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SWA in U/F floor slab

whjohnson
Got a job where a new submain - approx 25 metre run in 16mm 3 core SWA. Embedded directly into a new concrete floor where wet U/F heating will be installed. Am trying to work out the best order of installation - that is, should the cable go in first, then the insulation, followed by the U/F pipework,and finally followed by the slab. Am not sure what order the u/f heating side will be installed and am also thinking about how if any correction factors may need to be applied for the current carrying capacity. I have sized the cable with a little overhead in mind in terms of actual final demand, but am still a little concerned about final slab operating temperature

Comments welcome.

PS - Am not liking this new format - it is like writing inside a letterbox when compiling posts!
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    I think ideally Id install it under the insulation. (Its cooler there)


    But another option maybe - I don't often do houses anymore, but when I have done, I sometimes had this problem with Kitchen island units getting installed with wet underfloor heating - the insulation I've seen favoured for floors is 2" Kingspan (maybe it was 3"?) (I think its called Kingspan but might be something different for floors)) - and I'd be tempted to install 2" metal trunking on the floor slab (surrounded by kingspan on two sides, cold on the bottom. Heating pipes on top of that and then they tend to install quite a thick layer of (levelling compound?) - some type of concrete - 50mm or so I'd guess ontop of the insulation/around the heating pipes........I cant really remember the specifics of the build but the 2" metal trunking worked quite well for me. 


    Surely the cables in metal trunking would be cooler than the SWA buried direct? Allows for future cable runs or comms/networks maybe too..


    Regards


    Tatty
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  • 0
    I think ideally Id install it under the insulation. (Its cooler there)


    But another option maybe - I don't often do houses anymore, but when I have done, I sometimes had this problem with Kitchen island units getting installed with wet underfloor heating - the insulation I've seen favoured for floors is 2" Kingspan (maybe it was 3"?) (I think its called Kingspan but might be something different for floors)) - and I'd be tempted to install 2" metal trunking on the floor slab (surrounded by kingspan on two sides, cold on the bottom. Heating pipes on top of that and then they tend to install quite a thick layer of (levelling compound?) - some type of concrete - 50mm or so I'd guess ontop of the insulation/around the heating pipes........I cant really remember the specifics of the build but the 2" metal trunking worked quite well for me. 


    Surely the cables in metal trunking would be cooler than the SWA buried direct? Allows for future cable runs or comms/networks maybe too..


    Regards


    Tatty
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