Hydrohot no heat inside coach

[Roland DuBree]

Being warm weather people use Hydrohot heat in coach less than 85% of time  Mostly AC to cool. But it never fails. Almost very year in Jan or Feb when we finally get freeze nights in North FL I go the plugged in MH at the house to turn on the Hydrohot for heat at night to keep a 40*-45* temp. inside to keep pipes from freezing and the find NO HEAT. Turned on electric, set thermostats thought all good. Next day found out no heat. At first thought maybe electric element bad so turned on diesel sw.  It ran thru a cycle and shut off nothing but cold air at exhaust. Thought diesel controller bad again. Believe it only used to control burner? Then checked amps to coach electric and read 12 amps so element must be on. Opened access to Hydrohot felt outlet pipes to feel heat pipes to units inside coach and lines warm so electric is working fine but pumps will not run to put heated fluid into the units and coach will not warm up inside. No warning lights on Hydrohot panel, Green status light lite, Low temp green lite to show heat available.  WHY DO CIRCULATING PUMPS NOT RUN?  What do I look for to fix?

[Joel Ashley]

I’ve not had to do it myself, but many have advised tapping on the pump valves with a wrench or something that will help dislodge them if plugged inside.  But you indicate you can’t sense the pumps running (vibration/sound) at all?

If the pumps don’t circulate fluid, the heat stays in the unit so the burner sensor won’t cool enough to let the burner come on as often as normal.

Joel

[Steve Huber Co-Admin]

Roland,
If you haven't, press the reset switch on the controller. Check to see that you have sufficient coolant in the tank by removing the tank cap. Also verify the level float in the tank is free to move up and down. be sure to clamp off the line from the surge tank before doing this.
Steve

[Stan Simpson]

plugged in MH at the house to turn on the Hydrohot for heat at night to keep a 40*-45* temp.   What do I look for to fix?

Noticed the above comment as part of your post, Roland. As information for the future, you don't need to be plugged in to shore power to run the Aqua Hot. Plugging in to the house will keep the batteries charged, which are necessary to start the system, but that's all.

If you think about it, how would one run the Aqua Hot while boondocking for showers, or hot water at the faucet?

[David T. Richelderfer]

The only part of the Aquahot that requires shore power or generator power is the electric water-heating element.  Otherwise, all parts of the Aquahot run from the batteries/inverter.  So, when dry camping without shore power and without the generator running, the Aquahot will make heat but only by running the diesel burner.

[Eric Maclean]

Hi Roland
If your circ pump is not running check it to see if it is getting 12Volts to power it up.
If no power to pump follow back to the delay bank and check to see if the delay is energized.
I have had problems with the relays closing and not making contact inside If yours are the clear covered relays you can take the delay out remove the cover and clean the contacts with fine Emery paper and final clean with brake clean or contact cleaner.

There are a couple of things which can cause your no heat in the coach.
1) no power to 120volt element ( Breaker in breaker box may be shut off ) I do this to allow 30 Amp shore power use if for some reason it has been shut off the only heat source would be from the diesel burner.
You stated that the tank is not so we'll assume you have power to the heating elements and controls.
BTW the electric element thermostats are set approx 10 degrees higher that the diesel t stats so you can run both at the same time. The theory is that during high demand where the electric can't keep up the diesel will cut in with it's much higher BTU rating and supplement to meet demand.
2) If the system is low on boiler fluid it will create an air lock at the unit heater's ( the highest point in the system)
This can be cured by topping up the boiler itself and running the circ pump in some cases the unit heater will have to have the bleeds opened to remove the trailer air (not comon).
3) The relays as mentioned earlier can in some cases not be making contact.
4) bad circ pump ( not a comon problem but wearth checking ( see if it has power to it)
5) there is a one way check valve in the copper plumbing near the boiler which occasionally stick closed ( simply tapping on it usually frees it up) and allows the fluid and heat to flow.
6) this maybe should have been first (make sure the thermostats inside the coach are demanding heat ( IE. not set for A/C)

Hope this helps
Eric

[Michael Turnipseed]

Hi Roland
Mine is an aqua hot. So not sure if this relates to your unit. We recently lost our pumps but had hot water, turned out the diode wire that powers my pumps had failed. $10.72 plus shipping at Aqua Hot what a relief.
Hope you find your issue.