Robert L. Bass said:
The answer will depend on the types of windows you have. I like to use
concealed "contacts" (magnetic switches) on windows and doors. If they are
wood, double-hung (slide up and down) windows, I often use Sentrol's 1275
which is a 3/8" barrel type switch. If the window is one of the newer types
with very little room to bury a magnet you may have to get a little
creative.
I have a sequence of pages which teach how to install an alarm system on my
FAQ website. There are discussions of various types of windows, including
several popular brands and some generic information as well.
If there's no way to hide the sensor you can use one of the tiny 1035W
surface mount contacts. These are 1/4 x 1/4 x 1.5" magnets and sensors.
They're white so they "hide" pretty well on a white vinyl surface.
For wood doors or steel clad doors with wood edges I also like to use
Sentrol's 1275. For steel doors with steel frames consider a Sentrol 1078C.
These are designed for applications where the sensor has to go into a steel
frame where ordinary sensors may fail due to proximity of ferrous metal
(which slowly dissipates the magnet's force).
There are other brands which you could consider. GRI makes decent switches
which I use if I can't find exactly what I need from Sentrol. Stay away
from Tane contacts. They're cheap junk, poorly made, frequently bad out of
the box.
Note: Almost every manufacturer offers a lifetime warranty on magnetic
contacts, even the cheap ones. They don't expect you to bother shipping
defective contacts in for replacement. Besides, you don't need the hassle
so get the best you can find.
I carry Sentrol, GRI and several other major brands on my website. The URL
is in my tag line below.
Note to "Post'em":
Robert doesn't "use" any contacts what-so-ever. He's strictly an on-line
retailer and doesn't install or service the product he sells. He's given
you good advice here, but take it with a "grain of salt".
There are very few applications where you would use a plunger type switch
(which is what I think you were originally referring to). Over time dust,
dirt and moisture tends to clog up the works. Sealed magnet reed switches
(whether they're concealed or not) of good quality (Sentrol, GRI, Amseco,
Ademco) are better and pretty easy to work with. If you have sliding type
patio doors or windows you can position the switch so that you can install
two magnets about 6" apart. One that aligns with the switch in the frame
when the door or window's closed, and the other magnet will align with the
switch when the door or windows open about 6". This is what's referred to
as a "fresh air" opening. It allows you to open your windows to circulate
air on a hot day and still be able to arm the system.
There are several online dealers that participate in this forum that would
be only to glad to help. These guys also happen to run brick and mortar
alarm companies in conjunction with their online activities. The also
answer emails a bit more promptly than Robert does (who's received numerous
complaints both here and in other groups from people).
http://www.youralarmstore.com
http://www.alarmsystemstore.com
http://www.alarmsuperstore.com
http://www.diycomponents.com
http://www.alarmcontacts.com
There are lot's more out there and my advice would be to shop around for
good prices and when you settle on one store you feel comfortable with,
"dicker" for the best deal. Most merchants won't quibble over a few dollars
if the order's worth their while.
Good Luck!!
