25 Nov 2020
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United Kingdom
Hi, please can someone help me here. I’ve had my garage converted to a kitchen. Floor was lower in the garage compared to the level of the existing house. Anyway, I am having an island with a downdraft extractor. I have UFH installed and the builder has forgotten to put in the ducting for the extractor or put the power cables across for the hob and extractor.

I understand the cable situation can be resolved fairly easily, what I need advice on is the ducting now the screed has been done. There is three directions I can go in but two are significantly shorter than the other. The shorter routes only have a small amount of UFH running over. Does anyone have any amazing idea on how to overcome this issue. I know I can use recirculating but I understand that ducting is far more efficient.

The levels are as follows:-

- Existing concrete floor
- Celotex - 100mm
- Damp proof membrane
- Screed

Many thanks


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I’ve already purchased it, the builder knew this from the start. I really don’t want the overhead type and i’ve also got lights above the island
Was it on a plan/specification that the builder had and agreed? Or are you making it up as you go along?
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No, not making it up as I go along. It was always the case and he had the kitchen plans as well. I bought the extractor just after the extension started and it was discussed also about where the extraction route would go.
If it was on the plans, and the builder knew about it, then he has to sort it out even if it means ripping up the floor and starting again. His mistake. However, pragmatically I would get him to buy you an overhead extractor.
The downdraft I’ve bought already was very expensive. I don’t want an overhead, it would look rubbish in that position.
It's a shame your builder will have to lift up all that ufh pipe to install the materials he incompetently missed off the drawings.
Have you considered gouging out some of the celotex to receive some rectangular ducting? I presume it's from that unheated island area to an outside wall? Lot of messing about and making good but what's the alternative.
Where are the underfloor heating cables?

If they are on top of the celetex it should be possible to cut the screed without damaging.

The problem is repairing the floating screed, although it may be possible.

If 1 or 2 cuts damage the UFH cable it can be repaired.

If it's an inscreed system, i.e. Below the screed and it gets too damaged, then put new heating cables on top, latex over, ditra mat then tile

Do you actually have room for the downdraft extractor itself, ducting and motor in the island? -they take up a lot of space.

I've found customers end up preferring an overhead extractor built into a cloud. It can look amazing if the cloud has a recess formed where it meets the ceiling and LED tape built in - it makes the cloud look like it's floating. It works really well if the wall kitchen cabinets also have led tape on the tops
It’s not an UFH cable, it is pipe. It’s a ground source heat pump system.

i have plenty of space as it’s a large island. Don’t want anything overhead.
@cdbe, that was my suggestion to him. Means having to penetrate the dpm. There are units going on the perimeter and obviously where the island is going, it will be covered so my suggestion was to make a hole in both these places and channel through the celotex which is under the UFH pipes. There is only about a metre to breach of UFH, it’s just how you go about it. The flat ducting was also what I suggested...

I thought if you could somehow channel from each side through the celotex, it could prob be done?

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