do you change hot pipe size when changing to a combi boiler

Postby pmchammer » Mon Jun 21, 2010 9:29 pm

can anyone tell me if you need to make the hot supply to outlets half inch when changing to a combi boiler
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Simply Build It

Postby plumbbob » Tue Jun 22, 2010 4:24 pm

It would not be usual to down size the pipe simply because of fitting a combi boiler. If you are changing pipework, use 15mm instead of 22mm.
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Postby htg engineer » Tue Jun 22, 2010 9:37 pm

It is best to, as the supply to the boiler is 15mm, having a 15mm draw off, reduces the heat loss. As you cannot get more water out than you put in, there'll always be cooler water in the 22mm pipework.

htg engineer
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