Spacing of pipes for underfloor heating?

5 Nov 2009
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United Kingdom
I am having an orangery built (6 x 4m) that is going to contain a lot of glazing. Some photos attached of the design. The orangery is built on piled foundations and the concrete block & beams have been laid. The floor will contain 150mm celotex insulation before the underfloor heating is laid.

I am looking to have the Prowarm
high output water underfloor heating system installed. Can someone recommend the right spacing between the UFH pipes to ensure the orangery is nice & warm during the cold, winter months?


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Typically spacing is 200mm but can come down to 150mm - but I think spacing, pipe circuit length, flow rate, temperature all affect heat output - hopefully a pro heating engineer will be along to advice.

make sure you use the pipe with aluminium layer as it stays in shape better - it’s pretty difficult to get pipe work all nice and evenly spaced, I wouldn’t try and go closer than 150mm

a liquid screed or something like top cem from mapei has better thermal conductivity than standard cenentitious screed.

don’t forget perimeter expansion foam
It's all about heat loss, as it would be when doing calculations for radiators. Pipe spacing @ specific flow temperatures and rates determines heat output per M2.

Conservatories (orangey's) are a bit of a grey area though as far as building regs and heating is concerned. It's to do with planning, if it is connected to the house's central heating system then it falls under different regs and needs specific planning approval.
Thanks @Notch7 and @Madrab. The builders who are building the orangery will be laying the UFH. The orangery has already got approval from Planning and Building control. As part of the approval, I had to get a SAP assessment carried out since we are having an open flow from our existing lounge into the new orangery. The UFH will be connected to the existing central heating system but will have its own zone, etc so that the UFH will be controlled separately from the existing heating system. No stipulations were layed out from building control.

I can check with my builders on the right layout for the UFH or would it be better to get advice from the Prowarm company?
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You need to know the heat loss/U valves for the orangery, that would come from the manu I guess, that would then dictate what output is required from the UFH per M2. That would then drive the specification. TBH the UFH company should be considering that as part of the design layout.

If the UFH was included as part of the design work and submitted to the planners then that would be considered and passed as part of the approval. The reason for mentioning was that a lot of conservatories now don't require specific planning but if it's being heated from the house CH then it does.

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