Water heater thermostats

[chuckalanpayne]

Does anyone know why there are two separate sets of thermostats on the water heaters, My left set is bad and trying to order another one but not sure which to get. Its the two that are hardwired together and between 140 and 180 degrees. 120volts, 2012 Outback 260L...

[JRTJH]

The thermostat assembly (located behind the black rubber push plugs) is actually two devices. One is, as you indicate, a thermostat used to control the water temperature. The other is a "HIGH LIMIT" switch. Its purpose is to shut off all heating power (electric and gas) to the water heater if the water temperature rises above a set limit. This is a safety feature to prevent a possible explosion should the water heater thermostat fail and the water continue to heat above the boiling point (212F). Of course there is also another "safety valve" on the water heater, the pressure relief valve. They work together as a "safety device and a backup safety device.

So, the 140F "switch" is the water temperature control and the 180F "switch" is the temperature limiting device.

If your temperature limiting device happens to open, the "PUSH TO RESET" action (pushing on the black rubber cover) will reset the switch. Remember that it will not reset until the tank water temperature is below 140F, so going outside and pushing that plug because the water heater gas ignition won't light will probably not do anything but frustrate you.

[chuckalanpayne]

Ok found the limit thermostats, now having trouble purchasing them, its the one on left side, connected to red leads, it does not tell you if its 12v or 120v. Parts wharehouse doesn't know either. got any ideas. I need 140 to 180 degrees limit.

[JRTJH]

Your question is much like ordering car parts: ie: I have a mustang, it's either a 68 or a 69 and I need a water pump. There are 5 different pumps listed, one is for a 6 cylinder, one for a 302, one for a 351 and one for a 429, which one do I need? The answer: It depends on what fits the motor in your mustang.

It's the same with the water heater in your RV. So far, it's not clear if you have an Atwood heater or a Suburban heater, whether it's gas/electric or gas only, whether it's a "old model with a gas thermostat separate or if it's a newer type with a "set temp thermostat" so your water heater is very much like the water pump in a mustang.....

Look at the owner's manual that came with your water heater. There is a parts diagram near the end of the manual. Order by part number, not by location. The part number will "convert" to a specific component that was installed on your water heater. If you go by "it looks like it" you may not get the correct part.