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Open Roads Forum  >  Fifth-Wheels

 > Water Heater bypass valve.

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12thgenusa

Loveland, Colorado

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Posted: 10/16/21 09:52am Link  |  Quote  |  Print  |  Notify Moderator

SDcampowneroperator wrote:

There are 2 types of water heater bypass systems, the 3 valve - 1 each for in, out and bypass between the in and out. A fool proof design.
The other is a 1 valve bypass to inlet that then switches flow to bypass and depends on a auto check valve at outlet to close to prevent inflow to the cold water heater tank.
Failures are rare of manually operated valves, check valves do need a good slam of pressure to close. Build up your air or pump pressure to maximum before bleeding the water.
When pumping the pink be certain all valves are in winterizing position ( CLOSED) Run the pump until it pressurizes the system to cut off, then go- slowly- to each tap nearest to farthest , 2 times around allowing the pump or compressor to rebuild pressure to each tap


Edit, I think you pumped a/f too soon, without enough pressure to close the spring operated check valve.


The check valve is spring loaded closed (closed is normal position) and does not require water pressure to close it. When there is no demand on the hot water system, water pressure is equal on both sides of the check valve and it remains closed. When a tap is opened, the pressure in the hot water side drops below the water heater tank pressure allowing it to overcome the check valve spring and allowing water to flow.
They generally fail by gunking up with deposits and stick closed. However I am sure they can stick open the same way.


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cummins2014

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Posted: 10/16/21 10:00am Link  |  Quote  |  Print  |  Notify Moderator

12thgenusa wrote:

SDcampowneroperator wrote:

There are 2 types of water heater bypass systems, the 3 valve - 1 each for in, out and bypass between the in and out. A fool proof design.
The other is a 1 valve bypass to inlet that then switches flow to bypass and depends on a auto check valve at outlet to close to prevent inflow to the cold water heater tank.
Failures are rare of manually operated valves, check valves do need a good slam of pressure to close. Build up your air or pump pressure to maximum before bleeding the water.
When pumping the pink be certain all valves are in winterizing position ( CLOSED) Run the pump until it pressurizes the system to cut off, then go- slowly- to each tap nearest to farthest , 2 times around allowing the pump or compressor to rebuild pressure to each tap


Edit, I think you pumped a/f too soon, without enough pressure to close the spring operated check valve.


The check valve is spring loaded closed (closed is normal position) and does not require water pressure to close it. When there is no demand on the hot water system, water pressure is equal on both sides of the check valve and it remains closed. When a tap is opened, the pressure in the hot water side drops below the water heater tank pressure allowing it to overcome the check valve spring and allowing water to flow.
They generally fail by gunking up with deposits and stick closed. However I am sure they can stick open the same way.


That also makes sense , either way I am going to just replace it . As said in a previous post I have dealt with this same valve in two different fifth wheels for 13 years ,and this is the first problem I have had . Thanks

cummins2014

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Posted: 10/16/21 10:16am Link  |  Quote  |  Print  |  Notify Moderator

Another question , what are the thoughts on using shark bite fittings to replace this valve ??

SDcampowneroperator

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Posted: 10/16/21 05:41pm Link  |  Quote  |  Print  |  Notify Moderator

Shark bite fittings work very well. They are spendy, perhaps enough so that you could buy your own pex crimp tool and parts for the same money. Convenience comes with a high price. Look into that
Down the road a buyer of your unit will see the right fix, not a shortcut.
Other posters to my comment were correct I am wrong , about check valves the check valve in this application is to prevent flow so as a normally closed , low pressure would not be a problem.

cummins2014

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Posted: 10/16/21 09:23pm Link  |  Quote  |  Print  |  Notify Moderator

SDcampowneroperator wrote:

Shark bite fittings work very well. They are spendy, perhaps enough so that you could buy your own pex crimp tool and parts for the same money. Convenience comes with a high price. Look into that
Down the road a buyer of your unit will see the right fix, not a shortcut.
Other posters to my comment were correct I am wrong , about check valves the check valve in this application is to prevent flow so as a normally closed , low pressure would not be a problem.


Thanks again . I ordered the replacement, one day delivery from Amazon, I saw the tool, and the clamps . I agree I’ll go that route , once I know what fittings I’ll need .

alboy

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Posted: 10/17/21 09:14am Link  |  Quote  |  Print  |  Notify Moderator

Anderson makes a brass replacement valve that is a whole lot better,but not cheap.

cummins2014

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Posted: 10/17/21 10:42am Link  |  Quote  |  Print  |  Notify Moderator

alboy wrote:

Anderson makes a brass replacement valve that is a whole lot better,but not cheap.



Mt fifth wheel has that brass Andersen valve that's the tank fill, winterization , and city hookup, if that's what you are referring too. The problem is in a separate bypass valve for the water heater , that's a Thetford Valve ,which I am replacing.

I know if you are not careful with those Andersen valves under pressure ,and switching them back ,and forth you can blow an O ring. If say I am hooked to city water ,and want to switch that valve to tank fill, its a good idea to shut the water off first relieve the pressure , switch the valve then turn the water back on . Pretty sure there is no problem with that valve, its in the bypass valve .

ACZL

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Posted: 10/18/21 03:48am Link  |  Quote  |  Print  |  Notify Moderator

If you haven't torn apart things just yet, how about just replacing the check valve on the hot water tank 1st? It sounds like we have the exact same kind of docking station set up and the only thing I did from last year was just change the ck valve due to my screw up. So when I went to winterize it this year, no probs.

If you want to, PM me.


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