Hi

I'm trying to work out what detectors to use for my install in my selfbuild project.

I think I need to use dual-tech sensors in some areas, to reduce the chance of false alarms where there is a lot of glazing - it's inevitable that the sensors will face the glass to some degree, and the sun shines directly in during the morning.

At least two of these zones are adjacent, but open (ish) plan - IE no doors between them.

Do I need to worry about the microwave signal of the sensors interfering with each other ? Or are dual-tech sensors clever enough for this not to be an issue ?

Also - are any makes of dual-tech sensor regarded as better / more reliable than others ?

Thanks in advance.

Lee

Pyronix TMD dual-techs can be set to a tri-detector mode for much greater resistance to environmental disturbence and can be obtained in different microwave frequencies 'off the shelf' to minimise any cross-talk of the microwave elements.

It would be sensible to avoid the DT sensors to being literally back to back as I would expect some interference despite what any manufacturer might say. I have not had any issues from using Texecom Prestige or Mirage DTs in the past - however I haven't installed any too close together which I suspect is what you are planning.

The general rule is at least 1m apart and not directly facing each other.

Thanks for the replies. The sensors in question would be a good distance apart and not in sight of each other.

However I'm now wondering whether dual-techs are the right option.

My reason being - the glazed areas (4 x floor-to-ceiling french doors, that form an entire wall) that some of the sensors will face will have people walking past.

Am I right in thinking that the microwave pattern of a dual-tech will see through the glass ?

And I know they are adjustable, but in a room that's 4m x 4m in size, I'm guessing it won't be possible to reduce the sensitivity sufficiently.

After more reading round I'm wondering if the Optex FX50SQ would be the best bet - quad zone PIR, with their "Double Conductive Shielding" er, stuff - which is supposed to reduce risk of FAs from direct or reflected sunlight, headlights etc.

Cheaper too...

Does this sound a more sensible choice ?

Also, does anyone know if the Optex FX series sensors use mirrored optic or fresnel lenses ?

Many thanks for the help

Lee

Thanks for the replies. The sensors in question would be a good distance apart and not in sight of each other.

However I'm now wondering whether dual-techs are the right option.

My reason being - the glazed areas (4 x floor-to-ceiling french doors, that form an entire wall) that some of the sensors will face will have people walking past.

Am I right in thinking that the microwave pattern of a dual-tech will see through the glass ?

And I know they are adjustable, but in a room that's 4m x 4m in size, I'm guessing it won't be possible to reduce the sensitivity sufficiently.

After more reading round I'm wondering if the Optex FX50SQ would be the best bet - quad zone PIR, with their "Double Conductive Shielding" er, stuff - which is supposed to reduce risk of FAs from direct or reflected sunlight, headlights etc.

Cheaper too...

Does this sound a more sensible choice ?

Also, does anyone know if the Optex FX series sensors use mirrored optic or fresnel lenses ?

Many thanks for the help

Lee

Personally i wouldnt go with the FX50SQ but go with the Mx40pt, the detectors microwave transmitter should be shielded, so having the detectors back to back should be ok.

You are right when you say about the microwave being able to see through glass which may be an issue in a area which can get very hot, with the microwave looking outside, just think where you are mounting them !

:bruce_h4h:

Personally i wouldnt go with the FX50SQ but go with the Mx40pt, the detectors microwave transmitter should be shielded, so having the detectors back to back should be ok.

You are right when you say about the microwave being able to see through glass which may be an issue in a area which can get very hot, with the microwave looking outside, just think where you are mounting them !

:bruce_h4h:

Thanks for that.

The problem is that during first-fix, I put in the wiring for the PIRs in locations specified by a local (no-longer-trading) alarm company after they looked at my house plans.

So the mounting positions can't really be changed now that we're all boarded & plastered out & living in the house.

Having done a lot of reading now, regarding siting of PIRs, windows, sunlight, etc etc I realise that the wiring doesn't go to ideal positions - so I need to select my detectors carefully.

In some rooms I can't see any way that the dual-tech sensors could be used, without the microwave element picking up movement outside the glass, hence my thought that the FX50SQ would be ideal...

Pyronix TMD in tri-cover mode requires activation of 2 x PIR's and 1 x microwave to signal an alarm, also has 5-15 metre microwave adjustment (always going to be approx). They offer exceptional resistance to false alarms in 'hostile' environments.

Data Sheet

ugly as ____ though

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