On 15/02/2013 17:07, Dave Plowman (News) wrote:
In article ,
Nightjar wrote:
Many won't take on one installed by another security company, let alone
a DIY set-up. It is also of an age when detectors may start to fail,
which they won't want to risk.

Eh? I've not had to replace a PIR sensor at all on this home installed
system which is more like 15 years old. What fails in them?

BIIK I just know that when I had industrial units with professionally
installed systems, we started getting failures in a very small number of
sensors at around five years old. It may be relevant that they were
combined PIR and microwave sensors, rather than simple PIRs.

Colin Bignell