RE: [OT] Underfloor heating advice

["Young, Jeff" <Jeff.Young@xxxxxxxx>]

I know this is cross-posting but I've just put this up on Uk_selfbuild

..............................................

I've been a member of the UKHA forum for a while now and due to a
retrospective planning (listed building) application being APPROVED I now
find myself in the surprising position of being able to continue with the
work !

I 'm damp-proofing two underground/under-road vaulted cellars in Bath Spa.
Below are a few pics of the work in progress.  The idea is to create a
playroom and a storeroom.

http://www.perfectmotion.co.uk/pict1.jpg
http://www.perfectmotion.co.uk/pict2.jpg
http://www.perfectmotion.co.uk/pict3.jpg
http://www.perfectmotion.co.uk/pict4.jpg
http://www.perfectmotion.co.uk/pict5.jpg

The basic build so far has been a new concrete floor slab.  Insulation has
been installed under the concrete.  The Newton 500 damp system drains into
a
central drain between the two vaults.  I've run in a bunch of
CAT5/coax/audio signal cables from the main house and will be starting the
electric first fix soon.

The main question at the moment concerns the under floor heating.  The idea
is the walls are all curved and radiators would take up valuable wall
space.
In an ideal world I would like the under floor heating to provide enough
heat to heat the whole room.  The main problem I've got is head height. 
The
Vaults have low ceilings so I'm trying to keep the floor as 'thin' as
possible and avoid a thick layer of screed on top of the Newton membrane.
I'm also considering electric under floor heating as pumping water around
the rooms I'm trying to keep dry seems to be asking for trouble.

My current idea is a floating floor positioned on top the of Newton
covering
the floor .It would be made up of  a layer of 1 inch Selotex on top of
which
would go 18mm chipboard then underlay, followed by under-carpet heating
mats
then finally a low-tog carpet. So all in that's about 50 mm ( excluding
carpet ) of lost head height.

What do people think ? Is it possible to use a more conventional system and
only use 50mm in height.  Thanks in advance. Jeff


............................................
-----Original Message-----
From: Hawes,Timothy Edward (GEG) [mailto:haweste@xxxxxxx]
Sent: 26 February 2004 13:13
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] [OT] Underfloor heating advice


> -----Original Message-----
> From: Jon Whiten  Sent: 26 February 2004 11:35
>
> You say:
>
> 	finished screed - heating mats - latex screed - tiles
>
> Would
>
> 	Joists - chipboard - heating mats - latex screed - tiles
>
> work.  I am thinking about our upstairs bathroom here and, to
> get back on
> topic, this will be our next automation project!
>
> Also, you mention mains/low voltage.... Is there any
> restriction when using
> in a bathroom?  I'm thinking wet feet, electricity, bang, here.

With the Devi-Heat electric system the insulated heating wired is embedded
into the screed. The wire carries mains voltage (IIRC) but as the bit under
the floor is insulated so you don't get a shock. It's essentially a
domestic
version of industrial heat-trace cable.

Where you do need to watch the regs carefully is how and where you
terminate
the 'under-floor' wire to the normal house mains wiring. When I installed
mine, I terminated the cables behind a false wall, with an access plate
hidden behind a mirror i.e. well away from moisture ingress and impossible
to touch unless you'd first removed about 15 screws ;-) The controller was
fitted into the wall outside the bathroom, next to the isolation switch for
the extract fan.

The basic controller is thermostat-based only, with a temp sensor embedded
into the screed at the same time the heating mat is installed. You turn the
system on, set the temperature and the system cuts in & out to maintain
a
given floor temp. More recent controllers incorporate time-based switching
too.

Any questions give me a shout, either here or over on UK_Selfbuild :-)

Cheers,

Tim.

+


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