water heater

[hotpepperkid]

Does the water heater have a back flow preventer on the cold water inlet side

[Old-Biscuit]

hotpepperkid wrote:
Here is my problem when I turn on the water heater for the first time when I pull into a RV park as the water gets hot it put extra pressure back on the cold side. I can release the pressure by turning on any cold water fasute for a couple of seconds. So it has one and it failed what it do that?

Sounds more like 'air pocket' in top of water heater is lost or not being established in first place.

Air pocket is used to control the increase in pressure as water is heated.
When heated water 'swells'......w/o air pocket pressure will increase

Normally just filling water heater and then bleeding air from lines will establish the 'air pocket'.
Hot water outlet has a dip tube that is turned downward so top area of WH Tank is a void.

To establish air pocket
Turn water supply OFF
Open closest faucet hotside to relieve pressure
Open T&P Relief Vlave via lever----hold open until water stops flowing
Let T&P Relief Valve snap closed
Close faucet hotside
Turn on water supply


I have NO check valves on my Atwood.......I have 3 shut off valves (Cold inlet, Bypass, Hot outlet)
I don't have an issue with increased pressure on cold water system

I bet you do not have a check valve in cold inlet......maybe hot outlet if you have only 2 valves or less to isolate/bypass WH Tank

[hotpepperkid]

Here is my problem when I turn on the water heater for the first time when I pull into a RV park as the water gets hot it put extra pressure back on the cold side. I can release the pressure by turning on any cold water fasute for a couple of seconds. So it has one and it failed what it do that?

[Old-Biscuit]

If you have 2 valve or 1 valve system you will have a check valve in hot out (top)

Might have check valve in cold inlet (bottom)

3 valve system......probably no check valves

But it depends on RV MFG how they do their installs.

Check valve is internal of 'nipple' installed in tank fitting and will have a 'flow direction' indicated on nipple.

[TexasRangerRzR]

I had one on my the back of my Suburban 12g dsi water heater. The spring rusted and the thing failed closed, so no hot water in the rv. Took it apart and gutted it, but left it connected.

No issues since that I have noticed.

[mike-s]

The only way to tell is to look. If you don't know what you're looking for, take a picture which includes both the inlet and outlet, and post it. Someone will be able to tell you.

[hotpepperkid]

the one in my 5th wheel
its an atwood

[dougrainer]

Both Atwood and Suburban do NOT install back flow or one way check valves on the Inlet or outlet. The OEM determines if they install 1 or both. Doug

[mike-s]

Which water heater? Some do, some don't (standard). And, the factory may have installed one even if it wasn't standard.