Glycol dilution and reservoir temperature

[Mike Lachelt]

Hi all,

I have 3 questions. First, I'm looking at buying "brewer's glycol", and I'm wondering if it's normal practice to dilute it. If so, what dilution is recommended? Is it OK to dilute with tap water, or is something else recommended? (I suppose the idea behind dilution is just to reduce cost).

Second, what temperature should the glycol reservoir be kept at? My aim is to carbonate cider at around 3 Celsius, or 37 Farenheight. If the reservoir is too cold, maybe it will cause freezing? Too warm, and it will take longer than necessary. So, what's optimal?

Third, what's a good price for brewer's glycol? I'm looking at a quote for about $23/gallon, but that's in Canadian dollars...

Thanks!!

Mike

[gitchegumee]

Answers

1) You must dilute propylene glycol. Freeze protection is better with diluted glycol than with straight glycol. Not only that, but the heat transfer is much better with water dilution. So the cost of the initial glycol load isn't really the reason at all for dilution. You want to consult the chart for your particular brand and make sure that you get freeze prevention at the lowest temperature you would ever expect. Then add margin to that. Being in Canada, I'd use at least 35%. Maybe 55% depending on other factors.
2) A fairly standard temperature for you to set your chiller would be 5 degrees F lower than lowest temperature you wish to achieve in fermenter/BBT. Much depends on your loop, jackets, ambient, and other factors. Adjust as necessary.
3) You get what you pay for. Sometimes, not even. So I look for USP propylene glycol with inhibitors. Shipping ends up being a large cost, so look local. Plumbing shops often carry glycol for hydronic heating systems.