[HH] CO detectors self-destruct

[Federico Lucifredi]

Hi Tom,

>> Since my detectors were warranted for 5 years, the self-destruct timer
>> was set for 6 years.
> 
> Ideally, you'd like the two time-spans to match.

Actually, it is more complicated. See below.

> I see today the base price has dropped to $34, and the coupon is still
> there for further discount, which seems quite good. Now the problem is
> if I get a few more, I'll end up like Greg having all units from the
> same vendor expiring at the same time. I suppose I could always delay
> activating subsequent units by a month.

I do not believe this will work. My working theory is that the sensors have a known (but not covered by warranty) lifespan that is longer than what First Alert advertises. For example, the first set I had in my home were warranted 7 years, but lasted 8 before the annoy-a-tron triggered and forced me to replace all units.

Why is this? Why not warranting a unit for its known lifespan? I believe it is due to the fact that smoke detectors are installed by builders originally as much as by home owners as replacements. This leads to unit warehousing, and the sensor must still deliver its full warranty life to the customer once deployed. Therefore, an additional year or more is a reasonable buffer to avoid a return problem for the vendor.

This excess life span I detected in use leads me to think the sensor chemistry decays even when warehoused and not in powered use. I think the lifespan runs from the date of manufacturing, and exceed the warranty by an unknown amount (but it is at least an extra year in the case of the 7-year units).

Best-F

_________________________________________
-- "'Problem' is a bleak word for challenge" - Richard Fish
(Federico L. Lucifredi) - flucifredi at acm.org - GnuPG 0x4A73884C