Aquahot 400D bubbling fluid out of overflow

[DW_DX3]

Since we got to CO, with the Aquahot running on electric,the Aquahot has repeatedly emptied the entire reservoir tank out the overflow and onto the ground.

It's bad enough that I have lost a gallon of AF in a single day.

Watching it, it as if bubbles are coming from the tank and pushing fluid up and out. If I leave the cap open, it doesn't seem to do it.

We are not using the Aquahot for coach heat. Temp on the screen never goes over 185F. I have made sure the tank doesn't have air via the bleeder valve on top. Anyone else run into this issue?

As a side rant, this is the 4th problem on this trip of 1000 miles.

[DW_DX3]

Just to follow up on this, I have been working with Aqua-Hot on the issue, and the issue is a combination of high altitude usage, where water boils at a lower temperature, plus incorrect ratio of propylene glycol antifreeze in the system to start. With a correctly calibrated refractometer, the current concentration of propylene glycol is ~25%. This allowed the water around the heating element to boil, and send steam up the overflow, pushing the overflow liquid out with it. And since it was boiling off the water, that meant at the time it started, the concentration of propylene glycol was even lower than 25%. The manual states:

"A 50/50 mixture of propylene glycol / water ratio is recommended".

Which also explains why we ran out of hot water so quickly compared to what the manual says we should be getting, as well as the cabin heat radiator units did little good. The higher amount of water meant that not as much heat was stored in the heated solution.

I haven't touched the boiler liquid in it since when we bought it new last September, which means either the factory filled it or the dealer topped off the Aqua-Hot up wrong.

Now I am completely draining the tank and replacing all antifreeze on my time and dime.

[roonabeck]

As someone probably already told you, it takes about 4 gallons to refill.

[DW_DX3]

Originally Posted by roonabeck

As someone probably already told you, it takes about 4 gallons to refill.

About 5.25 gallons, including heater lines. At $41 per gallon.