Adding more Radiators 15mm or 22mm run

bhzmac1

Technical question for any plumbers / heating engineers.

Adding 3 more radiators to my current Condensing Combi system which the flow and return loops round the house and back to the boiler on 22mm pipe with each of the 8 rads T'd off the 22mm with 15mm.

The location of the new Rads means I need to T off the 22mm flow / returns very close to the boiler and space and the run to the new rads is tight and a little awkward meaning that running 22mm pipe to where I need it is going to be a pain. Is is ok to take the flow and return loops for the 3 extra Rads down to 15mm and run the 3 of them off a 15mm loop? BTUs of the 3 rads are 7754 / 1100 / 1900. Dont expect the smaller Rads to be running at full capacity as they are in a small WC and Utility rooms which are both super insulated. The new run is around 4 to 5 meters each way and will be the very first off the boiler.

Ruski

I wouldn't run three off 15mm, two max, but that's just how I work.

IMHO

HTH

Russ

bhzmac1

So I would be better running a separate loop for the big one and the 2 smaller ones on the same loop, mind you by the time I have done that It may be easier the struggle with 22mm feeds

Ruski

Perfect scenario is get 22mm to the first two rads, then drop down to 15 for the final one.

TBH if you're doing pipe runs anyway it's not really any different whether you're using 15 or 22!

HTH

Russ