Underfloor heating for large family room extension?

[CurrerBell]

We are building a double storey side extension which will create an L-shaped family room / kitchen.

Realistically we'll need at least two big radiators - but these potentially get in the way of how we can use the room.

Our builder has suggested underfloor heating but I'm not sure. Does it work well to heat a large open plan space (rather than just heating the floor)? And what flooring should we consider to work best with it?

I am also worried that having UFH plus flooring will raise the level of the floor too much, creating a step up into the family room. The first bit of the room is our existing kitchen, and the concrete floor is already flush with the finished floor in our hallway. Anything more than lino will make a noticeable step up.

Any advice (or comments on the plan!) would be much appreciated.

I have underfloor heating in my kitchen and it takes the chill off the room but wouldn't fully heat it. It's more for keeping your feet warm than a proper heating system. However, we only need one radiator for our large kitchen and would need two if we didn't have underfloor heating, so I reckon you could get away with just a radiator under the window beside the sofa in your layout.

Underfloor heating is expensive to run compared to regular heating.

We have a large open plan extension with only wet UFH. No rads at all. The builder was not keen, the architect said it would be OK and was right. It's hotter in there than the rest of the house - possibly because it's better insulated. Having the wall space is fantastic, we had the adjoining room also done - it has a hanging floor (void bare earth under the joists) and had the radiator taken out and it's also warmer. The thermostat is set lower than the rest of the house.

We have a kitchen extension with a lot of glass and wet UFH. On the very coldest winter day we need the log burner too (but I'm a wimp and always cold!) - but that is maybe 1-2 weeks per year.

Electric underfloor heating isn't nearly so efficient - I wouldn't do that for a big space.

We have a large kitchen/family space with underfloor heating. I was concerned, as there is a 10 mt. run of glazing down one side, but it works brilliantly.

If it is a concrete floor, you can put wet heating in, run off your boiler. However it will need controls and valves so it must be designed and installed by an experienced heating engineer.

You builder will (should) provide rigid insulation slabs and DPM under the layer where the pipes will go. If there is already a floor in the way it will have to be dug up.

Wet heating is expensive to fit, but not to run.

Electric heating is expensive to run, because energy from electricity costs about three times as much as energy from gas.

Try not to have it too open plan, as this will waft the heat away, especially if it can rise upstairs.

UFH in a concrete floor takes some hours to warm up and cool down, so it will need its own timer and thermostat, separate from the rest of the house.

We have wet ufch throughout the house, including a large kitchen/family room and a huge double height atrium. I find uf gives a much more all over heat than radiators and you don't get the spikes of heat. It is just a lovely, constant warmth. You do have to have a slightly different mindset to operating it,...no good just putting it on for an hour. As pp said you need a proper engineer to work it all out. I don't know how compatible it is to combine 2 different systems.

Thanks for the advice - really helpful. It sounds like wet UFH would work well for us. We have already had a new condenser combi boiler fitted, so hopefully our system is suitable.

There is already a concrete floor in the existing bit of the room - but if the floor isn't suitable or needs digging up, perhaps we could just put UFH in the extension bit (with a radiator in the soft seating area). I'll speak with our architect / builder about what is possible and about the floor levels.

I'm wary of having anything in the floor in case it goes wrong (having had to deal with corroded pipes in the concrete floor downstairs... The plumber dug a trench in our parquet floor...). But hopefully UFH would be reliable and help us make the best use of the space in the family room.

Whilst I wouldn't recommend electric ufh, my son's nursery is heated with ufh (I presume wet) and it's always lovely in there.

We're in the middle of an extension. We have had wet underfloor heating put in the new parts. Extra insulation but no UFH in the existing parts of the house that are becoming open plan. And electric underfloor heating (in addition to radiators) in the bathroom so the floor is warm after a shower :)

Watching with interest as we are about the start a similar extension.

We have a largish living room (size of 2 good sized bedrooms), and went for Thermaskirt - which is where you use the skirting board as a radiator. I really dislike radiators, and this room had 3 in before. We looked at underfloor but it would have been difficult because half was concrete, and we also wanted wood flooring.

It's been pretty good. We do have a woodburner in the room, so tend to use that when it is cold (haven't used it yet this winter though).

www.discreteheat.com/

BlueString - Thermaskirt looks very interesting. I had heard of it before, but wasn't sure if it would work in a large open plan space, or get round bifold doors etc. Or how it would work in the kitchen area. But I'll certainly investigate this further!

Good to hear all the positive comments about wet underfloor heating as well.

We have 2 circuits, one in each part of the room - so it doesn't go round the fireplace for example, or the door. There are 2 small pipes behind the skirting, one out, and one back, so you can just run it along one wall if you wanted to, if that makes sense?

Each circuit has a small thermostat/control, hidden in the corners of the room, which means that you could set them at different temperatures - so you might choose to have the kitchen area much lower due to the heat from cooking etc.

I have UFH and wood flooring on top- but my house is probably the size of what your kitchen will be - The house is all open plan . we have a step up of 14cm into the house from the entrace ( Kids sit on it to take their shoes off). I love it sooooomuch and have no problem with wood on the top ( have tiles in Kitchen and bathroom)

Our house is over 4000 sq ft and has wet ufh throughout. Under wood, tiles, carpet and God knows what else and it is absolutely wonderful. Not a radiator in sight. We don't have open plan or any large windows or glass doors though.

We've got underfloor heating run off our oil boiler in our conservatory - it's lovely, wish we had it in the rest of the house!

It's obviously on a separate zone which is programmed to come on at 5.30 and go off at 8.30am to reach a temp of 21deg. Although by 8.30 it has only reached 20 deg when it goes off, the heat is still being emitted from the floor for the rest of the day so even though it's timed to come on in the evening it doesn't as the temperature is too high still. Even with all that wind last night it was 22deg at 11pm in there.

You will need space for the manifold, pump and zone valve. We have ours in the Utility room which is right next to the conservatory and is also where the boiler lives.

If this is the route you want to go down ring round and ask if they have experience of installing before getting them to come out - not all engineers do!

24 hours - ha ha. If that were in the slightest bit true it would be the most ridiculous heating system ever.

OP contact some of the UFH suppliers, read their info. Talk to a heating engineer. Visit someone's house with wet UFH. Mine? I'm in West London. We have it throughout the house and under all different kinds of floor coverings. We have it embedded in concrete and above suspended floors.

@Pooseyfrumpture @sacbina would you mind sharing which wet UFH system you used? Sacbina I'm in South London, so not a million miles from you; who installed your for you, if you don't mind my asking..?

We used the Nu Heat wet ufh system. Main house installed 2005, kitchen extension 2015.
We installed the main house pipes ourselves but connected by Nu Heat engineer. The builders for the kitchen extension laid and connected themselves. Hth

Thanks, scabina.

I have underfloor heating and don’t use it. I hate having a set temperature all the time or having to plan ages in advance when to turn it on, I also like having heat in a particular place that you can get closer to when cold and further away when hot.

I find ufh leads to a hot stuffy house.