Approximations:
22mm 24kW
15mm 12kW
10mm 6kW
--
Dave

Strange!!!, in the admittedly very old tables I have, it says:

For a flow velocity not exceeding 0.75 m/sec (recommended for domestic)
22mm 7.6kW
15mm 3.07kW
10mm no figures.

For a flow velocity not exceeding 1m/sec (recommended for industrial)
22mm 14.65kW
15mm 4.7kW
10mm no figures

These carrying capacities are calculated on a temperature drop of 11deg C in
the system.

The figures are so far apart from the previous contributor there must be an
error somewhere.

Don