Underfloor heating pros / cons

[Sergeant Pluck]

Hi all

Our bathroom is due to get ripped out shortly. We’ve been wavering on a few choices regarding the floor. There has been a dalliance with Amtico / similar but we have now reverted to porcelain tiles. The question of underfloor heating arises.

While I could happily do without it, various thoughts come to mind:

- we aren’t going to get the chance to do it again
- it’s seen as a desirable feature when selling and we will not own this flat forever
- it is not that expensive to do, given the overall cost of the job
- nice to have even if only used occasionally. Partner is keen to have it available.

Advice and tales of UFH experiences appreciated. It’s a 2nd floor flat, in a small late 60s block, concrete floor. Any reason not to proceed, assuming flor heights allow? Guess my main concerns are - will it in any way compromise the stability of the tiles laid on it, and will UFH cause big issues if for example a tile needs removed / replaced?

[rogerzilla]

Electric or wet?  Electric is cheap to install, although not DIY for Part P reasons, and expensive to run.  If you're not there for long, it's probably your best option.

I've bought tiles for my bathroom job, and have only just realised how terribly cold they are going to be, even upstairs.

[Jaded]

It increases the depth of the floor, which may imoact on doors etc. and if wet needs to be installed very well to prevent leaks.

[chrisbainbridge]

We have underfloor heating in the house we own and I miss it terribly in our current house.  That was wet UFH on an insulated bed.

When we go back to the house I will be putting electric UFH in the large hall.  just walking on a warm floor makes you feel warm.

[hellymedic]

Beware that UFH can KILL pianos!

I wasn’t going to post this while a bathroom was being discussed!

[HTFB]

Beware that UFH can KILL pianos!

Oh, how so? We have UFH but no piano as yet.

Electric mat UFH is very easy to fit and doesn't take up any height. In the cottage in Wales it's been a revelation compared with the previous early-morning frigid tiles laid more or less straight onto bare mountainside [1]. We inherited it in the bathroom of our previous concrete second floor 60s flat, and put in wet UFH everywhere else. Unlike the main system we never really optimised how to use it: the thermostat embedded under the tiles had only a sketchy relationship with the temperature of the bathroom.

The bathroom is the of course one place where UFH doesn't save you wall space compared with radiators, because you probably also want a heated towel rail to dry things on. So you don't actually make room for a piano in there.

[1] Tell me, bird of midnight ghosty,
What makes my toes so nicely toasty?
Quoth the raven, Underfloor.

[hellymedic]

UFH creates convection currents of nice, warm air, that dry out wood and can warp/distort it. This is mostly a problem under grand pianos, which occupy a large floor area.
(Acoustic) pianos need a constant, low humidity to stay in tune.

Mats to place on heated floors, under pianos, are available.
https://countrywidepianos.co.uk/our-pianos/piano-accessories/protect-your-piano-from-underfloor-heating/#:~:text=Underfloor%20heating%20produces%20rising%20hot,both%20upright%20and%20grand%20pianos.

[rogerzilla]

Beware that UFH can KILL pianos!

I wasn’t going to post this while a bathroom was being discussed!

I bet Liberace had one in a bathroom.

[hellymedic]

Beware that UFH can KILL pianos!

I wasn’t going to post this while a bathroom was being discussed!

I bet Liberace had one in a bathroom.

I’l ask D, who visited his abode in 2017...

[Jaded]

Beware that UFH can KILL pianos!

I wasn’t going to post this while a bathroom was being discussed!

I bet Liberace had one in a bathroom.

Well, we will only have your word for that. 

[Sergeant Pluck]

Electric or wet?

Leccy.

[meddyg]

Our ten year old system (probably just a wiring laid in screed)
just blew up and electrician has condemned it saying ' you'll never find the site of break/burnout....'

What a cold kitchen we now have!
how much lower are our elec bills!

We'll probably use
https://www.warmup.co.uk/underfloor-heating

to re-instate. Sergeant Pluck might like to take a look.
They are German and have expertise in wet and electric mats- maybe just lay a new  mat on one end of the kitchen without fittings and furnishings for us! Though they reckon it's a micro thin mat which will barely raise floor lwevels. Hm.

[Vernon]

We installed a warmup mat under the tiles in the bathroom in our house in Portsmouth. It was about 2.5 square metres and used about 200w. We laid a flat cement tile under floor on the floor boards, laid the mat in a layer of screed and the tiles on top. The floor was 1cm or so higher, but the door sill hid all that. We nogged the floor joists from below to make sure absolutely nothing moved, but it depends on your floor. We had a sparky connect it to the heater controller.
I can thoroughly recommend it for warm feet, dry towels and a dry bathroom.

[Sergeant Pluck]

Thanks for all the above.

I had a chat with the bathroom fitter about UFH at the beginning of the process, during which he helped me to talk myself out of UFH. Things mentioned included:

- it’ll only warm the floor, not heat the room (fine, there will be a radiator / towel rail, it’s not a big room, and doesn’t get particularly cold. On the other hand, feasible size of said rad is limited)
- running costs, because you won’t be able to just “use it for short periods” as it takes time to warm up. Also, most inefficient to use UFH that way (dunno on this one)
- if it breaks etc. (Well in the course of talking about that he partially negated his argument by telling me about UFH setups that can tell you via an app where the break is. Guess it depends on how reliable these things are and correct installation)

I’m leaning towards getting it.

[chrisbainbridge]

Thanks for all the above.

I had a chat with the bathroom fitter about UFH at the beginning of the process, during which he helped me to talk myself out of UFH. Things mentioned included:

- it’ll only warm the floor, not heat the room (fine, there will be a radiator / towel rail, it’s not a big room, and doesn’t get particularly cold. On the other hand, feasible size of said rad is limited)
- running costs, because you won’t be able to just “use it for short periods” as it takes time to warm up. Also, most inefficient to use UFH that way (dunno on this one)
- if it breaks etc. (Well in the course of talking about that he partially negated his argument by telling me about UFH setups that can tell you via an app where the break is. Guess it depends on how reliable these things are and correct installation)

I’m leaning towards getting it.

UFH heats the floor which then heats the room.  The heating is best at the floor and the decreases upwards so the ceiling is unheated.  Radiators by convection heat the air above your head height which is a complete waste!

The greater the thermal mass of the whole floor the more benefit from having it on all the time.  I think electric undefloor on a small bed could be put on for a few hours at a time.

[hellymedic]

Beware that UFH can KILL pianos!

I wasn’t going to post this while a bathroom was being discussed!

I bet Liberace had one in a bathroom.

I asked.

D says he did, though seldom actually played his pianos in his later years.

[andrewc]

https://x.com/AlexanderFoxEtc/status/1783950979257307566

[Wowbagger]

I heard that Norman St. John Stevas kept a harp in his bathroom.

[hellymedic]

Leftmost leak-hole would need a very thin, poorly endowed client, methinks...

[rogerzilla]

Black urinals are a new one on me.  How are you supposed to tell if you've eaten too much beetroot?

[Vernon]

Black urinals are a new one on me.  How are you supposed to tell if you've eaten too much beetroot?

Taste?
 

[HTFB]

UFH creates convection currents of nice, warm air, that dry out wood and can warp/distort it. This is mostly a problem under grand pianos, which occupy a large floor area.
(Acoustic) pianos need a constant, low humidity to stay in tune.

I would have guessed that a grand piano, of which all the important bits are insulated from the floor by a good couple of feet of clear airflow, would be happily ambient?

I can see that warm air heating directing hot dry air out from under the floor (can I say "hypocaust"? I will, you know. Hypocaust) might be a problem, although it didn't seem to bother my grandmother's grand.  Underfloor heating has a large emitter area and so you can run it at a lower temperature for a given heat loss. In our previous flat it utterly failed to control humidity -- dry wood was the least of our problems.

[Cudzoziemiec]

https://x.com/AlexanderFoxEtc/status/1783950979257307566

If you sprinkle when you tinkle...

[hellymedic]

UFH creates convection currents of nice, warm air, that dry out wood and can warp/distort it. This is mostly a problem under grand pianos, which occupy a large floor area.
(Acoustic) pianos need a constant, low humidity to stay in tune.

I would have guessed that a grand piano, of which all the important bits are insulated from the floor by a good couple of feet of clear airflow, would be happily ambient?

I can see that warm air heating directing hot dry air out from under the floor (can I say "hypocaust"? I will, you know. Hypocaust) might be a problem, although it didn't seem to bother my grandmother's grand.  Underfloor heating has a large emitter area and so you can run it at a lower temperature for a given heat loss. In our previous flat it utterly failed to control humidity -- dry wood was the least of our problems.

I’m afraid it very much IS a problem!
I suppose the bulk of a piano body restricts air circulation, which will exacerbate the problem.

Pianos losing accurate tuning is a perennial problem. I doubt if there would be a market for sophisticated piano humidity management if this was unnecessary!

[HTFB]

Pianos losing accurate tuning is a perennial problem. I doubt if there would be a market for sophisticated piano humidity management if this was unnecessary!

That much I know. It's the particular alleged evil of underfloor heating that I can't comprehend. It's not like placing an upright against a radiator.