I have bought Wickes underfloor heating coil system which recommends tile backing board with 2 layers of adhesive plus the tiles which seems ridiculous as it will be so thick. The people who installed my kitchen have recommended the coil is taped down then they will apply latex over this and then I can tile, this seems more reasonable however I am concerned that as the coil is directly on the concrete (except for just primer) it will not be very efficient and it then has to heat through tape, latex, adhesive and tile as well as trying to heat the concrete floor. I appreciate this is the purpose of the backing boards but they are so thick - is there nothing else which could go under the coil to reflect the heat up?
CorinneX wrote: is there nothing else which could go under the coil to reflect the heat up?
I suggest you look up some products that are used for pool's insulation
I used a product of that kind in my own bathroom - it was called Map Elastic
and it's used to insulate pools - it can be laid pretty thin so it shouldn`t be
a problem with the thickness... that's what i've tried and it works ok with me
so you might wanna look it up
bear in mind that any deviation from the supplier's/maunufacturer's recommendations will invalidate the guarantee and immediately absolve them of any responsibility should a fault develop.
from your description i'd say that the directions given are pretty typical for that type of underfloor heating system. bear in mind that the thicker the backing board the greater the insulation and the less heat conducted down into the concrete.
you don't say if it is a wet or dry system - i'm assuming it's electric?