Fire Detection

[Sparks]

Hi,

I have a Menvier TS2500 alarm panel.

It supports fire detection zones, but I can only find 24v detectors. Are there 12v smoke and heat detectors available? or do I need to install a separate 24v power supply?

For the kitchen, should I install a rate of rise heat detector, or a fixed one?

Do I install a detector in the loft - if so, what type would be the best bet (It's all boarded, so not particularly dusty - it is a converted bungalow, so the loft space is quite limited, and hoes all around the two rooms up there, so I would guess I would need 4-5 detectors if that is worth doing.

Is it best to have a detector in every room, or just the bedrooms and hall? I guess I wouldn't put one in the bathroom as it is humid, and there isn't that much chance of a fire in there anyway.

We currently have 2 battery operated standalone smoke alarms in the house, one at the top of the stairs, and one in the hall near the kitchen as these are pretty old, I was going to replace them anyway, so I though it would be a good idea to just use the alarm panel to do everything. I set a normal PIR up as a fire zone, and when it was triggered, the internal sounder made a different noise to a normal alarm noise, and it pulses the external sounders all with the system unset - so this looks like it works to me! (I have loads of spare AUX outputs too, so I can wire in additional fire only sounders if required)

Do I need to use Firetuf cables for the fire detectors, sounders & power feed to panel? If I need to use it for the power feed, should I take it all the way back to the CU (I currently have a radial that serves the Fridge, freezer and alarm)

Thanks for any pointers!

Sparks...

[brian]

Its an American site but it may help

and by using Google I found 12 v detectors at must be more where they came from. Brian H

[Andrew Gabriel]

Don't know if a 12V panel would support 24V detectors with separate PSU -- it might not. Most fire detectors are 24V, but (unsurprisingly) Menvier do make 12V ones, and ISTR that CPC stock them (I've got one of their optical ones).

CPC also do a PP3-sized circuit board which you can fit into PP3 battery powered smoke detectors to run them from a 12V burglar alarm system. However, do check it works in your particular smoke detector -- I found they don't work in all EI ones which are a common make. Test with smoke or smoke detector spray, not the test button (which does work).

Note that if you require this alarm for regulatory reasons, you must use the accessories which are designed to work with it to meet the relevant British Standards.

I asked this about 5 years ago. Answer was rate of rise heat detector in kitchen and fixed one in the loft, but I don't recall the reasoning.

Usually just one at about 12" below the apex.

Top of stairs is the most important position, followed by bedrooms of any smokers.

My burglar alarm does this too. The fire sequence is a repeating pattern of 3 blasts with the 4th blast missing. I believe this is a standard fire signal in the US.

In which case, the fire detection system presumably depends on you programming the panel correctly?

Probably depends on what regulations you are trying to meet, but fire alarms in houses are not normally connected with Firetuf.

Sounds fine to me, but I'm horribly out of date on current fire alarm regs.

[David Hansen]

On Mon, 3 Apr 2006 18:39:37 +0100 someone who may be "Sparks" wrote this:-

It is best to have them in every occupied room and the hallways. Whether it is worthwhile depends on your views on the amount of work you want to do, assuming there are no unusual legal requirements on the house.

Pyro (Mineral Insulated, MICC) is the cable to use if you are serious about the fire alarm functions. Get the tools to make the joints and practice if you have not made them before. Personally I wouldn't go for anything else, but I'm old fashioned.

is a good guide to the various options for cabling, should you not wish to go for the best.

Not really, though it can look better to have the same sort of cable as the feed. The panel should have a battery that will keep the whole system going for some time.

[Owain]

You may not need a detector in the bathroom but can you hear the sounders above the noise of the shower running?

Until recently, you didn't need fire-protected cable for the detectors as those circuits should be fault-monitored to fail-safe. However, I think this has now changed. You would need fire-protected cable for the sounders and power feed.

Are your fire-only sounders on fault-monitored fail-safe circuits?

For power feed, a proper fire alarm system would require a dedicated circuit in red cable to the main CU (or better, a separate CU). The battery back-up in most intruder alarm panels may also be insufficient for a fire alarm system.

However, unless your intruder alarm panel is approved to the fire alarm BS, the system won't comply with fire alarm BS anyway. A few mains-powered interlinked smoke detectors would probably be a far easier way of getting a system that complied with the requirements for domestic property, and some emergency lighting on the escape route a good investment also.

Owain

[Sparks]

Ah, thanks, found a smoke one on page 1688, I will ask them if they can get the heat ones.

The current detectors are more than 15 years old, so I think they are in need of replacement now! I guess these boards just power the detectors? I want somthing linked to the alarm - It has an SD1+ Speech dialler on it, so I will connect a second input to this so it can call me and tell me the house is burning :-)

No, just peace of mind really, but would like to do a proper job.

I can't do that, as there are two rooms up there, the loft space is ablout 1 meter wide, all around the perimiter (with a door to if from both rooms)

No smokers here!

Probably the same here then, i didn't let it ring that long.

Yes, I should be able to do this, I have all the manuals, and I installed it anyway!

Okay.

Thanks for the reply!

[Peter Parry]

One at the top of the stairs will do 99% of the work. The others tend mainly to contribute to the false alarm rate. (I'm assuming this is a normal bungalow and not multiple occupancy).

There is a balance between having lots of alarms (and lots of false alarms which means people either ignore the thing or disable it) and having too few detectors. For a normal family house the most important detector is the one at the top of the stairs as it will detect fires downstairs earlier than a hall detector and will also detect upstairs fires.

You won't gain much by fitting lots more sensors.

No, if we are talking about a family house/bungalow by the time the cable is burned you are long dead. Don't forget the smoke and fumes kill long before the fire does.

[Christian McArdle]

The problem is that a panel type installation will require special cabling and fire protection to meet building regulations. This is hard to achieve.

What I've done in my house is install mains linked battery backed smoke detectors (Kidde Fyrnetics). I've then bought an auxilliary relay for it which is connected to the alarm panel. This way, conventional cabling can be used, and you have plenty of sounders with battery backup, whilst still getting all the features of the alarm panel (differential sound indication, external sounder, autodialer).

Well, every room is best. However, the really essential ones are in the hall, particularly at the top of the stairs. Put one on every floor. Any additional ones are at your discretion. However, if you are a really heavy sleeper, then one in the master bedroom would be indicated, more for its sounder than its detection capability.

Either is fine, AIUI. Just avoid any ionsiation or opticals.

Christian.

[Owain]

On self-contained systems it's also the sounder that's responsible for waking people.

No point in having any detectors unless the sounders can result in instant wakefulness.

Owain

[Andrew Gabriel]

Life is normally quoted as 10 years. I have a couple which are older and still work, but you must test them with smoke or smoke detector test spray, and not just the test button.

No, they have a relay to connect up to the alarm. They work my monitoring the current draw -- very significantly higher when the sounder is operating. Mine have a change-over relay and a jumper to select momentary or latched operation. You need a panel which can interrupt the power to the smokes to reset them if you choose latched operation. (Although mine can, I stuck with momentary operation so I can tell if/when smoke clears.)

However, a colleague bought some more recently and they were a different make without the jumper and I think just a single relay contact.