Fresh water pump trills

[Glacier Crews]

I have searched throughout our 42 North Pacific and cannot locate any fresh (or salt for that matter) leaks in any lines. Yet our fresh water pump trills from time to time when there is no water running. Is this an indication of a problem with the pump itself? There is no particular re-occurrence time. It happens during the day and sometimes at night. We live aboard so it's not too tough to figure out that there is no water "on" when the pump makes a quick "on and working" trill." Happens maybe 3 to 5 times in a 24 hour period.

Suggestions?

[transmitterdan]

There are two possibilities:

1) There is a tiny leak in a fitting somewhere and you don't see it.

2) There is some crud inside the fresh water pump that prevents one of the diaphragms from sealing. A small amount of water leaks back toward the tank and the pressure drops as a result.

[LLizzard]

I had the same problem. No leaks anywhere. Found out that on of the hoses on the pressure side was bad, causing it to blow up like a balloon. When the balloon deflated, the pump would run until enough pressure pumped it up again. it was maddening to try and find.

[44'cruisingcat]

Most likely is some dirt in the pump causing a valve to not seat properly. Or the pump may just be old and valves wearing out.


They're pretty easy to dismantle, and clean up, give the valves a light smear of silicone grease. (Food grade of course)

[UNCIVILIZED]

This is a guess (based on science), but if your pressure system has an accumulator tank with a bladder, the volume taken up in it by the bladder is going to change with changing air temps. And when this happens the pressure sensed on the liquid side by the pump would cause it to cycle on in order to correct things. Plus, nothing is fully air or watertight, so if a tiny bit of air bleeds into the water side through the bladder...

I'd think that it's also possible to have tiny quantities of water flowing back into the tanks, through a pump. With the obvious result of a small pressure drop in the lines, resulting in a pump switching on every once in a while.

[Lancerbye]

I have seen this on my boat as well. I have two accumulators and if the pressure is down close to the cut in point and it starts to cool down in the evening the pump will come on.

[HopCar]

When a pump cycles like that it is almost always the valves in the pump allowing water to leak back to the tank side. Pressure drops and the pump comes on, pressure builds and pump stops, repeat until valves fixed or replaced.

[zeehag]

have 3 that do that--all newly rebuilt. oops... i figgerthey all do it., so i turn mine on and off at the breaker and have plans for foot poweed manual pumps at the sources of need

[44'cruisingcat]

They don't all do it. Our pump doesn't run unless you are using water. If you switch it off at night, then back on again in the morning, it doesn't run. Holds pressure all night.


I did have this issue once though, when plastic swarf from the new tanks got caught under a valve in the pump. (There is a strainer, but one piece of swarf was fine enough to get through.)

[UNCIVILIZED]

No, not all of them do it. But you do have to consider the environment that they live in, being subject to cyclical partial G-load accelerations, day in, day out, 365. Whereas one in a house such as I used to live in have a pretty easy life by comparison. Just a static load unless in use, & little environmental wear & tear. So, little to cause their valves to leak.

[Redline452]

Originally Posted by Lancerbye

?... if the pressure is down close to the cut in point and it starts to cool down in the evening the pump will come on.

Ours does this also as the water in the water heater cools down. If the heater hasn't been running (say, docked) it can hold pressure for a week, but evenings at anchor it cycles regularly.

[Izikalvo]

Here is a problem i have with my fresh water system that you might know and help me with it.
when i power up my fresh water pump after few hours of not using it the pump will not build pressure because of air in the system only when i leave an open valve until almost no flow of water exist the pump will start to build pressure and will cut off with full pressure.

i have checked all the joints up to the pump, no leak.
i have put a new pump.
i have connected a shore hose to my outside shower hose to put pressure in the system, no leaks.

problem remain especially when i am using my bilge water tank that is lower than the other 2 tanks.

any idea?

thanks