Microbore advice - please! - New run pipe size before reducing to microbore

[Mike B]

Hi All
I want to add a radiator to a microbore system; the supply and return pipes are all 22 mm feeding a mixture of 10 mm or 8 mm microbore which are taken directly from the ends of the 22 mm pipes. I plan to "T" into the 22 mm supply and return pipes with a run of "large bore" pipe before dropping down the wall in 10 mm microbore. The radiator will be a maximum of 10000 btu. Can my run of new "large bore" pipe be 15 mm (before the 10 mm microbore) or should it be 22 mm?
Many thanks for your thoughts!
Mike

 

[Chester]

why not run your new rad from 15mm?

 

[Mike B]

I thought doing that may cause problems with balancing the system but I would be grateful for thoughts on this!

 

[Best]

I thought doing that may cause problems with balancing the system but I would be grateful for thoughts on this!

That's what the lockshield radiator valve is for, - reducing the flow for to balance the rad.
Flow from 8 or 10mm pipes over several metres of a run will not be adequate for a large radiator and worse in winter. Remember you have to add the flow and return pipe run together to get the full pipe length

 

[king of pipes]

Run it in 15mm off the 22mm 10mm wont be enough . kop