RV Repair: Surburban Hot Water Heater, hot water heater, pressure relief valve

Question
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Followup To
Question -
I have an Innsbruck travel trailer with a Surburban Manufacturing hot water heater, model SW6DE.  The water heater worked great for awhile and then it refuses to stay lit long enough to heat the water to the right temperature. The gas flame appears to be fine, right color flame. We replaced what appeared to be an external temperastats, to no avail.  Would possibly the one 115 amp electrical heating unit interfer with the gas in causing the unit to shut down prematurely? Gas unit as you probably know is electronic ignition. Or would you have any other suggestions that we could check out?  We have been trying different things for 2 years and still nothing works.      
Answer -
Kathy,
     If you have tried it both gas and electric and it isn't getting hot enough and you've tried changing the thermostats then I would guess that there is probably a problem with a by-pass kit used for winterizing the RV.  If it has the three valve type the top and bottom valves should be open and the center valve closed.  It is quite common for my customers to have the center valve open which allows cold water to mix with the hot water.  The water in the tank is hot enough so the unit shuts down, but it doesn't feel hot at the faucet because of the cold water mixing with it.  A real easy way to test to see if this is the case is to open the outside access panel to the water heater and after it has run a cycle on gas and shut down open the pressure relief valve and see if the water is hot.  I hope this helps, good luck and happy camping.

Darren

Darren,
We have already tried this.  We do have a switch in the kitchen that turns the hot water heater on.  We are now wondering if somewhere there is a problem with that.  Do you know is the light suppose to be on when heating? or is it on when it is finished its cycle?  Or would you have any other suggestions that we might try?

Thanks again,
Kathy

Answer
Kathy,
     If the switch in question is for the gas side the light should come on when you turn the switch on, then go out when it tries to light.  If it fails to light on gas then the light should come back on and stay on until the switch is turned off.  If the switch is for the electric side the light should come on and stay on until the switch is turned off.  If the water in the water heater tank is not hot then the problem has to be with the thermostats.  If the water is hot in the tank but not at the faucet the problem has to be with bypass kit.

Darren