Radiators or underfloor heating large space

[Skithepowder]

We will be having an open plan kitchen/dining/family room circa 46m sq. L shape with bifolds/glass on 4.6m of wall and another 3m and 2m section of the L. Total volume of the room 122m3 as part of the L has a vaulted ceiling. There are a few locations that could put radiators. It is renovation but have the option of using a wet underfloor heating system with panels such as Prowarm overlay panel. Is underfloor heating going to be much better at heating such a space than radiators? I assume will be little more efficient and saves wall space and maybe looks sleeker, but bigger upfront cost and radiators could be a bit of a design feature if done right. Purely from the perspective of heating a largish space with a large amount of glass is one much better than the other?

[JohnMo]

If your floor U value is 0.15 or better UFH is an option, otherwise your downwards heat losses are such that the running cost could be huge. Then radiators is the best solution.

 

Also radiators are better for on off heating, ufh really needs long run times to be viable.

 

 

[nod]

We have UFH on our first build and will have on our next As with you we would have struggled for locations for rads 

153m2 on the ground floor Inexpensive to run 

Rads ups stairs Though four years after moving in we still haven’t used them 

[Skithepowder]

41 minutes ago, JohnMo said:

If your floor U value is 0.15 or better UFH is an option, otherwise your downwards heat losses are such that the running cost could be huge. Then radiators is the best solution.

 

Also radiators are better for on off heating, ufh really needs long run times to be viable.

 

 

Thanks, about half of the floor space of the room is renovation, half is an extension. Not sure how good u value of current floor is. The system we have looked at is one of the overlay/warm panel wet systems like this https://solarandheatstore.com/product/prowarm-18mm-low-profile-overlay-single-room-kit/ not sure how much the heat conducting boards that are part of these systems aids the heat loss downwards etc in this situation.

[JohnMo]

Without 120 to 150mm (or more if you can) of PIR under the floor, the heat loss could be pretty large.

 

The boards are 18mm, pipes they are using 12mm, so 6mm of insulation.

[Nickfromwales]

You CAN put UFH in this area, but it would be expensive to run eg if this is a basic building regs property ( or worse ).

 

Where the original floor is you could consider oversized radiators there, and then just install UFH in the new area for comfort heating. You can run the overlay system throughout, but it's the very worst type of UFH out there. 

 

Another big influencer is what you then lay over it, with tiles being better, wooden flooring being worse.

[Radian]

1 hour ago, JohnMo said:

Without 120 to 150mm (or more if you can) of PIR under the floor, the heat loss could be pretty large.

 

 

I had a last minute change of plan and put a UFH loop in our garden room the day before the screed went in. It's only 18m² and with block & beam floor topped with 100mm PIR and 50mm screed but was a now or never decision that I'm glad I made. Yes it would be better with 150mm PIR but on the rare occasions when it's below 10^oC down here I can choose not to use it. Or pay a few extra quid to enjoy the close-up view of the snow (not that we get that either).

[JohnMo]

8 minutes ago, Radian said:

rare occasions when it's below 10^oC down here

Think it must be opposite up here, the rare occasions it's above 10oC up here

[Nickfromwales]

24 minutes ago, JohnMo said:

Think it must be opposite up here, the rare occasions it's above 10oC up here

Ouch...

[PeterW]

Rads all the way - unless this is part of a much bigger plan, and you’re installing buffers etc then just go with conventional heating here. 

[Skithepowder]

Thanks, I don’t think it makes sense for how it flows to other rooms to raise the floor by that much for insulation, seems standard radiators will be better. 

[Nickfromwales]

5 minutes ago, PeterW said:

Rads all the way - unless this is part of a much bigger plan, and you’re installing buffers etc then just go with conventional heating here. 

If it was my house, I'd do both. Comfort temps for the floor  vs having to heat the spaces with it ( so UFH just providing some uplift ) and 'decorative' rads providing the grunt.

[Radian]

46 minutes ago, Nickfromwales said:

If it was my house, I'd do both. Comfort temps for the floor  vs having to heat the spaces with it ( so UFH just providing some uplift ) and 'decorative' rads providing the grunt.

 

On its own a reel of PEX is really not all that expensive. My outlook on this was 'get it down before the screed goes in' and it's there if we want it. I also put a 100m loop in our garage extension play-room or whatever to call it but that's possibly never going to be used now as gas is triple the price it was and we've gone for A2A instead. But who knows what the future holds for energy prices. When A2W equipment prices come down to the equivalent of A2A then the sums might swing back in its favour. 

[health mechanic]

On 31/12/2022 at 19:02, Nickfromwales said:

You CAN put UFH in this area, but it would be expensive to run eg if this is a basic building regs property ( or worse ).

 

Where the original floor is you could consider oversized radiators there, and then just install UFH in the new area for comfort heating. You can run the overlay system throughout, but it's the very worst type of UFH out there. 

 

Another big influencer is what you then lay over it, with tiles being better, wooden flooring being worse.

Why is overlay system the worst type, as surely the best type for suspended timber flooring system if insulated between joists

[Nickfromwales]

2 hours ago, health mechanic said:

Why is overlay system the worst type, as surely the best type for suspended timber flooring system if insulated between joists

It's just a poor emitter tbh, vs what other options are normally employed with UFH. Expensive and cumbersome, with a lot of restrictions as to what can be applied directly atop.

I'm into my 3rd decade installing various heating types, and this is the type that gets the most amount of comebacks from promises made / not kept.

[health mechanic]

That's a shame....I'm planning to put overboard system on half the house where extension new floor block and beam meets old floor suspended timber, and the areas with just block and beam a screed system. Been told by most UFH that that was most viable option to regulate temperature in rooms with mixture of flooring.