underfloor heating

[deanomatthews]

I am after some advice. I am having a small extension to my house (20m sq) and would like underfloor heating in this room only. I believe that a wet system is more economical than plugging the heating system into the mains. Is this true?

Also how does the system work, is it a simple case of tapping into my radiator circuit? I am also wondering what the most efficient flooring would be that will transmit the heat from the wet pipes through the floor quickly.

 

[dextrous]

I am after some advice. I am having a small extension to my house (20m sq) and would like underfloor heating in this room only. I believe that a wet system is more economical than plugging the heating system into the mains. Is this true?

yes

Also how does the system work, is it a simple case of tapping into my radiator circuit? I am also wondering what the most efficient flooring would be that will transmit the heat from the wet pipes through the floor quickly.

Not exactly like adding a new radiator. It will have it's own independent control centre and pump.

Insulation will be laid on top of the concrete, then the pipes will be clipped to this, then 65mm of screed will be laid over this. After that, any floor covering you want - what are your intentions?

 

[deanomatthews]

ok so the installation costs for a wet Underfloor heating system compared to an electrical one is more expensive but I guess a wet system is cheaper to run. Any idea what the payback period would be and how much a wet system would cost to install for a 20m sq floor area?

 

[DeltaT]

Just look at it this way taffy, a radiator runs at 80*C & your wet UFH will heat the room at 35-40*C. You do the maths!!

It's a lovely comfy heat UFH, no convector currents so no dust moving around, so you can get your feet up in front of the telly, instead of dusting.

 

[deanomatthews]

Thanks JocK so does that me I need some sort of blending valve to reduce the temperature of the water from the rads to the UFH therefore I would not need a separtate pump/thermostat and system just to heat one room?

As I am no expert on plumbing I just want to understand what is required and to keep it as simple as possible.

 

[DeltaT]

On an area of 20M2 yes, you'll need a blending valve to reduce the temperature & a circulation pump. Simple enough wee job if you stick to certain installation rules. Don't buy a 'pack', they are far too dear!!

If your extension has no large glazed areas, you're put it in a concrete screed & it's built to current Building Regs, then 15mm pipes at 200mm centres will be fine.

 

[deanomatthews]

The extension will have large glazed areas so are you saying that building regs may not allow UFH..........

Also why would I need a separate pump if I am going to tee off from the rad circuit?

 

[dextrous]

The pipes get hot water from the main circuit, then pump it round independently from this circuit - it "needs" the water within the underfloor pipes to be cooler than the rest of the CH ones, so it blends some of this hot water with the cooler water within the pipe until the optimum level is reached...

 

[DeltaT]

The extension will have large glazed areas so are you saying that building regs may not allow UFH..........

Also why would I need a separate pump if I am going to tee off from the rad circuit?

No, you need to take special care with large glazed areas & UFH, heat goes to cold son.