Hi was just looking at the select range from hwos particularly the motorized valves and circulating pumps. I service and repair oil boilers but don't do any plumbing work as I'm not a plumber but I have done oftec 101, have a fga etc. What I'd like to ask is can you replace a 5mtr head circulating pump with a 6mtr head, or would that be to powerful or with these newer pumps can they adjust and find their own speed.