propylene glycol vs. methyl alcohol in loop

[mstrblstr3]

Yeah I put methanol in my loop, and I haven't had a single problem. No leaks whatsoever. I did a 20% methanol mix.

Is your loop holding a slight positive pressure?

I could be wrong but your methanol/water mix could still be flammable at this ratio. Our tech department cries if we add to much methanol because it doesn't transfer heat as well as water and a 10% mix still gets us 20 degree protection.

[rcameron]

i have never heard of picking up combustabile fumes from in around the pump flanges. if this is happening and not dripping but is wet, then i would say you have a leak. when we flush ground loops, we charge the loop with %22 methanol. i think you are over reacting, obviously there was a huge difference when you put pg in the loop. i would recommend putting methanol back in the loop. i could get the the numbers on how much methanol to put in your loop if you knew how much pipe you had in the ground.

[vespadaddy]

Just as a point of information--food grade propylene glycol is a requirement for a rebate program that was administered last year in MN. I know this because I was a lucky recipient of the rebate.

Would I rather have a more efficient fluid in my vert. loop (alcohol)? Yes.

Did I want alcohol more than prop. glycol enough to give up a $9,400 rebate check? Nope!

Edit: It is also worth noting that anyone who got this MN rebate MAY be required to allow energy monitoring equipment to be installed on their equipment, as stated in the rebate application. Thus, the use of a fluid other than the specifically-required prop. glycol may be discovered, though I have no idea what penalty, if any, this may expose the homeowner to experiencing.

[arc8]

Your choice may be sound and probably smart financially; but the extra cost in order for a PG loop field to work right (the right amount of Reynold numbers) would increase the installation cost (just about what you may have gotten back: your rebate). And let's not forget that the efficiency drops and so your operating cost goes up!

[vespadaddy]

Your choice may be sound and probably smart financially; but the extra cost in order for a PG loop field to work right (the right amount of Reynold numbers) would increase the installation cost (just about what you may have gotten back: your rebate). And let's not forget that the efficiency drops and so your operating cost goes up!

I'm just a homeowner, so I'm not claiming to be an expert, but it seems pretty unlikely to me that I would need an additional $9,400 worth of vert. loop field to make up the difference between alcohol and glycol, in terms of efficiency.

In case it matters, I have 750' of vert. loop, split up as 3 bores of 250' deep each, for a 4 ton system.

[arc8]

Vespa,

For a 4-ton here and equivalent efficiencies of the loopfield except for the pumping cost,

a Methanol (20%=15 degree) system; 5 bores @ 250' in mostly wet clay and some silt with a 2500 reynolds and a FC1 pump pak (1/6 hp 1.0 amp 220v).

vs

a Glycol (20%=22 degree) system; 3 bores @ 450' at half clay and parts in silt and/or limestone or granite (very expensive drilling) with a 2300 reynolds at best (low end) and a 1/2 hp 6+ amps 220v.