Floor Construction for Underfloor Heating

[UncleLumpy]

I'm thinking of putting wet underfloor heating in a conservatory I'm building as I've been advised it's more efficient. Anyone know what the floor construction should be?
I've been told to put 75mm of hardcore down followed by 100mm of concrete, then 50mm of polystyrene, then a 75mm screed to cover the pipes. But no-one can tell me where the damp course should go. Any ideas?

 

[sm1thson]

not what you are asking but you need to be aware:

under building regulations the conservatives heating has to be independent of the houses, this is because a conservatory does not meat heat loss regulations, but is exemrt as it is separate from the house (hence it must also have an external door inbetween the house and conservatory).

a wet system is more efficient in general but if you are using it in a conservatory all that heat from your boiler will be going straight out of the glass when ever you have the heating on.

for our conservatory we just use an electric fan heater when we require, although electricity is more expensive than gas its not on for long so it doesnt run up a bill.

electric underfloor heating helps the floor not feel cold but thats about it.

the ultimate solution is a heat pump. ie an air conditioning unit that can be reversed. thus you can use it to cool in summer and heat in winter (they are more efficient than electric heater because they move heat rather than generate it) -problem there is cost.

some people claim that having a way to independently turn of a wet system in a conservatory is sufficient to get round the building reg -a grey area. -if you go down that road you will still need an electric fan heater for times the conservatory is cold but the rest of the house isnt and you want to heat just the conservatory.

 

[UncleLumpy]

Thanks for that.

I think I'll build the thing, then see how much heating I need. As I said, I can put in rads very easily and also electric underfloor heating if need be.

Regards

Lumpy

 

[oisin]

under floor heating is dangerous when it comes to screeding.if you are getting it ready mixed and delivered make sure and get fibre in it!because your floor is still shallow at 75mm for underfloor heating.plenty of fibre will keep it from cracking.and a lot of houses i screed with underfloor heating have thick insulation.around 3.5 inches or so.but the fibre is important

 

[Tristar]

Very interested in this post as I am about to have a 25 sq meter conservatory on my house. Information gleaned suggests that, although cheaper, radiators/wet underfloor off the house system is not terribly efficient, due to stat positions, complications in setting timers, pipe runs etc. particularly in my case with the boiler at the other end of the house, and the conservatory at the end of a 40 foot pipe run. Despite this I intend to fit radiators anyway, as it is easier to carcase the pipes in during construction, and an underfloor heating mat (manufacturer says it can be in the tile cement!), however I am still thinking of fitting a split system heat pump. Does anyone have any experience of these systems? There are several makes on the market, the compressor is outside the conservatory and pipes come in to the wall mounted unit, they look pretty neat, and claim efficiency ratings of up to 3.5:1.

Thanks