Water heater NR valves

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TonyL

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Dec 10, 2017
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When we winterized our fifth wheel for the first time back in 2020, during the practice run I found that the non return (one way) valve on the back of the water heater was letting by. This would let the antifreeze into the heater and I've read that is not desirable. I replaced the valve and all was well.
Just tried a dummy run ready for next month and the new valve is letting by. Is this normal for that valve to need replacing every time you winterize?
I appreciate that it could be a little bit of limescale stuck behind the valve seat, but by the time I've accessed it to try and clean it, I could replace it and know the job is done.
Do others have the same issue?
 

Don C

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Jan 15, 2009
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Eaton Rapids, Michigan
Are you sure the new valve has failed?

On my fifth wheel, it had one bypass valve on the inlet to the water heater. It just bypassed the water to a "tee" connecting it to the output of the water heater. There was no check valve at the outlet so it allowed water to go into the hot water heater thru the outlet.

I just modified my winterizing process:
1. Bypass the water heater with the one valve.
2. Blow the lines out.
3. Pump the RV antifreeze into the lines.
4. Drain the hot water heater.

By waiting to drain the hot water heater, the water heater stayed filled with water preventing the antifreeze from going into the water heater. The first time I winterized the trailer without leaving water in the water heater, I used over 8 gallons of antifreeze. After I modified my process, it used 2 gallons.
 

Gary RV_Wizard

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No, it's not normal to replace the check (NR) valve annually, but if you have extremely hard water (lots of mineral salts) it could clog up fairly often. Did you flush out the heater tank thoroughly? There may be a lot of salts accumulated in the bottom of the tank and that can clog up a check valve quickly. Some of them are prone to such problems anyway. I've seen as much as a couple inches of white salts in the bottom of a tank after several months of use where there is a lot of lime (calcium or magnesium salts).
 

Kirk

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I suspect that Gary is on to the source of your problems. If you have not flushed your water heater, once you drain it get a flushing wand and useing it you will probably be amazed by the amount of white scale you can flush out.
 

TonyL

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Dec 10, 2017
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UK
When I did the dummy run, I removed the drain plug. The water ran clear right down to the last drop. Even running water back into the heater didn't flush anything out. From my experience with domestic and commercial cylinders and water heaters, any limescale in them was indicated by either particles coming out or the water coming out milky.
That doesn't mean that limescale isn't lurking in components. I guess changing the valve is my only option.
 

TonyL

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Dec 10, 2017
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UK
That idea would be sound Rene, if it wasn't in such an awkward place to get to. Re-plumbing also isn't going to be easy either.
At least replacing the valve gives me the chance to empty and clean the pass through locker.
 

John From Detroit

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Apr 12, 2005
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Davison Michigan
I would go back to a 2 or 3 valve system.. Less to go wrong.
Also as someone suggested (Kirk and Gary) Flush it out.
I had to replace a tank.. I had a good gallon of "Gunk" in the thing when I removed it and drained it.
 

Gary RV_Wizard

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Good advice from House Husband. If your heater tank is relatively clean, the next most likely cause of an early-life check valve failure is simply that it was a crappy component.
 

TonyL

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Dec 10, 2017
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Location
UK
The one originally fitted, and the one I replaced it with are both brass but with plastic inners, made or marketed by Valterra.
 

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