Central heating fluid.

[Micheal Ra]

Good Evening, I have two questions concerning central heating systems I'd like to put to the panel. Firstly, is it possible to measure the concentration of corrosion inhibitor currently in the system? If so, is it a DIY job and how do I go about it? Secondly, I'm thinking of installing a water softener which works using salt (I believe ion-exchange is the term for such devices). Can this be used for the cold supply to the central heating header tank or must this be unsoftened water? Any advice would be greatly appreciated.

Thanks, Mike.

[Andy Hall]

The answer to both is yes.

Fernox make a test kit for their products available from plumber's merchants. Sample of the water, add reagent and look for colour change.

Softened water (by virtue of ion exchange) is fine for use in heating systems. The salt is flushed through the softener during regeneration. The only significant chemical difference vs. mains water is that there will be a slightly higher concentration of sodium by virtue of sodium compounds replacing those of calcium and magnesium. I've used softened water in my system for nearly 20 years with no deleterious effect. Remember that the circuit is also closed.

.andy

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[Christian McArdle]

I don't believe there is any problem using softened water. However, assuming the system is working fine and not pumping over, there is no advantage to it. There is a finite amount of scale in the water. If the water is not being regularly replaced, the scale soon settles out and the water becomes naturally soft anyway.

If you have a slow leak or pumping over to the extent that water leaves the overflow, then softened water is probably quite useful.

Christian.

[Dave Liquorice]

Any pump over will mean the header tank getting rather warm, possibly up to the same temperature as the circulating water. This will lead to evaporation and a rather damp roof space if the tank isn't well covered. Then of course there is the waste of energy heating a few gallons of water for no reason and the worse one of all introducing oxygen into the circulating loop hastening any corrosion.