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Tiling concrete floor slab (Read 5043 times)
CWatters
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Re: Tiling concrete floor slab
Reply #10 - Aug 14th, 2013, 12:30pm
 
A simple approach is just to look at the thickness. If you add an extra 10mm of insulation to 150mm of existing insulation it's unlikely to have lower heat losses than using 160mm to start with. So at best the heat loss will be roughly 150/160 or 93% of what it is with just the 150mm.

The main benefit of using an insulated backing board will be the response time because the 10mm layer is going between the heat source and the large thermal mass of the slab.

There is no reall getting away from the fact that electric is expensive..

http://www.nottenergy.com/energy_cost_comparison

Electricity 14.47 p/kWH
Mains gas 5.1 p/kWH
Oil/Kerosene 6.5 p/kWH









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runninwata
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Re: Tiling concrete floor slab
Reply #9 - Aug 7th, 2013, 5:15pm
 
The MVHR Unit was specified at a very early stage we have a similar unit in our office and even when on full whack is not nearly as noisy as some fans on computers so not really needing to reasearch the genvex system or the vanvex system any further thanks.

Still undecided for the need to fit backer board, 100mm thick concrete with 150mm insulation and UFH being left on 24-7 anybody have any refernece for heatloss calcs based on this, we are now definately going down the route of porcelain tiles for the whole area!

any input greatly appreciated

Thanks

Steve
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Re: Tiling concrete floor slab
Reply #8 - Aug 1st, 2013, 10:13am
 
You've got to make sure it's insulated properly. here's a lot of money to be wasted on trying to keep the floor warm if it's not done right.
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Re: Tiling concrete floor slab
Reply #7 - Jul 28th, 2013, 7:01pm
 
Have you done your research on the mhrv/heat pump system you propose to use?

I suggest you ask for comments or search over on this forum..

http://www.greenbuildingforum.co.uk/

There is a known issue with combining the two. That is that the airflow rate required  to transport heat is higher than that required just to provide ventilation. So there is the potential for the mhrv to be louder than it would otherwise be if only needed for ventilation.
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Re: Tiling concrete floor slab
Reply #6 - Jul 27th, 2013, 3:53pm
 

Thanks ,
Its a new build extension, The slab is 100mm thick and the insulation beneath is 150mm (2 thicknesses of 75mm Kingspan)
The backer board is very expensive therefore would prefer to leave it out not only for the added thickness but for the added costs.
Im still undecided!!! Huh Huh Huh

thanks

Steve
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woodsmith
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Re: Tiling concrete floor slab
Reply #5 - Jul 27th, 2013, 11:15am
 
If you  are going to leave it on constantly then I would not bother fitting the backer board. This is as long as you are sure you have a massive amount of insulation under the concrete slab. If not I would not dream of fitting this ufh as it will cost you a fortune to run.

We stayed at an apartment where they had electric ufh and it worked OK as long as you kept an eye on the weather forecast and altered the heating the night before to suit. No idea what their electric bills were like though.
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Re: Tiling concrete floor slab
Reply #4 - Jul 26th, 2013, 3:48pm
 
Sorry,

I should have given more information, The house is built to a high degree of airtight standards using a valutherm kit,

airtightness so far achieved around 1.8,

Therefore we are installing an genvex premium MVHR and a vanvex cylinder, The main heat source is from the Genvex system but the underfloor heating will be on constant to warm the floor and provide the necessary extra heat required in the winter months,

so I suppose based on  the comments above

if I dont use the backer board it will take ages to heat up but will retain the heat in the slab longer

and If i use the backer board the tiling will heat up a lot quicker but once switched off it will lose the heat quicker?

It is our intention to keep it on full time in any case, we are installing 4kw of PV Panels to compensate for the electricity being used in the build

Thoughts??

and If I go down the backer board route does anybody know where I can get larger sheets approx 100m2 of floor area to cover!

Thanks

Steve
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Re: Tiling concrete floor slab
Reply #3 - Jul 26th, 2013, 11:59am
 
And it's often not a warm feel, just not a cold one.

Wink
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Re: Tiling concrete floor slab
Reply #2 - Jul 26th, 2013, 6:57am
 
The backer board is meant to prevent the heat from going down and being absorbed by the concrete, making heat up times quicker and the system less costly to run.

I am not a fan myself, but do like the warm feel  Smiley
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Re: Tiling concrete floor slab
Reply #1 - Jul 25th, 2013, 11:14pm
 
We had electric under floor heating in a bathroom but it cost so much to run that we took it out. Turned out that the builder had not fitted any insulation underneath the concrete but I would look into the running costs before trying to use it as your main heating source.

Even if you have a decent amount of insulation under the concrete the heating will have to heat up the entire mass of concrete for you to feel any benefit. If you turn it on you will have to wait a long time before the floor starts to feel warm, but then once it is warm it will stay warm for some time after you have turned it off.

On the other hand if you add insulation directly under the element you will get a much faster response time but once the power goes off so does any warmth.
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« Last Edit: Jul 25th, 2013, 11:16pm by woodsmith »  


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Tiling concrete floor slab
Jul 25th, 2013, 6:05pm
 
Hi folks,
Between illness work commitments and bringing up a family this is the first time I have posted for a while!

We are looking to install electric underfloor heating mat onto an insulated concrete slab, the mat will be used along with a genvex mhrv as the primary heat source for the building.

Question is what are the benefits of installing an insulated backer board beneath the tiles

Originally planned for Karndean flooring now swmbo fancies porcelain tiles problem now is all levels of Skirting and facings etc were left for Karndean and the backer board approx 12 mm so therefore I was thinking of just tiling straight onto the ufh to save on thickness and removing all skirting a blocks etc..


Any comments advice most welcome

Cheers

Steve
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