[Pluto]

I just ordered some century heat transfer fluid to refill the overflow tank on the aquahot because the level has slowly been dropping. 

I thought it might have something to do with the heater running, but on closer inspection I noticed that there was a small puddle of fluid near the back of the unit.  Looking around some more i found that coolant had been running down the AH exhaust pipe and making a puddle on the ground.

I'm not seeing a leak around any of the external piping or pumps so I'm assuming that it's coming for inside of the unit itself. 

I haven't found much in the manual about a leak and or how to fix it.  I am assuming that it's going to be a major operation to fix the problem but I don't know.

Does anyone know or have an idea of what could be leaking on the inside of the aquahot? 

Thanks in advance,
Tyler

[Pluto]

I thought aquahot took heat transfer fluid but, I just read an older post from 2020 stating that our older units take regular engine antifreeze. Our coach is a 1999.

Is this accurate?

[Trainer]

A 1990 Aqua Hot with a row of fuses and 3 clear relays uses motor anti freeze.

Check overflow hose at filler neck for a leak. And check filler neck joint for a leak. Another possible leak could be at the electric elements.

[Pluto]

Thanks for the information, Rudy. How do I check the electric elements?

[Richard]

To add to what Rudy said.

It is VERY important to determine the source of the leak. Spending extra time diagnosing could save you thousands in repair costs.

This is going to sound stupid, but keep in mind that water runs downhill.

So starting with the area where the filler neck joins the tank, and including the areas where the electric heater elements screw into the tank, and finishing with the area where the exhaust pipe is welded into the tank, stuff some white paper towels. You are trying to isolate the leak. The green fluid will clearly show up on the white paper towel. The highest point you have a green towel is the likely culprit.

Find the leak first, and then we can talk about the best way to address it.

[Pluto]

Thanks Richard. I agree, but I don't know how to access any of that. It looks like the outside metal cover needs to be removed, but it is riveted all the way around.

How do I get access to all of that?

[Pluto]

I removed the small panel for the electric heating element and didn't see any sign of a leak there.

I also removed the rubber skirt around the filler neck to see if there was a leak there, but with the cover and insulation in the ways i wasn't able to get a look at where the filler neck meets the tank.

[Richard]

Stuff a paper towel into the opening around the filler neck.

And stuff one from down under up into the exhaust opening.

What we are trying to do is identify the leak before we conclude it is the most expensive one. The most expensive one occurs at the welded penetration where the Aquahot exhaust penetrates the drum that contains the coolant. That one requires the tank to be replaced. My experience is if the tank is leaking there, that the area around that penetration is rusted through, and patching one leak only results in another. It may be possible to fix that by welding a large scab patch over the area, but that also involves removal of the outer copper coil that handles potable hot water.

[hypoxia]

Why not use a coolant pressure tester available for loan at most large auto parts stores?

[Pluto]

OK, I will give that a try and report back.