Central heating pipe layout question

9 Feb 2009
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United Kingdom
Can you helpful people please give me your opinion on the usual layout of the feed and return central heating pipes for a 2 storey house, 2 rooms upstairs (3 radiators) and 6 rooms downstairs (7 radiators).

I imagined that the feed and return central heating pipes would run as one continuous circuit from the boiler to serve all of the radiators, both upstairs & downstairs, and then back to the boiler. However, I understand that the upstairs is a circuit by itself and the downstairs is a separate circuit too. The pipes that serve upstairs tee off immediately by the boiler from the pipes that serve downstairs. Is this the normal layout?

The set up is a gas system condensing boiler controlled by two 2 port valves; one for the central heating and the other for the unvented hot water cylinder.

Thanks for your ideas.

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Depending on the construction of the house.
I like to run two backbones of 22mm pipe along the house upstairs and downstairs. I then branch off these with 15mm pipes to each radiator.
The flow and returns aren't in a circuit but you could think of them as two rails. A flow rail and a return rail. If you have the boiler on one side wall it is usually good to run along that wall both upstairs and downstairs with 22mm flow and return rails.
Thanks dcawkwell for your reply.

Your description does sound like the installation I have here. I know the upstairs has the flow and return pipes in 22mm copper which have been reduced to 15mm to the radiators as I have seen the larger pipes when I've lifted boards to lay insulation. This is what prompted my question, as I had assumed until now that the upstairs and down stairs were one complete loop, albeit with separate feed & return pipes.

I assume that the downstairs follows the same format.

Thanks again.


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