antifreeze/heat transfer fluid leak from AH - Printable Version
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+--- Thread: antifreeze/heat transfer fluid leak from AH (/showthread.php?tid=8770)
RE: antifreeze/heat transfer fluid leak from AH - Gem930 - 12-04-2025
Tyler,
I just went through your exact issue with my 2002 coach (#639). At first I thought I was lucky and it was only the overflow nipple, I re braised it in place, and….. Still leaked! Then I found out the neck itself was loose (or it loosened it re braising the nipple). I pulled the entire unit and took it to a radiator shop to fix the filler neck. I got it home and pressure tested it and found a leak under the coil and heat transfer mastic. I peeled the coil back thinking I could fix the leak and determine that the entire tank was just falling apart and rotting away. $4500 later I had a new tank from heat my RV and things seem to be working! Of course, with the new tank, I now have an internal coil and have to use the megabucks heat transfer fluid. All in all I feel like it ended up being a worthwhile repair/upgrade, just kind of expensive. I would not say replacing the tank is an easy ordeal, but it is certainly doable with basic plumbing and electrical skills. If you have any questions from an amateur, who did it himself, feel free to give me a call. Gregg - 530-228-5399. I actually found this thread because I have a question about exhaust for the aqua hot , but I will start another thread so as to not dilute any info here.
Tyler,
I just went through your exact issue with my 2002 coach (#639). At first I thought I was lucky and it was only the overflow nipple, I re braised it in place, and….. Still leaked! Then I found out the neck itself was loose (or it loosened it re braising the nipple). I pulled the entire unit and took it to a radiator shop to fix the filler neck. I got it home and pressure tested it and found a leak under the coil and heat transfer mastic. I peeled the coil back thinking I could fix the leak and determine that the entire tank was just falling apart and rotting away. $4500 later I had a new tank from heat my RV and things seem to be working! Of course, with the new tank, I now have an internal coil and have to use the megabucks heat transfer fluid. All in all I feel like it ended up being a worthwhile repair/upgrade, just kind of expensive. I would not say replacing the tank is an easy ordeal, but it is certainly doable with basic plumbing and electrical skills. If you have any questions from an amateur, who did it himself, feel free to give me a call. Gregg - 530-228-5399. I actually found this thread because I have a question about exhaust for the aqua hot , but I will start another thread so as to not dilute any info here.
RE: antifreeze/heat transfer fluid leak from AH - Pluto - 12-04-2025
I've been in contact with the folks at heat my rv and we're going to be ordering a complete rebuilt unit from them. We would have had it ordered by now but have been emailing back and forth with pictures that they need in order to get us the exact unit.
We're going to be keeping the Beckett controller and ignition system since it seems to be working properly, plus it will save us $980.
Not sure on exact price yet with tax and shipping but the unit itself is $8,000 with a $2,000 core charge on top of that.
I'll be keeping this post up to date as we find out more.
I really appreciate all of the comments!
RE: antifreeze/heat transfer fluid leak from AH - Pluto - 12-07-2025
Well, now I'm in a pickle and don't know what to do. Luckily we haven't ordered the new unit yet.
Since the original diesel control unit was replaced with the Beckett unit the original wiring has been cut and modified.
I don't really want to hack up an new unit just to install the beckett unit when we can (or could have) simply install the original controller. The problem is i don't know how the original controller was wired because all of the original plugs have been cut off
I want to return everything to OEM so we and whoever owns the coach next won't have to try and decipher how everything is supposed to work together.
Can anyone tell me what wiring we're going to have to move from the factory harness to the new unit so it will work?
I know that the oem diesel burner controller is expensive but it would have been so simple to switch out. Why make something so much more complicated than it needs to be?
Thank you,
Tyler
RE: antifreeze/heat transfer fluid leak from AH - Trainer - 12-07-2025
Tyler, call me, Rudy Legett 713/818-3234
RE: antifreeze/heat transfer fluid leak from AH - Pluto - 01-23-2026
After a month of waiting, we began installation today. Our new aquahot came in last Friday, but we had an unexpected loss in the family and had to postpone the installation until this weekend.
We spent all day on it and made some good progress, but got some more to do tomorrow. The two units are pretty much identical but there are a couple small differences. There is a green, a black and a red wire that goes through the case and to a sensor or something above the thermostat switches, however there is no hole in the no unit, so i have to figure that out.
We filled the unit with about 13 gallons of transfer fluid and have to top it off tomorrow as well as make sure all of the pumps are primed. We also have to get the unit wired, but hopefully we can get it finished up without too many issues.
Here is a couple of pictures of the unknown sensor and wiring that I have to figure out. It's not in the wiring diagram so I'm not sure about it.
RE: antifreeze/heat transfer fluid leak from AH - Pluto - 01-23-2026
Here is a picture of the unknown sensor and wiring that I'm not sure about. It's not in the wiring diagram and the hole that the wires pass through isn't in the new unit so I don't know.
RE: antifreeze/heat transfer fluid leak from AH - Pluto - 01-25-2026
We had ordered 17 gallons of Century heat transfer fluid from camping world to fill up the new unit, however several of the gallon jugs were nearly half empty and we didn't have enough to fill the unit completely. So instead of being able to finish the project yesterday, we had to drive 2 1/2 hours to St George yesterday to pick up 5 more gallons.
Regardless of the setback we were able to finish up the installation today!
We got all of the heating zones primed and blowing heat, we have lots of hot water, both the diesel and electric heaters are working and the engine pre-heat circuit is pumping like it should (i don't think it was working before).
The only problem that we're having is that the original thermostat in the bedroom and the one for the living room have quit calling for a ground signal and have to be replaced, that's next on the list.
I did have to call Rudy once for a simple question, but all in all I'm pretty proud of our work!
Cost breakdow:
Remanufactured AH with new OEM diesel burner controller - $10,986.85 (before $2,000 core charge)
23 gallons of Century heat transfer fluid - $539.00
Miscellaneous fittings, pex pipe, tools, etc. - ~ $200.00
RE: antifreeze/heat transfer fluid leak from AH - arcticdude - 01-25-2026
Good job! That’s only about $1000 more than it cost me almost 20 years ago to do the same job.
RE: antifreeze/heat transfer fluid leak from AH - Pluto - 01-25-2026
Thank you! I'm glad we decided to just replace the entire unit instead of trying to fix the old one.
RE: antifreeze/heat transfer fluid leak from AH - folivier - 01-26-2026
Just a guess but could that unknown wire be for the inside remote thermometer that shows the aqua hot water temperature?