Central Heating antifreeze

[monkeyhanger]

I have Fernox Alphi 11 in my boat central heating system as an antifreeze, which, as I don't live aboard seems a sensible idea. When I phoned Fernox to find out the lifespan of their product, I was told its life is indefinite. Does anyone else use the stuff? Would it be a good idea to change it once in a while? It's not exactly expensive at £33, but I could do without the hassle of changing it at this time of the year if it's not necessary. Any thoughts?

[Chewbacka]

48 minutes ago, monkeyhanger said:

I have Fernox Alphi 11 in my boat central heating system as an antifreeze, which, as I don't live aboard seems a sensible idea. When I phoned Fernox to find out the lifespan of their product, I was told its life is indefinite. Does anyone else use the stuff? Would it be a good idea to change it once in a while? It's not exactly expensive at £33, but I could do without the hassle of changing it at this time of the year if it's not necessary. Any thoughts?

The corrosion inhibitors life is probably not infinite, but given that Fernox say there is no need to change it then I certainly wouldn't change it before the spring or summer.  If you are worried about it's anti freeze properties (concentration too low) then you can check it with a refractometer using the scale for propylene glycol, or take a small amount out and pop it in the freezer and measure the temp at which it freezes, or freeze some and see what temp it melts at. 

You can get a 'car refractometer' on ebay for less than £15 which will do coolant (both types), battery acid and screen wash - not so useful on a boat.

Edited December 17, 2017 by Chewbacka
typos

[Tonka]

BMW now do an antifreeze which they say lasts for life so maybe the same as Alphi