15mm pipe on 10mm system

[woodi2]

Hi all. I am building an extension and installing 6 new radiators. The existing system is 10mm or 8mm microbore (havent measured it yet so unsure). I am thinking of installing 15mm speedfit in the extension, my question is as follows, has anyone ever mixed the 2 systems, using rads fed with 10mm and rads fed with 15mm. Does anyone have any advice on this, will the 15mm rads take flow and heat away from the 10mm rads, if so can this be counter acted by balancing the system.
Thanks

 

[sonray ltd]

that'll be fine long as you take the feeds from the main flow/return.

and not all six off the same spurs.

 

[woodi2]

Thanks for the quick reply. Will it be as i say then that the system will need balanced. Also, I take it then that it is OK if it 8mm rather than the 10mm

 

[sonray ltd]

just re-balance the system.

you'll need to check the boiler can have the added rads and is not already up to its limit.