"TheScullster" wrote in message
. uk...

"Roger Mills" wrote

It depends on the size of the rad(s) in the lounge, and whether there are
any upstairs rads connected to the same 15mm leg. The general rule of
thumb is that 15mm pipe will support rads up to a total of about 6kW.
--
From experience I would only use that rule of thumb for single large rads
or 2 rads back to back not far from the 22mm main.
Personally I would run 22mm close to rad take offs and only use long
convoluted 15mm runs where there was no realistic alternative.

i need 9000 btu's in the lounge diner
was going to fit a vertical in the dining area and a larger
std rad under the window in the lounge
22's all round then
Ta
--
Vass