Discussion in 'Vertical and Horizontal Loops' started by ClarkT, May 19, 2011.
Do you typically use methanol or glycol in your loops?
We use Glycol. You will need to check with your local authorities, not all will allow methanol.
We use methanol. It is allowed. Both will work well they just need to be handled differently in regard to your circulator pumps head capabilities. Glycol is viscous and needs higher head pressures than methanol to achieve the magic number.
New Utah Water Right rules require "enviornomentall acceptable" fluid in boreholes below 30' (regulated by water rights). Also dictate minimume hole size vs pipe diameter. Check DWR website for download of new rules. Last I spoke with Jim Goddard, they may also be requiring that you list the anticipated antifreeze on the permit. Of corse, HZ and boreholes less than 30' are not regulated by DWR.
I cannot see how methanol in the 15% dilution it is used in the pipes is not environmentally acceptable, or more toxic than glycol or ethanol.
We switched over from Glycol to Methanol 2 years ago, and I cannot see us going back. It has better heat transfer characteristics, is less viscous, you need a lesser amount and it is cheaper.
Most people are intimidated by it, but as long as you mix it down to 50% with water before you carry it into the basement, the risk is pretty much over. It is still inflammable, but not explosive anymore.
Same with ethanol, 100% is bad, it is sometimes used as a preservative, since it immediately kills every cell, but you dilute it down to 5% (beer), 12% (wine) and 30-40% (hard liquor), and dependent on the quantity, it becomes quite enjoyable to consume.
I would be interested in any scientifically based opinion which could show a negative environmental impact of a pipe leaking or even bursting.
I, too, think methanol gets a bad rap. As with many things, there are tradeoffs. For me, the decison to use methanol had to due with the ease of pumping against glycol here in our heating dominated climate.
I have no scientific study to offer up. I had a woman look at me cross eyed when I told her I used methanol as an antifreeze in my pond loop. What if it leaks she asked? I replied, highly doubtful, but if it did what effect do you think 15 gallons of methanol will have in 400,000 thousand gallons of pond water? Not a good thing on a number of levels, no doubt, but environmentally damaging short or long term? No way.
The fish can't even get drunk on that amount and have a party!
Keep in mind that it is fully dissolvable in water, evaporates when in contact with air (even when dissolved in water), and some bacteria in the soil would actually use it as food.
Beyond that, methanol is an easily biodegradable substance. In the event of a spill in the ocean, it is much less toxic to marine life than crude oil or gasoline (the Office of Pollution Prevention and Toxics concluded methanol is essentially non-toxic to the four fish species it tested.) In the event of a leak from an underground storage tank, methanol is expected to swiftly biodegrade.
I am with you completely.
Hopefully, the enviro wackos will not lobby DEC to ban methanol as GSHP's are more widely adopted here in NYS going forward.
I really think it an easy decison here in NY(especially upstate, the real upstate, not Westchester) with our near 30* EWT's in winter.
I also prefer Methanol as an antifreeze because of it’s flowcharacteristics and it is biodegradable but it is dangerous. Unfortunately, Utah DWR is not of the same opinion but will acceptsome variances.
Contrary to belief, methanol is not “dissolvable” in water (likesalt). Methanol is miscible inwater. That means it is an independentcomponent. At temperature, it will come off as a vapor(before the water vaporizes) and is flammable and explosive. In a 20% solution, a halogen light (and evenan incandescent light) too close to thefluid will cause the Methanol to vaporize out of the water and ignite. Unfortunately, it burns with an almost invisibleblue flame. It is still used inresidential applications, but you need to be aware of the danger. In commercial applications IMC Section 1207limits use of flammable mixtures and requires the flash point of the solutionat least 50 degrees (F) of the anticipated upper limit of the working fluid –Since most GXHPs are rated to 110 F EWT,that means the fluid needs to have a flash point above 160 F +/-. The methanol institute (Google) says thatthis concentration is ~7% - a freeze point of ~22F to 25 F. Still workable and very pump-able but willrequire a little more loop or a hybrid system (e.g. strip heat or boilerinjection).
Ethanol exhibits much the same pumping characteristics as propyleneglycol. If you don’t believe me, put abottle of Vodka in the freezer – it comes out like honey and is verydrinkable. See pages 4-11 and 4-14 inthe new IGSHPA manual for Ethanol’s properties.
I learned something today! Thanks.
If I understand you correctly, in hot climate with a working loop temp of 110F EWT, we should not use a concentration higher than 7% (keeping a 50F safety margin). However, at a climate where the geo pumps running at 110F, no one would use antifreeze. Only in heat dominated climate, with a LWT lets say less than 35-40 degrees, antifreeze is needed. In that application, flashpoint at 85F is 46%. I think the warmest the loop was here in Buffalo, NY was 65F.
Remember, the IMC is commercial. What I really advocate is a thoroughknowledge of the products we use and proper application for the situation.
A 110 F loop temperature is a design issue or a system problem as well as an upper limit in HP mfgr’s specifications. High temperature can happen in any environment, heating or cooling. What happens if, for any reason, you loose part of your loop? Does the ability for Methanol to vaporize under certain conditions say anything about safety precautions when opening the cap on an unpressurized circulating system? Remember Murphy’s Law… A good practice is to label the system with a tag showing date, antifreeze used (brand and type), any additional corrosion chemicals used, and any cautions appropriate. These systems are intended to run for many years and the next person to service the system may not be you.
The antifreeze needs to be tailored to the design and appropriate products used. For example,unless radically inhibited, propylene glycol can break down in lower concentrations. It is supposed to be“food grade” that means bugs can/will eat it too. Many time a very dark or black solution of PG means that the PG has been broken down and it is usually a bacteria problem. The pH will change and the solution may become both toxic and ineffective, may gunk, or eat the pump housing. Ask your chemical supplier and read the MSDS sheets on any product you use.
Good luck - probably way more than you wanted to know.
I certainly do want to know.
I have seen many older systems where the PG broke down, messy, slimy, smelly.....
with compressor and pump failures. One of the reasons we switched to methanol.
Welcome. Keep designing and installing. Your welcome to contact me if I can be of any help.
While the IMC is commercial, it is applied to residential applications when not in conflict with the IRC.
While as installers we would naturally be concerned about hurting ourselves, is there a real possibility for the home owner to be harmed by a leak in a 10-15% methanol system?
As for contamination of the ground/water from a leak, all the brands of propylene glycol that I've seen (and used in solar systems) have anti-corrosives and other additives that the manufacture clearly labels as toxic. [ Though perhaps not as immediately dangerous as the median lethal dose of 4 oz for methanol ]
Vodka would seem fairly safe but it is 'thick' and gastly expensive
Second questions: Where do you even purchase methanol antifreeze?
Suppliers around here don't carry it and the internet is not exactly bursting with inexpensive sources.
We buy from 2 different chemical supply houses in NJ. They ship truck freight.
We buy from Petroleum Suppliers
same place we get our glycol
We also use Methanol for all the right reasons stated above!
I train my guys how to safely handle it and let the rest be history!
A few years ago when speaking to a manufacture of glycol, they said that iron greatly reduces the life of the antifreeze.
So it would be important to use a bronze circulator instead of cast iron in a glycol system. [ There is quite a difference in price between them. ]
Does it matter with Methanol?
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