Community Forums

Ramona · 03-24-2019, 11:54 PM

Hello all. De-winterizing and trying to diagnose issue with RV water not getting hot enough. I am thinking that problem may be the water heater bypass valve is in the wrong position.

It occurs to me that I do not understand the purpose of the water heater bypass—my previous RV either did not have one and/or we never changed it since we used compressed air to winterize and not anti-freeze.
Is it (the WH bypass) just to keep anti-freeze out of the hot water heater?
Thank you.

Old-Biscuit · 03-25-2019, 12:02 AM

Cold water goes into bottom of WH Tank
WH heats it up and Hot water comes out top of WH Tank

Bypass connects Cold inlet line with Hot outlet line ////bypassing water in/out of WH Tank

WH Tank valving can be several methods
Cold inlet valve, bypass valve, Hot outlet valve
Cold inlet/bypass valve, hot outlet/bypass valve
Cold inlet, Bypass and Check valve in Hot out
Etc

Normal service
Cold In OPEN
Bypass Closed
Hot Out OPEN

BYPASS Service
Cold In Closed
Bypass OPEN
Hot out Closed (or if check valve vs shutoff valve then it closes when bypass is open)

3 valve system

2 valve system (check valve in hot out)

Waiter21 · 03-25-2019, 05:26 AM

Its possible that if the bypass valve wasn't completely closed, it could leak cold water past the valve into the hot water plumbing.

Gary RVRoamer · 03-25-2019, 08:59 AM

The only purpose of the bypass is to allow winterizing with antifreeze without filling the entire tank with antifreeze. The tank is bypassed (no water flows in or out) and drained for the winter season.

**Lt Dan** · 03-25-2019, 12:28 PM

Also, if you have an outside "shower" faucet make sure the valves are closed. Sometimes the cold and hot get mixed together in the faucet if both are left open. in addition, some water heater setups have a mixing valve to mix hot and cold since the hot side can be too hot for normal use. You might check for a mixing valve.

153stars · 03-27-2019, 08:07 AM

With the HWH still bypassed start flushing ...see if your are you getting any water in heater using its drain. if not the 3way valves probably are holding. I actual bypass valve feels tight is probably fine. Is it just your shower a lot of residential single knob shower valves have antiscald device. . you could shut off hot water heater in or out to see it stops hot at a faucet. ...Let tank get full temp drain tank in bowl take the temp see if it gets to proper temp.