Ground loop antifreeze

[Beck's Machine]

Hi Folks, I have been following the debate about proper antifreeze for the ground loops of a ground coupled heat pump.

Does anyone have experience with using Sierra automotive antifreeze?

I have read that you shouldn't use automotive antifreeze, but I am not sure if that was because "standard" automotive antifreeze is usually ethylene glycol as opposed to the Sierra which is propylene glycol?

Any thoughts or opinions?

Thanks, Dave

[Brian_UK]

This taken from the Engineering Toolbox...

Ethylene glycol should be avoided if there is a slightest chance of leakage to potable water or food processing systems. Instead solutions based on propylene glycol are commonly used.

So it seems there is a potential contamination threat to be avoided.

http://www.engineeringtoolbox.com/et...col-d_146.html

[Beck's Machine]

This taken from the Engineering Toolbox...

Quote: Ethylene glycol should be avoided if there is a slightest chance of leakage to potable water or food processing systems. Instead solutions based on propylene glycol are commonly used. .................................................................................................... .......................................... So it seems there is a potential contamination threat to be avoided.

Hi Brian, that was one of my reasons for the question. The Sierra brand automotive antifreeze HAS a propylene glycol base as indicated in my initial post. Dave

[desA]

Interesting thread. Thanks for the information BM & Brian.

[Brian_UK]

Yes, I suppose that you have to consider the result of a leak into you local groundwater area.

Not something that you plan for but things do bite you in the ass some times

[Abby Normal]

propylene gets hard to pump if you need the lower freeze protection temps.

Alcohols are common such as ethanol, methanol. Easier to pump.

You need to see what is allowable in your area.

I have never seen ethylene glycol ever allowed to be used in ground loops