[glen]

Barclay, Call me between 8 and 8 central time. I have several resources to see if there is a fix.

Which high limit is being judged as bad, electric element or diesel burner?

Rudy Legett 7 one 3 8 one 8 3234

[Archived]

I was able to contact Roger Berke, the owner of the Aqua Hot forum and seller of all things Aqua Hot. He has forgotten more about Aqua Hot than most men know. As soon as his registration on this forum is approved, he will post on this forum.

So, stand by.

forum.rvhydronicheaterrepair.com

parts.rvhydronicheaterrepair.com

These are his very helpful sites for Aqua Hot and Webasto burners.

And, this site is top notch for all things Prevost.

[Archived]

your issue is a High limit thermostat ? I recently changed both thermostats on my unit after pretty much replacing many other parts in an attempt to remedy a problem . So what exactly is your issue if you do not mind sharing . Thank you

[Archived]

Roger is in. Password sent.

[Larry & Diane]

Rudy Legett asked me for more information about the Robertshaw thermostats that were used in Aqua-Hot model 431 heaters prior to serial number 98001.

The underling problem is that the matching thermostats were discontinued by Robertshaw about 10 years ago. They quit offering thermostats with the correct high limit temperature range. The 431 series of heaters were engineered to run at around 190 degrees. The high limit portion of the thermostats currently offered (from memory) have a maximum setting of 160 degrees.

Aqua-Hot had offered a bracket (not sure about current status) that would hold the current type of snap disk thermostats. There was no way that I knew of to hold the bracket tight to the boiler tank without completely disassembling the Aqua-Hot and welding the bracket to the boiler tank.

Sorry, no good answers.

– Roger Berke – http://www.Parts.RVHydronicHeaterRepair.com

[Archived]

Barclay, please call me.

[al]

Hi Guys, and thanks much for the help on this! What I was told is that the high limit/control thermostat was the problem, but it was a while back and I don’t remember which part of that thermostat is bad. I have the service manual so I can go through the testing, but I was going to see if I can just replace both. It’s probably the control side.

So Roger, will the bracket from Aquahot work, if I can find one? Or does anyone make it or are there plans? Or are you saying that it doesn’t work and the only way is to weld it to the tank?

Will call tomorrow.

Thanks again!

[Archived]

Sorry if I missed your response but the question is What was the issue that was related to the thermostats ? No heat , no hot water, or unit shutting down , or not starting up ? Would like to know what a thermostat replacement repairs . Thank you in Advance

[Shelly]

Y’all were wise to suggest I do some more diagnosis and get clear on the real issue. I am not finding a thermostat issue. The unit fires up and heats to close to 190 (measured using laser thermometer on the side of tank near the thermostat) and then shuts down just fine. During the heat up and after I turned on all three thermostats in the coach and turned the temperature to full high. Two of the three blow inside and also show temperatures of about 150 or so on the coolant circulating lines (measured on the outside of the pipes). The one other line does not heat up and does not blow in the exchanger in the coach. I’m not sure but it might be that that line has always had problems. Given that it neither circulates (pump not running?) nor blows air (fan not running), is it likely a fuse or relay or something else? Heck it could even be an interior theromostat issue. Off to do some more checking!

[Ronald]

I’ll share what I’ve figured out so far about replacing the old style rectangular Robertshaw (discontinued) thermostat units. Camco still makes thermostats that are VISUALLY identical to the old ones, but they no longer make ones with the right temperature settings for the AquaHot. It looks like I don’t need to do this, but what I would try if I needed to, would be to take either the original thermostat, or a new Camco thermostat, like 07843 ($16 on Amazon) and remove the thermostat units from their aluminum frame, and then mount the new snap disc type thermostats in the old frame. I’m sure it would take a little engineering/fabricating, and a few new holes, screws or rivets, but it seems possible and the parts are cheap enough that if I messed one up, I just try again. Then the frame could be mounted on the AquaHot using the original mounting stud on the tank. The control thermostat looks to me like a 6UEA3 (150 close / 190 open) and sells for around $12. from Grainger or other sources. Again, I haven’t tried this, but it’s what I would do if it turns out one of my old-style thermostats is truly bad.