CO detector

[Terry Pinnell]

British Gas sold me one of those battery-operated carbon monoxide alarms a couple of years ago. Battery is apparently not due for replacement until 2012. But can someone please remind me:

1) What the Test button should do? Here it just illuminates a green 'Power' LED, but I'm wondering if it should also sound the alarm (as is the case with smoke detectors)? The instructions on the back merely say 'Use the Test button to check that the unit is working correctly'

- which is not very helpful!

2) How I could test it in practice? IOW, what is a safe temporary source of CO that should trigger it? I tried both an unlit gas ring and the boiler vent outside the kitchen, but neither triggered it. I suppose a predictable source would be the exhaust from my car?

[Stuart B]

This article mentions the test button only testing the circuitry and not the detector but also refers to an aerosol kit which is used to test the alarm detector.

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[Stuart B]

Oops Forgot the sales link

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[Peter Scott]

I think you'll find that its the device that must be replaced not the battery. Mine has a five-year life, then it's into the bin.

But can someone please remind me:

Should make the alarm noise. If you misunderstood the life expectancy praps the batteries are dead? Mind you it should have sounded to show low battery.

Or breath from a smoker???

Peter Scott

[dtechy]

press and hold the button until it should sound, if not contact BG for sdvice

[Al]

Unlikely. More likely the sensor will be fscked by 2012. The batteries will be long gone I suspect.

I cannot imagine any situation where an "alarm test" function would not actually test the "alarm".

ROFL.

Just buy a new one.

But, if you feel like *really* testing it, sit in your car in a closed garage, hosepipe from exhaust to partially open window, start engine and wait. SO much easier than phoning BG, buying a battery or buying a new alarm.

;-)

Al.

[Ed Sirett]

I would expect that presing and holding the test button should make it sound. If not it's defunct.

Unlit [natural] gas does not contain any significant amount of CO. The CO from a boiler in good order is also unlikely to trigger the alarm. A vehicle exhaust should trigger the unit.

The alarms are not a substitute for proper installation and servicing and have little benefit except with open flues appliances or jut maybe with flueless appliances.

[Terry Pinnell]

Ed, Peter: Thanks, both. I'll try it alongside my car exhaust tomorrow, and if that doesn't trigger the alarm I'll call British Gas.

[Huge]

If your car has a catalyst, it likely won't trigger the alarm. The CO is oxidised to CO2.

[Andrew Gabriel]

Yes, that's thrawted many a suicide attempt in the last decade.

In the interest of science, and at the cost of a slice of bread from my just baked loaf, I decided to test something I recall hearing many years ago (probably when I was at school), that a toaster gives off CO.

Turned timer up to max so it doesn't stop until I want it to, and start the toasting. No CO at all initially. Eventually smoke starts coming out, and then the CO slowly starts climbing. However, even with quite a bit of smoking, we're only up to

10ppm, and I doubt that's high enough to trigger a CO alarm. Measurement done with a calibrated flue gas analyser.

Note that some CO sensor elements used in home detectors are easily permanently poisoned by other contaminents, such as household cleaners, etc. Blasting such a sensor with various things to see if you can make it trigger may actually go some way to wrecking it, and this is also why they only have a limited life.

[dennis]

You could have got it higher by restricting the air flow. However it would probably catch fire or trip a thermal cut out.

[John Stumbles]

Are these de rigeur for Keston owners then? ;-)

[Dave Plowman (News)]

An older car probably would since they can be 5% CO plus. Newer ones with cats produce less CO than the existing concentration in many areas.

[Andrew Gabriel]

That was my original reason for buying it. There are about about 8 gas appliances I maintain in the family, and it's useful for them all, although if I work out the cost per check in terms of the purchase and calibration charges, it's probably £20/check.