Community Forums

Skinner2909 · 02-09-2023, 01:38 AM

Yet another weird issue with our Aqua-Hot 250D. It will not re-fire when on battery power. One of the sites we stay at here in California has some ridiculous quiet hours (8pm-10am) and no hook-ups. As such, we need the Aqua-Hot to keep us warm on battery power through the night. With the thermostat set the Aqua-Hot will fire and heat as it should. However, after temperature is reached and the Aqua-Hot shuts off, it will NOT re-fire again by itself. My wife is the first to wake up cold, then I'll turn off the Aqua-Hot and turn it back on. Again it will fire up and start heating, only to shut off again an not re-ignite. This condition is ONLY present on battery power - works perfectly on the gen or shore power. Has anyone had a similar experience?? Thanks!

**pasdad1** · 02-09-2023, 04:37 AM

What voltage are the house batteries at when it won’t fire again ? Simply turning the burner switch off then on again makes it work a second time?

Skinner2909 · 02-09-2023, 08:06 AM

Quote:

Originally Posted by pasdad1

What voltage are the house batteries at when it won’t fire again ? Simply turning the burner switch off then on again makes it work a second time?

Thanks for the reply. Voltages checked throughouth the night. First was 12.8, then 12.5, then 12.3. Each time woke up cold to a "Requesting Heat" message. The burner would fire right back up if turned off and on again.

**pasdad1** · 02-09-2023, 08:23 AM

This thread sounded like something similar to what you are experiencing….

https://www.irv2.com/forums/f115/aqu...te-372327.html

Skinner2909 · 02-09-2023, 10:03 AM

Quote:

Originally Posted by pasdad1

This thread sounded like something similar to what you are experiencing….

https://www.irv2.com/forums/f115/aqu...te-372327.html

Thanks for the link. I reviewed that post and unfortunately it's a different issue. I suspect that if it was a burner/nozzle or any other type of fuel delivery issue I would experience the same problem on gen or shore power, but mine is limited to battery power. It's almost like it's something in the thermostat control board (or even software) that is preventing the burner from re-firing, but ONLY on battery power.

vito.a · 02-09-2023, 02:24 PM

That's strange because the Aqua Hot is running on 12v power from your batteries regardless. The difference is when not on shore (or generator) power the batteries are not being charged.
How old are your house batteries?
What is the house battery voltage when the inverter is not charging?

Gary RVRoamer · 02-09-2023, 02:27 PM

So the "won't re-fire" occurs somewhere below 12.3v on the battery? That's low enough voltage that I would consider it a possible reason. The controller may disallow it if there is a risk the circulation pump or outlet fans won't run fast enough to adequately distribute heat. Or the burner gets hot because the pump is running slow and some sort of over-temp shutdown occurs. I'm not familiar enough with theAquahot to know if there are check lights and diagnostics for that sort of thing, so I'm just tossing out ideas.

Topperace · 02-09-2023, 06:57 PM

x2 what RVRoamer said about low voltage and the AH controller will not turn the "system" on, or it will act erratic...

Skinner2909 · 02-09-2023, 07:32 PM

Quote:

Originally Posted by vito.a

That's strange because the Aqua Hot is running on 12v power from your batteries regardless. The difference is when not on shore (or generator) power the batteries are not being charged.
How old are your house batteries?
What is the house battery voltage when the inverter is not charging?

Very strange indeed. Sequence of events was as follows. 1.) Generator ran for 10+ hours and house batteries reached full charge (coach and batteries less than 1 year old). 2.) Aqua-Hot turned on diesel mode at 8pm, 13.1V. 3.) Woke up cold around midnight, no heat, thermostat read "requesting heat." Manually turned off and back on, fired right up at 12.8V. 4.) This same thing occurred two more times, down to 12.1V and each time the diesel burner fired right back up manually.

Maybe a more fundamental question, are Aqua-Hots designed to run for extended periods on battery only without gen or shore power? Perhaps something in the control board is measuring the RATE of discharge and shutting it down??

bentjm · 02-09-2023, 07:43 PM

Quote:

Originally Posted by Skinner2909

Maybe a more fundamental question, are Aqua-Hots designed to run for extended periods on battery only without gen or shore power? Perhaps something in the control board is measuring the RATE of discharge and shutting it down??

It is a 12v system. It should run until it runs out of diesel or out of DC power.

How, exactly, do you have your thermostat set - heat pump or furnace?

Skinner2909 · 02-09-2023, 08:01 PM

My thermostat has the option for Aqua-Hot or Heat Pump. It was set to Aqua-Hot. Within the Aqua-Hot setting it has the option for Electric Element or Diesel Burner - it was set to Diesel Burner.

falconman · 02-09-2023, 11:19 PM

Does the “low voltage” light illuminated on the control board? If so, it’s reset by pressing on the reset button or switching the diesel burner off and on. You may have a low voltage issue and when you cycle the diesel switch, it resets it and the burner now works.

WatchMeRV · 02-09-2023, 11:24 PM

Can you determine whether the issue is at the thermostat or the AquaHot? Does this occur when you change the temp down-up, then down-up again? If you can make it fail consistently then you can test whether it's the thermostat or the AquaHot. Check if the Heating Status D1 light is on. What's the year, make, model of your coach? Also, you could call AquaHot in the morning, they are pretty good at diagnosing any control board issues. BTW, it could still be a power issue. FYI, I found this in the 250D manual:

Additionally, the burner switch can be used to reset a
low-voltage condition. This is accomplished by turning the
switch “OFF” for 30 seconds, and then turning it back on. This
is sometimes known as “power cycling.”

Skinner2909 · 02-09-2023, 11:37 PM

Quote:

Originally Posted by falconman

Does the “low voltage” light illuminated on the control board? If so, it’s reset by pressing on the reset button or switching the diesel burner off and on. You may have a low voltage issue and when you cycle the diesel switch, it resets it and the burner now works.

We're taking the motorhome out this weekend, so I'll give it a shot. Sounds like a plausible explanation! It would make sense that a (incorrect) low voltage condition was being reached at 12.XV, but not at 13+ when connected to shore power or generator. Thanks for your recommendation.