Kidde interlinked smoke alarms

[ianp5852]

Hello All, I have a mains powered - with 10-year lithium backup - interlinked fire alarm system comprising of 3 off Optical Smoke alarms and 1 off Heat alarm (for the kitchen) I changed the 2 Ionisation alarms to optical on the advice of Kidde - about 3 years ago after sporadic alarms occurred (usually in the early hours of the morning) when there was no cooking/ironing/smoking or anything triggering them. At this time the units were all about 3 years old. Kidde did not accept the units were faulty in any way but did replace FOC.

Now, here I am a further 3 years on and one of the 'new' optical alarms has started the same game. I have been able to determine which unit is at fault (this time the alarm continues for a period of 20 to

90 seconds giving time to run around and see which one has triggered) and have removed and disabled this unit. NB There have been no false alarms during this 3 year period from toasting/cooking/ or from the mysterious cause until 2 weeks ago and then had 3 alarms in this last 2 weeks

Does anyone else have this problem?

Should I expect the unit to need replacing at 3 yearly intervals? Each alarm costs around £40 so this gets a fairly expensive hobby (OK, I know its not much compared to saving your life but.....)

Has anyone any recommendations for similar function units from other brands that have proved more reliable?

TIA Please reply to group - email address is not monitored Ian

[Mr Pounder]

Get advice from a small local independent fire alarm company. Kidde are gangsters, always have been and always will be.

[Bob Eager]

We have six interlinked alarms. One heat rise, two optical and three ionisation (I think). They've been installed since 2005, and are all still going strong (actually, bar one which did keep triggering, at about the 4 year mark).

They fit a bayonet-style pattress so it's a 2 minute job to change them. They all use a PP3-style battery as backup.

Oh, Firex!

[Peter Parry]

That is rather odd advice, is the building two storey and where are the alarms located?

Ionisation tends to give earlier warning of the most dangerous night time slow start fires which emit no smoke in the early stages so are usually preferred over optical for a sole alarm.

Spiders or other small insects setting up home inside them are a common cause of optical alarms going off sporadically. This tends to occur at this time of the year. Use a can of compressed gas (dust-off or similar) to clean them out.

Batteries are temperature sensitive so when they start to fail they will usually trigger the low battery (but usually not a full alarm) early in the morning when the temperature is at its lowest. I wouldn't expect that to be a problem at the moment unless nighttime indoor temperatures where you are have been quite low. I assume the interlink is by wire and not radio?

It isn't uncommon, having too many smoke detectors can be as dangerous as having none - people get fed up with nuisance alarms and disable them or ignore them. With one heat alarm over the cooker and one ionisation alarms at the head of the stairs you have pretty good cover. Bedroom sounders may be required if anyone in the house is hard of hearing or habitually uses medication to help them sleep.

There are a lot cheaper units around for example

The Lithium battery isn't really required in owner occupied premises. Alkaline will be just as good if you change the battery every year or when it reminds you every couple of years by starting to beep (at

3AM!) .

[ARWadsworth]

BS5839-6 2004 recommends optical smoke alarms in circulation spaces such as hallways and landings.

Optical smoke alarms are more sensitive to smouldering fires than fast buring fires and when used in a circulation space such as a hallway or landing may give better protection than ionisation detectors if the fire is some distance away.

[js.b1]

Aico EI units are reliable, 9V alkaline duracell lasts nearly a decade, 10yr or so life. A few online suppliers replace Kidde CO & Smoke alarms with EI units.

[Bob Eager]

Yes, I fitted optical in hallway and on upstairs landing (latter is L shaped and long so I have one at the stairs end and one at the other end).

Ionisation in living room (two, because there's a deep beam down the middle).

Heat rise in kitchen.

[ARWadsworth]

I would go for fixed temperature detector in a kitchen.

[dom]

Hijacking the OP's post a bit - because there seems to be a lot of good advice available...

My building is open-plan with a woodburner in the main space. It will emit a little bit of smoke into the room occasionally if the wind is in a particular direction (or more frequently when starting, with an unfavourable wind).

What smoke detectors would be recommended?

[Peter Parry]

There isn't a simple answer as you need to start from where the greatest risk is. That isn't necessarily the wood burning stove if half the family smoke! Is the building one of more storeys? Are sleeping areas compartmentalised (have doors) Are you talking about a domestic house or something else?

As a start a heat (rate of rise) sensor fitted on the ceiling above the area of the wood burning stove would be advisable as that is one obvious area where an ember might escape, perhaps while topping it up, and ignite something nearby. Don't forget the same for the other major risk area of the kitchen.

Usually the next priority would be (in a two storey house) the ceiling above the stairs void. If your open plan has a single large central void with bedrooms off it you need to look at how air circulates. Smoke matches and pellets are easily available (eg

and produce a lot of smoke (too much really, you only want enough to follow air currents to the smoke match is preferable to the pellet). Read the instructions and evict the family and cat before using. See how the smoke spreads from possible sources of ignition so stove area, cooking area, washing area if you have a separate utility room. You will find it will tend to follow predictable routes. Depending upon your roof ventilation the top of the roof may not be the best place - sometimes it forms a void of still air and the smoke stays underneath. Having found where the smoke goes get a cheap battery operated ionisation alarm and try it in that place to see if you get nuisance alarms. If you get none go with an ionisation detector, if only a few an optical sensor may work reliably - if you get a lot it won't and you will need to rethink things.

Nuisance alarms are not false alarms - they are real alarms caused by combustion products, but not by anything particularly risky - so burning toast etc. The problem with them is that after a few people get fed up and disable the alarm. That's fine if the next cause is burnt toast, but not so wise if the next cause is the pan of oil someone put on the stove and forgot which is now blazing away. Hence too many alarms can be as bad as too few and minimising the level of nuisance alarms is very important.

[Andrew Gabriel]

I had a Kidde optical battery alarm go off at 4am. There was no one there at the time, but no sign of any fire on returning, and none of the other 3 alarms (all ionising) detected anything. It stopped after 35 seconds.

Although they are bog standard battery alarms, they are actually all linked back to an alarm panel, so I have a precise record of what happened. Never found the cause though. It was about 6 weeks after testing them all with smoke detector test spray (which reminds me, I haven't done that for over a year now).

No.

Expected life is normally about 10 years, and that's mostly about limiting dust build up in parts you can't clean. In a more dusty location, maybe you should change more often.

[dennis]

Been there, but the alarm went off before it caught fire. That was in the early days when alarms were expensive (about 20-25 years ago) and they were worth it then and are well worth the few quid they cost now.

IMO its best to remove the sources of the alarms not the alarms. If the alarm goes off then its in a good position and smoke is getting there. (I dumped the gas fish fryer and bought an electric one.)

[ianp5852]

The house is a pair of 2 storey cottages knocked together. There is one downstairs hallway across most of the length of the back of the house - a major thoroughfare. There are two stairwells/landings with bedrooms off. I would also consider these as thoroughfares. As did Kidde...hence the advice to have optical in these 3 locations (hallway and each landing). I felt having further (ionisation) alarms in the reception and bed rooms a little overkill.

I read that as well but also read conflicting advice. I went for ionisation on the 2 landings until discussing with Kidde after he isuse with false alarms 3 years ago

Now this is very good information. I had considered this as a possibility but I do vacuum them out every couple of months and remove them and give a good shake every 6 months. The offending unit is the one in the landing of the (considerably) lesser used stairway. The unit had been cleaned a few days before the early morning alarm. I note some possible replacements units in the TLC catalogue seem to make a marketing point of 'including a fly screen' This might be the way forward methinks

.....And shouldn't be a problem as mine are mains supplied. The interlink is wire.

Totally agree about point 1. SWMBO and I decided we'd rather fry than be woken up regularly in the early hours

Many thanks for all the constructive advice Please reply to group - email address is not monitored Ian

[dom]

Thanks for the advice, much appreciated!

To go into more detail:

2 storeys, old chapel converted to domestic use. All 4 bedrooms have doors, 2 upper floor, 2 lower floor - all open into the open plan area (and have means of escape windows as well).

There's a modern oil-fired Rayburn in the kitchen (ground floor, with doors) - which also has heat-sensitive cut-off valves for the oil

The upper floor smoke detector wiring is already behind plasterboard, consists of single point outside the bedrooms, above one door - and within 1.5m of the other door - also well exposed to the main space with the woodburner.

The lower floor wiring could still easily be changed, and consists of two points just inside and above the kitchen door (where I had planned to fit a heat detector and a CO detector), - and one point under a landing which is a natural catchpoint for smoke from the woodburner.

Another point the OP has drawn attention to - is placing them at a height to make them accessible for cleaning - which is a particular issue here.

Is it likely to be an effective solution (I would have to read up if it meets regs) to have smoke detectors in each bedroom, and only a heat detector in the main space with the woodburner?

I've just had a look at the cable routings, and changing to the above plan wouldn't actually be too difficult.

Finally, what are the relative merits of rising-rate and fixed-point heat detectors?

[David Robinson]

I had very strange symptoms with my Kidde alarms, and found it was due to the neutral not making contact at one of the (interlinked) alarms.

All alarms still worked, and the nuisance beeping was neither a normal "alarm", nor a low battery warning, nor localised (or even always present!) at the poorly wired alarm.

Cheers, David.

[Peter Parry]

I'd certainly put a heat detector above that.

The upper floor detectors are far more important than lower floor ones, especially with a large void.

I'd put a heat detector above the stove (not by the door). I'm not sure why you want a CO alarm. Under the landing may be the location which would produce nuisance alarms so try that with a battery unit first.

Yes - and they don't work well mounted on walls, you get a barrier layer and smoke rises a few inches out from the wall.

Smoke detectors in bedrooms are only really useful if you have someone who smokes in bed. If the door is closed it will alarm far too late on a fire outside the room. (The other use for an interlinked alarm inside a bedroom is simply to extend the alarm to wake people up - it will never trigger on its own detector)

Rising rate detect a fire a bit earlier on, they look for quite a fast rise over a short time, typically about 10deg C a min. They don't care what the absolute temperature is. They are good at detecting things like chip pan fires or oil boiler fires.

Point detectors require a trip temperature to be reached. Usually about 60-70 deg C. Point would usually be used in places like boiler rooms which can have fast temperature variations in normal operation. They are also appropriate in kitchens where there are high rates of change of temperature (a cooker near a back door for example where the door opening and closing can produce fast changes in temperature).

[Roger]

In message , [e-mail] writes

I assume these are the smart 2SF23/9HIR series. If so, your problem is well known to Kidde - who are a very reputable company btw. Ask them to replace them with their less attractive-looking Firex models

- it is understood that these do not suffer from the problem you report.