Source
r/Plumbing•
11787

Need antifreeze advice

We leave our Long Island NY house for 5 months to escape winter. I drain all the pipes, including the oil fired boiler, tankless coil and baseboards, put RV antifreeze in the traps and let the house freeze.

I would like to put an antifreeze in the boiler and not have to drain it and refill it.

What do the plumbers recommend? What percent antifreeze do I need? The lowest temperature I see was minus 7 in 1988. The antifreeze can turn to slush and that would do me no harm.

Posted May 26, 2016, 12:38 AM UTC

57
txplumber•

If you put RV antifreeze in your boiler, you're going to contaminate your water. Don't do it.

Use a nontoxic glycol antifreeze, or just drain it. (safest bet)

5
Ranch_Hand•

You should have a plumber or heating guy do it. They will drain the boiler figure it's capacity with a flow meter then fill with premix glycol accordingly. Not something you want to mess up. I would look into using what they call lowtox antifreeze for your traps it's environmentally friendly and costs less.

1
Throwastone1990•

You must be working on some big systems to actually calculate the capacity. Most guys I know use the self feeding glycol tanks or just mix it prior in a large bucket and just keep mixing more as needed

1
Ranch_Hand•

We do work on primarily commercial systems but I have witnessed first hand the result of a glycol system with not enough glycol.

1
Throwastone1990•

Well so far no issues.

What would happen should the lines freeze? I have never seen Pex or worse bow split when frozen, I know joints would suffer but there shouldn't be any joints on the loop regardless.

1
Ranch_Hand•

I have yet to see staple up or mains ran in pex split due to freezing, the fittings usually will break. In the slab I have seen them split. I think all the concrete around the lines and no where for that expansion to go causes them to split. If it were my system and I wanted to leave it full but off I would fill it with enough glycol to protect it to at least 20 below. Many will say well I don't think you have to go that far but there are only two things you sacrifice by doing it. The cost of actually getting glycol into the system and loss of efficiency to the system.

1
Throwastone1990•

Better off installing a glycol tank and have a HVAC/plumbing technician come in and use glycol water in your domestic heating loop and you will never have to worry about draining it. I would do this before draining it every year and letting oxygen rust out the inside of my boiler.

1