Anti-freeze in Primary Circuit

Is there a problem putting anti-freeze in the primary circuit to prevent radiators and boiler from freezing if the house is empty? It does not seem to be the done thing, but it must be in solar panel circuits

It will depend on the system you have and the conditions of the installation particular to your exact conditions.

For example, if your system is an open vented system, many are installed with the f & e tank located over the cwst. This is illegal however very common. It could also have it's overflow pipe piped into the cwst, also very common but incorrect. If your ball valve fails, it will overflow mixed anti-freeze into your domestic water.

If you have a sealed system, then I suppose the risks are the same that of a solar system, at the coil in the domestic hw cylinder. If this fails, anti-freeze will enter the domestic water system.

Shane,

Is there a risk of corrosion of pipework, components or fittings when using anti-freeze like that?

No it is not corrosive. It is manufactured for the purpose of using in domestic heating systems. I have not used it in heating systems and have not checked the ingredients of it but I presume it is a glycol mixture.

I will check it out and get back to you.

Glycol is well know on cars to seek out any potential leaks.
My system has the oveflow to the outside but it has a header tank, and I am told by a plumber that there there is no vent pipe, as installed now on later systems, don't know what happens when it boils.

The water will expand up through the feed to the heating system.

Here's a link to Fernox Alpha-11 Protector which is a combined anti-freeze and system inhibitor designed specifically for use in domestic heating systems. It is non-corrosive, non-toxic and environmentally friendly. It gives anti-freeze protection from -11C to -22C depending on the ratio of the solution used.



It is a mono-propylene glycol.

Thanks Shane007

Hi Shane,

Many thanks for your research on this.

It seems like an interesting alternative to the traditional solutions.


ONQ.