RV Hydronic Heater Repair



Serial numbers 03-675 TO 04-533

This model may also be known as:


AHE-120-03X, AHE-130-03X, AHE-140-03X

These are models that were built with dual electric elements

This model of Aqua-Hot uses the special Camco -100 Boiler coolant.




Changes From Previous Model


This model is a major redesign of the AHE-100-02S model


Starting with this model, this series has:


  • Electronic control board
  • Tank level coolant sensor (float switch)
  • Uses relay(s) to control electric element(s)
  • Single control thermostat for both diesel and electric, which is different than previous model.
  • Diesel and electric high limit thermostat, which is different than previous model.
  • Uses the PLX-09P-100 mixing valve
  • Most of the units in this model number used an electronic electric relay, which did not hold up well. (see comments below in common problems)
  • Had plastic / PEX drain valve (see comments below in common problems)
  • Different zone and engine preheat pumps (which are no longer available).  Pump upgrade kit, here: PLE-100-905-FRU
  • This model uses the special GRAS (generally recognized as safe), Camco -100 Boiler coolant, here:  MSX-300-270


Part Notes




Routine service parts and kits - Routine Service Parts      Scroll down page for filter and nozzle packages.

Common Problems


  • The PEX / plastic drain valve should be replaced (most have already been done), here:  replacement Drain Valve
  • The electronic electric relay did not hold up well.  Upgrade kit:  ELE-630-001-HYD
  • The PEX water lines should probably be routinely replaced.  If you have fresh water leak, then the rubber gaskets in the PEX fitting are hard and not sealing well.  Water Line Kit
  • 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

Service Manual


On Aqua-Hot website   AHE-100-04S