Obscure Water Pressure Problem

[David Rive]

So here's the issue ... our fresh water pump cycles momentarily (like max 2 seconds) about once an hour. I have examined the pump, the pressure tank, and every fresh water line and connection I can find on the boat - no visible leaks anywhere.

So I phoned Curt at American Tug (he is the resident engineering genius on all things AT) and he suggested it might be the pressure relief on the hot water heater. I checked that - no leak.

So I am stumped. Does any one have any other troubleshooting suggestions?

Thanks.

David

 

[cafesport]

Do you have a cockpit shower sink or other freshwater outlet above deck. Any fw in the bilge.

 

[Heron]

Mine does the same....

 

[greysailor]

If you are absolutely sure there is no leak in any of the lines or faucets, you probably have a bad check valve at the pump.

 

[O C Diver]

If you are absolutely sure there is no leak in any of the lines or faucets, you probably have a bad check valve at the pump.

Right idea except it would have to be 2 bad valves as both the intake and exhaust valves would act as check valves.

Ted

 

[O C Diver]

Did you check the water add to your vacuflush head? Dry the bowl all the way around just under the rim, then see if it gets wet after an hour or so.

Ted

 

[Lou_tribal]

Mine was doing the same and there was a tiny leak on my heater. It was barely noticeable as was leaking a drop every 10 sec and the drop was falling on the underside of the heater cover.

L

 

[Gordon J]

I just discovered

Did you check the water add to your vacuflush head? Dry the bowl all the way around just under the rim, then see if it gets wet after an hour or so.

Ted

This issue on my boat. The pump cycled on at around 2 a.m. I shu the pump down and figured I would find a loose hose clamp in the morning. Instead what I found was a toilet bowl full of clear water. I cycled the toilet a couple of times and everything seems good.

Gordon

 

[aboatman]

If you are absolutely sure there is no leak in any of the lines or faucets, you probably have a bad check valve at the pump.

Yes, the pump has an internal check valve and it can leak pressure back to the supply side Then the pump comes back on to bring the pressure back up.

You can install a check valve just before the pump and this may solve your problem. Or replace/rebuild the pump.

 

[DHeckrotte]

I second the motion.

If there is no leak anywhere then the pressure is leaking back through the clapper valves in the pump.

If there is no leak anywhere, you can replace the pump, rebuild the pump or add a check valve ahead of the pump.

If there is no leak anywhere, and you are not driven unduly crazy by the noise or the imperfection on your boat, you can ignore the cycling until you are driven sufficiently crazy.

If there is no leak anywhere, or even if there is an ignorable, itty-bitty one, you can turn the pump off so you don't have to listen to it, say, overnight.

 

[FF]

If the hot water heater was made warm by running the engine, as the water cools it lowers the system pressure, perhaps enough to kick on the pressure pump.

A larger accumulator will solve this , if there is one installed.

 

[High Wire]

If the hot water heater was made warm by running the engine, as the water cools it lowers the system pressure, perhaps enough to kick on the pressure pump.

A larger accumulator will solve this , if there is one installed.

Mine does the same after an engine run long enough to make hot water. The water volume contracts as it cools, the pressure drops, and then the pump brrrrps for a second maybe once an every couple hours.

 

[HopCar]

Another vote for the internal valves in the pump leaking. No need to add an external check valve, just replace the internal valves. This is a very common problem. If you can’t find a leak, it’s got to be the internal valves. Over time the valve seats get corroded or dirty and need to be replaced.

 

[Russell Clifton]

I had this problem this past fall. Turned out to be the check valve in the outlet of the pump. The only way I found it was to listen to it with a stethoscope. I could hear the water flowing thru it back to the inlet side of the pump. This may not work for you if it only comes on a few seconds every hour.

 

[Heron]

Good tips guys...Thanks!

 

[David Rive]

Great feedback from everyone ... many thanks. The water pump is quite new, so it "shouldn't" be the problem. I will investigate the fore and aft washdown systems further, and Ted's suggestion re the head. Onwards!

David

 

[David Rive]

Did you check the water add to your vacuflush head? Dry the bowl all the way around just under the rim, then see if it gets wet after an hour or so.

Ted

Well, as he so often does on this Forum, Ted put his finger on the issue. I have a very slow leak into the Vacuflush bowl. Thanks Ted. Now to correct it - where's that manual?

David