Removed check valve from bilge pump- now it won't stop running

[Panacea2183]

Originally Posted by CarlF

Much worse than a check valve is to have only a single bilge pump.

I don't understand how people can work up such emotion about check valves when they are low on the list of bilge pump failure modes.

The most frequent are : clogging at the inlet, fouling of the tiny impeller, or failure of the float switch. All of which happen on pumps with or without a check valve.

As others mention, the fix is to have two bilge pumps. A daily "nuisance" pump with a 3/4" or even 1/2" hose. This small pump will fit lower and keep the bilge dryer. I prefer one with the built in a backflow preventer (aka check valve) to keep the bilge as dry as possible.

Then add the biggest 2nd pump you can fit (I use the Rule 3700) raised high enough that it (and more importantly the float switch) are normally dry and out of bilge water. It will last the life of the boat and hopefully never be used. This pump should be connected to a loud alarm.

As for switches. While the Waterwitch is more reliable than the miserable Rule, I have had one fail. They are very sensitive to any algae covering the sensor. The only one I've found to be completely reliable is the Ultra switch. Expensive but you only have to buy it once. https://www.go2marine.com/Ultra-Safe...waAngcEALw_wcB

The problem is the check valve gets fouled by the smallest of debris. In my case causing constant cycling of the pump. I left the valve in place. The dual float switches just solve my cycling problem which is OP problem

[DShant]

I have multiple similar problems and the dual pump situation will solve it in cases where you have room to install them. In small compartments that need a pump and you can't fit two with switches it is a big issue. Condensate and grey water pumps are another matter. They are usually small tanks with no room for a double pump set up or sometimes even a float switch. You can buy the small pumps with an integral water sensing switch these days but you have the constant cycling problem when the hose water returns to the tank. It is a big headache and wears out the pumps sooner or later.
As usual lots of bad design on boats as the builders and subsequent owners do things that are convenient or required by some compromise. Lots of advice here. I generally feel that the less stuff and I mean anything other than a pump and direct electric line, in the bilge the better. Valves switches floats and relays are all failure points when the shtf.

[Blairfisher]

I have had your problem. Bought a new Rule bilge pump that cycles on very briefly to check for the presence of water. It has a check valve built in, which is exactly what I wanted. Works well for me.

[HopCar]

Originally Posted by mitiempo

The best solution I have found is a small pump (350 or 500 gph) in the lowest part of the bilge with a check valve. This is the daily dewatering pump to keep the bilge as dry as possible. This pump will not move a lot of water but on a daily basis it doesn't have to.

A larger pump (1500 or 2000 gph) is mounted higher in the bilge with a float switch also mounted higher. This is the pump that will move a lot more water when necessary. This pump should not have a check valve. It should only come on when the water is higher.

This works. I had several customers with the same problem resolve it by installing a smaller pump with a smaller hose that wouldn’t hold enough water to trigger the switch when it ran back into the bilge. They didn’t even need a check valve. One guy even attached a 3/8” hose to a pump designed for 3/4” to reduce the hose capacity.

If you don’t want to do that both Rule and Whale make pumps with joker style check valves built in.

[Kolchac]

Removed check valve from bilge pump - big mistake.
Learn what the siphon effect is. Close-hauled - and the outlet is under water.
Debris? - Maintain your boat!

[mitiempo]

Originally Posted by Kolchac

Removed check valve from bilge pump - big mistake.
Learn what the siphon effect is. Close-hauled - and the outlet is under water.
Debris? - Maintain your boat!

A check valve isn't designed to prevent siphoning.

You need an anti-siphon.

[cal40john]

Originally Posted by Kolchac

Removed check valve from bilge pump - big mistake.
Learn what the siphon effect is. Close-hauled - and the outlet is under water.
Debris? - Maintain your boat!

At least for my Rule pump I consider not following their instructions big mistake.

Do not install a check valve.

Do not place the outlet lower than 12" above the heeled waterline.

page 11
https://www.xylem.com/siteassets/bra...0-2000-gph.pdf

[CarinaPDX]

Check valves used in place of anti-siphons are a recipe for disaster - don't do it.

Check valves used to stop bilge pump cycling are a sound solution. Failure of the check valve will only result in the bilge pump cycling again - i.e. no big deal. The resistance issue isn't an issue - actually the "head" (the vertical lift distance) of the water reduces the flow of a centrifugal pump far more.

I have used the same Rule pump (with 1-1/8" hose) as the main bilge pump aboard Carina for the last 40 years, along with a Whale check valve to prevent cycling. These have never failed, never been jammed by debris. If they had failed, I had an emergency Rule 3700 pump ready to go with hose and electrical connection, as well as two manual 1-1/2" bilge pumps (one inside, one operable from the helm). Both manual pumps have strainers with "foot valves" (i.e. check valves) as well as the two check valves internal to the diaphragm pumps. Foot valves are intended to prevent losing prime between uses of a manual pump - a very old and honored application of check valves.

My new arrangement is to use a Whale "Bilge IC" as the main dewatering pump - it is a Whale Gulper 320 pump mounted above the bilge with an electronic sensor and foot valve in the bilge. The Rule 3700 is now permanently mounted in the bilge, with a check valve and Ultra switch (mounted high), and the two strainer/foot valves for the manual pumps there as well. I have replaced all of the old check valves at this time as well - rubber is not forever. All four of the bilge pump strainers (including the 3700 pump) are mounted on a piece of Starboard, 12" x 7", so I am not a believer in the complaint that small bilges don't have room for a proper installation.

Greg

[sailingabe41ds]

My Jeanneau 41DS has a small bilge that can only fit the switch. The pump is 8 ft away and the builder put a strainer a couple of feet from the bilge. I put a check valve after the strainer. I also added a Rule 3700 with alarm just above the lowest part of the "little bilge".


The strainer keeps the debris out of the check valve and the smaller factory pump and it is all backed up by the Rule 3700. That is how I addressed and resolved all the concerns mentioned.


Abe

[Marqus]

Originally Posted by Panacea2183

Install a high and low float switch with a relay

Attachment 237672

Panacea, there could be a graphical typo in your circuit - doesn't seem like the lower float switch will ever turn the pump on?

[Marqus]

Acknowledging that the solutions using two pumps, a check valve or an intelligent float switch can all work, for some simple scenarios (e.g. a skiff tied to a dock unattended) I have often wondered whether there could be a simple and cheap way to add a time delay to a stock standard float switch.

If a clever electronics wiz reads this post, can you please comment on whether/how a simple Resistor/ Capacitor/ Diode circuit can be added to a float switch to make the pump run for an extra (say) 20 seconds after the float drops below threshold?

I know there are hundreds of active circuits using IC's like 555's that could easily do it, but, a simple "passive" circuit would be nice (Kiss), one where you don't need a circuit board.

I suspect not, but you never know.

[RaymondR]

Originally Posted by Marqus

Panacea, there could be a graphical typo in your circuit - doesn't seem like the lower float switch will ever turn the pump on?

You have to have a normally closed, or a normally open upside down, bottom float switch. A normally open upper float switch, and a double pole relay.

You wire so that when the water rises above the lower float switch it closes supplying power to the latching circuit but not yet triggering it on. Then the water continues to rise until it closes the upper float switch which then supplies power to the solenoid in the relay switching it on which causes two things to iccur, the pump switches on and the latching circuit is activated to hold the relay closed.

As the water level lowers the upper float switch will open however the pump will continue to run because the latching circuit will hold the relay on.

However when the water level goes below the lower float switch it will open the latching circuit allowing the relay to open and the pump will stop.

The water in the hose will flow back and switch the lower float switch back on however the pump will not run until the water gets to the top float.

You can do the same thing with transistors using probes with a high gain device such as a Mosfet or Darlington pair on the bottom and an SCR on the top in series. The bottom device will power the circuit on when the rising water shorts the probes and the SCR will trigger on when the water shorts the high probe. The circuit will stay latched until the water drops below the low probe thereby removing base or gate voltage and current from the lower device.

Google "latching relay circuits" for circuit diagrams.

[cal40john]

Originally Posted by Marqus

Panacea, there could be a graphical typo in your circuit - doesn't seem like the lower float switch will ever turn the pump on?

When the water gets to the high switch the relay coil gets power. Once the relay switch closes power flows through the lower switch keeping the relay powered, with its switch closed even when the high switch opens. Power to the relay coil is lost when the lower switch opens.

So the pump doesn't turn on until the high switch closes, and doesn't turn off until the low switch opens.

[Marqus]

Originally Posted by cal40john

So the pump doesn't turn on until the high switch closes, and doesn't turn off until the low switch opens.

Got it, thanks John. Absolutely no typo, just a very nice and clever setup by Panacea.

[Marqus]

Originally Posted by RaymondR

You have to have a normally closed, or a normally open upside down, bottom float switch. A normally open upper float switch, and a double pole relay......<snip>

Thanks for the detail; needs careful reading but a lot of solid info packed in this post.