CH Btu carrying capacity of copper and plastic pipe

[Andy165]

Have got this copied down somewhere but cannot locate it amongst my many trade mags., MI,s and other mounds of printed information you keep for future reference The info. I would like to know is what is the CH btu carrying capacity of 10mm copper pipe, 15mm, 22mm, & 28mm? Is it the same for plastic pipework. I vaguely remember 15mm copper pipe can carry 15,000 btu,s and 22mm copper pipe can carry 22,000 btus (feel free to correct me if I,m wrong). Have got a conservatory to pipe up with rads. and the nearest one is on 10mm pipework and chipboard sheet flooring

 

[John506]

what kW is your boiler and how many rads already on the system?

 

[Andy165]

24kw non condensing combi with 8 existing rads on 10mm. microbore pipework. I know its well got the capacity but to add two more conservatory rads onto existing 10mm pipes could be madness. Existing Floors are laminate covered so this looks like a ball******** job.

 

[toasty]

Hi,

Not sure about plastic, but I guess it's much the same...

The heat carrying capacity of a tube is limited by the maximum velocity that can be accepted for noise reasons. This is generally taken as 1.5 m/s. The other key factor is the temperature drop of the system which is generally taken as 20°C for a condensing boiler, although greater or lesser temperature drops could be specified.

For 1.5 m/s and 20°C temp drop, the carrying capacity of each pipe size is as follows -

8mm = 4.5 kW
10mm = 7.3 kW
15mm = 18.1 kW
22mm = 40.2 kW
28mm = 67.5 kW.

However these figures are maxima and may need to be reduced to take account of frictional resistance and available pump head.

 

[toasty]

Oh, you said Btu, the conversion is
1 kilowatt-hour (kWh) = 3413 British Thermal Units (Btu).

Cheers

 

[D_Hailsham]

See Copper in Small Bore Heating Systems.

The maximum heat carrying capacity and flow of Speedfit pipe, based on 1.2m/s velocity and an 11°C temperature drop is shown in the table below.

[code:1]
Pipe size Max Capacity KW Max Flow litres/sec Headloss m/m pipe
10mm 1.948 0.042 0.283
15mm 5.941 0.129 0.319
22mm 13.604 0.295 0.084
28mm 21.991 0.478 0.062
[/code:1]

 

[Andy165]

Thanks for the replies