microbore or 15mm

[nottsrob184]

Hi all.
I've just finished the building work on a single storey extension and am about to start plumbing in the rads (x2).
The existing central heating is in 15mm pipe all over....i was thinking of connecting to the existing system in 8mm pipe (i think its 8mm?)...microbore pipe so its easier to hide behind the plaster board and skirtings.
Basically is this ok or will the heating be lower in the new rads because of the smaller bore size.?
Thanks

 

[Boilerman2]

You should NEVER carry out such an extension using Microbore unless the rest of the system is also microbore you should use 15mm for your project!