Radiant Floor Antifreeze

Just finishing up my install in my garage but before I seal the boiler should I put any addative in my boiler to keep the pex pipe in my floor(garage floor) from freezing(precautionary!!) and not damaging the pex pipe ???? Keystoker is the boiler(steel) should I use glycol??? car antifreeze?? open for suggestions or experience!!!!

Never auto antifreeze! It's not legal.

No, unless there is a NEED for antifreeze you don't want it.

I think you need something like...

Boiler antifreeze (Propylene Glycol) is non toxic and actually breaks down quite easily when exposed to air.

I plan to antifreez my system here at my store as some of the pex travels through unheated space. As Freddy says, don't use auto antifreeze it is toxic. A better choice is non-toxic antifreez stocked at most plumbing retailers made specificly for boilers. I would still install a backflow preventer to prevent antifreez from entering the domestic water.

If you are going to be holding a consistent temperature in your pex through out the cold season then I don't see why you would need it unless the pex travels outside in an uninsulated area? Since you just put the pex in, is it safe to assume you put insulation under the pex piping below the cement flooring?

Thanks for the replies guys. I,m not using a water coil it is just blank plated, the coil that was in the boiler was bad and I did not buy a new one other than just washing my hands in the garage the on demand water will act best for my application.I never really looked at the spec sheets on pex on what kind of chemicals could ruin the pipe, that is what I will b3e doing here, and my MAJOR CONCERN. I will be using the boiler only seasonaly, probably only 4 -5 months out of the year when I shut it down I will pull the stack pipe and burn a light bulb in the ash pit door to keep dowm condensation. that is why I didnt second guess car antifreeze, yes I have inch foam under the concrete floor, I was just worried if the fire goes out in the boiler or loss of power I did not want the floor to freeze up on me I just wanted something to help buy me some time.

I used automotive antifreeze in my slab system,, because I already had it, and my shop floor is totally isolated from any domestic water system.. as for it being toxic.. if the $$%^&% groundhogs burrow under the slab and chew through the concrete and chew a hole in a pipe, then they get what they deserve.

I would recommend the non toxic antifreeze, and only use enough to drop the freezing point to ~15*f or so. it will take quite a while for the slab to cool to below freezing, and you will have to have ambient temps below 15* for days to drop the slab temp that low.. A higher concentration of antifreeze will reduce the heat transfer rate of the water/mix, and make the system less efficient.

Greg L

Automotive AF is TOO expensive

Here is a little info regarding pex piping as I understand it. If the pipe freezes the pipe can expand without rupture,(valves,fittings different story) the extent of the freezing plays into it if there is a failure. With regards to a wet install (slab) don't know what would happen due to limited space for pipe expansion. Someone mentioned boiler antifreeze that breaks down when in contact with air, did you use pex pipe with oxygen barrier? if not then boiler antifreeze sensitive to air may be a waste.

have fun

Even copper usually doesn't break the first freeze, it takes a few cycles before it splits. Iron, different story. We fould 27 to be the magic number. Lot's of things won't break if they "just barely" freeze, but when it hits 27 if it's going to fail, it will.