On 22/01/18 18:35, Tim+ wrote:
BG came around to my Mums to look at her combi which wouldnt supply hot
water when the CH wasnt calling for heat.

[..]]
Tim

Not only the same name but i have the same problem!
a plumber spent half last week cursing and head scratching and driving
into town for parts. It's worse than ever now. New heat exchanger tomorrow.
TW