Looking for people’s experiences of installing and living with underfloor heating. We intend to remove a wall to make a big new kitchen diner, and would ideally like to install UFH during the process. The overall area is likely to be 30 (ish) square metres. Each room (current kitchen and dining room) has an existing wall mounted radiator. The new kitchen/diner design will be a lot more flexible if we can get rid of these, plus I really like UFH under hard floors when I’ve tried them at mate’s houses.

It seems you can pipe warm water under, or lay electric matting-type stuff. I expect the electric to be easier (cheaper?) to install but I’m concerned about running costs.

I’m a complete novice to this, so any info gratefully received. I’ll be along for more advice on the other 101 aspects of this project that I don’t understand later!

Cheers all

Tom

EDIT FLIP-WRONG FORUM! If someone could shift it I’d be much obliged

A wet underfloor system is generally a better bet all round but without ripping your floor up it’s not really an option. Electric matting has moved on a bit in the last few years but to heat a room of that size is going to be expensive. In my opinion retro fit mats are more suited to taking the chill off a tiled floor etc rather than actually heating such a large area. Hth

Concur with Wrighty – electric easier therefore cheaper to install, but very expensive to run if you are using it as your primary heating.

Wet best if you can, but you floor heights often dictate what you can and can’t do. Don’t be put off if not enough height with the existing screed as you could possibly put some under a floating floor.

Can recommend David Robbens if you want a quote and they should be able to tell you if feasible or not.

My bosses underfloor heating developed a break in the connection (electric).

She ended up installing a boiler and radiators as the expense of ripping up the flooring to find the break was ridiculous.

Underfloor heating works really well when you have a low temp heat source such as a ground source heat pump or solar water heaters or woodburner with a back boiler but they can run off a gas boiler it just needs to work at a lower temp than the rads for the rest of the house.

Our old house ran off the gas which worked fine but not that economical. This time around we were already digging up the entire garden so installed a Ground Source heat pump and a lot of buried pipes. And we were doing the floors, so could put in a nice engineered oak floor properly insulated for UFH. it’s cheap to run but you wouldn’t start ripping your house up unless – like us – you had too.

We have an electric UFH mat in one of the bathrooms and that works fantastically well but I wouldn’t want to put too much of it in as it’s expensive to run.

I put electric cable heating in the bathroom when I redid the floor. Trouble is I managed to mess up the floor probe thermostat after the slates were laid so I cant use it as it was intended with the programmer. We only use it occasionally now as it takes a good hour or so to get up to temperature. It is nice when it’s on tho.

A point to note is that if you do this in a kitchen it might get too hot when cooking etc. A friend found that out after having done this and therefore doesn’t use it a lot of the time either.
At least with a rad you can adjust the heat quicker.

Good luck!

Tom
I have gone down the electric route twice.
First was on the conservatory floor, and secondly in a wet room.
Both under tiles but on top of some insulation to stop your heat going down instead of up!
Living with both these is pretty easy. We set it to be ‘Warm’ not hot and leave it switched on controlled by the thermostat.
Beleive this is the most efficient way just to leave it trickling along. If its switched off and cools down it can take quite while to come back up to temp (1/2 day) and its this that will consume more power.

Mart

Sorry to hijack, but really interested in how you’ve done your ground-source HP Alex. I’ve just bought a new house which is pretty much 4 walls and a roof (and 3 of those are shonky) so I have total freedom to put in whatever heating system I want.

Did you do a deep borehole, or a low-depth, spread-out one?

Would really like to do wet UFH with the hot water coming from a GSHP, backed-up by a wood-burning stove and leccy if required.

What’s the chat with them in cold environments? (I live in the Alps, new house at quite low altitude so not terribly snowy, but pretty cold location).

We laid about 300m(!) of pipe at around 2.8m below ground level. Our garden looked like a WW1 trench for a few weeks.

Murphy – 11 months by Alex Leigh, on Flickr

Started like that so we had to dig it all out anyway. We have UFH downstairs, bigger rads upstairs and mains pressure Hot Water which is nice. Also have a solar feed into the tank but not done that yet. Wood burner is separate – Stoner of this parish is mr renewables and might be able to help.

Our worked down to -15 no problem, it fires up an immersion system if it can’t get enough from the heat pump. We’ve had ZERO problems since putting it in, it just works and it’s lovely how the heat is not concentrated to where the rads are.

We looked at a borehole first, but it’s pretty chunky rock where we live and it just wasn’t practical for a few reasons.

Email in profile if you want to know suppliers/etc. We did have storage heaters (rubbish) and a cold house, now we have a warm house and 30% of the heating/hot water bills.

Simple Electric or boiler is based on running cost and investment cost But the running cost has to take into account how much you use it ie electric clearly the way to go in a bathroom as you would almost certainly never save enough money by using the boiler to warrant the higher cost of investment. Moreover can you swithch off the the underfloor boiler fed option or more importanly will you bother? People I know who have electric underfloor in the bathroom always swithch of when not in use so the running cost may actualy work out cheaper?

Alex – Member
We laid about 300m(!) of pipe at around 2.8m below ground level. Our garden looked like a WW1 trench for a few weeks.
Started like that so we had to dig it all out anyway. We have UFH downstairs, bigger rads upstairs and mains pressure Hot Water which is nice. Also have a solar feed into the tank but not done that yet. Wood burner is separate – Stoner of this parish is mr renewables and might be able to help.

Our worked down to -15 no problem, it fires up an immersion system if it can’t get enough from the heat pump. We’ve had ZERO problems since putting it in, it just works and it’s lovely how the heat is not concentrated to where the rads are.

We looked at a borehole first, but it’s pretty chunky rock where we live and it just wasn’t practical for a few reasons.

Email in profile if you want to know suppliers/etc. We did have storage heaters (rubbish) and a cold house, now we have a warm house and 30% of the heating/hot water bills.
You have failed to inform us of the costs involved and the money saved? Which is the only way to back up your views. I would also add that E7 radiators are excellent nowaday as there insulation is much better ie they use waste very little heat when closed down. A mate who is all electric said his costs on a standard tariff was 50 pound a month all in(2 bed bungalow). Note prior to the recent rises in prices. His house is always warm (if not hot). In fact everyone I know with “modern E7” riadotors are very happy with them. I would never rush to dismiss them.

We have GCH and four rooms with electric underfloor heating, courtesy of the previous owners. We only use it in one room occasionally. It’s not cheap to run, but is very pleasant. I also set the room temp at 20C.

I’m in a very similar position to you Tom – also looking to take out the wall between kitchen and dining to form one big room. We’d be left with very little usable wall space for rads, central heating based UFH is a no-go due to floor heights, and electric UFH not ideal mainly due to expense. I’ve kind of settled on plinth heaters, which aren’t the best looking of things but offer good heat output at minimal outlay, and most importantly run off the central heating. This is based on having a wooden floor though – I can live with not having UFH as wood feels a bit warmer to the touch anyhow, though if it was a tiled floor I think it’d also need electric UFH – tiles feel very cold when directly laid on a ground floor slab!

Er not really. Steve was asking about how we did it, not what it cost. But for info, it’s not a project with a quick payback. The costs with all the groundworks, internal plumbing, new floor, heatpump etc was significant, but we had to do it as the existing heating wasn’t going to cut it and there is no gas supply to where we lived. Plus we didn’t have a garden, we had a car park (ex B&B)

The Rads we have upstairs are fine, as are the heated towel rails in the bathroom, but I much prefer the ‘feel’ of UFH. Also as an asthmatic having no carpets is of huge benefit.

I do know our Winter bill for the first year using the Storage Heaters was over a grand.

Oh on that note (sorry previous reply was to SD), we did look at drilling into the slab. It would have been an absolute nightmare. Eventually we “created” the 100mm we needed for insulation, floor, conduits, etc by raising the lintels. Which was exciting 😉

Thanks Alex, that’s really helpful!

As our place is a blank canvas at the moment, plumbing costs, etc. shouldn’t be excessive as we can design it in from the start. I’m hoping to be able to do a lot of it ourselves both inside and out – seems like a lot of donkey work rather than anything hi-tech.

300m of pipe is a lot though! Was that in one chunky trench, or did you excavate the whole garden?

It’s a ex B&B with 4 bedrooms and a extra room tagged on downstairs. Also not of the finest build/insulation quality 😉 So NuHeat (who we used for the design/supply) played safe as we were digging the garden anyway. We ended up with one long trench but it zig zagged all over the garden. One day I expect to have a new fountain 😉

I think as a blank canvas, it’s a great idea. Retro-fitting outside and inside is harder. I think our heat pump is “fighter” which is Swedish (maybe) and it’s very clever. We don’t set room temps and the temp of the return flows aren’t monitored. God knows how but somehow the whole ground floor stays the same temp.

Also it has different programs (temp curves) depending on the temp diff between inbound and outbound into the garden (the outgoing pipe has ice on it in the winter) so we just leave it be until it goes below zero and then hit the winter setting.

Thermodynamics is not my strong point as may be apparent 😉

We did all of the laying of the conduit/diffuser/insulation inside which took a couple of weeks but it was all planned by NuHeat. Contractors did groundworks, I help with the outside cable (crikey that was a beast!), the plumbing and sparks we left to professionals.

If you know what you’re doing tho, (I don’t so I’m merely quoting said professionals!) the wiring/plumbing isn’t difficult. We’ve a “James Bond Destroy the World” room full of a massive scud missile tank, expansion tanks, pumps, heat pump and bits of kit the purpose of which I am gratefully and totally ignorant.

Can take a pic when I’m home if it’s of interest… I fully understand it probably won’t be!

Thanks again! I’ve got a solid 5 years of thermodynamics training (Mech Eng degree!) so not scared of speccing the project myself to some degree.

We have a big garden but, being in the Alps, it’s pretty steeply inclined so not sure how/if that would affect things (maybe just need a more powerful pump). Digging the trench would probably be a good excuse to put some kind of terassed/stepped path in too, so kills 2 birds with one stone. I suspect we might have bedrock issues though.

Surely an excuse to hire some bigger diggers 🙂

Hi Tom,
this is tony i’ve got a slight problem if you can help me out..
we have under floor heating in our own home we had it off in summertime when we turned it on in the winter it didnt come on apparently was not working so we changed the pump and the pump is working now but the heating is still not getting hot and we checked the water level, everything is ok but when we turn the heating on all the pipes go cold and when we turn it off the pipes start getting warm.
could you suggest what is going wrong?

thanks

Have you put the pump on the wrong way round?