Overlay wet UFH - Advice
Discussion
We’ve decided to go for an overlay underfloor heating system. The concrete base downstairs is structural, so our builder can’t excavate it.
I spent 30 minutes on the phone with Nu-Heat this week after they were recommended here. They were excellent, but said straight away they would probably be about double the price my builder quoted. I’m waiting for their quote to confirm.
They recommended this product: Lopromax from Nu-Heat. It’s a screed-based UFH system, so it offers some thermal mass compared to the foam panel systems, which they described as being quicker to heat up but cooling down just as fast (more like radiators).
Has anyone here fitted an overlay system?
• Which one did you choose?
• How are you finding it?
I’m keen to hear your experiences. One thing I noticed: the screed system doesn’t include insulation under the ‘crate’ they put on top of the concrete, so you lose some heat downward.
I spent 30 minutes on the phone with Nu-Heat this week after they were recommended here. They were excellent, but said straight away they would probably be about double the price my builder quoted. I’m waiting for their quote to confirm.
They recommended this product: Lopromax from Nu-Heat. It’s a screed-based UFH system, so it offers some thermal mass compared to the foam panel systems, which they described as being quicker to heat up but cooling down just as fast (more like radiators).
Has anyone here fitted an overlay system?
• Which one did you choose?
• How are you finding it?
I’m keen to hear your experiences. One thing I noticed: the screed system doesn’t include insulation under the ‘crate’ they put on top of the concrete, so you lose some heat downward.
We installed an overlay system in the dining room/kitchen/lounge and it works very well. This is the one we had installed by our builder: https://baseufh.co.uk/system/12-ultra-low-panel-sy...
How much insulation do you have in the subfloor?
That should define what system you use.
If the answer is don't know/none, then you need to go down the route of Insulated trays with the pipe routing pre channeled out. Then a self leveller over the top.
Assume 40 to 50mm height build up.
That should define what system you use.
If the answer is don't know/none, then you need to go down the route of Insulated trays with the pipe routing pre channeled out. Then a self leveller over the top.
Assume 40 to 50mm height build up.
Been there, done that.
If you can handle extra height, simply attach pipes to the existing concrete with saddles and skim over the top, minimum 25mm (as the pipe is 16mm).
Keep 600mm away from outside walls to minimise heat loss.
If extra height is an issue groove the concrete.
The advantage of a lot of concrete is it stores a lot of energy, slow warm up, slow cool down.
Heat does not "disappear" downwards in concrete, but it will go out of the edge if your too close.
Andeh1 said:
How much insulation do you have in the subfloor?
That should define what system you use.
If the answer is don't know/none, then you need to go down the route of Insulated trays with the pipe routing pre channeled out. Then a self leveller over the top.
Assume 40 to 50mm height build up.
It is a I don’t know. The house is a 98/2000 Barrat home so I don’t know what building spec’s were like back then. I could dig some out and find out if it’s worth it. That should define what system you use.
If the answer is don't know/none, then you need to go down the route of Insulated trays with the pipe routing pre channeled out. Then a self leveller over the top.
Assume 40 to 50mm height build up.
The trays aren’t insulated from what I read and you can’t screed on top of them so there isn’t much thermal mass.
caziques said:
Been there, done that.
If you can handle extra height, simply attach pipes to the existing concrete with saddles and skim over the top, minimum 25mm (as the pipe is 16mm).
Keep 600mm away from outside walls to minimise heat loss.
If extra height is an issue groove the concrete.
The advantage of a lot of concrete is it stores a lot of energy, slow warm up, slow cool down.
Heat does not "disappear" downwards in concrete, but it will go out of the edge if your too close.
600mm seems excessive, how come so far? If of thought 30 would be about the tolerance. If you can handle extra height, simply attach pipes to the existing concrete with saddles and skim over the top, minimum 25mm (as the pipe is 16mm).
Keep 600mm away from outside walls to minimise heat loss.
If extra height is an issue groove the concrete.
The advantage of a lot of concrete is it stores a lot of energy, slow warm up, slow cool down.
Heat does not "disappear" downwards in concrete, but it will go out of the edge if your too close.
Why doesn’t it disappear downward this is what’s confusing me as the bottom of the pipes bar a bit of plastic are hitting the concrete base.
Year 2000 will have a degree of insulation in the floor, but not much!
Heat dissipates in all direction, but the subfloor will suck the warmth out of the pipes quicker then the air above it will.
600mm from the edges is a excessive, especially compared to subfloor heat loss. Walls will be cavity insulated so will slow heat loss there anyway. Maybe 300mm if you really wanted to avoid it there.
Heat dissipates in all direction, but the subfloor will suck the warmth out of the pipes quicker then the air above it will.
600mm from the edges is a excessive, especially compared to subfloor heat loss. Walls will be cavity insulated so will slow heat loss there anyway. Maybe 300mm if you really wanted to avoid it there.
This is what we did in our 1998 new building. 25mm Insulated trays with pipes in, then self leveller over the top. Total height build up of about 40 to 50mm. Afraid it's the only pic ive got.
Carpet layer then built a shallow ramp from the room into the hallway it hide it.
Worked very well!
037 said:
We use the 18mm pro warm LoFlo overlay boards on 90% of our extension projects . This can be screeded over then a LVT applied or Ditramatt style product then tile. works very well.
unless you are prepared to dig out the existing concrete then you may as well have this .
This unless you are prepared to dig out the existing concrete then you may as well have this .
We used the Polypipe system on the first house we did (2008). As mentioned with ditra mat and travertine tiles.
This house we've done the whole ground floor (2023) - 5 zones - with a slimline system and Amtico flooring.
Ranger 6 said:
037 said:
We use the 18mm pro warm LoFlo overlay boards on 90% of our extension projects . This can be screeded over then a LVT applied or Ditramatt style product then tile. works very well.
unless you are prepared to dig out the existing concrete then you may as well have this .
This unless you are prepared to dig out the existing concrete then you may as well have this .
We used the Polypipe system on the first house we did (2008). As mentioned with ditra mat and travertine tiles.
This house we've done the whole ground floor (2023) - 5 zones - with a slimline system and Amtico flooring.
Replying to a couple of points.
Concrete grooving is a god forsaken job. Keeping 600mm away from the outside edge of the foundations minimises heat loss to the outside - and reduces the amount of grooving to do. (In living areas pipes shouldn't be more than 200mm apart). 600mm from the outside edge can mean 300mm from the wall (depends on overall wall thickness).
A cold strip round the edge proves the point. A room can be warmed up with only half the floor heated.
Concrete is not a brilliant conductor of heat. Without any insulation under a slab, and a floor surface temperature of 23c (to give a room temperature of 21), there will be an effective "warm bowl" of concrete/ground.
Energy can't run away and disappear into the earth.
I used polypipe overlay lite system
Older property and concrete floors throughout. Overlay is 18mm with 12mm pipe and put laminate ate straight on top
Personally I'd put as much pipe in the floor as you physically can and did wall to wall including under kitchen cupboards
The more heat you put in the floor the quicker it'll heat the room and the quicker it will shut off, making it max efficiency
You've got the whole floor so might as well use it
Probably lovers up to 10% going down but you wouldn't notice it
Works a treat and would do again
Older property and concrete floors throughout. Overlay is 18mm with 12mm pipe and put laminate ate straight on top
Personally I'd put as much pipe in the floor as you physically can and did wall to wall including under kitchen cupboards
The more heat you put in the floor the quicker it'll heat the room and the quicker it will shut off, making it max efficiency
You've got the whole floor so might as well use it
Probably lovers up to 10% going down but you wouldn't notice it
Works a treat and would do again
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