Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 13, 2025 ...

Aquahot Diesel burner doesn't work

January 08, 2015, 01:36:39 pm

We just bought Shadow Beast late in November, so we're still working through the learning curve in soon many different areas.  I've managed to figure out most of the problems/questions by reading a lot of pre-existing posts and digging through the tech manuals that came with the rig.

We knew the Aquahot needed a new diesel burner, but that the electric worked fine.  After the marathon drive back to VA from Texas, we took the rig to the only Aquahot Authorized service location in Virginia and they replaced the burner and found that the electric eye (flame senser?) was bad as well.  Diesel burner was working perfectly after we picked it back up, but after refueling and driving down the road a bit the diesel burner refused to stay engaged.  Turn the Aquahot "Diesel" switch on, and it illuminates then turns itself off after 20-30 seconds.  The manual indicates that this means there is a "fault".

I seem to recall reading/seeing that you should not have the diesel burner on while fueling and that may have happened as we had not yet become aware of that sensible restriction.  Is there a reset somewhere that would need to be checked? Something that would trip and prevent the blower from running or something similar?

It's also possible that the Aquahot may have had the "Engine" option engaged while driving (again we hadn't dived into Aquahot details yet), could that have tripped something?

I did find a post that seemed to indicate that the electric heating option can overheat the system so that the diesel burner will not run until a reset located on the Aquahot unit under the access panel for the burner is pushed.  I tried to reset that and I *think* I found/pushed the reset mentioned after cooling the entire system, de-energizing the entire electrical system etc, but there was no change.  The Aquahot on our 1998 u320 4200 is readily accessed by pulling out the two slide outs in the main storage bay and taking off the panel.  I then removed the stainless side of the unit, and then the small square stainless plate that looks like it covers the burner.  There were 3 round components above and to the left if I remember correctly and one of them had a small raised red square that I pushed, though I did not feel any motion/click etc.

Any advice/tips would be greatly appreciated.   

James and Susan (Alex and Elizabeth)

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #1 – January 08, 2015, 01:50:54 pm

James,

If the problem started shortly after refueling I would think you may have picked up some bad fuel in the A/H.  I would look at putting a new fuel filter on along with replacing the nozzle. If either is stopped up not allowing for a flame it will trip out. This is the cheep simple things to start with. One of the other experts will chime in with more things to look at.

Did you have a problem with your engine loosing power also?  Check the engine fuel filter also.

Pamela & Mike

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #2 – January 08, 2015, 02:06:07 pm

Engine seems to be fine.  The fuel filter for the Aquahot is where?  I assume it's in the unit itself? I really should take some good pictures of the Aquahot unit itself with the covers off etc so I have them handy for reference.  It's a tad chilly this morning so I haven't gone down there to look at it yet (want to have hot water for a shower so I've been keeping the basement closed to avoid letting in freezing air).

James

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #3 – January 08, 2015, 02:30:30 pm

Howdy James,  On our '00 U320 the AquaHot Filter is located in the Driver Side very front bay(in front of the wheel).  The filter is mounted up high, towards the front of the bay.  Here's a link to Roger's great website for AquaHots:  http://forum.rvhydronicheaterrepair.com/forum.php 
Lots of good troubleshooting and help from Roger (FT owner)
Good Luck, Dave A

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #4 – January 08, 2015, 02:48:54 pm

James,

Your filter could be where Dave described or on some they are mounted under the removable cover. If inside it will be mounted on the wall above the burner head. 
By the way just because your diesel side is acting up your electric side should work just fine.
Pamela & Mike

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #5 – January 08, 2015, 02:59:53 pm

You have a number of issues but the filter is an easy fix. You did not say what year but the igniter is sometimes an issue and is not a hard fix but you can not tell until you remove it.  Hopefully you can get it working otherwise the guys up in PA can fix it up for you in Green Castle.

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #6 – January 08, 2015, 04:14:46 pm

James,

My A-H fuel filter is in the A-H cabinet on the curb side wall. 

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #7 – January 08, 2015, 04:16:34 pm

Currently in Savannah Georgia, heading out on the Disney cruise we promised the kids for the last three years (while we've been dealing with the asbestos contamination of our house etc ) on Sunday! :-)

After we get back we'll be staying here for a little bit then probably heading back north to take care of house related issues and getting ready for the trip down to FOT for our major renovation on Feb 24th. 

Does anyone know a decent Aquahot service location in Georgia, the Carolinas etc? 

@John S: Green Castle PA?  Not familiar with the guys referenced?

I did just crawl in to take some pictures, I also found that two of the three wiring harness plugs on the rear wall of the Aquahot seemed to be partially unplugged so I plugged them both the rest of the way back in.  After closing everything up and coming back inside I tried turning on the "Diesel" option again and this time the light stayed lit for WAY longer, maybe 5 - 10 minutes.  I was getting really hopeful that it might be working right, but then it did finally go dark again.  Now when I try to turn on the "Diesel" option again it stays lit for about 21 seconds and then goes dark again. 

I'll post the pictures below, but the filter (assuming that what I think is the filter in fact IS) looked pretty clean.  The rest of the system seems to be working perfectly, "115AC" and "Engine Heat" options seem to work fine, and the hot water and all the thermostat and heat exchangers in the interior seem to be working/blowing correctly.

James

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #8 – January 08, 2015, 04:33:23 pm

http://www.foreforums.com/index.php?action=media;sa=album;in=399

Does that provide access to the album of Aquahot images that I uploaded? Not sure if anyone else has access to that url, but if so that has the pictures of the Model/serial plate, what looks to me like a clean filter, and what seems like it should be the temperature monitor components with the what I think is the over heat reset button that I tried pressing to get the diesel burner to work.

James

Quote Selected

Re: Aquahot Diesel burner doesn't work

Reply #9 – January 08, 2015, 09:15:20 pm

James,

Google Aqua Hot Forum and click on the link.  Register for free and ask the question "My burner turns on, does not fire and faults".  Roger Berke will respond with a link for the proper trouble shooting info.

You may need to join the premium section of the forum which is a payment of $5, I think, or purchase parts from the parts website at the top of the forum home page.  Instructions are detailed and take hours to write and edit, hence the need for a small cash flow to cover the effort.

Roger Berke is the best AH service person in the US that does not work directly for AH.  The AH phone tech folks are also very good and available during the business day.

The filter is an inline fuel filter that does look clean.

The thermostats are the control thermostat with orange and white wires and the high limit thermostat with a reset button.  The high limit thermostat interrupts the fuel solenoid circuit preventing firing by not allowing any fuel flow.  It will reset.  If popped and the burner is faulting then resetting will restore burner operation.  If still faulting, high limit thermostat is not the problem.

The fuses are for the burner, fans and pumps.  The relays are for the living room, bathroom and bedroom.  The wires on top are for the thermostats, interior switch and the interior switch light.

Authorized Service Centers are shown on the AH website.  Click Service Help at the top of the home page, click on the map, zoom in on the area where you are to see the locations.

Quote Selected