DIYbanter - View Single Post - Alarm question - PIRs, window contacts or optical boundary?

Bill Wright[_3_]

On 27/09/2017 14:57, wrote:
When I re-furb'ed my last house I fitted window switches to all
accessible windows and external doors, so didn't need to bother with
PIRs. The current house already has a "professionally installed" alarm
with PIRs and door contacts, but no window contacts.
I was going to replace the PIRs with (a large quantity of) window
switches but am having second thoughts because of the unsightly wiring.

SWMBO is concerned about staying with the PIRs because, if we set the
downstairs ones at night, of what happens if someone goes down for a
drink or a wander around in the night. How does everyone else cope with
this?

I'm wondering whether it's viable to set-up an external boundary around
the house using infra red or laser beams/detectors (above animal
height). Has anyone used this technique?

Personally I'd forget window contacts. They do false alarm if there's a
gust of wind or a bird hits one. The actual units (Vipers etc) are prone
to damp. The wiring is very labour intensive unless it's done at first
fix stage in a new building. It is possible to make it invisible but
it's hard work.

PIRs are generally OK as long as they are wired (not wireless) and are
dual tech (microwave as well as IR).

I have external beams to protect the parking area. They're pretty good
for that purpose, but not for protecting the house when you aren't there
because of perfectly innocent callers (unless they send a silent alarm
to your phone and/or run the CCTV). The type with two independent
parallel beams are best.

With all alarms remember that one false alarm means that everyone within
earshot will ignore your alarm for the next ten years.

Bill