Hello,

I am a bit puzzled about heat detectors [that should be interlinked
with smoke detectors]. I understand that a smoke detector in a kitchen
could have false alarms and that this is why a heat detector is used
but I read a manufacturer's site that claimed building regs. say a
heat detector should be used in the lounge ("principle residential
room"). Is this true? Why should a heat detector be needed here if you
have a smoke detector?

If these alarm when the temperature reaches 56C, how useful are they?
I am guessing a fire goes from room temperature to very, very hot very
quickly. Is a warning at 56C likely to be useful or by then won't it
be too late? Is the idea that it may be too late to save the
kitchen/lounge but it will wake you and get you our of bed before the
fire spreads?

Would you bother putting heat detectors in the garage and loft?

TIA

On Fri, 06 Aug 2010 21:49:17 +0100, Fred
wrote:

I am a bit puzzled about heat detectors [that should be interlinked
with smoke detectors]. I understand that a smoke detector in a kitchen
could have false alarms and that this is why a heat detector is used
but I read a manufacturer's site that claimed building regs. say a
heat detector should be used in the lounge ("principle residential
room"). Is this true? Why should a heat detector be needed here if you
have a smoke detector?

The three rooms where fires most usually start are, in order of
popularity,firstly the kitchen (usually chip pans), secondly the
lounge (abandoned fag ends down the side of the sofa while drunk) and
thirdly the bedroom (falling asleep in bed in drunken stupor while
smoking).

The single most important location for a smoke detector is the ceiling
above the stair well, usually the landing ceiling. That will alarm
first in most fires (even before one in the room the fire starts in if
the doors are usually left open as most are.

With the exception of the kitchen where the nuisance alarm rate would
be far too high with an optical or ionisation detector all a rate of
temperature rise sensor in any other room will do is wake you just in
time to for you to die.

If these alarm when the temperature reaches 56C, how useful are they?

In a kitchen, with few flammable items, very useful. Put on the
ceiling above the hob they will give you warning of a pan fire quickly
enough so that you can respond.

I am guessing a fire goes from room temperature to very, very hot very
quickly.

Correct.

Is a warning at 56C likely to be useful or by then won't it
be too late? Is the idea that it may be too late to save the
kitchen/lounge but it will wake you and get you our of bed before the
fire spreads?

If your lounge is ablaze it is too late - it isn't fire that kills but
smoke. You need an ionisation detector to alarm at the first whiff of
the products of combustion - you can't afford to wait for the fire to
develop.

Would you bother putting heat detectors in the garage and loft?

Loft - no unless you had a boiler up there. Garage, possibly. For a
garage with a car in it I wouldn't bother. For one used as a home
workshop and especially if welding is done in it - yes (and a good
fire door to the house).

Fred wrote:
Hello,

I am a bit puzzled about heat detectors [that should be interlinked
with smoke detectors]. I understand that a smoke detector in a kitchen
could have false alarms and that this is why a heat detector is used
but I read a manufacturer's site that claimed building regs. say a
heat detector should be used in the lounge ("principle residential
room"). Is this true? Why should a heat detector be needed here if you
have a smoke detector?

It would normally be a smoke alarm not a heat detector in the lounge. Smoke
detectors need to be in the circulation spaces of a house (hallway and
landing)

If these alarm when the temperature reaches 56C, how useful are they?
I am guessing a fire goes from room temperature to very, very hot very
quickly. Is a warning at 56C likely to be useful or by then won't it
be too late? Is the idea that it may be too late to save the
kitchen/lounge but it will wake you and get you our of bed before the
fire spreads?

Ideal for a kitchen fire.

Would you bother putting heat detectors in the garage and loft?

I would not bother with one in the loft, but I would put a heat detector in
the garage.

I see your email address is not valid. Mine is, so if you email me via
hotmail or some other temporary address I will send you the BS5839-6-2004
"Fire detection and fire alarm systems for buildings" pdf if you fancy a
read. The offer applies to anyone not just the OP.

Cheers

--
Adam

"ARWadsworth" wrote in message
news:uN%6o.57860$zT3.55338@hurricane...
Fred wrote:
Hello,

I am a bit puzzled about heat detectors [that should be interlinked
with smoke detectors]. I understand that a smoke detector in a kitchen
could have false alarms and that this is why a heat detector is used
but I read a manufacturer's site that claimed building regs. say a
heat detector should be used in the lounge ("principle residential
room"). Is this true? Why should a heat detector be needed here if you
have a smoke detector?

It would normally be a smoke alarm not a heat detector in the lounge.
Smoke detectors need to be in the circulation spaces of a house (hallway
and landing)

If these alarm when the temperature reaches 56C, how useful are they?
I am guessing a fire goes from room temperature to very, very hot very
quickly. Is a warning at 56C likely to be useful or by then won't it
be too late? Is the idea that it may be too late to save the
kitchen/lounge but it will wake you and get you our of bed before the
fire spreads?

Ideal for a kitchen fire.

Would you bother putting heat detectors in the garage and loft?

I would not bother with one in the loft, but I would put a heat detector
in the garage.

I see your email address is not valid. Mine is, so if you email me via
hotmail or some other temporary address I will send you the BS5839-6-2004
"Fire detection and fire alarm systems for buildings" pdf if you fancy a
read. The offer applies to anyone not just the OP.

Cheers

--
Adam


Good grief its £196!

But here is another pdf about it, and you can google for lots mo

http://www.theiet.org/publishing/wir...s.cfm?type=pdf

S

On Fri, 06 Aug 2010 22:29:15 +0100, Peter Parry
wrote:

With the exception of the kitchen where the nuisance alarm rate would
be far too high with an optical or ionisation detector all a rate of
temperature rise sensor in any other room will do is wake you just in
time to for you to die.

I think some may not be as sophisticated as alarming based on the rate
of increase of temperature. Kidde told me there models alarm at 56C,
implying the rate at which it gets to 56 degrees doesn't make any
difference on their models.

In a kitchen, with few flammable items, very useful. Put on the
ceiling above the hob they will give you warning of a pan fire quickly
enough so that you can respond.

So does it need to be as close to the hob as possible then? I'm
thinking by the time it gets 56C at the other side of the kitchen it
might be too late?

If your lounge is ablaze it is too late - it isn't fire that kills but
smoke. You need an ionisation detector to alarm at the first whiff of
the products of combustion - you can't afford to wait for the fire to
develop.

The pdf I read was he
http://www.aico.co.uk/downloads/smoke_q&a.pdf

Page 5, question 12 (continued) talks about fitting heat alarm with a
smoke detector in the lounge. I can't understand why (except to
generate more sales!)

Would you bother putting heat detectors in the garage and loft?

Loft - no unless you had a boiler up there.

I wondered whether to have a heat alarm in the loft since nothing else
is suitable. Hopefully the upstairs light radial will never get hot
enough to start a fire! Other than that there is only the tv amplifier
up there but the problem with loft wiring is it is out of sight, out
of mind. OTOH by the time the loft gets to 56C I imagine everything
that can catch fire is already alight?
BTW it is an unconverted loft, used only for storage, so plenty of
flammable cardboard boxes.

On Fri, 6 Aug 2010 23:12:41 +0100, "ARWadsworth"
wrote:

I see your email address is not valid. Mine is, so if you email me via
hotmail or some other temporary address I will send you the BS5839-6-2004
"Fire detection and fire alarm systems for buildings" pdf if you fancy a
read. The offer applies to anyone not just the OP.

Thanks that is very kind. I will be in touch.

On Fri, 06 Aug 2010 22:29:15 +0100, Peter Parry
wrote:

The single most important location for a smoke detector is the ceiling
above the stair well, usually the landing ceiling. That will alarm
first in most fires (even before one in the room the fire starts in if
the doors are usually left open as most are.

I thought this was a very good point worth emphasizing. I hadn't
appreciated that the smoke might "float" along the ceiling and up the
stairs before triggering the alarm in the same room as the fire. Does
all smoke rise? Is there none heavier than air that crawls along the
floor?

On Sat, 07 Aug 2010 11:40:09 +0100, Fred
wrote:

On Fri, 06 Aug 2010 22:29:15 +0100, Peter Parry
wrote:

With the exception of the kitchen where the nuisance alarm rate would
be far too high with an optical or ionisation detector all a rate of
temperature rise sensor in any other room will do is wake you just in
time to for you to die.

I think some may not be as sophisticated as alarming based on the rate
of increase of temperature. Kidde told me there models alarm at 56C,
implying the rate at which it gets to 56 degrees doesn't make any
difference on their models.

Same goes for fixed trigger point alarms. By the time the ceiling in
the living room is at 58C your chances of survival if you are in bed
are very poor.

In a kitchen, with few flammable items, very useful. Put on the
ceiling above the hob they will give you warning of a pan fire quickly
enough so that you can respond.

So does it need to be as close to the hob as possible then? I'm
thinking by the time it gets 56C at the other side of the kitchen it
might be too late?

Correct, the role of the alarms differs. "Products of combustion"
(ionisation and optical) alarms are designed to detect a fire before
it becomes established. They should detect smoldering material for
example. Fixed temperature alarms detect established flames. In a
kitchen you need to identify where a fire is most likely to start -
usually the hob, sometimes the oven, and put the alarm on the ceiling
fairly close to those areas so any hot gasses from the fire go over
it. At least a foot out from the wall and above the risk area is
where you want them to be.

If your lounge is ablaze it is too late - it isn't fire that kills but
smoke. You need an ionisation detector to alarm at the first whiff of
the products of combustion - you can't afford to wait for the fire to
develop.

The pdf I read was he
http://www.aico.co.uk/downloads/smoke_q&a.pdf

Page 5, question 12 (continued) talks about fitting heat alarm with a
smoke detector in the lounge. I can't understand why (except to
generate more sales!)

Neither do I. There is a huge problem with BS5839 however. While it
merrily sprinkles alarms throughout a house it ignores the effects of
nuisance alarms ( a nuisance alarm isn't a false alarm but an
insignificant one. A piece of toast overcooking for example).

The more sensors you have the more prone to nuisance alarms the system
as a whole becomes and the more likely it is that people will disable
them. Too many sensors can be more harmful than too few.

Would you bother putting heat detectors in the garage and loft?

Loft - no unless you had a boiler up there.

I wondered whether to have a heat alarm in the loft since nothing else
is suitable. Hopefully the upstairs light radial will never get hot
enough to start a fire! Other than that there is only the tv amplifier
up there but the problem with loft wiring is it is out of sight, out
of mind. OTOH by the time the loft gets to 56C I imagine everything
that can catch fire is already alight?
BTW it is an unconverted loft, used only for storage, so plenty of
flammable cardboard boxes.

The chances of a fire starting in a loft are very small. It probably
won't hurt to put one there but it isn't going to make the house
safer.

On Sat, 07 Aug 2010 11:42:22 +0100, Fred
wrote:

On Fri, 06 Aug 2010 22:29:15 +0100, Peter Parry
wrote:

The single most important location for a smoke detector is the ceiling
above the stair well, usually the landing ceiling. That will alarm
first in most fires (even before one in the room the fire starts in if
the doors are usually left open as most are.

I thought this was a very good point worth emphasizing. I hadn't
appreciated that the smoke might "float" along the ceiling and up the
stairs before triggering the alarm in the same room as the fire. Does
all smoke rise? Is there none heavier than air that crawls along the
floor?

Smoke doesn't but the invisible gasses produced in combustion do. In
almost all house fires the ceiling alarm above the stair well triggers
first as the stream of combustion gasses rises and spreads.

Once you have one alarm in the downstairs hall (near the living room
not the kitchen) and one on the upstairs landing ceiling you have got
about 95% effectiveness. A temperature alarm in the kitchen above the
cooking area would be the next priority. Personally I'd stop there.
If you have any very heavy sleepers, people who use sleeping pills or
who use sound muffling ear inserts to sleep then consider putting a
linked alarm in their room. It isn't to detect fire - just to make
more noise where it is needed when another alarm goes off.

Don't forget that all these alarms are useless unless you also know
what you are going to do when they go off at 03:00. You have a minute
or so to get out so this is not a good time to start thinking about
your escape plan. In particular make sure all exit doors have locks
that can be opened from the inside without needing keys. If they
can't and you won't replace them (fires kill far more than burglars)
then make sure a key is permanently wired to the handle so it can't be
dropped.

If you have double glazing in bedroom windows get a few automatic nail
punches such as

http://www.rapidonline.com/1/1/3816-...tre-punch.html

and clip them near the windows. Pressing one onto a double glazed
pane near a corner will break it, throwing chairs and bedroom
furniture at it won't..

Having got your plan make sure everyone knows what it is :-).

Spamlet wrote:
"ARWadsworth" wrote in message
news:uN%6o.57860$zT3.55338@hurricane...
Fred wrote:

Good grief its £196!

Well it obviously is not £196 from some places;-)

--
Adam

On Sat, 07 Aug 2010 15:54:06 +0100, Peter Parry
wrote:

At least a foot out from the wall and above the risk area is
where you want them to be.

Sorry for the late reply. Thanks for all the informative replies.

The heat alarm in the kitchen is a metre or so away from the hob, so
when the kitchen gets redecorated, I will try and move it across.

The more sensors you have the more prone to nuisance alarms the system
as a whole becomes and the more likely it is that people will disable
them. Too many sensors can be more harmful than too few.

I know what you mean. I had some optical alarms that would go off at 3
in the morning. Never found out why. I blamed insects. Can spiders get
in or is the sensor too small? Perhaps we have a very dusty house! In
the end I replaced them with ionization ones.

The chances of a fire starting in a loft are very small. It probably
won't hurt to put one there but it isn't going to make the house
safer.

I don't know whether I'll put one in the loft or not. OTOH you don't
go up there much so you wouldn't see or smell any warning signs but I
do wonder if by the time a heat alarm had been activated whether the
loft would have burnt down.

Thanks again.

On 26/08/2010 13:45, Fred wrote:

I know what you mean. I had some optical alarms that would go off at 3
in the morning. Never found out why. I blamed insects. Can spiders get
in or is the sensor too small? Perhaps we have a very dusty house! In
the end I replaced them with ionization ones.

When I had the part time job as school site supervisor, I came to unlock
and take the alarm off once, and there was an alarm activation sheet
next to the door. They had to call out the alarm Co, who found that
alarm had been triggered by a spider that had got inside the infra red
heat sensor. When you think about it, the spider would have changed the
heat reflection as it crawled over it, or the window the sensor looked
out of it.

Dave