Is there a back flow valve on the hot water outlet

[Ltrip]

I am winterizing. Done this many times.
I flip the switch to bypass the water heater.
The anode is out of the water heater.
I put the tube into the gallon of anti-freeze and turn on the pump.
Anti-freeze comes out the drain hole.
I flip the bypass switch back and forth. Anti-freeze goes into the water heater in either position.
If the switch is in the bypass mode, and I open a faucet, anti-freeze does make it there, but some still getting into water heater.
Is there a back flow valve on the hot water outlet?
I assume that has failed.
Suburban heater.
Thanks!

[MrWizard]

The check valve will be in the hot water output line at the back of the water heater,
In my case it was almost impossible to get at, because of the way the water heater was installed, ( outside below the basement ,inside its own welded box, which i had to cut open, working under the rv with my angle grinder)

[wa8yxm]

IN theory if you look at the plumbing side of the water heater you will see any check valve if installed.. alas I've never seen one so I can not testify to that.

Check valves are a pain by the way.. they clog. Stick, And so on
The two vlave system is NOT supposed to need one.. you may have a defective valve. Only the single valve system is SUPPOSED to need one.

[marpel]

I have two valves on my system and when in bypass, some antifreeze gets in the hot water tank. Is there an easy visual way to determine, without taking things apart, if a system actually has a check valve? If mine does, maybe it needs to be replaced.

Marv

[wa8yxm]

You said you flipped the "Switch to bypass the water heater"

Never seen an RV with such a switch.. Valves yes. Switches no
If you have a SINGLE bypass valve then there is a check valve on the water heater outelt.

If you have two or 3 you need to change. there may or may not be (It is not needed. I had a 3 valve. no check vlave.

[fj12ryder]

Yes, should be a check valve, and those check valves are almost always plastic, and tend to have a short lifespan, sometimes measured in minutes if they aren't installed correctly, i.e. hamfistedly. 🙂

[BB_TX]

Should be a check valve on the hot water output of the WH.