Electric Underfloor Heating

[Jack1991]

So,

I’m currently getting an extension done 3m x 5.9m which will leave an internal kitchen dining space of 4.9m x 5.3m. After having the kitchen and stuff installed we would need underfloor heating covering around 18/19m2.

Under my floor i will have 150mm kingspan in between the floor joists, covered with chipboard. We will then have 6mm thermal UFH board, UFH laid and a 5mm screed, covered with porcelain tiles.

The extension ceiling will have 100mm kingspan with 25mm insulated plasterboard and 50mm kingspan in the wall cavity.

So my question is will the UFH be able to be my primary heat source to heat the entire room without needing radiators or other heaters.

Thank in advance.

 

[ericmark]

It did not work for me. Mother had a wet room built, and lucky fitted a towel rail. Both bathrooms and Kitchens need ventilation, and the extractor fan in wet room removed more heat than the UFH could replace, and air into room coming from hall which was cool but not cold.

In the main 27°C is limit for floor temperature, with water that is even so not too bad, with electric two types, simple resistive wire, which is subject to hot spots if some thing put an floor and reychem which is self regulating and does not need the pockets and floor sensors, only used reychem for trace heating not used for UFH. We used resistive type as covered with earth screen which was needed in a wet room, there was 9" of insulation under the floor, and as a result even with UFH off floor did not feel cold, but took around 2½ hours to get hot, and then it needed to warm room, so switch on before going to bed to have warm room in the morning.

Else where in the house we had programmable TRV heads so each room independently controlled, and only heated when required, whole idea is fast response times, ended up rarely being used. UFH was a white elephant.

P.S. have you looked at plinth heaters? reverse of UFH being very fast response time. Kitchens and bathrooms not used all day, so fast response time is good.

 

[oldbutnotdead]

Best do your heatloss calcs for the room as described and then check the w/sq m emitted by the ufh.
Ufh will probably keep the room to temp but you might want an alternative source (radiator or panel heater) to get the room to temp (ufh is very slow rrsponse)

 

[Jack1991]

I will look at plinth heaters, not heard of them before!

i will probably have a radiator on one wall but with the room so big might not reach the opposite end?

i was thinking about having ufh heating on timer, come on 2 hour before i get up, and 2 hours before i get home from work, i’ve heard with decent insulation and the screed/porcelain tiles it will hold heat quite well?

 

[Taylortwocities]

If you have conventional heating in the rest of the house (radiators for example) then you will be much better off with wet underfloor heating. Electric UFH systems are ok to warm your tootsies when you pop into the bathroom but (IMO) they are not much cop at space heating.

Plus, conventional domestic heating tends to be powered by gas to heat the water. The cost of this (per therm) is considerably cheaper than electricity.

 

[ericmark]

I have used a Myson fan assisted heater, and the plinth heaters are clearly fan assisted, and the big advantage was small size for the output, looking at some thing like 2.6 kW per heater, both hydronic (heated by central heating water) and electric, however I will admit they did work better with non condensate boilers.

Most radiators control heat output by how much water flows through them, but the fan assisted switches the fan on/off, so when it switches off hot water returns to boiler which can turn down boiler output, this does not seem to cause a problem with one heater, but may if multi fan assisted heaters are used.

 

[Jack1991]

I’ve been speaking with the missus, we’ve agreed as UFH throughout, with a radiator hung on one wall and a wall mounted electric fire under the TV which can be used for a quick blast of heated when needed!

Hopefully this will be enough to heat the room!

 

[SimonH2]

... they did work better with non condensate boilers.

How come ?

Most radiators control heat output by how much water flows through them, but the fan assisted switches the fan on/off, so when it switches off hot water returns to boiler which can turn down boiler output, this does not seem to cause a problem with one heater, but may if multi fan assisted heaters are used.

Bear in mind that since we do not have any boilers on the market designed for the 21st century, (most not even for late 20th century), they all rely on a bypass - whether that's an open radiator, or a bypass valve. As such, while the return water temperature out of the rads reduces with heat output (i.e. as the TRV throttles down), the return temperature back into the boiler increases due to the higher bypass ratio. This can result in systems which don't condense most of the time if the radiators aren't sized to allow sufficiently low flow AND RETURN temperatures to be used.

I’ve been speaking with the missus, we’ve agreed as UFH throughout, with a radiator hung on one wall and a wall mounted electric fire under the TV which can be used for a quick blast of heated when needed

As above, seriously consider wet UFH - especially as it sound slike you already havea wet heating system. For me, and I don't believe we are not typical, electric is around 3 times the price of gas per unit of heat. Wet is harder to install, but it will be much cheaper to run, and has other advantages ...

Electric is (except for some with fancy self regulating cables) a "constant power" input. If you insulate part of the floor, e.g. by daring to have a rug or furniture in the room, then that part of the floor will get hotter - potentially to the point where it's dangerous or damages something.
Wet is (sort of) a constant temperature system. The floor cannot get hotter than the water in the pipes - so if you have a rug or furniture, all that happens is that the floor underneath gets a little warmer (because it's losing less heat) and heat output is reduced from it.

 

[ericmark]

The old boiler only monitored output temperature, return temperature did not matter, so when the Myson fan turned off the raise it water temperature did not matter, it did not reduce the boiler output, but because the Myson fan assisted does not stop flow it allows hot water to return without the by-pass lifting, for one odd Myson in the kitchen as kick space heater this really does not matter, but for many heater it would be better piped in series not parallel, so the return water is cool enough to ensure the boiler only modulates when all rooms satisfied.

I looked at new Myson iVector and impressed, the big problem with the Myson fan assisted was noise of the fan, not much, but dead of night when watching TV with sound turned down so as not to keep anyone else in house awake, when Myson cut in would need to increase volume, but new one has I think 5 automated speeds, so much less noise.

Also the same unit can be connected to a heat pump so can cool as well as heat.

 

[winston1]

and a wall mounted electric fire under the TV which can be used for a quick blast of heated when needed!

Your TV won't like a heater underneath it and will have a short life.

 

[Taylortwocities]

Your TV won't like a heater underneath it and will have a short life.

Wow, I never heard of that as an issue. There are a lot of folk who have TVs in similar locations.
Can you post some interesting reading on this subject please?

 

[winston1]

Anyone knows that electronics fail when over heated, usually the capacitors. Putting TVs over a source of heat is asking for trouble.

 

[Taylortwocities]

I bet your TV is so old that it can only show the Relief of Makeking in black and white.

 

[winston1]

Don't know about Oxfordshire but colour TV came to London in 1967.

Edited to correct year. Thanks Bernardgreen.

 

[bernardgreen]

Don't know about Oxfordshire but colour TV came to London in 1968.

The first colour broadcasts in the UK On 1 July 1967, BBC2 launched Europe's first colour service with the Wimbledon tennis championships, presented by David Vine. This was broadcast using the Phase Alternating Line (PAL) system, which was based on the work of the German television engineer Walter Bruch.