Calculating BTUs for underfloor heating

[luckyglen]

Can anyone tell me what the BTU output of underfloor heating (15mm plastic pipes), laid in between joists, in screed, with insulation underneath. Wooden floor on top.

I'm trying to calculate the heat output so I know how far apart to put the pipes.

I've read a few things that state to put the pipes at 100mm centres, others say 150-200mm.

Even simple info such as BTU output of 100m of 15mm plastic pipe would be appreciated.

Ta

 

[ChrisR]

Get a copy of the Polypipe design book(s). They show several different installation methods for each floor type, with different outputs.

 

[markvirgo]

I have 150mm@10mm pipe.

This was specified by the manufacturer

 

[Weezbo]

that is a definite aid in design. one can do a heat loss calculation then determine how to meet that loss with various sized tubing and spacings and fluids,floor coverings .....room by room . Wirsbo might not ship this design manual from the US. however, those are some of my thoughts on what you are asking.

The manual also describes various heat plants and applications of radiant heating allowing a designer to qualify exactly what types of control strategies to use.

There are guidelines as to the BTU output per square foot ,surface temps of various floor coverings and recommended maximum supply temps.

from what you are describing i would think thick aluminium Plates would be the best in providing the lowest temp fluids to meet the heat loss and in distributing this heat as evenly as possible. *~/

you will have to excuse my spelling as i have been in the United States for decades and it is a slightly different form of the English language

 

[doitall]

The alu floor plates will answer that question (2 x runs per joist span).

The best plan is to insulate as thick as posible between the joists.

The heat deflector plates then press into to insulation, and the pipe fixes to that.

Avoid any, or, as much as posible, any air gaps under the wood finish as this acts as an insulation and can/will reduce the efficiency.

For heat calcs, as I said 2 runs per joist, (200mm centres ish) you can then control the heat output from the manifold and room stats by adjusting the flow rates through each set of loops.

 

[Agile]

You can usually assume 70 watts per square metre as a starting maximum output.

Then reduce it according to the top floor covering. Thats where the greatest loss of heat output is likely to occur particularly when thicker wood is used.

There is also another problem that many thicker wood floorings cannot stand the temperatures created by UFH.

Tony

 

[luckyglen]

Cheers guys.

Advice much appreciated.