RV Hydronic Heater Repair
This model may also be known as:
920/431, 920431/12, 920/432, 431
Most of these heaters were 12-volt,
however there were a few 24-volt heaters built.
This model of Aqua-Hot uses 'standard' ethylene glycol coolant (Prestone or equal). Keep it simple and use the same coolant that is in your engine and generator.
Changes From Previous Model
Thermostats are snap disc thermostats. When built, there was not electric high limit thermostat installed.
Upgrade kit for electric wiring and thermostats is here: ELE-560-024
Diesel Control (Blue Dot) ELE-L08-190
Diesel High Limit (Black Dot) ELE-L08-230
Electric Control (Red Dot) ELE-010-198
Electric High Limit (White Dot) ELE-254-010 (This thermostat was later added to most of these heaters)
3 zones + engine circulation pump PLX-809-200 Pump parts (scroll down - these parts are near the bottom of the page)
1650 watt electric element ELX-2E7-540 Note: that electric element rarely fails!
Most failures in electric system is electric high limit thermostat.
Replace filter and nozzle when exhaust gets smoky / smelly. Aqua-Hot recommends yearly routine service.
Pumps develop leaks, which require replacement of "O" rings. March Pump "O" Ring You have to remove pump to disassemble it to replace "O" ring.
Recommended Service Parts to Keep On Hand
Filter: VERIFY FILTER: Normally one of filters below.
Webasto - WPX-603-359
Racor R12T FLE-R12-TRA
Optional Service Parts to Keep On Hand
AHE-100-02S - On Aqua-Hot website