Alarm switches for steel windows

[nomail]

I want to fit alarm switches to a significant number of steel (Crittall) windows but I'm concerned that the reed switch types will get confused by the steel frame. Can anyone suggest alternatives?

[Tim+]

Why not try one first?

Tim

[Brian Gaff]

I think they mount them spaced away by a non metallic piece. Brian

[Dave Plowman (News)]

I assume you mean the common surface mount types? The flush ones I used would be a problem with steel windows.

But the answer would be try one and see. Just connect your DVM across the reed switch. Perhaps glue a small piece of wood to the frame and the sensor to that.

[ARW]

As what others say, hold one onto place and try it.

I fitted one to a steel door with a steel door frame last week with no problems.

[tabbypurr]

So use microswitches.

NT

[Capitol]

Yes, I've the same experience.

[nomail]

Clearly I'll try one before ordering the whole lot, but it's useful to hear that others have used them without problems.

[nomail]

I was considering microswitches (or, possibly, a slotted opto sensor) but I can't find anything that looks reasonable for a sensible price.

Hmm, I just tried to check the alarm input specs and discovered that all the sensors are wired in parallel with an "iD" signalling system, so it may not be straightforward to replace some of the PIRs with switches ... more study needed!

[ARW]

I don't know what you know about them but google for "ID biscuit alarms" etc

[nomail]

Until a few hours ago I didn't even know they existed, now I know how to use them and where to buy them. It seems that the system is a bit dated but they look simple to use and the current set-up works well so reconfiguring it shouldn't be too difficult. I need to check the IDs of the existing "biscuits" before ordering some new ones but there seem to be two types (black and white) and I can't find out what the difference is (apart from the obvious!) ... can anyone enlighten me?

[tabbypurr]

chocolate vs custard cream.

NT

[ARW]

Best guess without asking my mate (he is in Spain) it is that they have different resistances for certain panels and that they are a variation on an EOL installation.