Problem with Water Heater Bypass Valve

hobie16 · 11-12-2015, 07:10 PM

I am a new member and owner ( 1 month) of a 2015 Sequoia, 38HRL. Only the Sequoia is new, I am an old hand at RVing. I have a question about the water heater bypass system. I have noted that the cold water at the sinks isn't real cold. I attached my outside spray hose and ran the cold water and it was luke warm. Moved the valve to "Bypass" and got cold water. There seems to be a fault in the valve. Contacted Customer Service at Redwood and arranged to get a replacement valve (B&B Moulders, single red lever style).
However I got thinking of other possible causes, does anyone know if there is a check valve on the cold water inlet to the water heater? If so, it may be my problem and allowing hot water to siphone out. I can't see the input side of the heater unless I remove a section of the storage area wall.
Appreciate any info you give me.

atom ant · 11-12-2015, 09:09 PM

There is a check valve, but I think it is on the outlet. It prevents antifreeze from coming back in the tank when bypassed. However, any of the single handle faucets will mix if they are on, and your outside shower if you have both valves open.....(I think)

Andrew · 11-12-2015, 11:23 PM

I had the same problem in my 36rl you must of had the same plumber, if you will pm me maybe I can walk you through it

atom ant · 11-13-2015, 01:26 AM

If you folks work together and get it fixed- do let us know how you did it! I like to use these pages as a good reference.

hobie16 · 06-20-2016, 08:32 PM

I know people are interested in solutions when problems are solved so here goes:

I first noticed the problem last fall shortly after starting our Winter Flight south; we only had a week from trailer delivery to departure. I tried several troubleshooting paths that were the easiest to do, isolated each of the fixtures to insure no internal crossover, checked that fixtures weren't reversed connected etc. I thought that the problem was internal to the Bypass valve but replacing that and doing deeper troubleshooting had to wait until our return home. I didn't want to have a disabled water system while trying to live in the unit.
Got home in late may and just got to work on it last week. I had to empty the cargo hold and take down the service wall. I replaced the Bypass valve but that had no effect on the problem. Closer examination of the pipe connections revealed that the only point where the Hot and Cold systems are joined is at the output of the Bypass valve. Following those lines I found that the Cold line had a check valve that allowed water to move away from the Bypass in the "bypass" position. The Hot line didn't have a check valve. That was the source of the problem. Cold water moving past the bypass outlet line in the "Normal" position, would siphon cold water out and draw Hot water to replace it. The longer the system ran the warmer it became. So I installed a check valve in the Hot line from the Bypass. Problem fixed.

I am not sure if my system was incorrectly plumbed or if the Hot line check was left out.

Thanks every one