this came from someone, presumably the makers of CPTherm-G. however, there is more to the story than this…
Problems with Methanol..
Following the sudden dramatic increase in the price of Ethanol (due largely to demand from the biofuel industry) many geothermal contractors turned to using Methanol extensively as a loop fluid antifreeze. It was cheaper, had a reasonable viscosity, and long term stability. However a growing number of jurisdictions across North America are prohibiting its use due to its high toxicity, and the risk of leakage into aquifers.
In addition to the obvious environmental concerns, handling, storing, shipping, and job site deployment of such a volatile and dangerous product comes with its own set of hurdles.
Among the operational concerns already noted, something often missed by designers and contractors alike is the reaction between Methanol and iron based metals. To put it bluntly, methanol eats iron. It’s so acute in fact that one geothermal project recently inspected only had one iron component in it, a single iron bodied circulation pump. But the enormous amount of rust deposited throughout the loop system would make one think the whole ground loop was iron. In another installation, a new commercial building, only the flanges and a couple of nipples were iron. But again, rust was everywhere If contractors are going to use methanol, ALL parts of the system must be iron free. Better yet, use CPTherm-G and eliminate the methanol hassle entirely.
The geo guy says:
Yes, methanol does eat iron but oxygen eats it more. The hdpe pipe we use has no oxy barrier and microscopically, plastic looks like a fishnet. It will not pass liquids, but vapours will sail right through. The proof is the freezer burn in your own freezer. All the water vapour sublimates out, leaving you with yukky food. The oxygen goes reverse, into the pipe, eating the iron pump.
The eco-whiners, me being one, will complain about the toxicity of meth, but I tell them when they stop using millions of gallons of methanol in their windshield washer anti freeze spraying it all over every highway in the country and use Scotch whiskey instead, I’ll listen…
Methanol has low viscosity, is cheap, just don’t splash it in your eyes and don’t be so cheap using those iron pumps and buy a bronze one for 20 bucks more.
Another rant coming soon on burning the house down with meth…