I note from my Worcester Bosch combi boiler installation manual that the guarantee on the boiler will be invalidated if the pH level of the circulating water exceeds 8. Clearly this is for a good reason (corrosion of the aluminium heat exchanger?) and so I would like to keep an eye on this, even after the 2 year warranty has expired (and warranty on the heat exchanger is for 10 years).
A quick Google reveals pH monitors costing several hundred pounds - and also aquarium pH testing kits costing less than £7. I don't know if the latter would be good enough (or the measurement scale appropriate) for measuring pH levels in the heating system.
Any advice on the best (and cheapest) way to test the pH level of the CH system water?
Kev