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27th Oct 2021 Login  
Brine/Anti freeze needing replaced in GSHP
by CL at 2013-01-24 18:02:47 (Ask an Expert)
Hi All,

Does anyone know how often we need to replace the antifreeze liquid in our ground source heat loops, also does it all need to be replaced or can it be topped up by adding some new and replacing some old.

I am getting mine serviced and the engineer said they will test the antifreeze and replace if necessary at 150 litres in the system this could work out to be quite expensive, does any one have any experience of this.



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Brine/Anti freeze needing replaced in GSHP CL - 2013-01-24 18:02:47
Re: Brine/Anti freeze needing replaced in GSHP David Hobbs - 2013-02-02 13:30:25
--When mine was commissioned (three years ago) I was given to understand that the fluid should be good for the life of the installation. It's a closed system so the strength shouldn't change.

Kind regards,

Re: Brine/Anti freeze needing replaced in GSHP CL - 2013-02-04 11:50:47
Hi David,

I was told the antifreeze could degrade over time loosing its antifreeze protection, My system has been operational 4 years now. They came to service it and found one of the expansion vessels was not working and so the system was loosing pressure, it was replaced and the brine topped up with 25 litres of pure glycol

Re: Brine/Anti freeze needing replaced in GSHP David Hobbs - 2013-02-11 10:19:34
Well just to be sure I'm not giving out incorrect information I have checked with my supplier (Ice Energy) this morning and they have confirmed the antifreeze they use is good for the life of the system. Of course, if there were any leaks the system would have to be topped up with fresh mixture of the appropriate strength, but this would be a pretty catastrophic failure and the cost of fresh antifreeze would be the least of my worries.

For the record, my system contains 140 litres of antifreeze, giving protection to -18 deg. C. In a well designed system you would never expect to approach these temperatures. My own system has been in use through the last four winters and the return temperature to the ground loop has never fallen below -2.3 deg. C. Today, the return temperature is +0.5 deg. C.

I notice you say that the "brine" has been topped up with glycol. I don't think you would mix glycol with brine; surely you would use one or the other?

Re: Brine/Anti freeze needing replaced in GSHP CL - 2013-02-11 10:33:52
Thanks for the Info David,

I think I may be getting my terminology mixed up a bit possibly, I think my installer referred to the mixture of Gylcol and water as 'brine', this is the liquid that is running through my ground loops, I will keep an eye on the return flow temperatures.



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