RV Hydronic Heater Repair

 
Model
431 after serial number 98571

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

Part Notes

 

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

 

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.

 

Mixing valve (complete) PLX-4A8-180 - Rebuild kit PLX-4A8-18R

 

Radiator Cap - PLX-102-229 or with lever PLX-102-229-L

Common Problems

 

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.

Radiator cap should be replaced at least every other year (or as often as needed).  PLE-102-229  or Cap with Lever PLE-108-229-L

Routine Maintenance

 

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.

 

Radiator cap should be replaced at least every other year (or as often as needed).  PLE-102-229  or Cap with Lever PLE-108-229-L

Recommended Service Parts to Keep On Hand

 

Filter:  VERIFY FILTER:  Normally one of filters below. 

Webasto - WPX-603-359

 

Racor R12T  FLE-R12-TRA

 

Nozzle:  WPX-886-41A

 

Optional Service Parts to Keep On Hand

 

None

Service Manual

 

AHE-100-02S - On Aqua-Hot website