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Aqua Hot 250D Won’t Fire


Dae Sung
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Just bought 2021 HR Nautica 33TL with AH 250D.  When I turn on the diesel burner there is a message that displays briefly “Burner Fault”.  The unit hums but the burner does not fire.  The coach sat for a few months so I am thinking I need to replace the filter and nozzle?  Any thoughts?  Thanks!

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I'm not familiar with the Fleetwood installation but on the legacy Monaco installed systems you can try a system reset.  Turn all power off.  Unplug from shore power and turn off both battery sets as well as the inverter. 

If that doesn't help you are going to have to dig into the Aqua Hot system.  Remove the cover and follow the troubleshooting guide.  It could be the ignition coil, the igniter tips, the flame sensor, or one of the limit thermostats.  

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4 minutes ago, Dae Sung said:

No airflow out of exhaust -the unit hums when I turn on the diesel burner, but I don’t hear the burner kick in.  

No air flow means the blower motor/fuel pump is not turning… hopefully not getting power. Multiple faults can cause no power to the motor. Not familiar with a 2500 and what fault lights it might have to help troubleshoot. Downloading the troubleshooting guide is your best bet.

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Ok I turned on electric burner to see if it would work, and after about an hour it gave me hot water, then I out of curiosity turned on the diesel burner and the unit fired on.  The zones are producing hot air but the fan is not very strong.  Could this be because I am on 110 shore power?

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Being on shore power should only make things better since the batteries would be at full capacity. You should not expect very much of a strong flow from the registers. If you look behind them, you will likely find a couple of 12V computer type fans, they do what they can. Look if the register may need some vacuuming. I found one of the fans not functioning over time and they are easy to replace.

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Glad it’s working but not starting on diesel but then after using the electric element it does, doesn’t add up.
A Aqua Hot doesn’t need shore power to run on diesel as everything needed is 12V. Yes, the electric element is 110-120V which lets you get a fair amount of hot water when on shore power…enough heat to keep things from freezing when in storage as long as the power doesn’t go out on Woodstock.

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I’ll admit I’m not into annual much of anything except our annual doctor’s checkup. Our 600 A Hot has 2 electric elements so the diesel burner doesn’t get used much and even the previous single element one didn’t get a annual PM. Yes, if the diesel boiler gets 100 hours/year of use then the annual PM is probably a good idea IF it has a diesel smell after several minutes. All of them have a smell when first fired up. Even the recommended of starting the diesel boiler briefly ever month is probably overkill with ULSD fuel but it can’t hurt.

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On system panel board there is a reset button that states RESET .You'll need a paper clip [opened ]toreach in little hole and reset .Or you can jump circuit board by jumping #15 and #16 together to ck board.21 coach warranty?? Safe thing call for A/H service

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  • 3 weeks later...

I am having a problem again with my Aquahot , model AHE 100 12vdc. The burner will not start. Found that the 15 amp fuse (f) was blown. Replaced but the Aquahot still does not start. Checked that the relays for the zones are all good by turning on the thermostat control for zone 1 (living room, kitchen)  - good. And then for zone 2 (bedroom) and then separate bathroom heater switch - everything good. Fuse (f) still good. Then when I have the Aquahot switch turned on (no the burner does not fire) and the on light is illuminated in the switch and then I turn on the bedroom zone (fan is working) within 30 seconds or so fuse (f) will blow.  The fuse does not blow if I only turn the Aquahot hot switch to “on” to start heating water no matter how long I leave it on (but the burner does not start). The fuse does not blow if I turn on the zone 1 thermostat, only blows when I turn the bedroom zone 2 thermostat controller on. Could the relay board be shorting out?

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