Measuring pH level of heating system water?


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
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Ret. wrote:

When I was at school we used litmus paper. I see Johnsons do polypropylene test strips, which will give you more knowledge than just a red/blue indication.
Use one of these twice a year on some water from a bleed nipple. Doubt if you can get much cheaper than that!
Rob Graham
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Rob Graham wrote:

Thanks for that Rob. Are these strips available from chemists?
Kev
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Ret. wrote:

Ignore the above - I've found something similar on eBay - £1.68 inclusive of p&p - for 60 test strips!
Thanks for your advice.
Kev
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Ret. wrote:

GTHBOH
Rob
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