28 or 22mm primary circuit pipe

[coopersim]

I'm having a new boiler and tank fitted in a couple of weeks, both are capable of 28mm pipe diameter but my plumber says that 22 is perfectly adequate, the distance from boiler to tank will only be about 2 metres, will the be ok or am I better asking for 28 while I have the chance?

 

[GavThePlumber]

How are we/the internet supposed to know?

 

[Gasguru]

Depends of the cylinders coil rating (or in the case of tank in tank cylinders the heat transfer rating), the boiler size and whether it's to be set up as a hot water priority system.

 

[newbuildinstaller]

to be sure I usually go with 54mm...

Unless your boiler is giant 22mm will do.

You would need to give us:

Boiler output-
Heat loss required for heating
Coil heat req for cylinder
Distance to cyl (which you did)

 

[Richardthe3rd]

I'm having a new boiler and tank fitted in a couple of weeks, both are capable of 28mm pipe diameter but my plumber says that 22 is perfectly adequate, the distance from boiler to tank will only be about 2 metres, will the be ok or am I better asking for 28 while I have the chance?

Is it a direct cylinder you're heating CS or are there any radiators from these pipes? If you can please provide more details of the boiler & cylinder/tank then we can establish a size.

 

[coopersim]

Sorry for the lack of details

Boiler is a greenstar external 25/32
Tank is green store 210sl

I believe that there will be a three way port valve to switch from radiators (plumbed in 22 throughout the house) to hot water

There will be about 12 radiators in total

I'm afraid I don't know the answer regarding heat loss, sorry

 

[Richardthe3rd]

Thanks CS. I'd say 22mm will be more than enough, unless you have a huge hot water demand?!
Kids these days sometimes take two showers a day, when we were kids it was a bath once a week - if you needed it or not!!

 

[coopersim]

Cheers! Thanks for the advice