# Solid State bilge pump switch



## jr438234606 (Apr 25, 2006)

Has anyone used the new solid-state, "Mirus" type bilge pump switches made by Johnson? These are the ones that detect the presense of water via an eletrical field (no moving parts).

I'm looking for the pros and cons, reliability, etc. I'm looking for a switch that will detect even a minimum amount of water in the bilge.


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## TSOJOURNER (Dec 16, 1999)

I put one of these in last year. Not sure what brand it is right now without looking at my log book. It seems to work. Turns the pump on but it doesn't get the last little bit of water. It needs about 3/4" to start up and turns off at about 1/2".


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## SVCetacea (Oct 14, 2007)

I have the Ultima switch by Johnson. Seems to work ok when I test it. Haven't had a real leak to properly test it though.  
Turns out the Mayfair 2200 GPH pump I bought is made by Johnson, and the switch clips right on to it!


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## MedSailor (Mar 30, 2008)

Ahhh, a topic on which I can contribute with some authority. I know bilge pumps and their switches well. Why you ask? Well....

"Hello. My name is MedSailor and I was a wooden boat owner. I have now been 224 days without owning a wooden boat"

If you want to skip the following treatise, the short answer to your question is that they are FANTASTIC and REVOLUTIONARY and I can not recommend them highly enough. 

So my poor 31ft lapstrake converted lifeboat longed to live at the bottom of the sea. Many MANY times it tried to go there and each time what stopped it from doing so was one of my bilge pumps. I always had 3, each with its own switch, each with separate wiring, 2 to the house bank (one wired direct one not) and one wired direct to the starting battery. 

In my 6 years of owning her I went through about a dozen bilge pump switches and several pumps. Since the bilge was always wet and nasty, the switches were always immersed (even if just partially) and failures were seen early. 

All of the mechanical float style switches I used had problems. Everything from wire chafe as they move up and down, to cycling when going through a rolling or pitching sea (depending on orientation) to having bilge flotsom or wires mechanically obstruct the lever arm of the switch.

Also ALL of the mechanical switches at some time or other would be found in the up position, but would not have activated the pump. If you pressed the lever down and it floated back up, "presto" they pumped. Never figured out what that happened but it happened to all of them at some point or other. 

The only mechanical switches worth their salt were the ones with a metal ball on a track that rolls INSIDE the arm of the switch. Rule makes these and others might also. The arm is heavier (though still floats of course) and is much less prone to cycling in a pitching sea. They seemed to last much longer and not have nearly as many problems at the mercury switches. They still had issues though and were also prone to mechanical obstruction (though not as much). They can be found at the store by listening as you tilt the switch and you'll hear a marble sized metal ball roll down the arm of the switch and go "clunk".

Now for the solid state ones. I would always eye these with suspicion (better the devil you know) but would invariably try them out of frustration. There is one (can't remember who makes it) which was white and had a clear tube on the bottom that claimed to optically "see" water. It also had no test swtich. What a piece of crap. I never got it to work once.

The johnson switch on the other hand can be tested by touching your fingers to both sensors on the switch. You can then remove your finger from the top one and see if it keeps pumping, which it should. This switch has worked flawlessly for me for the 1.5 years I've had it on a SERIOUSLY sinking wooden boat. Also, because of its low profile it can essentially be mounted in a very low spot in the bilge. Just be careful not to mount it lower than the pump can pump out as it will cause the pump to run forever. This just takes some experimentation. 

The johnson switch also doesn't cycle in a pitching sea as it has to detect water for one full second before beginning to pump. So water sloshing by it will not activate it.

The only claim of the product which was not met was that after the bottom sensor is dry it is supposed to keep the pump on for a further 20 seconds or so in an attempt to dry the bilge. It would be a great feature but mine did not do this it simply turned off when the bottom switch was dry.

So this is one of the very few products I have ever come across that I can absolutely recommend without reservation. 

MesSailor

PS When it comes to bilge pumps remember "One is none. Two is one, and three is two. You should have two bilge pumps"


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## TSOJOURNER (Dec 16, 1999)

I have had good luck with the solid state style switches. I have a bilge sump that is too small for a submersible pump and a conventional switch, so solid state or the microprocessor controlled pumps are the only options. 

The only drawback I have found is that these tend to stick, metaphorically speaking, when something in the bilge causes bubbles or foaming, or if I slack on maintenance and bilge scum builds up on the outside of the sensor. Basically, it is possible to cause these switches to activate with enough moisture near their surface. Cycling the pump on and off manually usually fixed this, followed by a cleaning. With any bilge pump, make sure it can run dry without damage. I think most of the submersible pumps can.


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## mikeedmo (May 26, 2005)

From West marine website - user comments:


Product Reviews:
Electronic Bilge Switch  
Average Rating:  4.0 out of 5.0Submit a Review Return to Product Page
Number of Reviews: 7 


Submitted by Denis 
Date Reviewed: 2006-07-05 09:45:42  Strengths: Apparently none Weaknesses:Does not workReview Summary:I installed this switch and soon learned that it turned on but not off. I learned this after it burned out a bildge pump. At least with the old fashion switches, one can usually visualize the problem when it doesn't work.Overall Rating:






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Submitted by 
Date Reviewed: 08-03-2006 12.56.22  Comments:I installed the Johnson bilge pump switch and it worked fine for four days. The switch then stuck in the pump position. Fortunately we discovered the running pump before it burned up. The switch has a big bulge on the housing and how doesn't work at all. Have others had problems with this switch??

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Submitted by Eddie 
Date Reviewed: 2006-08-07 17:17:05  Strengths: No moving parts. The fact that it should not be affected by debris in the shower pump box I installed it in Weaknesses:The test method was a little suspect of putting two fingers on the marks on the sideReview Summary:It's good. I'm using to replace the attwood switch that I've replace twiceOverall Rating:






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Submitted by Chet 
Date Reviewed: 2007-05-02 03:48:17  Strengths: Reliable, from my experience Weaknesses:The tabs on sides of the dovetail slot on the switch body tend to crack after inserting the supplied mounting bracket, and the mounting bracket prongs dont lock well into the pump screenReview Summary:I've installed several of these new solid state switches with good results. They don't have the sensitivity to mounting angle that the mercury switches have, nor the tendency to stick as many of the lever types do. The dovetail mounting slot is weak- they nearly always crack when you insert the mounting bracket, no matter how gentle you are.Overall Rating:






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Submitted by Rob 
Date Reviewed: 2007-12-04 07:14:45  Strengths: None Weaknesses:Won't ever turn offReview Summary:This id the second one I have tried. The first one burned out the pump because it never shut off. Now after a few days, the second one won't turn off. Absolutelt the worst switch i have ever used.Overall Rating:






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Submitted by Gary 
Date Reviewed: 2008-01-07 12:50:54  Strengths: no moving parts Weaknesses:Concern about reported failures, although mine seems to work just fine, so far!Review Summary:This switch is made by Johnson Pumps, manufacturer of many crankshaft-mounted water pumps. Installed several months back, my "water sensing switch" is still working just fine. I just replaced a second Rule float switch with this same model. Because this uses field effect sensing, installation instructions should warn the installer to mount the switch so the sensors face toward open space in the bilge, at least 1" clearance, I would guess. Do not mount sensors against a stringer, against the pump body, etc. If using the screw-down mounting tabs, do not over-tighten the mounting screws to avoid cracking the housing. This can easily occur if the hold-down screws are not perpendicular to the mounting plate or if the mounting plate is not flat; either situation could twist the switch housing if the screws are too tight, causing a leak. This switch uses "field effect" sensing. Two internal sensors detect the difference between air and liquid in contact with the housing at each sensor location. The two sensors are vertically stacked to set the upper limit (pump turns ON) and lower limit (pump turns OFF). Circles are embossed in the housing to indicate sensor locations. The test method uses finger contact to simulate liquid contact: With one finger on each the upper and lower sensor locations, the switch turns on the pump. The pump continues to run even after the upper finger is removed, simulating dropping water level. As soon as the lower finger is removed, the switch turns off, and remains off until both sensors are again covered. Perhaps this is not as intuitive as the pivoting arm float switch, but I've had two Rule mercury switches fail in the last 5 years. The last Rule float switch failed by occasionally hanging in the up position, so the pump ran continuously. Too bad there's not more information about the reported failures. I wonder if water leakage was a factor. Also these switches MUST NOT be used with a 12V battery charger as the sole power source, that is, without an installed battery. Pulsating DC from a battery charger is guaranteed to cause erratic operation. As long as the charger is connected to a battery, charging pulses are filtered out. When a user reports more than one switch "never turns off" I gotta guess something is wrong with the installation. It's hard to imagine buying 2 dead-on-arrival switches in a row. Regardless, keep your receipt to take advantage of the W.M. "No Hassle" guarantee without questions or delays if the switch does fail.Overall Rating:






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Submitted by hideaweigh 
Date Reviewed: 2006-11-08 11:01:29  Strengths: Solid state! Weaknesses:None!Review Summary:I have replaced a variety of float switches in the past and they have always failed in some form. Although this device requires power that traditional float switches don't, the benefits of being solid state are worth it.Overall Rating:






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Submitted by Bob 
Date Reviewed: 2007-04-20 13:48:32  Strengths: No moving parts; can use in any position. Fairly priced. Weaknesses:noneReview Summary:This is a terrific little switch. It doesn't look like much, but it sure works great! There's no moving parts to jam or break. You can devise several mounting positions to use this switch, unlike a float switch, which gives you no choice. I do wish it had a delay to allow pumping several more seconds after it sensed no more water. This would allow the pump to more completely remove the water.Overall Rating:






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## jr438234606 (Apr 25, 2006)

Sounds like a mixed-bag. Decisions, decisions....


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## TSOJOURNER (Dec 16, 1999)

*Johnson Ultima Bilge Pump Switch*

Regarding the Ultima bilge pump switche made by Johnson, I don't recommend it. I expected it to last longer than one year, especially considering the price and the fact that it was sealed. It did not. I received water damage in my boat because of the switch failure. I will not buy another.


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## jhaley66 (Nov 4, 2008)

Medsailor,

_PS When it comes to bilge pumps remember "One is none. Two is one, and three is two. You should have two bilge pumps"
___________________

I think those are words to live by. Do 2 or more of your pumps share a common through-hull? Do you have check-valves installed to manage back flow?


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## scottyt (Jul 19, 2008)

i put the ultima switch in my boat, it works great. after getting max of about 2 months on every type of float switch i went to, including the one with the ball, it would not shut off all the time.

love it


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## delivered (Mar 19, 2010)

*The problem with electronics*

I started my career as a marine electronics engineer 30 years ago and the first thing I was taught was that the default state of anything electronic near a boat is broken.

As sensors most of the modern electronic bilge pump switches (Water Witch, Johnson etc) are fine. Where they fail is in their inability to drive a pump. For electronics a dc motor connected to a pump is a real problem. My high capacity rule pump nominally rated at 10A will take 10A when pumping, 5A when trying to pump air AND 25A WHEN THE ROTOR IS STALLED. The startup current can be just as high for a short period of time. It only takes this sort of current for a few thousandths of a second to wreck the electronics. It is possible to design an electronic switch to cope with these conditions but you would not want to pay for it.

The failure mode of most high current electronic devices is short circuit this is why you are finding your pumps burnt out and heat induced bulges in the cases of the electronic switches.

So use an electronic sensor and use it to drive a $5 sealed automotive relay mounted in the dry next to your bilge switch. Use the relay to switch your pump.

The relay has no problem with excessive current for short to medium periods of time and it reduces the wiring voltage drop for the pump. This way you get the best of both worlds, the smarts of an electronic switch and the ruggedness of a mechanical switch.


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## meuritt (Aug 25, 2008)

curious that West does not seem to carry the product any longer.


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## Rivertender (Apr 8, 2011)

*NO moving parts bilge pump switch...........*

........has been a dismal failure for me.

I have 2 installed.

Forward switch can be buried in water.................and not come on and yet, when you are not looking, it must come on and pump because the bilge never seems to flood. Nevertheless, I don't like mine and am taking them out of the boat this year.

There are test buttons on the solid state switch to see if it is working. I use them and it tests fine. Weeks go by and I look down near the switch and water is 1/2 way or better up the switch and it is not coming on.

I am in the process of replacing my solid state switches with the standard, funky, at-some-point-it-will-fail, archaic, overpriced bigle pump float switch.


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## mdbee (May 2, 2007)

What about magnetic reed type of switch? I have seen them used in the petroleum industry. They have a donut style magnetic float. They may need more travel of the float than what a bilge pump application has.

I used a fuel tank sensor from this company. Very high quality. (I hated to hide it in my tank) 

I see they also make bilge pump switches:

Stainless Steel Bilge Pump Switch & Alarm and Switch Panel System by WEMA USA, Inc.


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## j34035 (Nov 10, 2006)

I have used the water witch brand for years with no failures. Having said that, I will probably have a failure in the near future.
DD


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## GaryHLucas (Mar 24, 2008)

The recommendation to use a relay to handle the pump current is a very good one. Doing that means that you have virtually removed electrical switch failures as possibility. I have used reed type magnetic switches in a tachometer application and with many hundreds in the field experienced no failures, at 5 volts and a couple of milliamps load. Some had 6 Billion cycles on them!

The electronic switches are vulnerable to coatings. If it gets coated with conductive material it stays on. If the coating is non-conductive it won't go off. The real problem is the desire to maintain a very low water level in the bilge. All of the mechanical switches would be extremely reliable if placed a substantial distance from the bottom.

I have used capacitive proximity sensors on plastic tanks in the past. These would probably work really well, as they sense mass not conductivity. I once used them to detect a wooden paint brush handle in a poly bag. You'd need two, one for on, one for off, and a relay as a latch and to carry the pump current. The best way to buy industrial controls--low prices, fast shipping and superior service. sells them for $71 each, about $15 more for the relay. I'd try it myself just to see how well it would work, but my boat is an Etap, so it doesn't have a bilge pump!

Gary H. Lucas


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## mdbee (May 2, 2007)

*Relays*

The WEMA comes with a relay for $48.00. I have no experience with their bilge switches but I have bought their tank sender unit. Very high quality. Although not an "electronic" switch, it may be an option.

Stainless Steel Bilge Pump Switch & Alarm and Switch Panel System by WEMA USA, Inc.



GaryHLucas said:


> The recommendation to use a relay to handle the pump current is a very good one. Doing that means that you have virtually removed electrical switch failures as possibility. I have used reed type magnetic switches in a tachometer application and with many hundreds in the field experienced no failures, at 5 volts and a couple of milliamps load. Some had 6 Billion cycles on them!
> 
> The electronic switches are vulnerable to coatings. If it gets coated with conductive material it stays on. If the coating is non-conductive it won't go off. The real problem is the desire to maintain a very low water level in the bilge.  All of the mechanical switches would be extremely reliable if placed a substantial distance from the bottom.
> 
> ...


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