Methanol in hydronic system?

GW

I’m not much of an anti-freeze expert, I try my best to stay away from the stuff.Glycol seems to be the most basic necessary evil.

I know methanol is preferred for geothermal systems, has anyone ever used it for residential hydronic, in the house?

I need to order some for a Geothermal customer, but I have another job with an attic air handler.

Thanks, Gary

mattmia2

Methanol is very corrosive, there are few resilient sealing materials that will stand up to it.

Zman

I don't have any first hand experience with the stuff.
You absolutely should not put it in a heating system that is tied to domestic water, even with a backflow device. It is poisonous.
The flammability part would be a deal killer for me as well.
http://www.geojerry.com/earthloopantifreeze.html

mattmia2

You can buy a lot of propylene glycol for what the backflow prevention device that you would require for methanol would cost.

Jamie Hall

All these^^^ plus: methanol mixtures have a lower boiling point -- which can be within the range of the higher temperatures of a heating system. Somewhere around 170, varying with concentration. This you do not want, as the resulting vapour coming from your "air" eliminator is highly flammable.

Don't use it as an antifreeze in your diesel truck, either -- pretty well guarantee a runaway engine, which is not pretty.

ethicalpaul

I'm not sure where you got that methanol is preferred for geothermal...maybe once it was or among certain areas or something.

But when I hired an engineer to size my system I installed in CT, he said "use glycol" and I did.

My system had a closed ground loop so there was no back flow stuff required (if I'm understand the above comment correctly).

Edit: It strikes me that you might be talking about the radiant loop though. I want to be clear my use of glycol was in a closed ground loop.

GW

OK thanks, I’ll stick to the good old fashion glycol.

GW

Paul what is your geothermal system running out for temperature? I have Geothermal as well, no anti-freeze. Most of our systems run without antifreeze. The lady that I mentioned, needing to order antifreeze, she’s keeping our house at 75°.

mattmia2

not sure how the specific heat of methanol compares to water, i know it is a fair bit less for propylene glycol

ethicalpaul

> @GW said:
> Paul what is your geothermal system running out for temperature? I have Geothermal as well, no anti-freeze. Most of our systems run without antifreeze. The lady that I mentioned, needing to order antifreeze, she’s keeping our house at 75°.

I sold that house, but I would start out in the fall with water coming in at 55 and by Spring it would be coming in at 45 or so. I had the flow damped down to give me a 10 degree delta, so the outgoing water would get close to freezing.

The glycol was a “just in case”...I’m not sure I ever hit 32 but someone running warmer temps probably would, like your 75 degree customer

GW

Yes I’m such an anti antifreeze guy i would rather roll the dice and see if it freezes up. Seems like your engineer is simply more of a rubber stamper. If the performance is good and you’re happy that’s all that matters

clammy

GW I know another hvac contractor who uses a corn based anti freeze in process cooling and geo therm .states it’s cheaper and doesn’t break down nor go acidic I really never looked into I believe it was a Dow chemical product ,but I sure it was corn based product ,at the time I thought nothing of it and did ask for more info should have .i know it was also food safe being it was being used flash freezer application w some sort of barometric freezer , I was there for the chiller replacement had other concern . Check Dow,s product line peace and good luck clammy

Solid_Fuel_Man

Use vodka! I'd go bottom shelf for such purposes though....

hot_rod

Some pump folks consider it a flammable liquid. Common circulator are not approved for pumping those.

ethicalpaul

> @GW said:
> Yes I’m such an anti antifreeze guy i would rather roll the dice and see if it freezes up. Seems like your engineer is simply more of a rubber stamper. If the performance is good and you’re happy that’s all that matters

No, I dont think he was a rubber stamper. He was a long-time geothermal proponent and impressed me with his care and calculations. He did a very detailed heat loss calculation on my house.