Under floor heating

[dj_jay_smith]

Hi All,

I am looking for some advice on underfloor heating. My situation is that I am based in germany and looking to put underfloor heating into a house as it is being renovated.

We got an approx. offer from one heating expert (awaiting final offer) who has done work before for my father in law. But, to be truthful I am not sure if I trust what he is saying. My (basic) understanding of underfloor heating is that it runs on water runs @ about 50-60 degrees C compared to the normal 80 degrees C for normal CH. So you save on heating costs a bit (~30% cheaper).

But this heating guy said that the room temperature set by underfloor heating can not be as high as you have to walk on it. Therefore, because of the cold in Winter you will ALSO need radiators in all the rooms as well.


I don't disagree with the temperature statement but I understand that;

• Underfloor heating has a larger surface area, so heats more of the room and you don't need it so warm.
  Heat rises, and hence underfloor heating goes from the bottom up to the ceiling making it feel warmer.
  Because the floor is warm then you feel warmer than with the same temperature with radiators.

Therefore, I don't see that you should need both! Plus, is it not the case that both underfloor and radiators would have to run off two separate systems with two separate boilers (because of the water temperature difference)?

The price he has then quoted is about 170 euros/sq meter which is about 115 pounds. Ok, this includes a boiler in the cellar as well but it still seems steep to me!

Any advice and information would be appreciated.

Thanks

 

[Agile]

Oh dear! What a lot of misassumptions!

First one boiler is needed and the system takes care of the temperature.

Its the heat used in kW that determines the cost NOT the supply temperature to the rads or UFH.

UFH can be more efficient in the best installations because sometimes it enables the boiler to condense more.

UFH operates at a max of 50° when its in plastic pipe.

UFH has a long thermal inertia of often 1-3 house and needs to be timed differently to any rads.

UFH only gives up to 50w/m² and if that heat output is not enough then rads will be needed.

For most weather and in larger rooms UFH is usually adequate but in small rooms say less than 3m x 3m it may not be enough in the coldest weather.

Due to the low output per m² UFH should only be considered for reasonably well insulated rooms, not with the draughty sash windows we often see in the UK where owners dont want to double glaze or replace them.

Tony

 

[Balenza]

Correct on most points except the heat output per sq meter.
UFH heating has many outputs and many much higher than 50 watts per square meter.