Pipe sizes info

[mutley racers]

Hi guys

Am just after a bit of help. What i want to know is, is there any point in converting the 15mm cold main into 22mm and running it to a 24kw boiler into 15mm then off to the toilet, shower and basin in 22mm also.

And then, coming out of the hot in 15mm and converting up to 22 mm for shower, and basin and kitchen sink?

Another query on the heating side, is there any point in running 22mm flow and return pipes and then just branching off 15mm to the radiators?

Its only a little 3 bed house with 6 rads and a towel rail.

Am in need of a bit of guidance on why this would be done?

Thanks

Leroy

 

[J c stokes]

personally i'd run the cold main in 22mm to the last tee before the boiler and then 15mm to the boiler. Hot i'd prob just do in 15mm if not to long a run

Flow and return I normally run no more than 2 raditors off a single 15mm run so if you got 6 i personally would use 22mm

 

[Dannypipe]

Depends on the size of the pump, the radiators and the pipe run lengths and bends.

Good rule of thumb is 11KW for a 22mm pipe. If you exceed that with your radiator outputs then you could be pushing your luck. Want it in BTU - about 40K.

You can get away with a bit more, but why push your luck. The rest has been answered for you.

 

[mutley racers]

Nice one guys. That really helps.

Regards

Leroy

 

[mutley racers]

when you say run the cold in 22mm before the last tee, so i run to the tee before the boiler in22mm, branch off to the boiler in 15 and then 15mm upstairs to the shower, basin and toilet?

 

[Nat]

If your main comes into the house in 15mm I don't see the point in upping to 22 as you are not going to ever exceed the pressure or flow rate coming through that initial piece of 15mm. Am I wrong here?

 

[mutley racers]

To be honest Nat, that is exactly what i thought?

 

[diamondgas]

Mutley racers ... If the supply is 15mm then uping it to 22mm will make little if any difference regards cold water mains, and it'd make for a much larger quantity dead leg on the hot water!! Your C/H will benefit from using 22mm F&R's though. Back when i use to do installs we'd run 22mm till the last 2 take off's or at most run 2 rads of 15mm. It made ballancing a lot easier and reduced strain on the pump etc.

 

[AWheating]

i am assuming this is a combi boiler?

it may be an advantage to run 22mm cold pipework dependant on lenght of run, route etc... it wont increase the amount of wasted water on the hot, if it did then the principal of increasing to 22mm has worked as its supplied the boiler a better flow rate!

if you stick with 15mm then try make sure the first connection after the stop tap is the boiler especially if you cold flow rate is less than 20lpm, this will help reduce the amount of flow drop on the hot when a cold tap is opened.

 

[diamondgas]

... it wont increase the amount of wasted water on the hot, if it did then the principal of increasing to 22mm has worked as its supplied the boiler a better flow rate

You're right AW, just re-read my post and it reads like I meant uping the mains supply would increase waste water:freak: I was replying to the posts thoughts on increasing the hot water pipe sizes which would increase the lag before the hot arrived but didn't make that clear! ........... It was gettin late...lol

 

[mutley racers]

Thanks guys. All your opinions have been taken in. Am still not sure what i would do. MIxed thoughts from you guys and so indecisive me.

I guess, when i check the incoming main flow rate and its less than 20lm, up the main to 22mm?