Aqua Hot 400 diesel burner operates properly 2-4 hours then goes to fault

[BBC Cobra]

Bought our DX-3 new about 14 months ago, used the electric element for trips totaling about ten weeks during that time. Now we are in Tucson AZ and low temps in the high 20’s to mid 30’s and need the diesel burner to work. It will cycle properly for 2-4 hours then trip out, the green light in the burner on/off switch goes out. I have gone and checked the control panel at the unit after it trips and the LED’s are green, none red. I can turn the burner switch off for 5 seconds as the manual says to do and turn it back on and the burner will again cycle properly for 2-4 hours and trip again. I have also hit the reset on the control panel earlier today, but it tripped again later. My fuel talks are at 3/4 and the fluid reservoir is about midway between the hot and cold level marks and I bled a little air out that was visible in the tubing. Any helpful suggestions much appreciated.

[joet19711]

BBC. Here are a couple of tips:
Go to aqua hot.com and download the service manual
After a successful run cycle, the expansion tank should be on the full mark
If not add boiler fluid up to the full mark
Are you handy with a meter.
Take the right side cover off, look at the diagram, and find the hi temp thermostat, it is reset able you can push the reset or it maybe going bad.
But my guess is that you may not have enough fluid and it goes out on high temperature or it is bad.
Give it a look

[steverkemp]

Here are two links for both the green propelyne glycol and a fluid transfer hand pump.

Century Chemical TF-1 Heat... https://www.amazon.com/dp/B01BDWQXM2...p_mob_ap_share

Carbyne Fluid Transfer Pump - Gallon https://www.amazon.com/dp/B01N0X03T2...p_mob_ap_share

Good luck!

[FOURWHL]

Has the burner/nozzle had it's annual service? I believe things are supposed to be cleaned out every 12 mo

[bclemens]

Originally Posted by FOURWHL

Has the burner/nozzle had it's annual service? I believe things are supposed to be cleaned out every 12 mo

^^This^^

We just had them in there for training and the #1 question they ask..."have you run it, did you do the service?". They say just like anything, it needs to be used or things start to gum up.

He said we never really have any issues with someone in colder climates, they always using them. We suggest turning them on to run the furnace and water heater at least once a month. When we see most problems is when someone lives in the south, they never use the furnace (just the water heater) and then they take a trip up north and wonder why the furnace that hasn't been run in over a year, isn't working right. (His words by the way, not mine).

He did point out, the thermostat is the #1 thing that can go out and also a check valve for the fluid can seize up after non-use. And burner nozzle.

[Worm43]

I had the same issue among others. There is a safety button inside the right side cover. It needs to be pushed in for the deisal burner to work. Mine kept coming out even after taping it and pushing the cover in. I had to it taken off eventually. It works great now.

[BBC Cobra]

Guess I will get by on the electric element and the fireplace until I get home, then change out the filter and nozzle. Then if the problem persists, check out the high limit switch etc. Thanks for the feedback.

[Wolf Alaska]

Originally Posted by BBC Cobra

Guess I will get by on the electric element and the fireplace until I get home, then change out the filter and nozzle. Then if the problem persists, check out the high limit switch etc. Thanks for the feedback.

Ron & Jane, my experience w/AH is electric won't heat when Temp is less than 40 or 45. Also, low batteries voltage will trigger low voltage fault & shut down AH heat. Than can be reset with toothpick in small port below red light on control panel.
How about ruined batts & no heat @ 20 degrees?
Happened to me...first night.

[BBC Cobra]

We are on shore power not batteries, but batteries are topped off. The electric element will work at pretty much any temperature, it just isn’t capable of creating enough heat to satisfy the thermostat setting (72) when outside temps drop into the 40’s or lower. Thanks

[Wolf Alaska]

Originally Posted by BBC Cobra

We are on shore power not batteries, but batteries are topped off. The electric element will work at pretty much any temperature, it just isn’t capable of creating enough heat to satisfy the thermostat setting (72) when outside temps drop into the 40’s or lower. Thanks

In my previous post, I was relating my experience with Aqua-Hot in cool temps. At Deer Run, in Oct., we were on shore power & the coach was heating on AH electric for fuel. Overnight, the temp dropped to 38 degrees. I awoke @ 5:30 AM to a cold coach, IAT @ 62 degrees. I got up, went outside to check the control panel. Everything was OK.

I guessed and switched over to diesel and the heat started up OK in about 8 minutes, then overheated the coach.

Called AH, & a very nice tech told me that below 40 degrees, the central control will shut off the air blowers if running on electric. I got the impression that domestic water would still be heated. She said, always switch over to diesel if OAT is 40 degrees or less. So, I don't think the electric heat will work at any temperature, disagree with you on that point.

Keep in mind, that is it as far as heating. The Heat Pumps on the A/Cs don't supply much/any heat when OAT is less than 40 degrees. I may put some compact space heaters from 1 or more of my other RVs as back up heat. But that seems kind of retrograde for a complex machine like a Grand Sport GT.

BTW, how many hours on your AH unit? Mine has 1493 hours. I have no idea of when/if it has ever been serviced. When did you replace the burner screen and the fuel filter? I have my new ones in the AH compartment, but I haven't been trained how to do it. I won't do it until I see a trained tech do the service. My AH runs just fine. If I go messing with it, it might not !

[Wolf Alaska]

To:Ron & Jane - 'Happy Campers'
2018 Dynamax DX3 37TS
Southeastern Tennessee

I tried to reply to your recent post, in an attempt to help you while you are out in the cold temps with no heat.

But I could not because for 2 days, each time I tried to log on to the forum, I was met with the Warning Flag that I was using an invalid email address.

Yet, the forum was using that email address to send me emails at the same time !

I sent a message to the Admin, & was told to delete the cookies. I have never seen a way to delete cookies when logged in to Internet on my Samsung fone. I eventually reset my password, etc. jumped through the hoops and successfully logged on 25 minutes ago.

I'm in North Alabama & often in SE Tennessee around Monteagle and Signal Mountain. Just discovered a new CG near Tracey City that I want to explore. Perhaps we will meet on the road soon.

Best regards, Wolf

[William Thompson]

Our unit has been working great until last night when temperatures outside dropped below 20 degrees, now the burner won't light, switch goes green for a minute then goes out. Is it possible for diesel fuel to get so cold it won't go to the furnace? Any suggestions? Panel lights are green, just cannot get burner to light.

[joet19711]

Originally Posted by William Thompson

Our unit has been working great until last night when temperatures outside dropped below 20 degrees, now the burner won't light, switch goes green for a minute then goes out. Is it possible for diesel fuel to get so cold it won't go to the furnace? Any suggestions? Panel lights are green, just cannot get burner to light.

Not that this is your problem, but it is a good video to watch

https://www.youtube.com/watch?v=nj_BqehNu64

[BBC Cobra]

Diesel fuel can gel in cold temperatures below freezing, the paraffin in the fuel crystallizes and accumulates in the filter effectively blocking it. There are fuel additives available to prevent this, or you can add some #1 diesel fuel.

The problem I was having with my unit turned out to be a bad control board on a one year old unit that had only been used a couple of times, it cost me $500+ before I found a service facility that could figure out what was going on, no thanks to AH whose standard line is ‘do the annual service’.

[Worm43]

We have used our AH electric in temperatures down to 35. Is slightly chilly in the morning but it still runs. I supplement with two electric heaters.You are correct, heat pumps don't even turn on under 40.