My dormer bungalow has its ch run from the Worcester Bosch combi (which seems more than adequate BTW) in a 15mm ring, with tees off in 10mm to the rads.
I'm about to add a rad to the newly-built conservatory - any reason why I cant run the flow and return to/from the ring entirely in 15mm?
The reduced diameter of the pipework to the original rads' will cause the new radiator to be fed easier than the other with 15mm pipework going to it. You could take 15mm pipe close to the new rad' then reduce it to 8mm or 10mm before it connects to the valves. This would help balance out the load to all the rads'.
True, but care is needed because 8mm pipe will only support 1500W and
10mm pipe only 2500W over typical house distances.A conservatory could easily need 4kW, depending on size and desired temperature..
Does this mean that each radiator fed by 8mm can be up to 1500W? My system appears to be a mix of 8mm feeds to the radiators upstairs and 15mm downstairs. Without going under the floor its impossible to say how long the 8mm and 15mm pipe runs are. CM.
This is a rough rule of thumb, Charles.
8mm over a few metres (less than about 10) will support 1500W. THis is based on an assumed flow rate to minimise noise and that transfer of X amount of heat means moving Y volume of water with a temperature drop of T.Really one should look at the flow resistance effects as well and there are tables to do that at the web site of the Copper Development Association. They have an application note with sizes and lengths and formulae. Normally one should work on the basis of the pipe size required to support a given amount of heat at a certain pipe run length when designing a system.
As far as the installation is concerned, your upstairs 8mm runs may either run to manifolds on the main 22mm pipes from the boiler or they may be tapped into the 22mm or possibly even 15mm runs directly.
It's possible that the downstairs ones are 15mm because the radiator sizes call for the flow to support them.
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