installing a 2 zone central heating system

[stevetheplumber]

Just looking at your sizing of pipes and yes it does look a bit ott generally you can get the last 2 rads of the 22 in 15 unless they are massive so at the 3 from last your branch of twice in 15 one to that rad and 15 to next with 15 tees to the next
dont get to hung up on velocities generaly for domestic work its done by eye and you have no control over the pump with most combis

 

[Tinno]

ok thx stevetheplumber. Anybody know what is the max distance a 15mm pipe can go from the main 22mm piping to a radiator? can it go on for ever, for example if i had a rad say located 10m away from the 22mm pipe is it ok to run 20m of 15mm pipe (flow + return) without any detrimental effect? I have been working on the principle of getting the 22mm pipe as close to the rads as possible so that the 15mm is not too long.

 

[dontknowitall]

10m is fine for a 15mm pipe. I did a run of around 14m metres using 10mm pipe and (apart from an air lock) it works fine too (on a sealed system).

To be fair Tinno, someone would have picked up a potential problem for you by now if you were doing things wrong! The written word is fine in all those books, but there's nothing like the real life version to prove the books wrong (...or right!)

Just go for it!!

 

[doitmyself]

That's one of the reasons for fitting lockshield valves so you can regulate the flow of the water through the radiator.

But it's easier to reduce the flow if the rad is fed from the correct sized pipe as the pipe itself acts as a flow reducer.