CaptPat Posted May 25, 2023 Share Posted May 25, 2023 (edited) I have an AH 450-DE2, annual service was performed in March 2023 and the unit has run several times since then without issue. I normally store the coach without power and the batteries disconnected. Today I powered up the coach and noted that the Low Battery Voltage Fault light was not lit, as it normally is following power restoration. I depressed the Low Voltage Reset with a non-conducting insert from a Bic Pen just in case the light was burned out. I turned on the Diesel Burner in the coach, the green light came on and the AH motor started as normal. However, it would not ignite, the following lights on the control board panel were lit green: Low Temp Cutoff Status, Diesel Burner Status, and Heating Status. After about 30 seconds the green light inside the coach for the Diesel Burner extinguished. After turning off the Diesel Burner switch the unit runs for several minutes and then shuts down. I've tried the sequence several times with the same results each time. I also tried the electric element, the light on the switch in the coach turns green, I observe an increase of 11A AC on my power monitor, and the Electric Heating Element Status light is green, though no other lights are lit on the control board. The boiler water overflow tank level is filled to about halfway between the hot and cold lines, external temperature is 70 degrees. I called AH and they apparently are only responding to email inquiries, no response so far. Any thoughts or suggestions on the next steps? TIA Edited May 25, 2023 by CaptPat Link to comment Share on other sites More sharing options...
GranPrix Posted May 25, 2023 Share Posted May 25, 2023 The symptoms sound like the flame sensor is bad. My diesel switch has a red light strip in it and the red light started flashing instead of steady red, flame sensor was the culprit. Link to comment Share on other sites More sharing options...
96 EVO Posted May 25, 2023 Share Posted May 25, 2023 Did the boiler fluid eventually get hot on electric? Should take 45- 1hr. The stir pump doesn't run on electric, until I 'believe', you run hot water. Link to comment Share on other sites More sharing options...
CaptPat Posted May 25, 2023 Author Share Posted May 25, 2023 12 minutes ago, GranPrix said: The symptoms sound like the flame sensor is bad. My diesel switch has a red light strip in it and the red light started flashing instead of steady red, flame sensor was the culprit. I'm not getting any red lights. The issue with the low voltage light makes me suspect something in the control board, but I'm not ready to purchase a replacement yet. Just now, 96 EVO said: Did the boiler fluid eventually get hot on electric? Should take 45- 1hr. The stir pump doesn't run on electric, until I 'believe', you run hot water. I didn't let it go that long. Link to comment Share on other sites More sharing options...
96 EVO Posted May 25, 2023 Share Posted May 25, 2023 Their online service manual's have a pretty good troubleshooting section. Could be several things! Link to comment Share on other sites More sharing options...
vito.a Posted May 25, 2023 Share Posted May 25, 2023 I agree with Gary. You can run through the troubleshooting procedures but I would probably ohm check the flame sensor. Then call Hannah Carrillo at "Heat My RV" and order a new flame sensor. They are relatively inexpensive and easy to change. If you need advice, John is the tech expert but Hannah will get the parts out to you. Hannah Carrillo 720.448.1068 Good luck! Link to comment Share on other sites More sharing options...
CaptPat Posted May 25, 2023 Author Share Posted May 25, 2023 (edited) Ran the electric element for an hour, water got hot electric element and heating status light both green. I’ve looked through the manuals, could be a number of things I was hoping to narrow the list of candidates some. I’ll start with some of the easier things first. Still bothered by the low voltage light, is it a separate issue or part of the diesel burner not firing. Edited May 25, 2023 by CaptPat Link to comment Share on other sites More sharing options...
96 EVO Posted May 25, 2023 Share Posted May 25, 2023 Pretty sure your house batteries would need to be down about 11.0V for the red low voltage light to come on, or, are you shutting down the battery disconnect, and used to see it on? Link to comment Share on other sites More sharing options...
CaptPat Posted May 25, 2023 Author Share Posted May 25, 2023 44 minutes ago, 96 EVO said: Pretty sure your house batteries would need to be down about 11.0V for the red low voltage light to come on, or, are you shutting down the battery disconnect, and used to see it on? It’s the latter, as I said in the OP Link to comment Share on other sites More sharing options...
96 EVO Posted May 25, 2023 Share Posted May 25, 2023 Ok, so if the battery disconnect switch kills power to the unit, where does the power come from to illuminate the red light 🤔? Link to comment Share on other sites More sharing options...
CaptPat Posted May 25, 2023 Author Share Posted May 25, 2023 When you restore power the light is illuminated and it needs to be reset. That’s how it has operated since 2009. Link to comment Share on other sites More sharing options...
96 EVO Posted May 25, 2023 Share Posted May 25, 2023 Ya know, I don't recall ever pressing that reset, and I've turned off battery disconnects, replaced batteries..... Link to comment Share on other sites More sharing options...
CaptPat Posted May 25, 2023 Author Share Posted May 25, 2023 Well doesn’t look like AH will be of much help, here’s their response Thank you for reaching out to Aqua-Hot! I am sorry to hear you are experiencing difficulties with your Aqua-Hot, there are a couple options that you can do, the first option we would recommend is that you have an Authorized Service Center look at the unit and troubleshoot the issue. If you are not wanting to go that route, another option would be to go to Aqua-Hot Manuals (aquahot.com) and review your manual for more information or visit our Aqua-Hot - Frequently Asked Questions (aquahot.com) for more information. Link to comment Share on other sites More sharing options...
timaz996 Posted May 25, 2023 Share Posted May 25, 2023 I would guess they get so many questions that is their first response. Link to comment Share on other sites More sharing options...
CaptPat Posted May 26, 2023 Author Share Posted May 26, 2023 I had heard on this forum and others that AH Tech Support was... well useful. I guess that changed with their new corporate name. Link to comment Share on other sites More sharing options...
Ivylog Posted May 26, 2023 Share Posted May 26, 2023 I have a hard time seeing which lights are on… can at night. Are you sure no fault lights are on? Unlike the electric side, there are many things that stop the boiler lighting: Easiest one, low on fuel… less than 1/4 tank not these gauges are accurate. Blower motor running means you have fuel and air so why no spark? Easiest possibility is the high temp Tstat that can be pushed to reset behind square metal box near the top once you remove the covers. From here it requires removing the boiler motor. Link to comment Share on other sites More sharing options...
Dr4Film Posted May 26, 2023 Share Posted May 26, 2023 I would never rely on Aqua-Hot in Colorado to provide ANY useful help. That is only my humble opinion. The only people that I trust so far are Roger Berke, John Carrillo and Butch, the Aqua-Hot service tech at Hitching Post of Ocala where I have my unit serviced regularly. I won;t let anyone else touch my Aqua-Hot. There could be a myriad of reasons for your Aqua-Hot to default and shut down. Each time it does that, you build up extra un-burnt diesel in the chamber. Once the unit does fire up you will have LOTS of white smoke until all of that diesel has been dispersed. My suggestion is to run through the troubleshooting steps in the manual for your specific model. That will narrow down the possible problems versus shooting form the hip. Link to comment Share on other sites More sharing options...
CaptPat Posted May 26, 2023 Author Share Posted May 26, 2023 7 minutes ago, Ivylog said: I have a hard time seeing which lights are on… can at night. Are you sure no fault lights are on? Unlike the electric side, there are many things that stop the boiler lighting: Easiest one, low on fuel… less than 1/4 tank not these gauges are accurate. Blower motor running means you have fuel and air so why no spark? Easiest possibility is the high temp Tstat that can be pushed to reset behind square metal box near the top once you remove the covers. From here it requires removing the boiler motor. It's dim enough in the bay to clearly see what lights on the control panel are lit and their color. I have a full fuel tank and the AH has worked fine on several occasions following completion of annual maintenance. I'm beginning to think that it's not getting fuel, I don't smell or see evidence of diesel after each aborted cycle. Other possible culprits after the T-stat are the fuel solenoid and fuel pump. I may check a few simple things like the T-stat and flame sensor, we'll see after I talk to a local tech today. There are a few T/S procedures in the manual that I don't have the equipment for, there's only so far I can go. Link to comment Share on other sites More sharing options...
Ivylog Posted May 26, 2023 Share Posted May 26, 2023 (edited) Why this frigging site won’t publish my posts is one of the reasons I rarely post on here… won’t publish a second post. Anyway…I had the same situation and the above was the picture I added to my detailed post. Good Luck Edited May 26, 2023 by Ivylog Frigging site won’t publish my posts Link to comment Share on other sites More sharing options...
CaptPat Posted May 26, 2023 Author Share Posted May 26, 2023 Maybe it's fixed???? I disconnected the power and batteries overnight. Today I connected the power and the batteries and all seems to be operating normally now. Including seeing the low voltage light, which I reset at the panel. As expected a lot of smoke initially was reduced significantly during the first burner run. As I read the manual the low voltage light and reset are operating as expected, though the manual says that as an alternative the low voltage light can be reset by cycling the diesel switch in the coach to the off position for 30 seconds then turning it back on. I've never done it that way so I can't confirm it. I'm always a bit suspicious that cycling the power to the unit is a final fix, will be monitoring closely in the near future, and hopefully the situation is resolved. I did talk to an AH tech about this after is up and running, and he thought maybe the high temp thermostat or possibly the igniter coil might be the culprits. Fingers crossed at this point. Link to comment Share on other sites More sharing options...
Ivylog Posted May 26, 2023 Share Posted May 26, 2023 While a high temp Tstat can be reset, it can’t do it by itself. Glad it’s working now! Link to comment Share on other sites More sharing options...
amphi_sc Posted May 27, 2023 Share Posted May 27, 2023 A few years ago my diesel burner functioned sometimes and other times it would go thru the cycle you were describing of not lighting and shutting off after the "cool down" period. Electric worked fine. Drove me crazy for a few weeks. Turned out to be a flakey cut off sensor. My unit has two, one for the diesel burner and the other for the electric element. Next time yours fails you could listen for the ignitor to click, a flame ignite but then shut off which seem to point to a flame sensor. OR you get motor running, clicking on the ignitor but no ignition which would imply to me no fuel. As I understand it, the cut off sensor prevents the fuel solenoid from opening so swapping the electric & diesel cut out sensors could narrow it down to a bad sensor vs bad fuel solenoid. Anyway, a new cut out sensor fixed mine, and as they were cheap and both the same, bought two with the theory the remaining "good one" could likely fail too being the same age. BTW, mine is an 03S and thus not the same model as yours so things could be very different. FWIW Link to comment Share on other sites More sharing options...
Dr4Film Posted May 27, 2023 Share Posted May 27, 2023 1 hour ago, amphi_sc said: Anyway, a new cut out sensor fixed mine, and as they were cheap and both the same, bought two with the theory the remaining "good one" could likely fail too being the same age. BTW, mine is an 03S and thus not the same model as yours so things could be very different. Are you referring to the thermostats in the 100-03S when you call out the term "cut out sensor" as I have never heard of that term being used when discussing Aqua-Hot systems? If you are, then to clarify for others that aren't so familiar with the Aqua-Hot systems and models, the earlier models, 100-01, 100-02 and the 431/12 had FOUR thermostats mounted to the front side near the tank under a cover. Two are for the diesel system and two are for the Electric Assist system. One of the two is called the Control Thermostat which regulates when the diesel (190F) or electric (198F) comes ON and then OFF. The second of the two is called the High Limit Thermostat which is there to prevent either the diesel or electric from running wild ALL the time. Those two are set for 230F. Then when they came out with the 100-03 and 100-04 models, they only had three thermostats and one float switch. One thermostat is used for controlling when the diesel or electric turns on or off. The other two are High Limit thermostats, one for the diesel and one for the electric assist. The float switch is self explanatory. When the boiler fluid gets too low it triggers the float switch. Later, when they introduced the 400 series models which includes the popular 450D model, because the size of the boiler tank was reduced to 5 gallons the entire thermostat control system was changed and the interlock systems so if you have one of those models it''s best to download the manual at the Aqua-Hot website and read the manuals thoroughly to understand how the system works. Personally, I am not a fan of the 450D model due to it's size and capacity. My Windsor came with a 100-01, then when that failed after being in service for a little over 4 years it was replaced with a rebuilt 431/12 which is identical to the 100-01 and 100-02. My current 06 Dynasty has the 100-04S model and I love it! Link to comment Share on other sites More sharing options...
amphi_sc Posted May 27, 2023 Share Posted May 27, 2023 By "cut out" I should have said limit. When it gets way to hot (or goes flakey) the limit cuts out or cuts off operation for safety. And my model, unlike earlier models, the electric and diesel kick in at the same lower fluid temperature. If I ever have to change I'd want a 600D. Hope I didn't thoroughly confuse people by mentioning what fixed my 100-03s. Link to comment Share on other sites More sharing options...
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