Central heating pump size

[Viking]

Which central heating pump should I buy ?.

I have an average 3 bed semi with a traditional open vented boiler Potterton profile 50E. Eight radiators in all. Existing pump is a 15/50 5 meter head.
My loft has been converted into a 4th bedroom and a new radiator will soon be installed making 9 in all. The header tank has been re-positioned above head height in the loft.
I want to replace the ageing circulation pump but not sure if I should buy the more powerfull 15/60 with 6 meter head. Not sure exactly what this means. Can any heating engineer advise please.

Dan.

[htg engineer]

The 15/50 will be adequate for the average heating installation, the 15/60 is required for a slightly larger system and for systems with a greater resistance for example mini-bore pipe or like yours that extra height.

The head (m) refers to the vertical height the pump will operate effectively to - before the pressure/circulating capability is reduced.

I would install the 15/60, remember to flush and add inhibitors to the system when you're finished.

[Viking]

Thanks for the response and advice, very much appreciated.