Central heating pipe sizing question

[rob7475]

Hi,

I had a new boiler installed back in 2011 and some radiators replaced at the same time. The house is a 3 bed semi built onto a slope so the boiler is in the cellar and two floors of rooms above.

The CH flow and return form the boiler are 22mm for the first few metres before splitting off into 2 x 15mm circuits - one feeding the ground floor and one for the second floor. I'm doing a bit of work in the house and wanted opinions on whether I should change the two circuits to 22mm? The radiators do seem to take a while to get hot but I may be expecting to much.

There seems to be conflicting advice between using 15mm and 22mm. The boiler is a WB Greenstar 30si combi running 11 radiators

 

[winston1]

In a word, no.

 

[ericmark]

My last house had 22 mm dropping to 15 mm dropping to 8 mm and it all worked A1, it does not really matter as to size when pumped, where it does matter is thermo syphon, we fit 15 mm pipe then a lock shield valve so the flow is rather low, I like the idea if not broke don't fix it, if no problems why change?

 

[Mottie]

Perhaps balancing the system may help?