Reducing floor thickness with UFH

[pjrich]

To comply with the 17th edition IET wiring regulations the heating film would have to covered with an earth shield / grid. Extract Below

753.411.3.2 RCDs with a rated residual operating current not exceeding 30mA shall be used as disconnecting devices. In the case of heating units which are delivered from the manufacturer without exposed-conductive-parts, a suitable conductive covering, for example, a grid with a spacing of not more than 30mm, shall be provided on site as an exposed-conductive-part above the floor heating elements or under the ceiling heating elements, and connected to the protective conductor of the electrical installation.

I have spoken (at length) to the NICEIC about this and have confirmed that if a flooring system is not supplied with an earth shield integeral the to heating, then a seperate earth grid must be installed.

These regulations only came in to force on the 1st July 2008.

I have spoken to a few manufacturers / suppliers of carbon film heating and ,as yet, none have advised me of a solution for providing the necessary earth grid.

If anyone knows of a solution I would be very interested to hear it.

Peter

 

[DHTiling]

Cheers peter...Has the 17th edition altered anything to do with standard mat or loose wire systems..?.... by that i mean fixers are still ok to install as long as no connection is done ....no change to that then......?

My son is a sparky but hasn't looked into that bit yet....

 

[pjrich]

Dave,

The main points of Section 753 - Floor and Ceiling Heating Systems are:-

1) Must be protected by a 30mA RCD
2) Heating must have integeral earth or be covered with earth grid.
3) Max operating temp must be 80deg C, floor surface must not exceed 35deg C.
4) Heating cables, etc must comply with BS 6351
5) Heating cables, etc must be IPX7
6) Specific information of the installation must be left with the end user.

The above is just a summary, the full section is 3 pages. I will try to post more detail later.

Peter

 

[DHTiling]

I know that bathrooms have to go on a sepaerate RCD unit now so how will that effect tilers if just putting UFH in.....?..

Kitchens will not be a problem it's more bathrooms we need to know about pete if you can please......

 

[pjrich]

Just had another conversation with technical at the NICEIC to confirm my thoughts and this is what I've established with regard to bathrooms and electric underfloor heating.

1) If the electrical installation has no existing RCDs then you should either upgrade the consumer unit to 17th edition requirements (likely to cost £400 +) or use fused spur with an integeral RCD to power the underfloor heating (Total power must not exceed 3000W)

2) If the electrical installation has a relatively modern consumer unit with RCD protection on the ring main(s) (Sockets) then it is acceptable to use a normal fused spur off the local circuit.

3) If an completely new circuit has to be installed from a consumer unit then is must be protected by a 30mA RCD.

Hope this helps, if anything is needed let me know and I'll do my best.

Forgot to mention that all UFH systems supplied by www.uheat.co.uk comply fully with the current regulations :yes:

Peter

 

[DHTiling]

Cheers pete..that makes sense really...........

 

[wetdec]

Removed

 

[grumpygrouter]

To comply with the 17th edition IET wiring regulations the heating film would have to covered with an earth shield / grid. Extract Below

753.411.3.2 RCDs with a rated residual operating current not exceeding 30mA shall be used as disconnecting devices. In the case of heating units which are delivered from the manufacturer without exposed-conductive-parts, a suitable conductive covering, for example, a grid with a spacing of not more than 30mm, shall be provided on site as an exposed-conductive-part above the floor heating elements or under the ceiling heating elements, and connected to the protective conductor of the electrical installation.

I have spoken (at length) to the NICEIC about this and have confirmed that if a flooring system is not supplied with an earth shield integeral the to heating, then a seperate earth grid must be installed.

These regulations only came in to force on the 1st July 2008.

I have spoken to a few manufacturers / suppliers of carbon film heating and ,as yet, none have advised me of a solution for providing the necessary earth grid.

If anyone knows of a solution I would be very interested to hear it.

Peter

Does this apply in Scotland as well because I think we have different regs up here?

 

[pjrich]

The 16th edition regs only used to ask for earth screen, etc in the bathrooms / wet rooms etc.

The new 17th edition wiring regulations require earth screens / grids for all electric underfloor heating installations, not just specific rooms.

Using electrical separation is no longer an acceptable method of installation to comply with the current wiring regulations. It was acceptable up to 1st July 2008 when the 17th edition came in to force.

I believe IET wiring regulations cover scotland as well, but I will check and come back to you to confirm.

Peter

 

[Dan]

A complete electric underfloor heating solution for new build - Suspended Timber Floors.

A Unique Under Floor Heating System that is installed under the floor, between the timber joists to provide either primary heat or supplementary heat in new build projects. To achieve the best results, insulation must be installed below the heating element.

The result is a warm, dry which is maintenance free and has a reduced installation height


Quick Installation


The film element for this type of wooden floor application should have a maximum heating effect of 90W/m . The maximum floor temperature should be controlled by an effective floor temperature sensor to a temperature recommended by the flooring manufacturer, usually 27 C. Particle chipboard flooring is recommended for installation over Ecofilm elements. Care should be taken when Pine T&G boarding flooring is used as some stability problems may occur. An un-coupling membrane should be used when tiling onto any wooden sub floor to prevent cracking caused by latteral movement.

Available in 3 widths; 300, 400 and 600mm to match joist centres. The product is perforated along the 50mm clear edge. This allows the border to be bent to a right angle (90 deg) to allow attachment to the joist when installing, Maintain a 40mm space between the perforation and the top edge of the joist. The element should be attached with staples to the wooden joists.




Hows that ............






..

cough cough - that "unique" system is manufactured by a company called Flexel International based in Scotland, and it's actually unique to them.

Uheat may be able to get you that if you want it. Cheaper than Varme sell it.

 

[wetdec]

Yes thats right, Flexel also make an earth shielded cable version for wet rooms, bathrooms etc. Varme do a similar cable system but not the film thats why we changed.

tiler

..

 

[aflemi]

A complete electric underfloor heating solution for new build - Suspended Timber Floors.

A Unique Under Floor Heating System that is installed under the floor, between the timber joists to provide either primary heat or supplementary heat in new build projects. To achieve the best results, insulation must be installed below the heating element.

The result is a warm, dry which is maintenance free and has a reduced installation height


Quick Installation


The film element for this type of wooden floor application should have a maximum heating effect of 90W/m . The maximum floor temperature should be controlled by an effective floor temperature sensor to a temperature recommended by the flooring manufacturer, usually 27 C. Particle chipboard flooring is recommended for installation over Ecofilm elements. Care should be taken when Pine T&G boarding flooring is used as some stability problems may occur. An un-coupling membrane should be used when tiling onto any wooden sub floor to prevent cracking caused by latteral movement.

Available in 3 widths; 300, 400 and 600mm to match joist centres. The product is perforated along the 50mm clear edge. This allows the border to be bent to a right angle (90 deg) to allow attachment to the joist when installing, Maintain a 40mm space between the perforation and the top edge of the joist. The element should be attached with staples to the wooden joists.




Hows that ............






..

I found this very useful post when searching how to fit ufh in my en-suite, hope you don't mind I dredge it up, Wet-Dec and ask for advice?
I have had an extension built with an en-suite. The floor has been suspended up to 450mm (to allow for a sunken bath). I have also had a 'wet-area' dropped down where I will use a former and tanking membrane on the walls. The floor has been suspended on 6x2 joists and consists of 18mm ply (lightly screwed down initially for access).
I intend to install ufh on the rest of the floor but am also slightly concerned that splashing from the bath, wet-area etc could soak through to the ufh. Would the system described above (1) with ufh underneath the ply base give out enough heat ie through the ply and tiles?
I had intended to (2) secure the ply properly, lay insulation board over, then ufh, then tanking membrane. Then adhesive and tiles. Would the membrane be ok laid to close over the ufh?
The thickness of the insulation board adding to the depth is not a big issue although all else being equal, I would prefer the floor lower rather than higher.
In summary I have 2 questions: Under (1) would the ufh give out enough heat through the ply. Under (2) would the membrane be stable laid over the ufh (obviously in a layer of adhesive).
Thanks for help....

 

[Uheat]

I found this very useful post when searching how to fit ufh in my en-suite, hope you don't mind I dredge it up, Wet-Dec and ask for advice?
I have had an extension built with an en-suite. The floor has been suspended up to 450mm (to allow for a sunken bath). I have also had a 'wet-area' dropped down where I will use a former and tanking membrane on the walls. The floor has been suspended on 6x2 joists and consists of 18mm ply (lightly screwed down initially for access).
I intend to install ufh on the rest of the floor but am also slightly concerned that splashing from the bath, wet-area etc could soak through to the ufh. Would the system described above (1) with ufh underneath the ply base give out enough heat ie through the ply and tiles?
I had intended to (2) secure the ply properly, lay insulation board over, then ufh, then tanking membrane. Then adhesive and tiles. Would the membrane be ok laid to close over the ufh?
The thickness of the insulation board adding to the depth is not a big issue although all else being equal, I would prefer the floor lower rather than higher.
In summary I have 2 questions: Under (1) would the ufh give out enough heat through the ply. Under (2) would the membrane be stable laid over the ufh (obviously in a layer of adhesive).
Thanks for help....

Hi ya,

If you are fitting Tiles then your best product to use would be a cable system, either loose cable or Mat. If you are intending on using an insulation board then 160w/m2 should be suffiecient to give primary heating.

you would cover the cable with a thin layer of SLC (Mapei Fibreplan a good one) so the floor construction will be insulation board, cable, SLC, Tanking membrane

Please see Wetdec for the best membrane to use.

Hope this helps

 

[aflemi]

Great Aaron, many thanks. I'll be onto you for the mat when it's time.
Cheers.

 

[Uheat]

No problems. If have any further questions please get intouch