Originally Posted by B47
Lou - you say "Remove the rubber protective covers on the high/low limit thermostats."
My Suburban WH manual only says to press the covers if the WH doesn't run on AC. Is that a fix (replacing melted fuses) that you discovered or that a generic fix for all RV WH nakes?
Every water heater out there (except perhaps the "on demand" types) have some form of high/low limit thermostat. There are two in units that run on propane and AC because they are two separate and independent systems that share a water tank.
The reason is there has to be a way for the water heater to decide the water is hot enough to shut off (high limit thermostat opens) and cold enough start (low limit closes). The unit is sold as a "set" of thermostats and the thermostats are connected by a fusible wire.
As I said there are two different ones; one for AC (black wires) and one for the DC control of the propane burner (red wires) in this photo.
The reason the manual stops at pressing in the rubber covered buttons is that there is power on those thermostats (120VAC in the case of the one on the left) and you could get shocked if you don't know what you are doing.
If the high limit thermostat "bellows" gets stuck open, the electric will not heat the water. Pressing on then rubber disk will collapse the bellows and close the circuit. If the fusible wire is gone, this will not fix the problem and the entire thermostat unit must be replaced.
The Atwood thermostat looks like :
Atwood 140° Thermostat Kit with ECO, #91447
The Suburban one like
RV Suburban Water Heater Thermostat/High Limit Switch, Part # 232319 | eBay
They are not expensive and with care (and some electrical knowledge) are easy to fix.
This is from the Suburban manual.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW