irvo the conventionally used maximum that can be fed from 15mm is about 4 kW, so it depends how big your radiators are.
In practice it will also depend how far they are from the boiler, etc. The figure can be worked out from a given temperature drop across the system, maximum desirable flow rate of the water, pipe resistance etc. If you use a figure around 3kW you should be able to get the full amount of energy from the rads.
The same sums would tell you that you need 28mm pipe from a 100,000 Btu/hr (approx 28kW) boiler, though boilers of that size typically have 22mm connections! Some mfrs DO tell you to go up to 28mm from the 22.
I disagree that any of this stuff is remotely difficult. If you want to find out about it, half an hour with a library book will tell you most of what you need to know.
In practice it will also depend how far they are from the boiler, etc. The figure can be worked out from a given temperature drop across the system, maximum desirable flow rate of the water, pipe resistance etc. If you use a figure around 3kW you should be able to get the full amount of energy from the rads.
The same sums would tell you that you need 28mm pipe from a 100,000 Btu/hr (approx 28kW) boiler, though boilers of that size typically have 22mm connections! Some mfrs DO tell you to go up to 28mm from the 22.
I disagree that any of this stuff is remotely difficult. If you want to find out about it, half an hour with a library book will tell you most of what you need to know.