Water Heater or Propane

[azflycaster]

I have been having an issue with the water heater not staying on and shutting off before the water gets to temperature. It is a manual gas only heater. A new thermocouple did not fix it, but it seems to be working now since the LP tank ran out and it switched to the other. Could the tank being low cause this to happen? We can have the water heater replaced tomorrow, but should we? We are parked at the mothership in Jackson Center.

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[AtomicNo13]

Check the high limit switch if equipped. These are available in the parts store , cheap, and require no tools or skill to swap.

[Gregsch]

Makes sense to me that you are just out of gas. When you have very little liquid propane in the tank it will be slow to turn to gas, If the tank sits for a few hours what little liquid in the bottom will eventually evaporate and you appliance will run. But , in short order that little bit of gas will be consumed and the flame will go out. If you tried to relight it right away it probably would not fire up. If you let it sit for a few hours the whole process would repeat itself. I use a lot of propane in the winter for temp heat for construction projects. In extremely cold weather the process of liquid turning to gas inside the tank is much slower. We often have to pigtail 2 or 3 tanks together so that you have more surface area inside the tanks to promote the liquid turning to gas.

[azflycaster]

Found that the water heater is still failing. The tractor will be here in an hour to move the trailer to the service area.

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[overlander63]

Richard, if nothing else, this is an opportunity for an upgrade. A water heater with electronic ignition and an electric heating element will add to your flexibility, as well as save LP when you are plugged in to 30 amp.

[HowieE]

Check the continuity through the limit switches when the heater just shuts off. If there is an OPEN there one of the limits has opened an shut the heater off. They are replaced as a set of 2.

If the limits are good then check to see if the main flame is pulling the pilot light off the thermocouple.

One ohter thing to check would be go back to the original tank and turn the Heater, not the hot water heater, and see if the heater will stay on. Both the hot water heater and the heater draw about the same amount of gas and this will test the tank and hose up to the regulator. Not likely but something you have to know before spending for a new HWH.

[overlander63]

Most standing pilot water heaters do not have limit switches.

[HowieE]

Originally Posted by overlander63

Most standing pilot water heaters do not have limit switches.

ALL hot water heaters have limits switches That is what turns the heater on and off. They are the 2 discs behind the black insulator on the face of the heater.

[idroba]

Originally Posted by HowieE

ALL hot water heaters have limits switches That is what turns the heater on and off. They are the 2 discs behind the black insulator on the face of the heater.

Those only are on the electronic ignition water heaters, the pilot light models do not have them.

[HowieE]

I think you should take another look. What do you think controls the heater if it is not the limit switches?

[idroba]

On pilot light models, there is a mechanical thermostat (usually labeled from warm to hot) which controls the gas to the main burner. When the finger on it, which is inserted into the water tank senses the water temperature has decreased, it turns the gas on to the main burner. When the water has heated up, it turns it off. The thermocouple in the pilot flame tells the main control that there is a flame available for the ignition. It will not allow the gas to flow if the thermocouple is not hot from the pilot flame.

If the main burner does not shut off due to some malfunction the temperature/pressure relief valve pops off. That is the ultimate limit switch.

There are no electronics other than the thermocouple on a pilot light only RV water heater. There are no electronic limit switches.

[HowieE]

I stand corrected.

[AtomicNo13]

I was with HowieE, always thought there were thermal switches which regulated the gas flow. I too am corrected, thanks for the great info.

[idroba]

The thermal switches and electronics are very common now with the newer Direct Spark Ignition(DSI) water heaters . But the older pilot light only WH system was mechanical thermostats, and they are still available. I love my newer DSI water heaters though, Turn the switch on and they go. No matches, wind, rain, dark and cold. Just nice hot water. And they do have the temperature control and high limit switches HowieE talks about.

[azflycaster]

Had the water heater replaced at the Airstream Service facility at the factory and the new heater is functioning perfectly. Hot showers are great! Jan is happy and life is good.