anti freeze for a hydronic heat system?

Question

i am finally finished with my heat system. it's a hot water solar collector, with a heat exchanger from the woodstove. it then travels thru the concreet slab for heat. the problem is that i'm getting mixed messages from people about what type of anti freeze to run in it. the solar pannels will be turned off at night and will get very cold. i was told that i need some special fluid for the system at $ 22.00 per gallon. i need 30 gallons! my origanal plan was to get some recycled anti freeze from a local auto salvage. any thoughts? thanks john

Answer 1

Check with your local building inspector on this.As a contractor I can not put regular car anti-freeze in a heating system but in our area it is legal for a homeowner to do this.I would strongly recommend that you have a back flow prevention device on the domestic water line that feeds the system[this is code in most places],and if you use car anti-freeze you will want one that has an atmospheric dump instead of just a double check system.Some one has suggested RV anti-freeze,never use RV anti-freeze in a heating system because it is an alcohol base and will evaporate out of the system in a very short time.Now with all that said I would still use the non-toxic anti-freeze for boiler systems rather than used car anti-freeze.Used anti-freeze could be contaminated with oil,heavy metals,and other chemicals and may also be acidic these are things that you do not want to add to a new heating system that you have spent I assume several thousand on.

Answer 2

Yes there is a special anti freeze that you need to put in the system. don't use auto anti freeze. I think that $22 a gal seems a bit high but what if you system froze and cracked you solar panels. I would bite the bullet and get it in asap. Talk with you local distribute and they will recommend what type to use.

Answer 3

wal-mart, RV antifreeze,