[Trainer]

Adrian,

The diesel burner will bring the 16 gallon coolant tank up to temp from ambient and cycle off in 20 to 30 minutes.  The diesel burner needs to be used at least once per month to keep fresh diesel on the nozzle.  If left sitting unused for weeks or months on end, the diesel on the nozzle will congeal ruining the fine mist spray pattern creating the need for service.  You will see smoke from the exhaust pipe and the smell will increase.  You may not get the smell with the exhaust above the roof.

You have two (2) electric elements in the heater coolant tank.  One is 120 vac 1650 watt and the other is 240 vac 4500 watt.  The relay that turns them ON is above the heater on the wall toward the front of the coach.  It has a grey cover.  There is a 240 vac high limit thermostat in the heater above the burner.  One or more of the above failing plus a bad connection could cause the electric not to work.  Don't forget to check the circuit breakers are ON, two 20 amp.

The 16 gallon coolant tank in the heater should be fully flooded to the neck of the radiator cap with 50/50 antifreeze.  The 13 pound cap and the over flow hose to the overflow tank should be air tight, not brittle and no cracks.  There should be no pin hole leaks in the solder joint of the radiator cap neck to the tank pipe.  The straw in the over flow tank that is under where the over flow hose is attached must be in place.  Remove over flow tank cap and stick your finger in to feel the straw.  If it has fallen into tank, remove tank, get the straw and stick it back into the over flow hose connection.

I and other Factory Authorized Service Centers scattered across the country can fix any of the above.  If you wish to take on the task, order the parts from the Aqua Hot Forum parts banner.  There is a modest discount and no shipping charge.  Roger Berke, the owner of the forum, has every AH part known to man and then some including the 240 vac high limit thermostat and grey relay. Roger will answer questions on the AH forum or I will here.  If you come to me, I have a full hook up site for you where I stay or I will go to any RV park in Southeast Texas.  Here is a link to the parts website --http://www.parts.rvhydronicheaterrepair.com

If you have the unlikely pin hole leak in the solder joint, Roger Berke has a unique part to fix that.  No soldering is required and can be done easily in less than an hour.  Brittle cracked overflow pipe and/or old radiator cap are the number one culprits causing low coolant level in the heater tank.

Lastly, with the AH turned OFF, do not let it sit in freezing conditions unless you have winterized the fresh water system with pink RV fresh water antifreeze.  You can not drain or blow all the water out of the fresh water coils in the heater.  If you freeze the fresh water coils, a new heater will be the result.  They sure are nice but it is a $$$$$ event.  I replace 4 this past heating season, two that were allowed to freeze.

Drop lights or portable electric heaters in the AH bay will keep it above freezing unless the temps are really frigid or you loose grid power for hours on end.

I also might suggest you check the high limit thermostat to see if it is tripped. It is on the heater tank above the burner behind the removable panel. Just push oh the red reset button. Turn inside electric switch OFF to de-energize the AC wires going to the thermostats.

Hope this helps.