In article ,
"dennis@home" writes:


"Andrew Gabriel" wrote in message
...

8

Both conservatory and garage can be liable to false triggering from
PIR sensors, due to significant sources of heat causing movement of
hot air - conservatory from the sun, and garage from a parked car
with hot exhaust/engine. In these cases, a dual tech sensor (PIR
and microwave) may be necessary, although in a conservatory, careful
adjustment of microwave power will be needed to avoid sensitivity
from outside the glass.

The PIR half wont work through the glass so it shouldn't matter.

If someone walks past outside and is picked up by the microwave
whilst there's heat movement inside, you get a false alarm.

If someone walks past outside and is picked up by the microwave
whilst there's no heat movement inside, and the dual-tech has
anti-masking (most do), it will generate a masked alarm (which
depending on model will generate either a movement or a tamper
signal), and you also get a false alarm.

On the other hand, if you set it up correctly, then it will work
well.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]