why is my combi boiler not staying fired for central heating. water fine?

Possibly the diverter valve is duff.

Glow worm offer a fixed price call out of about £300 including labour and bits. The only things not covered are the heat exchanger and the expansion vessel.

They alspo ooffer a minimum term maintenance contact that does cover labour and all the bits. This is for 6 months at £50 per month and drops to about half that if you want to carry n afterwards.

https://www.glow-worm.co.uk/homeowner/support/repairs/index.en_gb.html

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February 2017