thanks for your help. I'll give that a go, maybe i didn't get all the air out of system when i refilled it. would air in the system be a possible reason for temp going up rapidly then heating or hot water cutting out then coming back on intermittently.
Hi My name is Dave
I have a glow worm 12 hxi condensing boiler. Heating would only come on if hot water and central heating were on together or if I put diverter valve to manual. So I replaced the mid position valve and since refilling the system when I turn on heating or hot water temp goes up...