Underfloor Heating - the biggest con ever

Eldi_Dos

Given that dark colours are better at emitting heat I do not think I have ever seen a radiator painted black, if it was behind a radiator cover the aesthetics would not matter to much.

One for anyone involved in installing UFH, is a colourant added to the screed and would it make any difference?

grumbler

Eldi_Dos said:

One for anyone involved in installing UFH, is a colourant added to the screed and would it make any difference?

No, it's the floor colour that matters and, if it's screed, only the colour of it's surface.

beckysheffield

Your house is well insulated.

end of story 

Chickereeeee

Eldi_Dos said:

Given that dark colours are better at emitting heat I do not think I have ever seen a radiator painted black, if it was behind a radiator cover the aesthetics would not matter to much.

One for anyone involved in installing UFH, is a colourant added to the screed and would it make any difference?

'Anthracite' coloured radiators are fairly common. Also, white radiators give out 30% more heat than chrome for the same size, and black ones even more.

Brie

Numerous cats and dogs likely think it's wonderful.  and people who walk around with bare feet.

Chickereeeee

ComicGeek said:

Chickereeeee said:

ComicGeek said:

Chickereeeee said:

I don't really know why UFH is called 'radiant' anyway, as most heat dleivery would be via conduction or convection. 

UFH is typically 60% radiant, 40% convective - however the heat has to be delivered to the surface of the floor via conduction before being delivered as radiant and convective heat.

Radiators are typically 70% convective and 30% radiant. 

I still doubt that. With no evidence whatsoever, I would have though that heating the air local to the floor would account for most of the heating effect. 

Fortunately science isn't based on random thoughts, so thermodynamics still functions as the universe intended despite some people not believing it. 

The temp of the UFH floor surface is relatively low, normally 26-27 degrees, so the convective effect is limited by the amount of heat that the air can pick up to generate convective currents. Compare that to a radiator which might be 70 degrees. That's the difference. Also the fact that the parts of the room furthest from the radiator will be much colder, and that drives the convective currents, and particularly if the radiator is under a cold window. 

Then think about the physical area of the heated floor compared against the front face of the radiator that you would see - even though the floor is not as hot, the radiant effect is provided by the sheer size of the floor.

So, in an empty room (no furniture) the radiant heat is heating the ceiling (and walls)?

Black floors and silvered ceilings it is then!

Eldi_Dos

Brie said:

Numerous cats and dogs likely think it's wonderful.  and people who walk around with bare feet.

If the floor covering was an environment friendly product that would fit in with the leave only footprints ethos

ComicGeek

Chickereeeee said:

ComicGeek said:

Chickereeeee said:

ComicGeek said:

Chickereeeee said:

I don't really know why UFH is called 'radiant' anyway, as most heat dleivery would be via conduction or convection. 

UFH is typically 60% radiant, 40% convective - however the heat has to be delivered to the surface of the floor via conduction before being delivered as radiant and convective heat.

Radiators are typically 70% convective and 30% radiant. 

I still doubt that. With no evidence whatsoever, I would have though that heating the air local to the floor would account for most of the heating effect. 

Fortunately science isn't based on random thoughts, so thermodynamics still functions as the universe intended despite some people not believing it. 

The temp of the UFH floor surface is relatively low, normally 26-27 degrees, so the convective effect is limited by the amount of heat that the air can pick up to generate convective currents. Compare that to a radiator which might be 70 degrees. That's the difference. Also the fact that the parts of the room furthest from the radiator will be much colder, and that drives the convective currents, and particularly if the radiator is under a cold window. 

Then think about the physical area of the heated floor compared against the front face of the radiator that you would see - even though the floor is not as hot, the radiant effect is provided by the sheer size of the floor.

So, in an empty room (no furniture) the radiant heat is heating the ceiling (and walls)?

Black floors and silvered ceilings it is then!

The heat is radiated out to any surface which has a lower temperature than the heated floor/radiator. It's trying to create an equilibrium where everything is the same temperature. However this never happens where the floor/radiator is being replenished with heat. You feel the radiated heat from a radiator as the temperature is much hotter than your body - you don't physically feel it from UFH as the floor temperature is slightly lower than your body temp.

It's not significantly heating up the ceiling and walls, as air flow then removes some of that radiated heat via convective from the surface (and then hopefully your thermostat turns off the heating when the required air temp is reached). You want the surfaces to be warm though, as that is a key part of comfort - if the surfaces are too cold then your own body will be radiating heat to them, and you feel cold.  

avoidtheupsidedownbottles

JohnB47 said:

If it wasn't for the ridiculous price of electricity, electric under floor heating is, I think, a good idea. In small areas, that is.

We have it in our bathroom and we have it coming on for around an hour before we get up in the morning. It definitely makes the bathroom feel very cosy and it's great to have the warmth on your feet.

No longer than an hour though and only between November and March.

Always thought UFH in the bathroom would be a good match with Economy7 for an hour or two before getting up time.  Also for upstairs bathrooms, you don't have the problem of needing an insulated floor like one does at ground level

theoldmiser

JohnB47 said:

If it wasn't for the ridiculous price of electricity, electric under floor heating is, I think, a good idea. In small areas, that is.

We have it in our bathroom and we have it coming on for around an hour before we get up in the morning. It definitely makes the bathroom feel very cosy and it's great to have the warmth on your feet.

Have you thought about wearing slippers, and using a bathroom mat?