I went to a breakdown Tuesday and told "old baxi conventinal boiler overheats after a minute". I went out thinking pump gone but it was spinning it was making a noise but seemed OK,next header tank and found it empty and ball valve broke so I fitted new one and filled system and after venting rads and circs now the 3 port is a old hand type servo warm style valve and I got water hot then opens it to both and the rads were slow so I put ch only on and it was a balancing job but seemed OK but just had a call rads not working on ch only 2 out of 8 working. The flow and return from boiler are half inch two feet after 22mm from boiler. I would like to ask lads do you think it's the pipe size,pump or ?. The lAdy said "what will fix it 100%" I said "a combi,22mm from boiler to first tee and get trv's and l/shields fitted As the valves are old and I am scared when turning them down as they will start leaking unless lucky" that suggestion was turned down so I'm going back tomorrow and I'm not up for balancing them again as if they leak I ll be blamed so ? Shall I run away thanks lads