Antifreeze for a gas hot water cast iron multi zone heating system

51fordf1

What is a good antifreeze to use for a hydronic heating system. We are replacing a system we added Cryotek to a few years back. I am not sure if there is any corrosion inhibitor. We saw blue green staining at some drains and auto air vents.

PerryHolzman

Why add any aniti-freeze? I live in Wisconsin and have a 66 year old monoflow T system (iron pipes, cast iron rads, except for modern copper connecting things with the new boiler) 2" rockwool insulation in walls - that has never had antifreeze in it. Just plain water?

Perry

pecmsg

I somewhat agree. Why antifreeze and if your using it the minimum amount required.

I have no problem with Cryotek. The Blue green is from leaks and or drips.

Jamie Hall

PerryHolzman said:

Why add any aniti-freeze? I live in Wisconsin and have a 66 year old monoflow T system (iron pipes, cast iron rads, except for modern copper connecting things with the new boiler) 2" rockwool insulation in walls - that has never had antifreeze in it. Just plain water?

Perry

It's really a matter of balancing possibilities. First off, I strongly feel that any hot water heating system should, at the very least, have corrosion inhibitors. Antifreeze made for heating systems contains them, but they are available separately.

Antifreeze itself has some advantages and disadvantages. Among the disadvantages are, perhaps most significantly, somewhat poorer heat transfer capabilities, so the system will have to run slightly hotter (it's not a big deal, but it's there) and second having antifreeze in the system makes repair work a lot harder, as it is harder to properly clean fittings and they may leak more easily.

The advantage is where you have to really balance your thinking. Basically, how likely is it that you will experience a heating system failure in cold weather long enough to freeze at least part of your building? And, if it seems to be a reasonable probability, what plans do you have to drain down the system and subsequently restore it to operation -- particularly if the building is unoccupied. If you think that it's not very likely, or you have good plans, then you probably don't need antifreeze. If you prefer to be more conservative -- and aren't sure you can protect against that situation -- then you probably do. Keeping in mind that one burst pipe in a building, under the right (wrong?) conditions can result in a total loss of the building and contents, and probably isn't insured.