Floor's still up prior to UF and we have a dilema.

I'll re-explain the situation as it's been a while.
Bedrooms/Bathroom downstairs, Lounge/dining/kitchen/hall Upstairs.

UFH going down in the whole of the upstairs living area.

Problem - Bathroom is currently illuminated with 4 x LV "eyeball" lamps
set in ceiling. No problem so far, but UFH + Isulation etc will bring
base level down by 3" in an 8" joist, plus, in order to reduce sound
levels downstairs I am filling the void under the base ply with
rockwool, which will reduce air circulation to very little.

So, question is, is a 5" space above a LV Halogen enough to prevent
possible "heat" implications. If this is too close to the limits, what
could anyone suggest as alternative lighting to put in the holes left by
the LV lights.

Many thanks

Pete

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In message ,
Pet wrote:


So, question is, is a 5" space above a LV Halogen enough to prevent
possible "heat" implications. If this is too close to the limits, what
could anyone suggest as alternative lighting to put in the holes left by
the LV lights.


Can't directly answer the question but a few thoughts spring to mind:

1: All the halogen downlighters I've installed recently (mains and LV)
simply state a minimum clearance around the fitting. This seems to vary
between fittings but is always in the 50mm to 150mm range (2" to about
6"). They say nothing about the airflow...

2: Having noted that, all the installation diagrams I've seen recently
show the light installed in an "open" box - they are showing a typical
situation with a floor above, ceiling below and joist to one side. They
all have the fourth side "open" (and don't mention sides 5 & 6 :-)

3: An ordinary ceiling/floor void will probably be quite airy -
plasterboard and wood are counted as "thermally conductive" for the
purposes of cable sizing for example. Surrounding your fitting on 5 out
of 6 sides with quite a lot of very good insulation, and not only that
but heating the top (slightly, through the insulation) would, I would
have thought, give potential for quite high temperatures in whatever
cavity you arrange around the fittings. Whether or not this is
detrimental to the bulb and bulb holder (probably not) this should
certainly be taken into account when you consider the cable you use to
attach the lamp to the transformer. Ordinary PVC is only rated to 70C
and even "high temperature" PVC or rubber cable (as used on heaters for
example) is only rated to 80C IIRC.

4: Speaking of the transformer, don't forget that this (these?) will
also need ventillation.

As for possible alternatives... well, all incandescent lights produce
copious amounts of heat... LEDs?

Hwyl!

M.


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Martin Angove wrote:


Can't directly answer the question but a few thoughts spring to mind:
snip

Many thanks for your pointers Martin,
I have been looking at alternatives, possibly even just trying Mains
Halogens, as at least there isn't a transformer adding to the heat build
up..... then again, would it be technically incorrect to have 240V
halogens above the bath I wonder?

I could also do away with some of the rock wool around the lights as
it's only the bathroom so sound won't be such an issue, besides, 45mm
cellotex with 15mm screed on top will already deaden the transfred sound
somewhat.

Also bveen looking into LED lights, but have no idea whether a 9 LED
unit would give enough light t replace the halogens.(one in each place)

Thanks again for taking time to respond.

Cheers
Pete

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In message ,
Pet wrote:

Martin Angove wrote:


Can't directly answer the question but a few thoughts spring to mind:
snip

Many thanks for your pointers Martin,
I have been looking at alternatives, possibly even just trying Mains
Halogens, as at least there isn't a transformer adding to the heat build
up.....

I would think that the bulk of the heat comes from the lamp itself
rather than the transformer. Transformers tend to get "warm" in use,
but would you attempt to touch a lit 50W halogen? Dichroic lamps are
worse in this respect because the reflective coating is designed to
allow the IR (heat) through to the back of the lamp whereas ordinary
silver reflectors bounce a proportion of the heat forwards too.

It is possible to get both sorts in both 12V and mains versions, but be
aware that some lamp holders are not specified for dichroic (also known
as "cool beam") lamps, and the mains versions have a differently shaped
ceramic base which means that although you can install a reflective lamp
in a fitting designed for dichroic you can't the other way about.

then again, would it be technically incorrect to have 240V
halogens above the bath I wonder?

It's perfectly allowable to have 240V fittings subject to certain
restrictions :-) The thing to look out for is the "zone" in which you are
installing the light and the minimum IP rating of fitting required for
that zone. Oh yes, and if they are earthed fittings (many are not) they
must also be part of the bathroom supplementary bonding.

If your ceiling is 2.25m high or lower then the part directly above the
bath is zone 1. I don't have my copy of BS7671 or the OSG to hand but
IIRC you can install 240V lighting in this area so long as it is
protected to IPX4 *and* is supplied from a 30mA RCD.

If there is no over-bath shower then zone 2 starts immediately outside
the bath and at a height of 2.25m above it. In zone 2 you still need an
IPX4 fitting, but don't need the RCD.

I could also do away with some of the rock wool around the lights as
it's only the bathroom so sound won't be such an issue, besides, 45mm
cellotex with 15mm screed on top will already deaden the transfred sound
somewhat.


This is something I really can't answer. Common sense says to me that
clearing the Rockwool to leave a cuboid around the fitting of minimum
dimensions (for example, 4") would leave a well-insulated cuboid within
which the temperature could very easily reach well into three figures.

If your LV lighting transformer is installed in the same space as the
downlighter (e.g. as is common with "through hole" transformers feeding
just one lamp each) then check the transformer's Ta (ambient operating
temperature; sometimes stamped on the device) This is unlikely to be
higher than 50 or 60C.

I would be tempted to forget the Rockwool altogether above the bathroom,
or at least only install it between joists where there is no downlighter
fitted.

Also bveen looking into LED lights, but have no idea whether a 9 LED
unit would give enough light t replace the halogens.(one in each place)


I've never used LED lights in this role. It is possible to get LED lamps
which directly replace GU/GZ10 mains halogens but I would be very
surprised if the light output was in any way comparable. There have been
some lengthy LED/CFL/incandescent debates here within living memory, it
might be worth your while looking one or two up.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Our Standard: Exellence; Our Goal: Perfection; Reality: Murphy.

Pet wrote in message . uk...

Also bveen looking into LED lights, but have no idea whether a 9 LED
unit would give enough light t replace the halogens.(one in each place)

not the remotest chance.

NT

In message ,
Martin Angove wrote:

In message ,
Pet wrote:

[...]

Also bveen looking into LED lights, but have no idea whether a 9 LED
unit would give enough light t replace the halogens.(one in each place)


I've never used LED lights in this role. It is possible to get LED lamps
which directly replace GU/GZ10 mains halogens but I would be very
surprised if the light output was in any way comparable. There have been
some lengthy LED/CFL/incandescent debates here within living memory, it
might be worth your while looking one or two up.


Neglected to mention, of course, that it is also possible to get CFL
lamps in GU10 format. These may be more acceptable than LEDs, subject to
the debates I mentioned :-)

Hwyl!

M.

--
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