (this is a bronze valve from West Marine, with a metal flap pivoting on a horizontal axle). But after a day or two, it was stuck and the poor little pump was just whirring away.

I am not sure if mounting it as the top of the hose will work but it seems worth a try.


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## Classic30

MastUndSchotbruch said:


> Well, I tried that. And what happened is exactly what MaineSail and other have predicted: the small Rule (centrifugal) pump could not open the valve against the water column. Probably some crud played a role there too since it actually worked when I cleaned everything nicely and wiggled the flap (this is a bronze valve from West Marine, with a metal flap pivoting on a horizontal axle). But after a day or two, it was stuck and the poor little pump was just whirring away.
> 
> I am not sure if mounting it as the top of the hose will work but it seems worth a try.


Mast, check valves can be bad news and are usually not required.. and, personally, I wouldn't use a heavy bronze check valve with a little pump. That is simply asking for trouble.

For your application (and the information of others) the majority of check valves sold for bilge pump applications are not air tight. Installing it at the top of the hose *does not * stop the water in the hose flowing back into the bilge once the pump stops - nor do you necessarily want it to.

If (for some reason) you want to hold the water in the hose, you need to buy a more expensive vane or diaphragm pump - a centrifugal pump is not designed to do this.


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## MastUndSchotbruch

Hartley18 said:


> Mast, check valves can be bad news and are usually not required.. and, personally, I wouldn't use a heavy bronze check valve with a little pump. That is simply asking for trouble.
> 
> For your application (and the information of others) the majority of check valves sold for bilge pump applications are not air tight. Installing it at the top of the hose *does not * stop the water in the hose flowing back into the bilge once the pump stops - nor do you necessarily want it to.
> 
> If (for some reason) you want to hold the water in the hose, you need to buy a more expensive vane or diaphragm pump - a centrifugal pump is not designed to do this.


You may well be right. But I now have everything and I will play around with it a bit more.

In case anyone is interested, the application is to eliminate a puddle on my deck behind the house. The reason why the backflow is annoying is that the hole in which the pump (and float switch) live is pretty small. The water in the hose is enough to fill the hose up to the level where the switch is closed, leading to cycling of the pump. The check valve solves the problem perfectly but only for a day or so. Next time it rains, the puddle is back, the pump sucking empty the battery but not sucking in the puddle  . It only takes a little wiggling of the valve and everything works again but I don't want to do that each time it rains.


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## Maine Sail

MastUndSchotbruch said:


> You may well be right. But I now have everything and I will play around with it a bit more.
> 
> In case anyone is interested, the application is to eliminate a puddle on my deck behind the house. The reason why the backflow is annoying is that the hole in which the pump (and float switch) live is pretty small. The water in the hose is enough to fill the hose up to the level where the switch is closed, leading to cycling of the pump. The check valve solves the problem perfectly but only for a day or so. Next time it rains, the puddle is back, the pump sucking empty the battery but not sucking in the puddle  . It only takes a little wiggling of the valve and everything works again but I don't want to do that each time it rains.


Here's a trick, but please don't do this on a boat. On the hose right after the pump, but just before the check valve, drill a small hole on the bottom of the hose. You may need to experiment with hole diameter. This small hole acts like a "relief" and can allow the pump to create enough pressure to open the check valve by not just sitting there spinning and cavitating. Yes it will spit some back into the puddle but not much..


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## GaryHLucas

I work with centrifugal pump design every day. What's missing here is our basic tool, the pump curve supplied by the manufacturer. A centrifugal pump always runs on the pump curve, for every head condition along the curve there is a corresponding flow rate. The left end of the curve is the maximum head at zero flow, called shutoff. If you look at a pump curve you'll gain a whole new appreciation for the difficulty in applying centrifugal pumps.

You can learn a whole lot about your bilge pump by putting an open hose on it and running it in a shallow pan. Start with the open end down low and watch how much flow you get. Slowly raise the open end and watch how fast the flow rate falls off. At the height water stops coming out of the hose you have reached shutoff head. Measure the flow into a bucket and draw the curve for the pump. Some pumps have relatively flat curves downward to the right. A small amount of additional head pushes the pump back on the curve to the left and flow falls off very quickly. I attached a pump curve just to show what they include, curves for different impellors, efficiency points, horsepower curves etc.

I see here talk about having a loop well above the heeled water line. The fact is you want the loop as little above the waterline as will gaurantee you won't back flood when heeled. Any more greatly reduces the flow that you can actually pump. You might notice they rate bilge pump flow at about 2 feet of head. Lifting water 3 feet can cut the flow in half or more, and you might not get any flow at 4 feet!

There is also talk about venting the loop, to prevent a back siphon. This is true, however a forward siphon from a loop well above the water line to a discharge point above the water line actually will increase the pump flow a lot. So a tall vented loop can defeat your pump as well. When you do the test above trying raising the middle of the hose way up in the air with the open end near the ground. You'll see that the pump will move a lot of water way up high as long as the siphon on the downhill side pulls the water along. Drill a tiny hole in the top of that loop and the flow will fall way off.

A really important point missed here is discharge hose size on the pump. When you have only 2 feet of head to work with you really must avoid any friction losses. So jumping a 3/4" pump discharge up to 1" or even 1-1/4" can make a big difference, especially if it must run more than a couple of feet.

The comment about a small hole in the hose right at the pump discharge is a good one. In the instructions no one reads for commercial submersible pumps there is always a statement about drilling a 1/8" hole to prevent air locking. A bubble of air forms in the pump housing and the impeller can't grab enough water to build pressure enough to push water up the pipe. In a 44 story building in Manhattan I had to pull two pumps out of 18 foot deep tanks to drill the two holes that no one thought was important because those pumps air locked all the time!


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## Maine Sail

GaryHLucas said:


> I work with centrifugal pump design every day. What's missing here is our basic tool, the pump curve supplied by the manufacturer. A centrifugal pump always runs on the pump curve, for every head condition along the curve there is a corresponding flow rate. The left end of the curve is the maximum head at zero flow, called shutoff. If you look at a pump curve you'll gain a whole new appreciation for the difficulty in applying centrifugal pumps.
> 
> You can learn a whole lot about your bilge pump by putting an open hose on it and running it in a shallow pan. Start with the open end down low and watch how much flow you get. Slowly raise the open end and watch how fast the flow rate falls off. At the height water stops coming out of the hose you have reached shutoff head. Measure the flow into a bucket and draw the curve for the pump. Some pumps have relatively flat curves downward to the right. A small amount of additional head pushes the pump back on the curve to the left and flow falls off very quickly. I attached a pump curve just to show what they include, curves for different impellors, efficiency points, horsepower curves etc.
> 
> I see here talk about having a loop well above the heeled water line. The fact is you want the loop as little above the waterline as will gaurantee you won't back flood when heeled. Any more greatly reduces the flow that you can actually pump. You might notice they rate bilge pump flow at about 2 feet of head. Lifting water 3 feet can cut the flow in half or more, and you might not get any flow at 4 feet!
> 
> There is also talk about venting the loop, to prevent a back siphon. This is true, however a forward siphon from a loop well above the water line to a discharge point above the water line actually will increase the pump flow a lot. So a tall vented loop can defeat your pump as well. When you do the test above trying raising the middle of the hose way up in the air with the open end near the ground. You'll see that the pump will move a lot of water way up high as long as the siphon on the downhill side pulls the water along. Drill a tiny hole in the top of that loop and the flow will fall way off.
> 
> A really important point missed here is discharge hose size on the pump. When you have only 2 feet of head to work with you really must avoid any friction losses. So jumping a 3/4" pump discharge up to 1" or even 1-1/4" can make a big difference, especially if it must run more than a couple of feet.
> 
> The comment about a small hole in the hose right at the pump discharge is a good one. In the instructions no one reads for commercial submersible pumps there is always a statement about drilling a 1/8" hole to prevent air locking. A bubble of air forms in the pump housing and the impeller can't grab enough water to build pressure enough to push water up the pipe. In a 44 story building in Manhattan I had to pull two pumps out of 18 foot deep tanks to drill the two holes that no one thought was important because those pumps air locked all the time!


Also the voltage makes another HUGE dent in performance of these pumps. Suffice it to say that a Rule 2000 when installed in a sailboat may not even pump 25% of its face value rating... Many of these pumps are rated at "open bucket" (which means NO HEAD) and at charging voltages... Often times the little diaphragm pump with the $hitty GPH rating will outperform the centrifugal pump when "installed"...


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## Brewgyver

MastUndSchotbruch said:


> Well, I tried that. And what happened is exactly what MaineSail and other have predicted: the small Rule (centrifugal) pump could not open the valve against the water column. Probably some crud played a role there too since it actually worked when I cleaned everything nicely and wiggled the flap (this is a bronze valve from West Marine, with a metal flap pivoting on a horizontal axle). But after a day or two, it was stuck and the poor little pump was just whirring away.
> 
> I am not sure if mounting it as the top of the hose will work but it seems worth a try.


Mast, when I replied to your previous post, you said your question was NOT a boat application, that you wanted to pump water uphill, and not have it flow back when the pump cycled off. You DIDN'T say you were actually using a Rule bilge pump. 
The solution to your problem is to get the right pump. Note: the right pump will have a power cord that you will plug into a 120 volt receptacle. It will have sufficient head to pump the height you need to pump to and overcome the head losses from the discharge hose, turns, bends, and check valve, if used. It will likely be 1/6th hp, perhaps 1/4, impossible to say without knowing all the specifics.


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## GaryHLucas

Maine Sail said:


> Also the voltage makes another HUGE dent in performance of these pumps. Suffice it to say that a Rule 2000 when installed in a sailboat may not even pump 25% of its face value rating... Many of these pumps are rated at "open bucket" (which means NO HEAD) and at charging voltages... Often times the little diaphragm pump with the $hitty GPH rating will outperform the centrifugal pump when "installed"...


You are right, and rating a pump at charging voltage constitutes fraud in my book. I didn't think about the voltage when I was writing, I seldom see anything other than 480 volts 3 phase, and voltage is seldom a problem!

Gary H. Lucas


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## Brewgyver

Gary, I'm in the same boat!


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## Maine Sail

GaryHLucas said:


> You are right, *and rating a pump at charging voltage constitutes fraud* in my book. I didn't think about the voltage when I was writing, I seldom see anything other than 480 volts 3 phase, and voltage is seldom a problem!
> 
> Gary H. Lucas


Rating these pumps at charging voltages and OPEN BUCKET (no head) rates IS FRAUD but that is how its done. I hate these pumps but people don't want to pay for a real bilge pump when you give them the quote.


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## MastUndSchotbruch

Brewgyver said:


> Mast, when I replied to your previous post, you said your question was NOT a boat application, that you wanted to pump water uphill, and not have it flow back when the pump cycled off. You DIDN'T say you were actually using a Rule bilge pump.
> The solution to your problem is to get the right pump. Note: the right pump will have a power cord that you will plug into a 120 volt receptacle. It will have sufficient head to pump the height you need to pump to and overcome the head losses from the discharge hose, turns, bends, and check valve, if used. It will likely be 1/6th hp, perhaps 1/4, impossible to say without knowing all the specifics.


I would be happy to put a pump there that will plug into a 120V receptacle. Problem is there is no 120V receptacle to be found near it  The pump is powered by a deep discharge battery which in its turn is powered by a solar panel.

As I said in an earlier post, this is to remove a nuisance puddle. We are talking about lifting a few gallons of water up by 2 1/2 feet after each good rain.


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## Maine Sail

Also just came across this from Rule:

"The Rule Pumps FAQs.
*
Can I install a check valve on the pump discharge?*
Check valves are not recommended

*Why doesn't Rule Pumps want check valve on the pump's discharge?*
Check valves are prohibited by the American Boat & Yacht Council for use as an anti-siphon device-and with good reason: They're notorious for failing in both the open and the closed position, which respectively leads to flooding or failure to pump. If the valve is close to the pump, the pump may not be able to overcome the weight of the water on the other side of the valve, rendering the pump ineffective

*Why does my automatic Rule Pumps turns off if I install a check valve on the discharge of the pump?*
The automatic bilge pump turns on about every two and a half minutes to "check" for high water. If water causes resistance on the pump, it continues to pump until the resistance lowers. With the check valve installed at the pump, it cant feel the weight of the water, and shuts off, allowing the bilge to fill with water!"

They must have read my mind....


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## SloopJonB

Maine Sail said:


> Rating these pumps at charging voltages and OPEN BUCKET (no head) rates IS FRAUD but that is how its done. I hate these pumps but people don't want to pay for a real bilge pump when you give them the quote.


That kind of fake rating is common in many industries. Air compressor motors are frequently rated at the point the motor burns out, stereos used to be rated at "peak music power", lots of electrical tools & appliances have phoney ratings.

Technically it isn't fraud if it can actually do it - the fact that the device melts or otherwise self destructs at that point is a fact not considered by the law. 

Quick rule of thumb for electrical devices - 7 amps is roughly equivalent to one HP on 110 voltage. If they don't declare the amperage, either don't buy it or assume they are "lying" about the HP.


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## Waltthesalt

I wouldn't use a check valve on an automatic centrifugal pump where's there's not problem to solve. A problem would be that you have such a long discharge hose that when the pump stops the hose water drains back causing the pump to cycle again. The risk you have with an automatic pump is if the valve sticks when you're gone your pump is OOC until you get there and fix it. Over time that may burn out the pump.
I do use a large bronze foot valve on my large manual diaphragm pump which reaches down into a bilge pocket that's about 2 feet below the waterline. This has a large hose and I'm pumping a lot of air to get to the water. The biggest risk is of it being stuck closed in an emergency so I have to flush it periodically. I can pull the hose and bang on it if it's stuck.


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## last mango

Been reading lot of posts on this subject. Just put in a West Marine centrifugal pump with electronic float switch. I know I won't put in a check valve after reading. The deep section of the bilge is around 30" deep then starts to the stern rising another 8-10" guessing. Originally had a diaphragm pump that gave up the ghost. It was mounted toward the back of stern. Where the hose met there and then went to the discharge it went up about 2' under the cockpit seats and over to the back and then down to the discharge. The drain discharges under the stern. Sits about 6" off the water line. Have the issue off backflow so it won't turn itself off. Replaced the hoses. Using 5/8. What I have not seen is where best places are to make a loop and how much is really needed. Wondering if I could find a spot behind the engine area and make a shorter loop. Does it need to be a vented loop or just loop the hose up. Also intend to put a large high volume above it when I get this one corrected. Is it better to have the discharge straight out the back of the stern vs underneath

Thanks
Bruce


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## transmitterdan

It needs to be a vented loop with the vent as high above the water line when heeled as you can get.

Some people use a big centrifugal pump with inlet a few inches from bottom of bilge. Then a small diaphragm pump with the intake at bottom of bilge. The diaphragm pump has an integral non-return valve. But still the hose should have a vented loop although the hose can be smaller than the big pump hose.


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## captain jack

Classic30 said:


> Agreed, you need to prevent back siphoning which includes a high loop and a siphon break.. but you're *quite wrong *about having the check valve up high defeating the purpose. Hose drain back is irrelevant - it's, what, 1 litre of water max?
> 
> Think about what happens when you put the gunnel under on a flush-deck boat with the bilge pump exit out of the side just above the waterline - even with a high loop and a siphon break.
> 
> Boats have sunk because of that.


when i ran my bile pump, i didn't run it to a through hull. i ran it out, under the starboard cockpit bench, to exit on the side of the bench, above the cockpit drain well. it dumps right into that and then out through the cockpit drain. since it's not actually outside of the boat, i don't have to worry about that. which is why i did it that way.

this is a picture of the outlet just above the cockpit drain well.

[URL="http://

this is right after i installed it. you can still see the remnants of the price tag on the drain fitting. but i don't have a cleaned up picture.


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## Boredop

So you ran your pump outlet to somewhere not outside of your boat? Does anyone else think this is a bad idea?


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## ccriders

Boredop said:


> So you ran your pump outlet to somewhere not outside of your boat? Does anyone else think this is a bad idea?


I've always read that this is a bad idea, however if it keeps your small pump from backfilling the bilge, then maybe not so bad.
John


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## tommays

First and foremost as a land pump person my electric pumps are there for a convince 

That being said I have a high pump and a low pump in a small deep section of the Cal 29 bilge 

Both pumps have siphon breaks well above the waterline (rub rail) height and the deep pump has the jabsco check valve which is needed due to the tiny capacity of the deep section 

The valve works fine 

Of course I also have to manual pumps BUT there also only going to cover minor things as unless you have seen water with a small amount of head pressure geyser out off a 2" hole you have no idea how fast things flood


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## captain jack

Boredop said:


> So you ran your pump outlet to somewhere not outside of your boat? Does anyone else think this is a bad idea?


it's not run to a place inside of the boat. it's run to the cockpit and dumps right in the cockpit drain well. there is a well, on the boat ( what you are seeing in the picture ) just in front of the transom, that is for the purpose of collecting any water that gets into the cockpit. at the bottom of this well, a little above water level, is the cockpit drain. it's a fairly good sized drain hole.

the bilge pump dumps the water into this well, and it runs right out of the cockpit drain hole.

and it works beautifully. when i bought the boat, it had no hatchboard or companionay hatch ( the first two things i made for the boat ) because it had been abandoned and the marina had to break into it. it had water in the bilge because of rain. no interior water damage but, water in the bilge. i installed the pump, ran the hose, and turned it on. it worked perfectly. it was several gallons of water and it was flawless. no problems.

the boat has never taken on a drop of water, since i fixed the issue of having a completely open companionay. however, the first test of the set up worked so well i don't need another.

the beauty of the way i ran it is that i don't ever have to worry about the through hull dipping below the waterline and letting water come back into the bilge. in fact, if there is enough water in the cockpit to let that happen, back flow through the bilge pump through hull ( which doesn't actually go through the hull ) is going to be the least of my worries.

at first, i was going to run it through the hull. then, i started really looking at it and asked myself why. not every boat has such a well in front of the transom. so, my solution probably wouldn't work for evetryone. but, if you have an early cal 27, the pop top type, it ill.


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## HUGOSALT

captain jack, 
The way i see it, if you take on some water and settle down in the 
stern a little your drain well will help you for a little while...but then if you settle further,
with your bilge pump emptying in the boat rather then outside...well not a good
situation. ...Thinking Titanic.
Maybe set up ok to pump out rain water, with a 2nd bilge pump exiting transom.


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## transmitterdan

Cockpit drains can be plugged by debris (leaves, bugs, etc.). If that happens then you have to ask does the bilge pump system still work?

Most boats won't sink if the cockpit drain is plugged. The cockpit is usually designed so it will not hold that much water. But if the cockpit is also the bilge drain then probability of sinking goes up.


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## captain jack

transmitterdan said:


> Cockpit drains can be plugged by debris (leaves, bugs, etc.). If that happens then you have to ask does the bilge pump system still work?
> 
> Most boats won't sink if the cockpit drain is plugged. The cockpit is usually designed so it will not hold that much water. But if the cockpit is also the bilge drain then probability of sinking goes up.


if this cockpit drain was like the ones on my holiday 20, i'd agree with that possibility. however, it's not. it is much larger in diameter. bugs would never be able to clog it...well, maybe prehistoric bugs or a few of those giant madagascar cockroaches washing down to the drain all at once. i am at the boat every week, often more than once, and am thinking about doing the live aboard thing. it would take a bit of seriously gross negligence for the drain to get clogged with anything. i have never measured the hole but i'm betting it's over and inch and it has no tunnel that could get clogged. it's just a hole in the bottom of the transom.

i suppose in some sort of case of extremely odd circumstance that might be a concern but, i really don't see that as being a likely event...not on this boat.


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## captain jack

HUGOSALT said:


> captain jack,
> The way i see it, if you take on some water and settle down in the
> stern a little your drain well will help you for a little while...but then if you settle further,
> with your bilge pump emptying in the boat rather then outside...well not a good
> situation. ...Thinking Titanic.
> Maybe set up ok to pump out rain water, with a 2nd bilge pump exiting transom.


that is thinking 'titanic'. the drain is around 6" to 8" above the water. if i take on enough water to make the boat sit that low, my bilge pump, although the one recommened for my size boat, will never be up to the task of saving the day.

i suppose, thinking with such an ultimate calamity in mind, if i decide to blue water sail my 27' cal, i will need to think about getting a much larger bilge pump and route it out through the transom.

here, in the bay, i can't think of anything that would let that much water fill my bilge short of a hull breech. my bilge pump will most definately not keep her afloat in that sort of situation...regardless of how i route the hose. i have to wonder how many non-blue water sailors' boats have bilge pumps that could deal with that kind of situation.


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## tommays

Well

My Cal 29 would most certainly have and issue IF the cockpit drain clogged and there was a big rain storm


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## captain jack

tommays said:


> Well
> 
> My Cal 29 would most certainly have and issue IF the cockpit drain clogged and there was a big rain storm


i believe IF is the telling word, there. as i said, without my extended absense or gross negligence, i simply don't see it getting clogged up.


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## tommays

The ONLY DRAIN on the Cal 29 is 1" and can clog with an errant potato chip 

At lest the J24 has TWO 1-1/2 scuppers


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## alctel

I have a check valve on my low capacity 'dry-bilge' pump and then none on the higher up, bigger capacity 'oh ****' pump.

If the low capacity pump jams im not that bothered - ill notice at some point and fix it. I want the 'oh ****' pump to be worked at all times though (its wired direct to the battery, while the little lower one is wired to a 3 way switch/breaker)


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## Nomad Skipper

Sabreman - I am sailing a Sabre 38 Mk I and just ran into the problem that you discussed back in 2006. My bilge pump stopped working and after lots of fiddling around, including replacing the pump, I figured out that the check valve was the issue. The problem is that without a check valve, the very shallow bilge of the Sabre refills quickly from the reflow. The pump cycles continuously as it pumps water out, stops and then the bilge fills with the backflow from the hose, starting the pump again. If the check valve is a risk, how can this problem be fixed in a shallow bilge boat? 

Thanks, Nomad Skipper

Sabre 38 #83 "Nomad"


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## albrazzi

Nomad, I had a similar situation on my slack bilged CS30 and after sorting all the things that let water into the Boat like stuffing box and Ice boxes draining into the bilge area (part of a list of PO setup bad ideas) I am to the point where the only water that gets in the Boat if from cleaning my knot meter, I temporarily close off the limber hole to keep it in that compartment and some sneaks in through the keel stepped mast and is unavoidable. To further complicate drying the bilge there are limber holes all over the stringer grid and its very difficult to get all the water no matter what the method. 
Although I don't have the short cycle issue others do I don't want water down there all the time so I test the pumps regularly by introducing water using a garden hose normally and then shop vac it dry. I will be doing other things like experimenting with rising limber holes on various compartments. 
On previous boats with enough bilge I would just wash everything down regularly to keep trash from washing into the pump sump, a 8-10" sump is all I want.
Everyone needs one of those shop vac 5 gallon bucket toppers from Home depot they are only $20 and you use the bucket for other things when its not a vacuum.


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## GaryHLucas

You need a loop in the hose above the water line with a vacuum breaker valve on top of the loop. Don't make the loop too high as the vacuum breaker prevents siphoning out, which helps the pump flow. With a vacuum breaker in the line the pump has to lift the water to the top of the loop. Make the hose larger while you are at it. You now have a longer hose and you don't want any friction loss on a pump that can't produce very much flow against any kind of head, friction or height.


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## Capt Len

Gary, the problem there is that when the pump shuts off the water still in the longer bigger hose runs back and the pump starts up again.My solution was adding a small pump and small hose to the system. Triggered by a time delay switch from auto head light delay. It got its power from the hot side of the float switch and trigger from the other side.After the big pump shut down it ran for(adjustable )up to 3 minutes and slurped up the dregs Also used same idea in the head to run the vent fan .(needed after I'd left the room)


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## BryceGTX

Capt Len said:


> Gary, the problem there is that when the pump shuts off the water still in the longer bigger hose runs back and the pump starts up again.


I agree.. My discharge hose is about 30 feet long.. Lots of water in that hose. The loop does not work because the loop is at the end of the hose. Absolutely useless for the back flow problem. Fortunately Rule has a pump that is design with a tricuspid valve for bilge pump applications.. ..specifically for this back flow problem.. It is the Lopro 900..

It is the only centrifugal pump that really works in my boat. The big problem with centrifugal pumps with or without one way valves at the outlet is mostly that the pump chamber gets air in it after emptying the bilge. The one way valve does not let the air out, so the pump cavitates next time it turns on.

So the pump must be designed to let this air out. This problem plagued me in my fridge pumps, air conditioning pumps and shower pumps until I realized what was happening.
Bryce


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## Gary Krieger

I had the same problem. Someone recommended I take the spring out of the non-return valve and cut it down, then replace it. That might help.
Gary


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## Capt Len

GTX, is it possible to to take the discharge hose straight up to highest point and then 30' to the outlet. (anti syphon off course) That way only the vertical part drains back.


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## GaryHLucas

Don't over complicate this. Install the second small pump completely separate from the big pump, with its own switch and through hull. Put the switch lower than the big pump switch. The little pump will then take care of all small leakage. If the big pump ever kicks on you clearly have a big problem to deal with. But it won't be clogged or worn out, and your battery will stay up much longer.


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## jhwelch

One thing I have not seen in the recent posts is changing the method by which the pump is being activated. My pump has a non-mechanical sensor with two sensing spots. The high position starts the pump and the low position shuts if off; the difference in their heights allows for a generous amount of run-back from the hose (but then my bilge is very generous in size, so I don't suffer from the run-back problem).

One big advantage of an non-mechanical sensor is that it will never jam and fail on or fail off.


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## Classic30

jhwelch said:


> One big advantage of an non-mechanical sensor is that it will never jam and fail on or fail off.


That's right.. one day it will simply not work. 

I check my mechanical switch most every time I visit the boat - simply lift it up to ensure the pump runs, pumping out what little trickled in since my last visit.


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## smurphny

Classic30 said:


> That's right.. one day it will simply not work.
> 
> I check my mechanical switch most every time I visit the boat - simply lift it up to ensure the pump runs, pumping out what little trickled in since my last visit.


Yep. I made up a nice s.s. mounting bar extending into the bilge with two of those expensive electronic switches ("Water Witch" or some such thing) mounted at different levels only to have one fail after less than a year operating a miniscule Rule pump. I would not buy another. Just writing it off as a failed experiment.


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