Interlinked smoke alarms - wireless or wired? Recommendations?

Wired, rechargeable lithium battery backup, remote test/locate/hush switch, interlink with CO detectors, AICO.

Owain

As Mr Parry said in that thread:

"The ability to communicate successfully using any wireless system is

inversely proportional to the need to do so"

Does that answer your question?

Which is what we have but as far as I know the batteries are 10 year life lithiums not rechargeables. It also links with relay modules to release, say magnetic door catches, when the alarm is triggered.

I re-did my system a few years ago like that and I heartily endorse these words.

Bill

Years ago when kids lived at home and cash was short I tried wireless alarms perhaps from Wickes. They were hopeless. I will confess to not having wired ones now, but I have plenty and they are loud enough to carry almost right through the house. A mixture of 10 year lithiums and ordinary PP3 types.

The AICO RF range is working well on all the jobs I have done. I have done over 50 installs of them. I prefer hard wired but it's not always practicable to do that.

"10 year rechargeable lithium cell back-up" are common - though they only come with a 5 year guarantee and the battery is "not replaceable".

Anyone had one long enough to explore how "not replaceable" they are?

I've found that on one batch of smoke alarms the lithium batteries lasted less 5 years. The battery compartment was made tamper proof with a melted plastic rivet holding on a cover - which was easily drilled out. The lithium battery was a standard PP3 configuration which I replaced with a 9V alkaline battery.

I have since replaced all my older smoke alarms.

I have friends in rented accommodation with interlinked smoke/CO alarms. My recommendation is to teach everyone in the household how to silence the alarms as having to perform that task for the first time that they all go off can be a deafening experience!

AIUI and especially for CO alarms, the reason for making the batteries non-replaceable is because the sensor also only has a limited life, which happens to coincide approximately with that of the battery. So you shouldn't really be using such an alarm after the battery has died, because the sensor's died as well, but that's not so obvious.

False alarms are usually down to incorrect sensor type selection and/or incorrect siting of the detectors themselves.

I have 16 interlinked detectors comprising of several different sensor types, ionisation, optical and rate of temperature rise and CO sensors.

In the 7 years since installation, there has never been a false alarm due to cooking, toasters,running a wood burner, steam from bathrooms/showers etc.

The times it did go off were due to:

A CFL lamp burning itself out before finally failing and hot work involving the soldering of copper pipes....

S.

IME smoke alarms have a sensor life of 10 years. I think that's why they advertise them as "10 year life" batteries.

Thanks. But may I just check if that was a /rechargeable/ lithium battery?

I'd have to find the destructions but I think ours have a "ten year guarantee" and isn't "replaceable".

Useful, ours still have few years left before they should be dumped and replaced. Seems a waste for the sake of a lithium PP3 but what is the half life of Americium 241? Ah, 432 years so sensitivity won't be greatly affected.

Think I'd tell others to use the "Locate" rather than "Silence" switch. May even mark it with a big arrow or "This One" and an arrow.

"Mains powered with ten year rechargeable lithium back-up"

previously Grade D was just a mains powered alarm with a battery back-up, we now have D1 ? a mains powered alarm with an integral tamper proof battery back-up and D2 ? a mains powered alarm with a replaceable battery backup. Whereas F was previously a battery only alarm, we now have F1 ? an alarm with a tamper proof battery power supply and F2 an alarm with a user-replaceable battery power source.

Owain

Re-read the quote.

Of course they'll all work fine for testing, there is "no need" for the RF bit to work. That changes to "must work" in the event of a fire...

Will the furthest away (acoustically) from your bedroom wake you up when none of the others sound as well?

On my system, I have relay boxes on one of the CO alarms ( all interlinked) and another relay box on the smoke/heat detectors ( also interlinked).

The relay boxes are wired into two 24 hour zones on my alarm panel. The alarm panel can also send text messages so I get a text on my mobile phone if there is a CO or heat/smoke event.

I think it's the CO sensor that has a limited life, not the smoke sensor.

Yes, they are the ones I had in mind (and which come with a *5* year (limited) warranty). But I wasn't clear if alan_m had had one of those rather than one of alarms with a "10 Year Lithium Battery" which isn't rechargeable (and some of which do come with a 10 year warranty). Eg

CO sensors are certainly "time limited" not so sure about ionization based smoke detectors on that time scale.

Yes the Americium 241 will be less active after 10 years but with a half-life of 432 years is that really significant?

One of the big problems with CO is that it's so insidious. It's not quite like the single "get out" alert that a smoke detector gives. The CO alarm we have has three if not four "alarm" states varying from a couple of silent warning "there is some CO about, you ought to do something" and "there is more CO about, you REALLY ought to do something" to a sounding "there is too much CO about to be good for you" and "you're dead". Indicated by various coloured flashing/steady LEDs and intermitent/constant sounds, I think, it's far to complicated to remember...