Aquahot 100-02s leaking coolant

[joefromperry]

I hope I do not have to pull the whole unit out. Okay, here's the situation. In my 2003 Signature, which I've owned for about a year, the aquahot was working fine. Then last summer/early fall, I started losing coolant. I discovered the overflow tube to recovery tank was cracked, so I fixed it. Then I also found that one of the heater hoses to the front zone had cracked near where it comes from the circulation pump. I replaced that section and all was good all winter, both in cold Ohio and warm Florida. When we got back to Ohio in early April, running the aquahot for heat while getting some things done in the coach, I discovered I was losing coolant again. (Domestic hot water was fine.) I found it leaking from where the exhaust pipe exits the bottom of the unit. After consulting on the rvhydronics site with Roger Berke, I dried off everything in and around the aquahot unit and the filler neck. Then I placed paper towels all around the filler neck, and also on the base of the unit under the plumbing and the burner. I refilled the coolant and replaced the radiator cap (which was new) and started it up again to see where the paper towels would start getting wet. After a short while, the paper towels started getting wet along the base of the metal wall that separates the burner/plumbing area from the boiler area; the towels around the filler neck didn't show wet. This is what led me to believe the problem had to be on the boiler side of the wall, which can only be accessed by removing the unit. Maybe someone here might have some insight as to what I might try or look at before I pull the whole thing out unnecessarily. Thanks.

[Paul Busch]

I had this problem with my 05 sig. turns out nothing but a crack in the plastic return line fitting on the bottom side. Replaced it with a brass fitting and worked as should since.

good luck

paul b

[Ivan K]

I was in a similar situation years back and after checking everything that was accessible, I pulled the unit out to find a pinhole leak around the exhaust port. Before removing the tank, which is a considerable effort, I poured a quart of boiler sealant fluid into it and it sealed the leak after few cycles running it outside of the rig on electric. Probably 4 or 5 years ago and no more leaks. No issues with sticking valves etc. Not saying that it is an ultimate fix, which it isn't, but it worked for me. Of course, I could have done it without removing the unit but at that time I did not know where the leak is and wanted to find it, hoping to find an easy fix. Ours is the one with external water loop and yours is probably too so I don't worry about fresh water contamination. Just my experience...

[Busnut]

 Rvhydronics site with Roger Berke sells these.  Mine was leaking around the base of the filler neck. I put one on mine. Fix my problem. I didn't even take the cover off. The bottom clamp is a shrink wrap hose clamp.

Edited May 26, 2021 by Busnut
more information

[joefromperry]

17 hours ago, Ivan K said:

I was in a similar situation years back and after checking everything that was accessible, I pulled the unit out to find a pinhole leak around the exhaust port. Before removing the tank, which is a considerable effort, I poured a quart of boiler sealant fluid into it and it sealed the leak after few cycles running it outside of the rig on electric. Probably 4 or 5 years ago and no more leaks. No issues with sticking valves etc. Not saying that it is an ultimate fix, which it isn't, but it worked for me. Of course, I could have done it without removing the unit but at that time I did not know where the leak is and wanted to find it, hoping to find an easy fix. Ours is the one with external water loop and yours is probably too so I don't worry about fresh water contamination. Just my experience...

Please tell me more about boiler sealant fluid. I've never heard of it. Brand? Source? Thanks.

[joefromperry]

17 hours ago, Busnut said:

 Rvhydronics site with Roger Berke sells these.  Mine was leaking around the base of the filler neck. I put one on mine. Fix my problem. I didn't even take the cover off. The bottom clamp is a shrink wrap hose clamp.

This might be the way to go if I find the leak at the cap, but $240 is a bit high for me.

 

[Ivan K]

2 hours ago, joefromperry said:

Please tell me more about boiler sealant fluid. I've never heard of it. Brand? Source? Thanks.

This is what I used and there are other types. This one is brown but I saw them clear as well, I believe in Home Depot.

 

[joefromperry]

My aquahot uses regular green antifreeze instead of boiler fluid. I wonder if it matters, or if regular radiator stop leak would work. Or if I could just replace all my fluid with boiler fluid if I have to drain it anyway to remove it.

 

[Frank Bergamo]

Joe,

 

any good radiator repair shop can make up the filler neck, all you need is a piece of silicone hose and two hose clamps and you are good to go. You will have to drill a small hole in the cabinet to get to the lower clamp with a screw driver. Very doable and economical. Hope this helps.

[Ivan K]

It'll depend on where your leak is. I had a leak at the filler neck and an other one at exhaust pipe at different times and got rid of them my way. Years later, still good.. There are different ways and if you search the AH posts, you will get to number of them. Some cheap, some complete rebuilds. I mixed the sealer into the green antifreeze and it worked for me. It was just a drip-drip leak. It was a final attempt to avoid welding which would have been a definite and correct but far from effortless fix with the coil wrapped around it.

[Dr4Film]

Another excellent product which I used on my leaking side engine radiator is IronTite All Weather Seal which you can buy from Amazon.

I highly recommend it!

https://tinyurl.com/x77srbk