jimmylawman Registered User

Smoke alarm went off last night repeatedly. On (increasingly irritable) investigations, not a fire in sight.

It did coincide with the coldest night of the winter so far. I believe temps hit -12 here in the early hours.

Some online research suggests this can happen -

Smoke detectors go off between 2am-6am because the ambient temperature drops considerably then. This causes the battery voltage to drop below the smoke detector’s low voltage warning level and bingo, off she goes!!!

It is worse in winter of course. Houses are nice and cosy when the heater is on but when everyone is off to bed and the heater has been turned off, the temperature drop is exacerbated. As with all batteries, especially car batteries, cold winter weather usually sorts them out. Hence, lots of battery warnings will occur during winter.


Question: Why does the alarm go off during cold weather?

Answer: The unit may go into alarm only when it is very cold out or if a door adjacent to a heated area is opened, such as in an entry way. This is due to condensation (water vapor) in the detection chamber. The sensor is a particle-sensing device and when water condenses in the sensor, the unit will go into alarm. The operating temperature on FireX smoke alarms is between 40 and 100 degrees Fahrenheit (4 - 38 degrees Celsius). If the unit is in a garage or attic, you may consider replacing it with a heat alarm which is not effected by condensation.

Has anyone else experienced or heard of this?


Green Hornet Registered User

Bingo! Same here. The last three or four nights it's been beeping randomly from about 3 in the morning. Driving me crazy.

Thought it was the battery origianally but looks like it's the temperature alright. It stops around 9 in the morning again.

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