1/2" or 3/4" pipes for new CH system?

[Henrik]

Hi,

getting quotes from various installers for new gas fired CH system. There'll be a total of 17 rads - 52,000 BTUs, plus hot water cylinder. Some installers are saying pipe it in 1/2", others saying due to size of system pipe it in 3/4". Any suggestions as to which is correct?

Thanks,

Henrik

 

[EliteHeat]

The answer is that some of it should be in 22mm and some of should be in 15mm. Just like every other system really.

 

[Bamber gaspipe]

getting quotes from various installers for new gas fired CH system. There'll be a total of 17 rads - 52,000 BTUs, plus hot water cylinder. Some installers are saying pipe it in 1/2", others saying due to size of system pipe it in 3/4". Any suggestions as to which is correct?

Thanks,

Henrik

All from boiler to cylinder & back in 22mm. Main flow & return in 22mm. Branch off to rads in 15mm, any drops to rads in 15mm.

 

[nickso]

they should have worked it out properly, ask them how they did it.

17 rads is quite big and depending on the lengths of the pipe runs and the boiler you may need to go bigger for some of it.

 

[Bamber gaspipe]

17 rads is quite big and depending on the lengths of the pipe runs and the boiler you may need to go bigger for some of it.

Just finished 25 rad installation all piped up in 22mm & reduced to 15mm to all rads, works fine, as long as the boiler/pump is adequately sized there shouldn`t be a problem.

 

[nickso]

17 rads is quite big and depending on the lengths of the pipe runs and the boiler you may need to go bigger for some of it.

Just finished 25 rad installation all piped up in 22mm & reduced to 15mm to all rads, works fine, as long as the boiler/pump is adequately sized there shouldn`t be a problem.

fair enough im not disagreeing.

all im saying is there are proper ways to work out pipe size.

ive been to many a system under 17 rads that are struggling due to poor sizing.

the OP hasnt given us much information regarding the length of the runs. a bit of caution at the planning stage never hurt anyone.

 

[Bamber gaspipe]

"nickso

all im saying is there are proper ways to work out pipe size.

What`s the proper way?

 

[nickso]

there are tables you can use to work it out

 

[Bamber gaspipe]

there are tables you can use to work it out

Where?

 

[nickso]

hmm ive got my own copy from years back.....dunno where you would find some

 

[Bamber gaspipe]

hmm ive got my own copy from years back.....dunno where you would find some

Please hurry & find them if you could because I`m on a full hit in a nightclub next week, possible 25/30 rads & I wouldn`t want to undersize, let me know if you find them calculations, (will put job on hold). It`s a fully pumped system, why would he need anything larger than 22mm? ( in a domestic installation)

 

[namsag]

Simple answer to the question is, No it should not be piped in just 15mm it should be piped mainly in 22mm with say max of 3 rads on 15mm drops/legs

 

[Bamber gaspipe]

with say max of 3 rads on 15mm drops/legs

Bollo**cks

 

[namsag]

An why ******s

 

[Biggles..]

Sure i was taught way back that the following general rules apply for sizing heating runs: 28mm will take/pass/provide 80.000btu's, 22mm = 40,000btu's and 15mm=20,000btu's.
These figures are laid down somwhere but off hand cant remember where could be a CIBSE book, i think.
Lee