Underfloor heating - do you also need a radiator??

[Littlessweepy]

I am in the middle of an extension and renovation on a stone built Victorian house. Extension is for a kitchen and will be joined to a dining area in original house (which was the old kitchen). Planning to have wet underfloor heating in this whole room - the extension plus the dining area. Tiled floor.

The dining area is about 4m squared and the kitchen is about 5.5m squared. The ceiling in the dining area is about 2.5m and the kitchen will have an apex ceiling, peak night of 3.2m. Quite a bit of glass in kitchen, 2 sets of glass doors and 4 velux windows on sloped ceiling. Other relevant details … will only get morning sun and we are in Scotland.

Asking for opinions, will I need radiators in the space as well? Builder says no, architect says yes. I want to be able to have that room cosy for comfort and of course once it is done don’t want to have any regrets. For those that have a similar space, or have experience with wet u/f heating, what do you think??

floor plan attached (I hope!)

@Littlessweepy DS is an architect he wouldn't recommend underfloor heating in a property such as yours to any of his clients as the sole means of heating. Nor heat pumps. They have to work flat out 24/7 in cold weather so energy bills rise to ridiculous levels. This is in Wales

the whole point of underfloor is that it's either off or on. the lag in time between you realising it is cold and the floor being turned on and getting up to desired heat can be a long time. ours goes on fully say end of september and stays on till end of spring perhaps. stone floor, 5,5 by 8 m room with half length of room being glass ceiling (think victorian side return extension) no wall radiators.

with a room thermostat. we live in the kitchen mostly

Are you adding insulation to your house? We’re nearly done doing our Victorian house, and we’ve added super insulation and UFH throughout the house. No radiators anywhere.

It’s taken a few weeks to finesse the UFH, mostly due to incompetent plumbers and an issue with the boiler. We had about six weeks when the UFH was not working properly, yet the house still stayed at around 18C, just through insulation and the UFH working on one floor.

But now, with boiler and plumbing finally working, the house is toasty and warm. The UFH is programmed and comes up to be warm in the morning and evening, and cooler when we’re not at home in daytime.

I’m so glad we don’t have radiators, I don’t like how they look and take up space. Furniture placement and curtains are much easier without them.

I would definitely invest in insulation if possible, it’s a game changer. It can make a huge difference to how warm your house is.

@Newhousename - please can you say a bit more about the internal insulation you're planning to add to the inside of the original part of your house? We've got a huge north facing exterior wall in our hallway that goes right up through the house, and I'm sure if I could insulate that it would make a big difference to warmth overall. I'd like to try internal insulation too, if possible.

I would say, it depends on how well insulated the house is throughout, a new build should be well insulated but a Victorian house probably not.

We have wet UFH in our kitchen extension. The extension is large 5mx8m and has kitchen/diner. It's on the back of the house which was built in 1900 so has single brick construction walls and floorboards over a large air gap (typical period house). We do not have a radiator in the kitchen. We would never need it. The tv room opens fully onto it but has doors that can be closed and that radiator barely comes on. The rest of the house has single glazed sash windows and thus isn't fabulously insulated. The extension is really well insulated (has to be built as such due to building regulations) just to give you an idea.

So I would say you definitely do not need a radiator.

We did a full renovation on a Georgian house and have only wet underfloor throughout, under wood plank floors. It's well-insulated (or as well insulated as is good for an older house to allow breathability) and double glazed, and the UFH works extremely well and has actually been very efficient. We have it programmed to come on, set to 22, early for a few hours and then switch off and then same again in the evening. When we're WFH we have the programme run a bit longer, but I think the longest is about 8 hours total. I suppose it's always on in that we don't let it go below 18, but it's it's not been more expensive than our old house with radiators, and it's somehow a nicer heat, more ambient and less intense.

When they did the heat calculations, there were two rooms they were worried might not get warm enough, so we did have them put in the infrastructure for radiators, but it's actually been very comfortable there, so it won't be necessary.

Those asking about our insulation, the attic has loads, there is some floor, and we have put in double glazing. But nothing on the walls. The extension will be insulated to current standards, though we are double glazed rather than triple glazed doors (that’s another story)

Maybe a tiny one for tea towels?

I'm in a 3 year lease and new build townhouse with a very large kitchen diner taking up most of the ground floor. Two of the four walls are entirely glass. We have wet underfloor heating and tiled floor throughout.

Have had no problems with keeping warm this winter, in fact I have been too warm at times and have had to turn it down! We have a good thermostat set to a comfortable temperature and it clicks on and off as needed. Only seems to need to be on for about an hour in the morning and evening to keep a good temperature all day. It's great for drying clothes as well, a full drying frame full is dry within a couple of hours.

No way should a decent underfloor heating system with a proper spec need radiators as well. Don't know what your architect is thinking.

We are also in Scotland (NW) and have wet ufh. We find it's fine most of the time, but on days when the temperature changes dramatically (like a few weeks ago we had -8 one day, and 10 degrees the next) it will take a lot longer to change the room temperature than the rooms in the house with radiators and no ufh.
Luckily someone suggested we put in the plumbing for a radiator whilst building, to make it easy to add a radiator later if we want to. If we decide to go for it we only have to burrow a small hole in the plasterboard and connect it up (pretty much). Could you do this?

Appreciate this is an old post. But hoping for someone else's experience. We have similar set up to yourselves and are extending out, so to new regs nicely insulated etc. Not sure I want to go down the route of putting UFH in the whole of the back area that we will have opened up, part solid part wooden floor. But considering just adding to new build part. This would be esiest as avoids digging up the existing floor to get the depth required for the UFH. Also may be difficult to add UFH to suspended floor. I would only consider wet UFH and not electric. Any thought? Thanks

We have underfloor heating and electric radiators. If the weather cools fast underfloor heating needs to be on man it's slow so I tend to put on the electric wall heaters

The lag would be bad for me.

As others have said when you turn on the UFH, it takes longer for the house to heat up than it would with radiators.

So depends how you use your heating. If you tend to keep your heating on all the time, then just UFH is probably OK.

If you turn the heating on and off a lot, for example if everyone is out during the day it probably pays to have some radiators as well, because then the house can warm up more quickly.

If I had a choice I would make sure all the radiators were on internal walls because that way more of the heat goes into the house rather than escaping through the external walls. However you do need to consider the fixing if you are fixing them to stud walls as radiators can be pretty heavy.

Does it really cost that much more to have the fittings for radiators put in place, then fitting them retrospectively if they are required ?

I saw someone posted on my old thread and awakened it I thought I’d update!

Went with just the wet underfloor in the kitchen diner. Decided to add extra floor insulation and didn’t put rads in or plumb for them incase we wanted to add them later either.

Verdict is the place is definitely warm enough. We’ve been through winter now and honestly it’s lovely and cosy. We have it set to be on all day every day even if we are out all day but be off at night. Because of the lag it comes on at 5am and goes off at 8pm. Set to 19.5 degrees.

Downside is my heating bills are high. I just got my energy bill today for the last month and gas on it’s own was £325 :(

This is exactly what I did. Fleetingly considered putting wet underfloor heating in old part of house but realise now that would have been insane once I saw what it actually involved. We have rads in the original part of house. We have a manifold and everything is app controlled and individual rooms can be set on individual timers. Works perfectly, just need to figure out how to bring the costs down.