Check valve on pressure water system?

[HopCar]

Several people have said it but I'll say it again.

If the pump runs and there are no visible leaks, the valves in the pump are going bad. They are allowing water to go back to the tank.

When you get tired of listening to the pump, replace the valves. It's not hard.

A fine mesh strainer on the intake side of the pump can extend the life of the valves.

[TrentePieds]

Is it a Shurflo impeller pump, or a Shurflo diaphragm pump?

Mine is a diaphragm type, and its behaviour is what one would expect from a cheapie pump. Three or four times a night this infernal device mounted directly under the ear I sleep on will go "Brrrrr" - just enuff to wake me up - and then go dormant again.

The problem is that the diaphragms are incompetent. They let pressure leak back into the supply side of the pump away from the pressure switch. No way of fixing that on a cheapie pump, and in most applications it doesn't matter at all.

The remedy (which is on the upgrade schedule for this season) is to deep-six the pump in favour of foot operated pumps at both sinks, the water from the tank feeding by gravity to the intake side of the pumps.

IMO in a thirty-footer pressure water is, like wheel steering, merely a silly affectation. If you need pressure water because you have a shower installation, you have a justification for an electric pump. Maybe. But why not do the sailor-like thing and set up a Whale Gusher that you can pump by hand while you shower?

TrentePieds

[Rick Williams]

I had the same problem so I called shurflow tech support who told me it's the built in check valve and they're very easy to replace so I did and he was right.
4 bolts, take the old on off, put the new one on and you're good to go.
It's the easiest fix I've had in a long time on this old boat.
Popeye

[ramblinrod]

Originally Posted by TrentePieds

IMO in a thirty-footer pressure water is, like wheel steering, merely a silly affectation.
TrentePieds

You are certainly entitled to your opinions, but please don't assume your opinion is "the correct one" or reflective of the majority. ;-)

[rwidman]

Originally Posted by ramblinrod

You are certainly entitled to your opinions, but please don't assume your opinion is "the correct one" or reflective of the majority. ;-)

Agreed!

Some folks like to do everything the hard way and if it makes them happy, that's fine. Just don't get the wrong idea that everyone else likes to do things the hard way.

When I want water, I like to just turn the knob and have water.

[double u]

the vast majority of the on-board pressure-pumps are multi-chamber - 2 to 7 - diaphragm pumps. the valves in their "heads" are small rubber discs that seat on ~1mm wide circular "seats". the smallest tidbit sticking to one of these "seats" will cause the pressure being lost (back to the tank) & the pressurswitch kicking in & running the pump. the prefilters are allimportant for these types of pump, the finer the better!
before replacing anything: take the pumphead apart & clean the valves & their seating surfaces.

[zeehag]

i found my leak finally--it was the fitting on the pump. loose and water came from under pump.
now, for first time in 7 years i have no pump cycling..bilge not filling with my precious tank water, and life rocks
this initially is not visible to human eye--is why it continued despite my searching for cause of fail
i even had my tank re welded for leakage--but that was not the issue, not hoses nor clamps--it was the pumps fittings....

[Mycroft]

Excellent zeehag! Always great to fix a vexing issue. First time mine did that, I tracked it down to a loose fitting in the head. Next time was a blocked pump ck valve and the most recent was the deteriorated water heater gasket. So nice when the pump doesn't kick on every minute or two.

[HopCar]

I went through a similar problem to what Zeehag had. I finally found the leak by running my hand over the whole system until I felt the wet spot. It was in a poorly lit location that was hard to get a flashlight on. That's a trick I'll remember for next time.

[44'cruisingcat]

Originally Posted by double u

the vast majority of the on-board pressure-pumps are multi-chamber - 2 to 7 - diaphragm pumps. the valves in their "heads" are small rubber discs that seat on ~1mm wide circular "seats". the smallest tidbit sticking to one of these "seats" will cause the pressure being lost (back to the tank) & the pressurswitch kicking in & running the pump. the prefilters are allimportant for these types of pump, the finer the better!
before replacing anything: take the pumphead apart & clean the valves & their seating surfaces.

FINALLY, the correct answer!

I'd also suggest a very light smear of (food contact grade) silicone grease on the valves during reassembly.

[Capt Gill]

Lots of ideas of what it may be,but why not go about it logically ? By using the process of elimination it will narrow down the field of possibilities,e.g., pinch the hose off at the "out" side of the pump. Does it cycle as before ? Yes:then the problem is somewhere from the pump to the feed tank fitting. No - then pump is eliminated,therefore problem is somewhere after the pump. Continue to eliminate parts of the system until the problem is found.
Personally,I don't find much satisfaction in replacing/rebuilding parts until one gets it right,although I see it done frequently,not only by DIY's,but so-called pros. Acquiring/learning diagnostic skills will save you time and money.
To head off criticism of the above: yes,there are exceptions to this method,e.g.,where the problem is common it may be efficient to go after the "usual suspects" esp. where the diagnostic process is time consuming,use your judgement.

[lancelot9898]

Originally Posted by Capt Gill

Lots of ideas of what it may be,but why not go about it logically ? By using the process of elimination it will narrow down the field of possibilities,e.g., pinch the hose off at the "out" side of the pump. Does it cycle as before ? Yes:then the problem is somewhere from the pump to the feed tank fitting. ..........it may be efficient to go after the "usual suspects" esp. where the diagnostic process is time consuming,use your judgement.

Yes that is good in theory, but looking at the details is where the problem arises. Just how to you pinch off the hose? Do you lose the prime after doing so? (I suppose if the feed hose was removed from the pump and the prime is lost then it must be the check valve.)

Another poster said that replacement of check valve was easy. Did the pump manufacture supply that part? Another said that these are diaphragm type pumps....I thought they were impeller type, but maybe they make both types in the pressure pumps? Good discussion all.

[travellerw]

I will add to this thread in case someone encounters a similar problem.

We spent months trying to figure out our pump cycling problem. It was very random and sporadic, but we noticed it happened more at night. In the end, it turned out that we weren't completely bleeding the air from our lines. Since we have 2 tanks on our boat we will run one dry before switching to the next one. Of course this introduces air into the lines which we weren't completely bleeding off. We have 2 faucets on our boat that we never use, so air was getting trapped there. The reason our pump cycled more at night, was that the air would cool and shrink dropping the pressure.

Anyway.. Long story short, once we started bleeding everything the cycling problem went away. Could be something easy for someone to try if they are having this issue.

[mitiempo]

Originally Posted by lancelot9898

Another said that these are diaphragm type pumps....I thought they were impeller type, but maybe they make both types in the pressure pumps? Good discussion all.

Most if not all are diaphragm pumps.