maximum pipe-length on 10mm pipework (Index circuit)

25 Aug 2005
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United Kingdom
I'm using rad manifolds on a my dorma-bungalow house.

8 rads, 6 downstairs and 2 upstairs.

I want to put in 4 x 4 port (10mm) manifolds off the 22mm CH feed/return.

It would be easier for me to install the 2nd set of 4 port manifolds downstairs and run 2 pairs of 10mm upstairs.

The rads upstairs are :-

1KW (8m length (4m feed, 4m return)

1.8 KW (16m length (8m feed, 8m return)

Is this going to restrict the flow upstairs, will it be a pig to balance the system. Should I just 15mm/22mm upstairs instead and then reduce down. I've looked at some calculation but i'm struggling.

Any help appreciated
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i am not a plumber or heating engineer, but if you are saying can you run 10mm pipes upstairs to a manifold then put 4 rads on it the answer is yes, the thing is they probably will not work very well since the pipe diameter is so small, run 22mm instead. better to do the job once
We recently had a thread on using 8mm and 10mm pipes here. Read through it and come back with anything that isn't clear. 10mm will be Ok for almost any rad, even with long runs (e.g. 15 metres).
Hi , I am not saying run a 10mm pipe to a manifold.

I am saying run a 22mm pipe with a manifold downstairs with a 10mm feed and return to 2 rads upstairs on 15m piperun.
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That's what I thought you were saying.
Your plan of 22 to upstairs then 2 x 10mm is fine :)
Except that 22mm is way bigger than you need. The total load for the 2 rads is 2.8 kW, which you could supply in 10mm pipe, even allowing for the longish run! Certainly no more than 15mm for the pipes up.

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