Magnetic Contacts Sticking on Un-Opened Windows

[Eugene's DIY Den]

So a lot of my contacts need to be replaced, most of them on windows which are never really opened. A few are on doors and windows which are regularly opened. The switches are sticking closed.
Is this typical if the reed switches aren't "exercised"?, or did I just get low standard switches when I installed my alarm almost 20 years ago?

[Amps]

  On 10/10/2017 at 17:29, Eugene's DIY Den said:

 standard switches when I installed my alarm almost 20 years ago?

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I think these contacts have done you proud. Time to replace them.

[Eugene's DIY Den]

Two more questions!

 

Do magnets lose their strength over the years. I tested a new contact I replaced with both the old and new magnet. Both contacts opened when the magnet on the window moved outwards 1 cm. It's probably good practice to replace both contact and magnet?

 

Second question:

 

The PVC windows have a chamfered edge, so I can't butt the contact up against the magnet because it would be proud of the window opening and likely to get knocked if anything is passed through the window. At the moment, the contact only opens when the casement is pushed out 1 cm. Tapping the contact hard doesn't seem to open it when the window is closed, so the reed switch seems to be securely closed. Do you think this is good enough, or am I going to have problems down the line with nuisance triggering because the pair aren't close enough?

[MrHappy]

  On 10/10/2017 at 17:29, Eugene's DIY Den said:

So a lot of my contacts need to be replaced, most of them on windows which are never really opened. A few are on doors and windows which are regularly opened. The switches are sticking closed.
Is this typical if the reed switches aren't "exercised"?, or did I just get low standard switches when I installed my alarm almost 20 years ago?

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The reed is just little bit of metal in glass tube....

 

I reckon most of the branded alarm contact manufactures buy in the same Reeds...

 

The gases escapes for the glass tube & they either FA or just fail (open or closed)

 

I suspect those the fail early have been thrown around or the screws knocked in with a hammer when fitted

  On 10/10/2017 at 18:19, Eugene's DIY Den said:

Two more questions!

 

Do magnets lose their strength over the years. I tested a new contact I replaced with both the old and new magnet. Both contacts opened when the magnet on the window moved outwards 1 cm. It's probably good practice to replace both contact and magnet?

 

Second question:

 

The PVC windows have a chamfered edge, so I can't butt the contact up against the magnet because it would be proud of the window opening and likely to get knocked if anything is passed through the window. At the moment, the contact only opens when the casement is pushed out 1 cm. Tapping the contact hard doesn't seem to open it when the window is closed, so the reed switch seems to be securely closed. Do you think this is good enough, or am I going to have problems down the line with nuisance triggering because the pair aren't close enough?

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IIRC 13mm operating gap, thats look way too far apart

[Eugene's DIY Den]

  On 10/10/2017 at 18:21, MrHappy said:

 

The reed is just little bit of metal in glass tube....

 

I reckon most of the branded alarm contact manufactures buy in the same Reeds...

 

The gases escapes for the glass tube & they either FA or just fail (open or closed)

 

I suspect those the fail early have been thrown around or the screws knocked in with a hammer when fitted

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I fitted the contacts, so there was TLC involved! However they seemed to fail after a few years on the windows which weren't opened. The currents involved are only milliamps, so they hardly weld closed?

[Lwillis]

  On 10/10/2017 at 18:26, Eugene's DIY Den said:

I fitted the contacts, so there was TLC involved! However they seemed to fail after a few years on the windows which weren't opened. The currents involved are only milliamps, so they hardly weld closed?

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The metal pins inside the glass tube just doesn’t Spring back. 

Replace the contacts job done 

[Eugene's DIY Den]

  On 10/10/2017 at 18:21, MrHappy said:

 

IIRC 13mm operating gap, thats look way too far apart

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The bottom edge of the magnet to the closest edge of the contact is 11mm.

Edited October 10, 2017 by Eugene's DIY Den

[MrHappy]

  On 10/10/2017 at 19:11, Eugene's DIY Den said:

The bottom edge of the magnet to the closest edge of the contact is 11mm.

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there on surfaces which are stepped apart, a "chunky contact" does 30-40mm gap I wouldn't fit then in the locations you've got 

 

 

[Eugene's DIY Den]

  On 10/10/2017 at 19:20, MrHappy said:

 

there on surfaces which are stepped apart, a "chunky contact" does 30-40mm gap I wouldn't fit then in the locations you've got 

 

 

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What would be the consequences of spacing the pair this far apart?

Edited October 10, 2017 by Eugene's DIY Den

[MrHappy]

If the gap is too wide the reed may not close / may open after a period of being set

 

Depending on the case design you mage be able to double up the magnets which give them more "pull"