water pump cycling on

[Socrates]

Just wondering how often this happens to water pumps. After de-winterizing the plumbing system, I found it necessary to replace the shower valves because they were leaking out the shower head even when turned off. Replaced the shower valves, checked around the connections for leaks and didn't see any. The fresh water tank is filled. With the pump turned on, every few seconds it cycles on for a half second and then shuts off for a few seconds then keeps repeating this cycle. I'm assuming there is a leak somewhere that I haven't found, or could it be that the seals in the pump are worn and allowing some back flow toward the fresh water tank when the pump is off? Is this a common occurrence with these pumps? Replacing the pump would be a lot easier than tearing the whole trailer apart looking for a hidden leak somewhere. Thanks for your help.

 

[Mr. Dan]

Does your unit have a winterizing kit/valve for introducing antifreeze into the system? If so and that valve is not totally closed (handle in wrong position or valve failed), it could produce these symptoms.

 

[Socrates]

It does have an inlet for the antifreeze, which I did use in the Fall. Can you tell from the photos which is the valve that might need adjusting? Thanks Mr. Dan

P.S. the photos are old. I haven't opened up the hot water tank yet.

 

[Socrates]

OK, I just found that one of the low point drains is leaking. It leaks more when I turn the pump on, which confuses me. I didn't think the low point drains were in the pressurized system. I couldn't tighten it enough to get it to stop leaking, and I guess you're not supposed to have to overtighten them anyway. I'll have to try to change out the cap and see what happens. It's the cap for the hot (red line attached) water. It shouldn't matter that I still have the hot water tank bypassed, right?
Changing the orientation of the black valve didn't make any difference. It's now still pointing down toward the fresh water tank.

 

[5picker]

Yes low point drains are pressurized.
The cap is likely missing the cone washer inside it that seals the cap or it's boogered up.
Maybe this simple diagram will help...

 

[reidfo]

@5picker is correct. And even if the WH is bypassed you still have pressurized water in the hot lines.

On a side note, you can likely expect leaks at some point from the rest of the plumbing you showed. Sadly, most RV manufacturers improperly install PEX fittings on braided (flexible) hoses. These will leak. My RV is afflicted too. Just wanted to make you aware of a potential future failure point.

 

[Socrates]

Yes, I realized after my last post that of course it's part of the pressurized system. Duh, my bad. You're right, there is no cone washer on the hot drain but there is one on the cold water drain, which is not leaking. I'll see if my local hardware store has these things. That's a nice diagram, 5picker. And thanks for the heads up about expecting more problems in the future. Great news. We're actually getting this trailer in shape to put up for sale, so it may in fact be someone else's problem in the future. If I were a really nice guy, I'd tell the buyer what you said about the PEX fittings on braided (flexible) hoses??

 

[Oaklevel]

Some leak some do not we have PEX fittings in our 2017 and earlier trailers never had a leak yet. ( since I said that will now )

 

[Aussieguy]

During storage in hot weather you will surprised how much pressure builds up in the lines just by the heat alone
I can get close to two cups of water on real hot days … in Florida

store it with pump off
and crack open the kitchen faucet which is right near the pump switch (in my trailer anyways)

If you forget to close faucet when you turn on the pump you won’t have to run far to turn off the faucet

Keeps the pressure buildup and leaks to a minimum