central heating pipework

[RMS]

Hi,

asking this question for a friend (plumber). He has had a disagreement with another plumber at work about the following;

When installing a central heating system (combi boiler is it acceptable to re-use the 22mm pipework for the hot water? Can this have any implications on water flow through the pipe and does this comply with the manufacturer's requirements. The heating system is a Bosch worcester.

Any help appreciated.

 

[Corgigrouch]

There is no technical reason why you can't but the reason why you shouldn't is that it will take longer for hot water to get to the tap that you are using because of the higher volume of water in a 22mm pipe than a 15mm pipe. In some circumstances I have taken a 10mm pipe to supply hand basins, teed into the main supply for the bath from close to the boiler and run it parallel. This way the hot water arrives at the basin quickly and you are not wasting lots of water... Especially handy if the basin is a long way from the boiler