2 bed house central heating - 22mm ring main - OTT?

[gwernybwch]

Hi,

I'm currently renovating a two up, two down terraced house and will be repiping the central heating throughout. It will feed 9 (Acova steel column) radiators and run off already installed (about 3 years old) Worcester combi boiler.

I've just had a Plumber to come around to give me a quote and he has recommended that I have a 22mm ring main which then branch off into 15mm for each radiator.
I was surprised by the recommendation of a 22mm and was expecting both the ring main and the spurs to be 15mm.

Therefore do you think that a 22mm ring main in a small terrace house is OTT?

Thanks in advance for any replies?

 

[Tibbot]

Ring main and spur are electrical terms. In central heating speak, for 9 rads you generally require a 2 pipe (flow/return) system in 22mm with 15mm branches to/from each rad until you get to the last one on the system where again you can reduce to 15mm.

 

[gwernybwch]

Ring main and spur are electrical terms. In central heating speak, for 9 rads you generally require a 2 pipe (flow/return) system in 22mm with 15mm branches to/from each rad until you get to the last one on the system where again you can reduce to 15mm.

Am I right in thinking that a main system of 22mm would be 'standard practice' even in small terraced houses?

 

[twgas]

Yes, 22mm pipe is the norm.

 

[jeff the gasman]

15 mm no more than 3 average radiators.
Jeff

 

[Agile]

The norm is to use 22 mm to each floor and then supply each floor with 15 mm as that is usually adequate.

The rule of thumb is that 15 mm can supply about three rads and a maximum of about 4 kW. That should work in your case.

But that's a slightly out of date method as it was used before condensing boilers which needed a greater flow through the rads. Its still generally used now but in many cases its possible to supply a little more power with a condensing boiler although doing that makes careful balancing essential.

Tony

 

[D_Hailsham]

I'm currently renovating a two up, two down terraced house and will be repiping the central heating throughout. It will feed 9 (Acova steel column) radiators and run off already installed (about 3 years old) Worcester combi boiler.

15mm pipe can carry 12kW if the system is designed to run with a 20°C differential.

Which model & kW Worcester do you have?

Do you know the heating requirement of your house? If not use Whole House Boiler Sizer

Have you purchased the rads?