Century Heat Transfer Fluid, Non-Corrosive, Non-Toxic Propylene Glycol RV Antifreeze for Heating Systems | Ready to Use | Recomended by Aqua-Hot, Oasis & Timberline. - Red 1 Gallon

This is the correct fluid for an Aqua hot system no mixing

Quality product, I just wish it hadn't increased in price so much over the last year or so.

Works great!

Good fluid.

Had a boiler failure and had to replace Hydro Hot 500-09M tank. Fluid drained was not as clear as it should be so since everything was drained, I disposed of the old fluid, flushed the system with distilled water to remove all the sediment, and refilled the system with new fluid. Seemed very pricey initially, but once I thought about it, the cost is fairly cheap insurance against boiler failure. The fluid should be tested at least annually, and likely replaced every few years to ensure the chemistry of the system remains appropriate to avoid corrosion induced failure. I am leaning toward replacement every two to three years, whether I get it tested or not. I tried to get five gallons but was limited to four. Didn't try to go around the ordering system since I had a quart of concentrate to make up a little of the difference. Didn't need too much of that as it turned out.

I like this stuff for two reasons, it has great longevity with out breaking down. Plus as it breaks down it looses color so you know when you should add more.

I purchased to carry in our motorhome. It’s an exact match to the product in our system.

Expensive!!!! But it is the correct fluid for Aqua Hot systems