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!)

I’ve got a new build with wet u/f heating all through downstairs. No radiators, it’s fine.

You don't need radiators.

I wouldn’t question it if it was a new build, with the better insulation and lower ceilings.

I'm in victorian terrace with underfloor in the kitchen under quarry tiles and never use the radiators, it gets really warm but it is electric, don't know if that makes any difference 🤷

No!

Not usually with wet, no.

Underfloor heating is a bit all or nothing. A couple of well placed kickspace fan heaters might be useful for those cooler spring/summer/autumn evenings when you need a bit of a heat boost for a short time. I think modern ones aren’t too noisy.

I'm in a new(ish) build (self build).

My main living room/kitchen has only wet underfloor heating, Only this year, (year 4) with rising utility costs, have I really worked it out. I have managed through the worst of the winter with 1 hour morn and eve heating. The trick is to start the heating the second - if not before - that the room starts to get colder. It can then be switched off as soon as the temp increases by .1 degree. It continues to get warmer for the next couple of hours and then, very slowly, cools down.

Upstairs, however, I have electric underfloor heating, with much less in the way of insulation and heat retaining flooring. In my bathroom I have electric ufh and also use a couple or oil filled rads in order to warm the room. It isn't great and is expensive to warm up.

So - good heating system (wet preferably) with good insulation and draft proofing the heating is brilliant but definitely needs planning.

Poorer insulation, and less heat retention, then ime it's not great and is quite pricy.
I ran out of money when building the house. I wish I could have afforded wet throughout, and if I knew then what I know now, I would have borrowed even more beyond my means and it would have paid me back pretty quickly

@NannyGythaOgg so helpful thanks.

I will probably just stick to the underfloor.

I think there's a greater chance the architect has done the calculations to see what level of output is required to sufficiently heat the space than your builder. But that might be a generalisation. I'd be asking the architect to clarify why he thinks you need the radiators, then you can make an informed decision.

Watching with interest…our architect just told us the same thing “you probably would want to get one or two radiators as well”. The whole point in getting the ufh was to avoid radiators so I’m a bit 🫤 . He said it was that we might find the UFH isn’t enough and so useful to have the radiators to boost. Now I’m thinking we just ditch the ufh and go with radiators after all!
I wonder if we have the same architect (also Scotland!)

When we extended our old Victorian the kitchen/dining/family room became all open plan (about 30% was new). 3m ceilings or higher. We had slate floors and underfloor heating was essential. It worked a treat and no need for radiators. It was a bit less successful in the older part of the house (living and dining rooms - wood floors) but still no need for rads.

Wet underfloor heating in the kitchen extension of a Victorian house here too and definitely no need for radiators. It’s the warmest room of the house by far and kicks in far less than the rest of the heating.

Good to hear. In bathroom (original house) we are doubling up radiator and u/f heating on advice of the radiator guy who was calculating BTUs etc. Bathroom has 2.5 walls external and 2 windows and he thought u/f heating would do little more than heat feet but that will be electric (and so am sure we’ll have to ration it based on who expensive it will be to run)

Same radiator guy didn’t even look at kitchen diner - presumably because we told him we weren’t planning radiators in there lol. Might ask him for a second opinion.

No idea why your architect would think that radiators are needed to, the whole point behind ufh is that you don't need radiators as well! Is your architect experienced? I would question their knowledge with just knowing this!

Yes very experienced, it’s the details in the OP… cubic area, no direct warm sunlight, lots of glass, cold climate, old house, external stone walls …

I have underfloor heating in my kitchen and it's soooo nice and toasty. Defo don't need a radiator on top

@Littlessweepy - the middle way might be to put in the c/h pipes to strategic places in the room, so if you feel you do need radiators going forward, you could then have some fitted without having to have any upheaval in putting in pipes later on.

With the parameters you set out and being in Scotland where it's potentially much colder, personally I'd go belt and braces and have both.

The other thing you might consider is something like an electric or gas log burner type stove, so you have an instant source of heat to boost it up if you need to.

We put in underfloor heating 12 years ago in a North facing kitchen extension with lots of glass on a Victorian similar to yours, but in Brighton, and I did regret not having an additional radiator in that room as we often had to supplement the heat with a oil filled electric plug-in radiator / convection heater.

But equally I think part of the problem was finessing timings, as it takes a while to heat up and cool down, so just having it on at the right time wasn't as easy as radiators. We were there for 12 years and never quite got the hang of it – albeit I think that's partly cause my husband liked to keep turning off to save money as he has hot blood!

We are just about to start a kitchen conversion in our current Victorian and had planned wet underfloor heating, but it alone is quoted as costing £7000 - so we are now thinking of going for Large Victorian-looking radiators (which look fab and kick out a huge amount of heat - if you like that kind of look) instead - and engineered oak rather than tiled floors.

I know people do use engineered wood with underfloor heating, but I've always thought that seems a bit weird as Wood is a very good insulator, so I just can't see how that can work as effectively. But that might just be me. We had a limestone floor in our old place and it was lovely when it warmed up with the UFH

As long as the BTUs for the space are calculated it will give you the definitive answer as to whether or not you need rads too. You calculate the cubic area of the room and compare it to the thermal output of the heating you are installing. Go for a slightly higher out put than you need. There are calculators online. It's the accurate gold standard. Absolutley sell worth spending an hour doing. The floor you lay on top also makes a difference to the heat conductivity.

@CorsicaDreaming UFH doesn't just go off and on like radiators - it is about giving it enough heat that the floor retains it over time. If it was switched off a lot I'm not surprised it didn't heat it enough.

@MrsJamin - yes totally agree - and that "lag" in response time means you either leave it on nearly all the time, or it was often too cold when we got in, then too hot after cooking with ovens on too... and I've got another friend with UFH who also finds it difficult to get the temperature right and to balance consistently because - as you say - you cannot turn them on and off like radiators, so the lag time means it can be fairly unresponsive to changes in temperature due to weather / cooking /etc

In principle I really like UFH, but it does have some drawbacks too.

Renovated our Victorian a few years ago with mega insulation in the new kitchen extension, I wanted a radiator but our architect advised against it, she was right! It's the cosiest room in the house, if only rest of the house was the same!

Have you explored adding wall insulation to the old part of the house? I am having a big extension with ufh and the new building regs means this will be super well insulated. So I am taking the chance to add insulation panels to the inside of the outside walls in the old part of the house at the same time. Will lose a few cm in room size but hoping to feel snug next winter with only ufh downstairs

We renovated our very old house and put wet underfloor heating in the kitchen (approx 7x4m) It's very warm! We chose it specifically so that we wouldn't have to haven radiators. It gave us more flexibility to lay out the space without radiators taking up wall space. No regrets at all. Would do exactly the same if we ever renovate another house.