UFH maximum temperature with LVT

[Danzka]

Hi everyone, we have a 1920s house with solid brick walls. The small front carpeted lounge (1.9 combined tog of underlay/carpet) with its own UFH circuit is struggling to get to 20 degrees. The UFH pipes run under about 5m of LVT to get to the front lounge.

My question is, can I boost the flow to the lounge to increase the temperature to above a floor temperature of 27 degrees or will that permanently damage the LVT directly above the circuit pipe running under the LVT to the carpeted lounge?

Does anyone have any experience with a client who has run their UFH above the recommended LVT floor maximum temperature of 27 degrees with no negative effects on the LVT? I’m aware manufacturers mostly build in a safety margin, so can that 27 degree boundary be pushed at all?

When it does get too high does it affect the glue and cause it to debond, or does it damage/discolour/shrink the LVT?

Many thanks for your advice.

 

[exedon2]

We do a fair amount of underfloor.
I do now that the major manufacturers (karndean and Amtico) recommended a maximum of 27c . Even recommended a floor sensor to make sure temperature is correct.
What type of underfloor do you have in lounge? In screed? Overlay?
Was the installer aware of your intentions re carpeting?

 

[EvilDrPorkChop]

Yeah my dad runs his UFH at full whack at 60oc on the manifold with Polyflor LVT. Not sure what Floor temp that equates to.

He's had a very very small amount of shrinkage, although my bathroom where I haven't got UFH and LVT has shrank slightly too. So not sure the UFH contributes to that.

 

[Danzka]

We do a fair amount of underfloor.
I do now that the major manufacturers (karndean and Amtico) recommended a maximum of 27c . Even recommended a floor sensor to make sure temperature is correct.
What type of underfloor do you have in lounge? In screed? Overlay?
Was the installer aware of your intentions re carpeting?

Thanks for responding, it’s wet under screed and yes the designer and installer knew it would be carpeted. Brand of LVT is Moduleo

 

[Danzka]

Yeah my dad runs his UFH at full whack at 60oc on the manifold with Polyflor LVT. Not sure what Floor temp that equates to.

He's had a very very small amount of shrinkage, although my bathroom where I haven't got UFH and LVT has shrank slightly too. So not sure the UFH contributes to that

Danzka
Thanks for responding, that’s really useful informatio. Our installer knew our property had solid walls with no insulation so he set the temperature and circuit flow rates as high as he could to maximise heating potential. He set the manifold to run at 44 degrees to achieve the 27 degree floor temperature so at 60 your floor temperature must be well above that!!!

We have Moduleo installed, no shrinkage to date. I wonder if I’m brave enough to creep the flow rate up to see how the floor handles it…

 

[EvilDrPorkChop]

Yeah it will be. I suspect it's probably 35oc. I can actually test it at some point.

I think he never gave it a thought, he'd been used to doing concrete screeds with tiles and never gave the LVT a second thought. It's been on that for 5 years now and not any issues so far. It's also not in a screed, overlay system.

 

[Danzka]

Yeah it will be. I suspect it's probably 35oc. I can actually test it at some point.

I think he never gave it a thought, he'd been used to doing concrete screeds with tiles and never gave the LVT a second thought. It's been on that for 5 years now and not any issues so far. It's also not in a screed, overlay system.

From my background in engineering, I know tolerances are always built into any specification to provide room for error. It’s not unusual for tolerances to be quite over the top because engineers want to protect themselves from criticism. Often they go too far, hence my question.

Will be interesting to see if your experience is an anomaly or other people have increased their floor temperature above the manufacturer’s recommendation without any negative consequences….

 

[exedon2]

I assume your operating the underfloor with a backset temperature no more than 4c below target temperature ?
Do you know what pipe centers of underfloor are? Easy enough to calculate how close they should be for required output.

 

[IND_Nick]

Do the pipes just run straight through the LVT flooring, ie direct to carpeted room? If so raising the flow might not create much of a rise in a small section of floor. I would also assume like you that there must be a tolerance probably 10% ish on the 27 degrees. So wouldn't worry too much as long as the floor stays under 30.
We have had loads of issues with UFH and carpet. Even following all manufacturers requirements it still never works as it should. Response times are slow and struggle to get temps unless it is on all the time.

 

[Danzka]

I assume your operating the underfloor with a backset temperature no more than 4c below target temperature ?
Do you know what pipe centers of underfloor are? Easy enough to calculate how close they should be for required output.

I don’t know what that means sorry . I don’t work with UFH generally ..

 

[Danzka]

Do the pipes just run straight through the LVT flooring, ie direct to carpeted room? If so raising the flow might not create much of a rise in a small section of floor. I would also assume like you that there must be a tolerance probably 10% ish on the 27 degrees. So wouldn't worry too much as long as the floor stays under 30.
We have had loads of issues with UFH and carpet. Even following all manufacturers requirements it still never works as it should. Response times are slow and struggle to get temps unless it is on all the time.

Yes they do, about a 5m section of LVT. I’ve allowed the 10% as well, but it still doesn’t seem to hit 20 degrees very well…

Maybe I need to replace the carpet with LVT and put rugs down to provide an area to play on…

 

[exedon2]

I don’t know what that means sorry . I don’t work with UFH generally ..

I assume you have room thermostat in the room where underfloor is?
If you want room to be say 21c when your using it you should never let temperature drop below 17c .
You should have a room stat capable of doing that,
You don't operate underfloor like a radiator system the floor slab needs to remain warm.

 

[EvilDrPorkChop]

I always tell everyone with UFH to run it 24/7 at the set point. Don't even have a set back, otherwise it never works correctly.

 

[hometech]

I assume you have room thermostat in the room where underfloor is?
If you want room to be say 21c when your using it you should never let temperature drop below 17c .
You should have a room stat capable of doing that,
You don't operate underfloor like a radiator system the floor slab needs to remain warm.

or you could just get a real engineer to calculate things for you, perhaps an real engineer who is confident of his math rather than one who needs cover himself so they don't face criticism lol

 

[EvilDrPorkChop]

or you could just get a real engineer to calculate things for you, perhaps an real engineer who is confident of his math rather than one who needs cover himself so they don't face criticism lol

Go on then, get cracking.

 

[hometech]

Go on then, get cracking.

I'd rather teach to fish.
with water its all linear values so makes it easier.

Specific heat capacity - Temperature changes and energy - Edexcel - GCSE Physics (Single Science) Revision - Edexcel - BBC Bitesize

Learn about and revise the relationship between temperature and energy and also about changes of state with GCSE Bitesize Physics.

www.bbc.co.uk

Water Heating Calculator for Time, Energy, and Power

The calculators on this page compute how long it takes to heat water, how much energy is consumed, and how much heating power is required.

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and my all time favorite site https://heatpumps.co.uk/2021/03/11/heating-simulator/
1. How much energy do I need to heat the space..should be read as how much do I loose and therefore need to top-up once I have reached my target temp.
2. As the medium being used is water, how much water do I need @ a given temp to produce the Energy needed to heat the space
3. The variables are the substrate(s) on top and under the pipe, insulation levels effecting the pipe and space to be heated.
4. Given that the pipes are already down its probably too late (should have used the math first)

 

[Danzka]

I assume you have room thermostat in the room where underfloor is?
If you want room to be say 21c when your using it you should never let temperature drop below 17c .
You should have a room stat capable of doing that,
You don't operate underfloor like a radiator system the floor slab needs to remain warm.

Thanks for responding - on the recommendation of the installer, I set the room thermostat to 16 degrees at 2100 hrs and 20 degrees at 0430 hrs. You think 1 degree would make a difference. I have an infrared thermometer and the floor temperature is only getting to 21 degrees, whereas the LVT is hitting 27 degrees elsewhere around the house.

 

[Danzka]

or you could just get a real engineer to calculate things for you, perhaps an real engineer who is confident of his math rather than one who needs cover himself so they don't face criticism lol

Most engineers don't come with a 'real' or 'fake' label on them so they're hard to identify. It seems to me that they are more common than not though...

 

[hometech]

I assume you have room thermostat in the room where underfloor is?
If you want room to be say 21c when your using it you should never let temperature drop below 17c .
You should have a room stat capable of doing that,
You don't operate underfloor like a radiator system the floor slab needs to remain warm.

i operate radiators just as you would underfloor (low temperature/oversized and running 24/7). Why would there be any difference?