22mm vs 15mm?

[ColJack]

the pipes from my boiler go up the wall into the loft space in 22mm.. ( second storey maisonette.. )

as soon as they enter the loft they are reduced down to 15mm which then feeds 5 rads..

1 large ( about 1800 double ) rad in the lounge, 1 small ( 600mm double ) in the kitchen both fed off the same branch..

1 small rad in the bathroom ( 400mm single ) on it's own branch

1 med rad in the back bedroom ( 1200 double ) on it's own branch

1 small rad in the front bedroom ( 600 double ) on the end of the run..

would changing the main line to 22mm make any difference in the noise etc of the system?

 

[hi-spec plumbing heating]

shouldn't be a problem.

 

[Bahco]

Don't know about reducing noise but the rads will heat up quicker and be easier to balance.

 

[ColJack]

that's my next job when it gets warmer then..

the pipe at current run too close together to get insulation round properly and are 100mm above the ceiling joists in most places.. makes storing stuff up there a pain..
can I run the pipes in between the joists under the loft insulation ( surely better this way anyway as they get insulated and any loss would be downwards into the habitable space? )

is there any way to "zone" the heat with room stats and three port valves? ( IE each room would have it's own stat instead of trial and error with the TRV's? )