Central Heating inhibitor

pboae

A colleague has had a leaking radiator for ages, and has been regularly topping up the combi with the filler loop to make up for it. I've tightened the joint now, and the leak is sorted, but I'm not sure how much water has been swapped out of the system, I am guessing it may well need more inhibitor. I'd rather not get into draining the whole system down. Can I just bung a litre of inhibitor in? Does it matter if there is some other brand of inhibitor in there already? Is own brand stuff OK or is Fernox, etc worth the extra?

pboae

...Bump :-)

Igol

2 nails and 2 jam jars
Nail in each jam jar and top one up with tap water and the other up with water from the CH.
Leave it for about a week and it'll give us an idea if you need to stick anymore inhibitor in.

pboae

Thanks! I'll try that.

andrew-b

Too much inhibitor won't do any harm. The bottles always say not to mix chemicals from different manufacturer so i would take that advice. If they don't know what is in there already (check if it's written in the boiler's log book) then drain it all down, flush out at least once and refill with inhibitor added. I think both Fernox and Sentinel have a testing service where you can send off a sample or they also do testing kits.

Andy