Underfloor heating

[Tan]

Hi

We are looking to build an extension (25 square metres and height of 3metres) and have underfloor heating in it.

We want warm water system as it can be connected to our boiler, would this be sufficient to keep the room warm on its own or would we need radiators also?

Any advice on companies or brands to look at?

Thanks

Tan

 

[def90cars]

I recently looked at two houses with underfloor heating (wet) and from how warm they were I would say no need for radiator.

My mum have underfloor heating in ensuite (electric) and if you keep it on all day (even at 16C over night - then 20C in the day) it is incredibly effective.

 

[Deleted member 113659]

I'll second that Tony. No need at all for additional rads. Especially with current building regs regarding insulation.

The new extension will have its own room stat so it'll be working independent to the rest of the house.

We have loose cable system underfloor heating in our bathrooms. They're on 24/7 on 20 degrees and very efficient. But wet underfloor heating installed correctly with the right insulation is even better.

Ant.

 

[renault12ts]

You are building a modern, well insulated extension of 25m...hell yes it'll keep it warm!!


We have it in our 50m+ kitchen, which is of mixed 1873 and 2005 construction...and we are warm 24/7.

 

[Deleted member 113659]

..and we are warm 24/7.

And your landing is also lit 24/7.

 

[renault12ts]

And your landing is also lit 24/7.

Indeed, but the light is on 365 also, the UFH is only on for about 6-7 months.

 

[Tim203]

You must have a very dark landing Renault!!

 

[Minden99]

Do it yourself. It's ridiculously easy. You need branch off your exist radiator circuit. To a separate circuit pump and temperature equaliser to reduce water temp from 70'c in central heating system to approx 40/50'c any higher you could damage floor. Then you connect i'd say 100 metres of special plastic piping to pump on 50mm floor insulation with u clips. It took me a day but saved 1500 quid but good feeling when worked. I'll try find parts supplier

 

[Minden99]

Cannot find the make. But here is all you need bar the insulation under the piping.

http://pages.ebay.com/link/?nav=item.view&id=300519744517&alt=web

 

[renault12ts]

Do it yourself. It's ridiculously easy. You need branch off your exist radiator circuit. To a separate circuit pump and temperature equaliser to reduce water temp from 70'c in central heating system to approx 40/50'c any higher you could damage floor. Then you connect i'd say 100 metres of special plastic piping to pump on 50mm floor insulation with u clips. It took me a day but saved 1500 quid but good feeling when worked. I'll try find parts supplier

You left out the next bit...screeding the floor...not generally a DIY job.

 

[renault12ts]

You must have a very dark landing Renault!!

Only when the light is off.

 

[Minden99]

Screeding is never a diy job. But least the floors prepared for them to screed after pipe laid. Then its just like any other floor. All be it the insulation around screed edging to wall.

 

[grober]

Try to envisage the day when it might go wrong. Want to dig up your floor or merely change a radiator/ wall thermostat? The word you should think about is ACCESS

 

[jonnyboy]

Try to envisage the day when it might go wrong. Want to dig up your floor or merely change a radiator/ wall thermostat? The word you should think about is ACCESS

Oh, the scaremongering.......

Have you actually had a bad experience with ww UFH ?

I'd love to know what you think could go wrong with a single length no joint plastic tubing circuit that is protected by at least 75mm of concrete.




To the OP - go for it. You just have to think of how to branch off at the boiler. You'll need it to be a separate circuit as UFH works in a different way to rads. So a separate 2 port valve and control circuit, with a room thermostat in the extension. Effectively, a bit more disturbance than just teeing off existing rad system but to me the controllability and independence is the key. As it is only one UFH zone you don't need manifolds or any of that malarkey. Rads are on/off high temp then cool down. UFH uses the screed as its "radiator", its very slow and steady release so won't be on/off/on/off as long as insulation is done correctly and the loop length/spacing has been calculated accurately. Especially important with a 3m ceiling.

The above comes from real world experience of building a circa 2000sq ft extension, the ground floor being ww UFH. Regrets? Yes. Should have bit the bullet, pulled up the floors in the remaining 4 downstairs rooms, and converted those too. I rarely hear ours on, except early morning/lmid evening at this time of year. Constant temperature is so nice, and it's cheaper to run by far than rads.

I used wundafloor I think, may have been nu-heat. Will check. They were excellent, and still are (rang them for an instruction booklet that I had mislaid, no problem even though 4 years ago).

 

[jonnyboy]

Actually, I forgot to put in my last post - if there's any issue with floor levels, have a look at an anhydrous screed. It pours like milk, so can be pumped in cleanly through the window, largely self-levels, is six times more thermally efficient and strong than concrete so can be laid from about 25mm thick instead of 75mm minimum of concrete, meaning potential for more insulation/thicker flooring if you're going for engineered timber for example, and no expansion joints required unless massive area.
However, it isn't cheap - so may not be cost effective on a smaller area unless theres a contractor who can time it with a "job around the corner"

 

[Peter103]

You must have a very dark landing Renault!!

Renaults landing, is his Batman cave,

 

[grober]

One aspect to take into consideration as highlighted by the last post is hysteresis. UFH uses the floor mass as its radiator as stated - just don't expect it to shut off with the thermostat when the sun comes out . Next door neighbour had electrical UFH installed in her bathroom- beautiful tiled /wall finish walk in shower etc . 2 years in---- the control thermal sensor buried in the floor along with the heating elements failed. She now relies on a small wall mounted towel radiator to heat her rather large bathroom. Needless to say she has strong opinions on UFH

 

[renault12ts]

One aspect to take into consideration as highlighted by the last post is hysteresis. UFH uses the floor mass as its radiator as stated - just don't expect it to shut off with the thermostat when the sun comes out . Next door neighbour had electrical UFH installed in her bathroom- beautiful tiled /wall finish walk in shower etc . 2 years in---- the control thermal sensor buried in the floor along with the heating elements failed. She now relies on a small wall mounted towel radiator to heat her rather large bathroom. Needless to say she has strong opinions on UFH

But that's like comparing apples and pears. Her's is an electric system...totally different to wet. My system will be 11 years old this year.

 

[jonnyboy]

But that's like comparing apples and pears. Her's is an electric system...totally different to wet. My system will be 11 years old this year.

Exactly. The OP wants warm water........

 

[grober]

I should point out that the heating elements didn't fail it was the temperature sensor buried in the floor. Due to the wiring run impossible to replace in situ------ needless to say the whole thing installed by professional bathroom specialists. I can actually see the argument for UFH in a bathroom where you perhaps want to maintain a steady temperature all year round but I would think carefully about installing it in an extension say with a lot of glass area subject to solar influence where daily temperatures may fluctuate quite rapidly.