BOILER WATER CHEMISTRY :
Propylene Glycol Antifreeze
Where the Ethylene glycol has some serious health and toxicity issues propylene glycol can be a refreshing change with grades that are even classified for human consumption and used in products like children's cough syrup .... but it comes at a cost!
Propylene Glycol: Antifreeze for Home Boilers?
- Food Safe: low toxicity although recognize that it does come in different grades and thus "certified" for different levels of contact with the human digestive system.
- Solvency: Does dissolve a wide range of organic compounds and is completely water soluble.
- colourless and odorless
- Burst Protection: propylene glycol continues to shrink in size as it gets colder and will not expand until temperatures reach in the range of -50° F , so it provides excellent "burst protection".
... But The Disadvantages:
- Concentrations: Propylene glycol if used as an antifreeze for home boilers must be applied in higher concentrations to provide the same freeze protection as an equivalent volume of ethylene glycol.
- Thermal transfer: Propylene glycol is not nearly as efficient at transferring heat as its ethylene cousin, thus may be required in higher volumes or increased circulation.
- Expensive: Propylene Antifreeze is both more expensive in actual cost per litre but also because of its reduced thermal efficiency and higher concentrations required for the same freeze protection.
- Uninhibited glycol can cause extensive corrosion to metal boilers if appropriate chemicals are not added to the mix.
Although Insurance companies certainly appreciate the non-toxic nature of propylene glycol antifreeze for home boilers they are still very nervous. They will still strongly recommend NOT using it.. so again ASK FIRST!
I have heard of one case on the east coast of Canada where they were hit with a $50,000 clean up bill. I know this makes no sense for a product that is rated as "non-toxic" but then the same bureaucrats also legislate "sawdust" as a toxic substance and I can't even take it to my local dump.. so what's the logic here??
If you are thinking of sneaking under the radar and using Automotive Antifreeze for a home boiler then read on..