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abaerga 10-17-2014 05:21 PM

Atwood water heater bypass problem
Hello all, I'm trying to winterize and can't seem to keep the pink stuff out of the water heater. I've bypassed the supply side but there doesn't seem to be a valve on the hot return side. Is there supposed to be an inline one way valve there? My suspicion is the fluid is going in the top hot water out. I thought there was a check valve there but don't see one. Any help is appreciated. Not sure how to add a photo.

Skip426 10-17-2014 05:54 PM

Information on adding a photo is in the " FAQ " drop box in the blue bar under your welcome message.
One way check valve on the hot water line is brass and about 1 1/2" long threaded into the tank out let.
You didn't mention a second valve, usual is 3 valves for by-pass, 1, cold in , 2 hot out, 3 in the interconnection line .:confused:

abaerga 10-17-2014 10:51 PM

I have a one valve bypass. I believe there is a checkvalve in the hot out that's failed. I will most likely install a second valve just down from the hot out. That would be easier than pulling the heater to replace the check valve.

abaerga 10-17-2014 11:00 PM

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I hope this pic uploads...

abaerga 10-17-2014 11:04 PM

I'm considering taking out the tee to the right of the three way valve and replacing it with another three way to isolate that hot out.

Skip426 10-18-2014 01:13 AM

You'll need to do something, for the life of me I can't figure out how the system in the picture could possibly work to by pass the heater.:confused:

I'll see if I can find a picture of a standard set up.

Skip426 10-18-2014 01:25 AM

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Here is a picture of the common water heater by-pass.
The three valves are on/ off, not directional control like the 1 in your photo.
In this picture all 3 valves are open, the center valve should be closed for hot water use.
For winterizing the top and bottom would be closed and the center open.

wa8yxm 10-18-2014 07:31 AM

First: you are winterizing wrong.. Check out the DRY method where you blow out the lines

Water heater bypass come in 3 flavors

1: Valve
2: Valves
3: Valves
The first uses a check valve on the hot water outlet to prevent back flow
The second uses two 3-way valves.. One in the cold sends water either into the heater OR into the bypass line one on the hot side accepts water from the heater or from the bypass line. This design does not need a check valve but they often put one in.

3 Vlave designes have one in the cold, one in the hot and one in the bypass these are USUALLY quarter turn valves and again no check valve is needed, may be installed anyway but is not needed.

Do not understand the industry infatuation with check valves.

abaerga 10-18-2014 10:42 AM

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I would use the dry method however I don't have a threaded water inlet and can't get a good seal.

Skip426 10-18-2014 10:55 AM


Originally Posted by abaerga (Post 2274522)
I would use the dry method however I don't have a threaded water inlet and can't get a good seal.

I think you should have a separate city water hook up, not just the fresh tank fill that you've shown in the picture.
Also blowing the lines can leave enough water in the 12v pump, to damage it in freezing temps.

Gary RVRoamer 10-18-2014 12:16 PM

In a single lever bypass system, the check valve is at the exit from the hot tank. If the check valve is stuck open, you get a backfeed into the tank when the supply is switched to bypass. If the valve is stuck closed, you get no hot water when the supply is in normal use mode.

The check vale is often part of the fitting that goes into the tank, so not an obvious separate check valve. However, you can add a separate check valve if you have room in the line.

By the way, it's not an Atwood plumbing thing - the bypass system, if any, is added by the coach builder, or as an aftermarket upgrade if the coach builder did not include one.

abaerga 10-18-2014 12:29 PM

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OK so I added a nice Seatech stop valve that just fit nice and snug after the hot water out. The system pressurized just fine with no pink stuff in the WH! Thanks all for your comments. I hope this experience can help someone in the future. As far as the dry method, I do have a threaded city water inlet, never thought of using that, duh.:banghead: thanks for the insight!

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