Propylene Glycol - Solar AntiFreeze

[UlsterRugby1999]

Hi all - I am about to install my solar hot water system. I have researched the liquid to be installed into the pipework that circulates from the manifold through to the heat exchanger in the tank and so on. The one that I have found recommended is Propylene Glycol at a 50:50 mix ratio. It isnt cheap in this country and would require delaying the job until I get it from the UK. Is the information I have found correct or could I use regular antigel that is usually installed into central heating pipework and radiators etc. What do you folk think. Cheers. Paul

[Anton Redman]

Suggest you look up anti freeze poisining - I would not use car of central heating ant freeze in a system where a leak could contaminate drinking or cooking water. For a central heating only system with a one way valve possibly.

[UlsterRugby1999]

Mmmmmmmmm - great point Anton. I hadnt considered that aspect of things. I live in the SE Vienne, do you have any thoughts on suppliers here. Thanks Anton. Paul

[Anton Redman]

No local ideas - suspect it something I would add to the long list of buy in the Uk items. Any idea of comparative costs France and UK ? and volune you would need ?

Web search of say Zyke or other pool suppliers might turn it up at a resonable price.

[Gardian]

[quote user="UlsterRugby1999"]Mmmmmmmmm - great point Anton. I hadnt considered that aspect of things. I live in the SE Vienne, do you have any thoughts on suppliers here. Thanks Anton. Paul[/quote]

UR99 !!!!  Where have you been? No trace of you during the RWC.

(sorry - nothing to do with your plumbing problems: just a greeting.)

[Bob T]

Some systems these days just use water, mine does. The controller measures the temperature in the manifold on the roof and just circulates the water if it falls below a certain level.

[chirpy]

Both propylene and ethylene glycol have been used in anti-freeze solutions.However ethylene is not recommended in systems where it can contaminate drinking water.

Not an engineer,but would expect the propylene may be better for the end use and if  a  sealed system, it is not after the initial installation need much topping  topping up.So why change something which may cause problem.The cost may be minor.

[UlsterRugby1999]

Anton - prices here in France seem to vary from 50/60€ to 90€ for 5 litres. Ive estimated that I need 6 litres of total liquids as its only a very short run from the panel to the tank. The pipe work will be 22mm and there will be a total run of approx 16m including the coil in the tank. Im planning on the 50:50 mix. What do you think?

Hi Bob and thanks for your input. I dont actually know if my system is as cleveras that. To be honest I havent checked to documentation that came with the kit but I will now. That said, I doubt it will do that.

Agreed Ab – the little extra expense is worth it.

Anyway, thanks guys, as always much appreciated input. Cheers. Paul

[Araucaria]

Paul

I bought the anti-freeze for my self-installed solar heating in the UK because of the price difference. A 10 litre container of ready-mixed (50:50) propylene glycol is £30. I still regard this as expensive, but it is cheaper than I could find in France.

For that matter, I bought most of the other components in the UK too.

I don't like the idea of doing without anti-freeze and having the controller circulate the liquid when the temperature is below zero. Effectively you would be using some other heat-source to warm up your solar panels so they can radiate heat out into the atmosphere.

There are (unpressurised) drain-back systems, used extensively in the US, where the liquid is only pumped into the solar panels when it is warm enough to gather heat from the sun: that strikes me as a better idea but my layout made this impossible.

Good luck with your system.

[UlsterRugby1999]

Cheers Araucaria - I have decided to go with the propylene glycol. Safer than sorry I guess. I bought the entire kit, incl delivery to the Vienne, for under 1500€ so Im with you on that score.

As an aside, Im down in the beautiful Auvergne at end of January as Ulster are playing Clermont ASM in the Heineken Cup. We'll be staying Chastreix if you fancy a beer.

[Stephbaker]

Propylene glycol has become a very common heat transfer fluid which is used in the solar heating systems as an anti-freeze. But the alternative of it is very toxic which is ethylene glycol, any many do not recommend it for household heating system. Many are unaware of its characteristics and it toxicity which poses a danger. You will have to look for propylene glycol supplier that can formulate glycol products which are compatible with solar heating suppliers. There are suppliers like alibaba to for this. I guess they sell at a reasonable price. I think propylene glycol is what should be used. The rest I guess depends on what kind of solar heating system is used. If the manufacturer recommends something else that might be suitable. I hope this is helpful for people who would have a similar doubt when they come to this thread.