Central heating pipe sizes

[jamesr36]

Hello,

Carrying out some alterations to my heating installation and would like some advice on pipe sizes. Currently have 28mm for the first 2m from the boiler, then everything else is in 22mm apart from the 15mm tails. Boiler is about 5m pipe run away from the HWC/pump etc.

How far should I ideally go with the 28mm? or is 22mm adequate.

System has an old conventional boiler (will get replaced soon), pumped system, ventilated, indirect HWC, 7 average size rads, average 3 bed house.

Thanks

 

[OLLIE20]

Coolant???????? Care to elaborate on this please?????

Generally an average 3 bed gaf with 7/8 rads, indirect hw cylinder doesnt need any 28mm, generally 22mm main circs, then 15mm legs to rads will do the job

 

[Agile]

James, no one can advise you without knowing what type and power of boiler you have!

Generally up to about 30 kW is OK in 22mm on a condensing boiler.

An older 30 kW non condensing boiler would usually have had 28mm pipes, not so much because it was essential but more because years ago people were more keen to do things better are use larger pipe sizes.

But any house needing a 30 kW boiler would be 6+ bedrooms and not your normal three bed semi. A semi usually needs 10-12kW !

Tony