15mm or 22mm central heating pipe

[bengasman]

recently did a complete install in 3 bed semi with 4 x 2kw, 1 x 1.5 kw 1 x 1kw and a small rad maybe 0.5 kw. so total about 11kw

all in 15 mm plastic so even smaller bore than copper. still had to turn the lockshields almost completely shut to get my 20K drop, and the house heats up in no time from stone cold to short sleeves.
the reason i started doing whole installations in 15 mm is that i had the greatest problems getting my 20K drop when working in 22mm. since i started using 15mm throughout, it all seems to work a lot better.

i wonder if the whole heat carrying capacity needs thorough reviewing for condensing boilers.

I have heard the arguments for the use of 22mm many a time, but suspect that all the data that is commonly available is based on old open vent systems which traditionally suffer from airlocks, sludge, flowproblems and overpumping in tanks

 

[jackthom]

Isn't the most common setup to run 22mm (or even 28mm) from the boiler towards or beyond the centre of the house and then take a number of 15mm tees off that at suitable points, each feeding up to two or three radiators.

Maybe I've misunderstood the OP, but the suggestion that all of the boiler output might pass through only one 15mm circuit seems bizarre.

 

[mowerman400]

im intending to re locate a radiator is there any reason why i can use 22mm pipe to radiator instead of redusing to 15mm
im intending to fit a 3 pannel radiator

 

[mowerman400]

i watch a dvd about brasing copper pipes but is soldering still the faverit with plumbers

 

[Madrab]

Soldering so much easier for copper on copper, braising's a whole different kettle of fish and far more critical that even and equal temperatures, induction seems to be the choice these days, are high enough to allow the braise to take properly. It's more relevant when mixing metals, say copper n steel etc with a silver braise