[bestgenman]

I picked this thread because it more closely mirrored a problem we experienced.  

Edith informed me we had no hot water.  She couldn’t do her dishes, she gets upset when her routines are interrupted.  My first thought was the fluid was low since the temperature was in the 200’s but, that was not the case.  The tempering valve is under the burner and the knob has suffered from age and heat so the splines were gone and that made it impossible to turn.  Removed the burner, shut the pumps off, bled down the pressure and removed the cap on the valve exposing the internals.  I’ll call this scenario  RB, it repeats! Kinda reminds one of the statement “ doing the same thing over and over expecting a different result “.  

Replaced the whole internals with new from a complete new valve, reinstalled the burner.  Same thing!   RB, this time removed the temperature sensing device. Tested this time without reinstalling the burner, same result!  There must be something under the valve seat.  Each test requires pressuring the water system and then bleeding it down to try something else.  Tried pushing on the spring loaded seat, no deal!  Tried forcing water through the seat, no deal.  Tried air pressure, no deal.  By this time (two days), I’ve had enough.

Cut the valve out
   

Bypassed the hot and capped the cold
   

Replubmbed to a more convenient location 
   

Inspection of the old valve revealed the seat was worm out and would try to  close canted allowing cold water to flood into the hot.

Edith is happy now!

[folivier]

Nice job Gordon. So you moved the tempering valve out from under the Webasto?
Curious but did you find much calcium buildup on the valve and seat?

[smagown]

Gordon, nice install on the relocation. What does that Grundfos timer do above the tempering valve?

[bestgenman]

The inside was tarnished in a greenish hue but very little buildup anywhere.  Our tank is filled from the well here at home unless we are on trips of over a week, so the water quality stays pretty much the same.

The old valve is 23 years old, I suspect it is worn out.

[bestgenman]

It provides hot water at the furthest faucets without running a lot of water.  There is an orfice at the faucet and is included.  

These pumps are kinda pricey.

I’ve been asked several times how this pump works. It provides a slight pressure increase (1 psi or less, I believe) over the cold and the orfice at the faucet lets a small amount flow into the cold side keeping hot from the AH at the faucet. Yes, it does make the cold a bit warm at first but that quickly dissipates with flow from the faucet. It works great for us and I think it saves quite a bit of water when boon-docking. Plus it is so nice to have hot water nearly instantly and we all do enjoy high end machines.

[Andriy Dyachuk]

Pat,

On edit, I see Forest posted while I was writing my reply so I second checking the coolant level.  Here is my reply.

There was a recent thread on hot water cooling off that turned out to be low coolant level in the heater tank.

You can check the tank level by cooling off the heater (run the hot water for a while to get the heat out of the tank) and then gently removing the radiator cap.

If low, refill to the neck with 50% coolant and 50% distilled water.

Then check the tube from the radiator cap neck to the overflow tank.  If brittle and split, cut off an inch or so and re-clamp to the barb on the tank.  You must use a clamp to insure an air tight seal.

If your tank is full, the next suspect is the mixing valve located just below the black burner case.  To test with the heater up to temp (electric and diesel switches ON), turn on the hot water and feel the pipe coming from the tank to the mixing valve and feel the pipe going from the mixing valve to the coach.  Pipe from tank should get real hot and stay real hot.  Pipe from valve to coach should get real warm (120 degrees F) and stay that way.

With you experiencing hot water cooling off and a full tank of coolant, I would be looking for the pipe from the tank getting real hot and staying that real hot but the pipe from the mixing valve getting real warm and cooling off.  This is a symptom of a failed mixing valve.

The fix is to replace the guts of the mixing valve which is not hard to do.  Order the parts from Roger Berke at

http://www.parts.rvhydronicheaterrepair....egoryId=-1

The only fly in the ointment here is if you are using water from the water hose in cold conditions, the heater may not be able to raise the water temp enough for you to have hot water.  The spec is 55 degree rise in temp at a flow rate of 1.5 gallons per minute. So if your incoming water is 40 degrees, the best output water would be only 95 degrees and would feel cool.

The fix here is to turn the hose off and use water from the coaches fresh water tank.

Hope this helps you.

Trying to use the link for Parts what do you provide some reason it's not working do you have another working link for aqua hot parts thank you

[Trainer]

Andriy, If you want Aqua Hot parts from me, just call

7 one 3 8 one 8 3234 between 8 and 8 central time