Water flow issues

After taking a shower and having no water issues, I went to use the kitchen sink and had no water flow from the hot faucet, but had water flow from the cold side.  I checked the outside shower and bathroom and both had no flow from the hot water side, but both had good flow from the cold water side. I rechecked the shower since it was the last thing we had used and the shower had no water flow, either cold or hot side.  All facets have water flow from both cold and hot side if I put the water heater into bypass. The local RV dealer is perplexed. Any suggestions would be appreciated.  I have a 2004 Winnebago Brave with an Atwood 6 gallon hot water heater.

The local RV dealer is perplexed.

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He shouldn't be, it is a very common problem. Simply replace the one way valve at the output of the hot water tank. It is likely stuck closed.

Alfa38User said:

He shouldn't be. Simply replace the one way valve at the output of the hot water tank. It is likely stuck closed.

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Welcome to the forum.
He isn't much of a dealer if he responded in that way. Like Stu said, it will be your check valve on the output side of the water heater. That will be the top pipe. Hopefully you'll have access to the back side. First, shut of the electric to the heater if you have the electric option. Next,  drain the tank then disconnect the top pipe from either a brass or plastic fitting. That fitting is the check valve. Using the biggest wrench you can get in there, remove the check valve. It may break hard if it's been in there for a long time.  For a temporary fix, using a screwdriver and hammer, knock out the internals to the check valve. This valve is used during winterizing. If you live in an area where there is no need to winterize, just leave it that way. Reinstall the valve and you're done. If you need to winterize, sometime just go to Home Depot and pick up a new check valve. 
Note: some manufacturers also install a check valve on the input pipe but I think that's rare. 

http://www.homedepot.com/p/Watts-1-2-in-Brass-FPT-x-MPT-Service-Check-Valve-1-2-SCV/203804502

Thanks. That is what he initially thought since it is common the to 10 gallon tank, but this six gallon tank has no access to the check valve. The perplexity also comes from the fact that the shower gets no hot or cold, but all facets gets both when the heater is put put into bypass.  Compounded by the fact that there is no access to the rear of the hot water heater, so hesitant to pull the heater.  I'll circle back to him. And again, thanks for the help!.

fbrisbois said:

Thanks. That is what he initially thought since it is common the to 10 gallon tank, but this six gallon tank has no access to the check valve. The perplexity also comes from the fact that the shower gets no hot or cold, but all facets gets both when the heater is put put into bypass.  Compounded by the fact that there is no access to the rear of the hot water heater, so hesitant to pull the heater.  I'll circle back to him. And again, thanks for the help!.

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This is very common to both the 6 gallon and the 10 gallon heaters.
Sometimes there may be a access opening maybe by removing a drawer or the backside of a cabinet. There has to be a way to get to it. Check again real close.
I have a friend in FL who had the same issue. I had to get to the back of the heater by cutting out a section of the wall of his basement compartment.  That was where the bypass valves were and there was no access so it had never been winterized. It was originally from FL so no need to.

What Stu and Rene said, it's a very common problem. One more thing to check is make sure your outside shower is shut off (if you have one of course.)

John Canfield said:

What Stu and Rene said, it's a very common problem. One more thing to check is make sure your outside shower is shut off (if you have one of course.)

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John, I don't think it would be the outside shower because they have no water flow on the hot side.

Outside water is off.  There is no access to the rear of the heater from either under the coach or from the interior.  It looks like the only options to get to the back is to remove the heater or possibly cut a hole in the floor under the couch, which sits over the heater location. Ugh.  I just found an Atwood service agent near my location, so I'll try him in a few days.  BTW, I've winterized the unit the past two years and unit has always worked fine.

Rene - you're right. Mea culpa.

Frisbee - before you go any further, give Winnie Owner Relations a call, they should know (many of them came up from production.)

Alfa38User said:

He shouldn't be, it is a very common problem. Simply replace the one way valve at the output of the hot water tank. It is likely stuck closed.

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Alfa38User
That is excellent advice.... with this caveat:
Be aware that sometimes that back flow preventer is in the input line ....and that some RV water heaters have 2 back flow preventers... 1 the hot (output) water line and in the cold (incoming) water lines

mel s said:

Alfa38User
That is excellent advice.... with this caveat:
Be aware that sometimes that back flow preventer is in the input line ....and that some RV water heaters have 2 back flow preventers... 1 the hot (output) water line and in the cold (incoming) water lines

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Must be an echo in here.  ;D

Thanks to all of you!  I have certainly learned a lot from you. In any case, I threw in the towel and dropped the motor home off at an RV service center today that is an approved Atwood service center. My career has been helicopters, missiles, and boats, but this has me stumped.  I'll let you all know what the findings are in the hopes it will help others. Happy and safe July 4th to all!

Well is was in fact the hot water outlet check valve.  The mechanic who actually fixed it was not around when I picked it up, so I was unable to find out exactly where the valve was since I could not find access to any water lines to the heater.  The service manager did say it required a lot of disassembly and working with mirrors for 1 1/2 hours. The no cold from the shower was because the shower faucet, a Moen , needs pressure on both sides to work. Thanks again everyone and safe travels!

Frisbee22 said:

Well is was in fact the hot water outlet check valve.  The mechanic who actually fixed it was not around when I picked it up, so I was unable to find out exactly where the valve was since I could not find access to any water lines to the heater.  The service manager did say it required a lot of disassembly and working with mirrors for 1 1/2 hours. The no cold from the shower was because the shower faucet, a Moen , needs pressure on both sides to work. Thanks again everyone and safe travels!

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Thanks for getting back to us with the results. Safe travels.

^^ Indeed ^^
I'm assuming the Moen mixer wants to have pressure on hot and cold sides as a safety factor.