It Has to be Something Simple . . . ?

[NA8M]

I have a class A MH with a propane water heater. The manufacturer plumbed in a bypass valve. It's a simple lever. "Normal" or "Bypass" are the options.

 

I bet this valve was NEVER placed in bypass. The last time the MH was used the water heater provided hot water just as you'd expect. That was probably three years ago. Yep, lots of gathered dust.

 

Water runs into the water heater and is heated. Water heater works fine.

 

But do you think I could get hot water out of that water heater? No Way. I've mulled this over for months. I then pumped the plumbing full (seventy psi) of air and still the water refuses to flow through. There are no water leaks in the plumbing. The faucet in the "wet bay" is turned off. There's just not a drop of water running out of the hot water taps. None. Anywhere.

 

This simply has to be something incredibly dumb on my part. But what?

 

Before I send in a professional can you please suggest a few more things to check.

 

I sure appreciate the assistance of the accumulated brain trust on this site.

 

Bill, NA8M

[Darryl&Rita]

Check valve on the hot outlet stuck?

[Devilishjim]

x2 theres a check valve at the outlet of the water heater

[SCClockDr]

If there is a mixing valve in the tank outlet I would suspect it is corroded and malfunctioning. Not a cheap replacement and many remove it and install a manual bypass to portion the hot and cold. When mine failed I opted to install a stop in the bypass and eliminate the mixing valve. We then used the spigots to regulate the temperature.

[NA8M]

I am humbled by the depth and breadth of the collective knowledge available here for the asking.

 

Thank you so very much for the prompt attention to my question. I now feel confident to proceed.

 

Bill, NA8M

[teacher's pet]

Had the same problem last year, bad check valve at the tank outlet line.

[Kirk W]

Had the same problem last year, bad check valve at the tank outlet line.

I too would look to the check valve first. When you get back there it will probably look more like a plumbing nipple than like a check valve and usually the RV builders use the cheapest plastic ones that they can find. It will probably look something like the first picture, could be the second and the third is what I'd use to replace it.

There are a few other possibilities and the hot/cold mixing valve is probably next on the suspect list if you have one. They aren't yet common but are getting more so and would be worth checking. If you have one it will have a water line from the water heater and one from cold, along with another outlet to the hot water system. Here is a picture of an Atwood mixing valve.

[NA8M]

Just a quick follow-up. You guys NAILED it. The rv fix-it guy insisted it was the "normal or bypass" valve. When he plumbed past the valve he took your suggestion. I guess there's a really nice brass check valve on the output of the water heater now.

 

Thank You all.

 

Bill, NA8M

[Kirk W]

Thanks for the feedback.

[oldjohnt]

When I was buying and selling RV's if one had sat a long time unused I found a few to have a stuck check valve. However in my own personal RV's that got a lot of use I NEVER had that happen. Good to hear you're up n runnin

 

John T