HELP! UFH system causing boiler temp drop/excessive gas consumption

[chris watkins]

The pipe work coming from the boiler to feed these is 22mm copper BUT to the 9 port manifold where it goes into the ceiling there is a section of plastic speedfit on the flow/return which I understand has quite a significant reduction in bore

It goes from copper to plastic but does the external size reduce ie. 22 to 15mm.
The flow rates through plastic are a little less but the plastic normally has less resistance due to less fittings & smoother bore.

 

[chris watkins]

You could get an idea of the flow rate by looking at the temperatures on each of the manifolds (F&R) & the temps back at the boiler with just the 9 port one on.

 

[JVTrades]

I almost jumped in earlier in the thread to say the same. A buffer tank would improve things I'm sure. Also, that's a large area - 650 cubic meters ish and a similar sized extension. Without knowing all the building specs don't know but I would suspect that the boiler at 24 KW is too small