additive to hot water heating system to protect from freezing

fran_4

Thanks for the information. It will help me make my decision on what to use. Thanks again

fran_4

I have a hot water heating system and I would like to know what additive I could put in the system to stop the water from freezing in case the area i am located in should lose electrical power and I am away for a few weeks.

Weezbo

what will protect the potable in that unlikely event?

Brad White_9

Propylene Glycol

is the most common, but beware that it requires testing, maintenence and adjustment for pH (acidity principally). The other downside is, it has a low surface tension and may allow weeping or minor seeping leaks where water alone does not.

Concentrations should be selected modestly for burst protection (actual freeze protection is a higher concentration but you lose performance and increase the cost and maintenence). Here in Boston, we specify 30% PG as a default mixture by weight. Your area may vary.

I usually specify Noble No-Burst or Dowtherm, made for heating systems. It is commonly stated not to use automotive anti-freeze (Ethylene glycol) in hydronic systems but so far no one to my knowledge has said exactly why. Those that say so are pretty emphatic, so we shy folks just do what we are told

Drew from Noble is an occassional contributor to this site. He and others can illuminate far better than I.

hot_rod

EG

ethylene glycol is commonly used in larger commercial hydronic systems. Dow and others offer EG built for hydronic systems. it is less expensive and a bit better heat transfer than PG. It also has a higher toxicity rating and needs careful handling. Altough it does bio degrade faster than PG.

I'm told EG is used as plane de-icing also.e

Automotive antifreeze should never be used. It contain silicates as their inhibitor (less expensive than hydronic inhibitors) and will settle out in pump volutes, etc over long shutdown periods. It will actually "glue" the impellers stuck. I have pics somewhere.

There are some PG automotive glycols out there, but still the wrong inhibitors for hydronic use.

hot rod

Brad White_9

Thanks for filling in the blanks, Hot Rod

I figured the silicates had something to do with it...

It is odd with the toxicity that they use is for deicing planes.

That may explain the lack of stray dogs on the Tarmac in the Airport Operations Area....

Drew_2

Freeze protection

You guys have hit most of it right on the head. The only thing I'll add is about Ethylene Glycol (the one most used as auto antifreeze). The toxicity is to mammals, it shuts down your kidney functions. Attached is the antidote used for EG poisining. Yes, EG is used to deice planes. It is gathered in leak resistent holding ponds. I'm told,in some areas it is desposed of, after breakdown, into the sewer system and in other areas hauled away by a hazardous waste company.

Brad White_9

Drew Knew

Thanks for the background, Drew. Noble of you