Yale P89 Nightlatch - Deadlocking Problem

6 Mar 2009
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United Kingdom
I’ve just replaced an existing nightlatch with a Yale P89 non-automatic deadlocking one, with new lock barrel, which should deadlock from outside with a reverse turn of the key.

I was expecting the deadlock to require a 360 degree anticlockwise turn to engage (ie the opposite direction to unlocking), but the key will physically not turn through 360 degrees, only 180 - and, obviously, can then only be removed by turning it back clockwise so the lock slot is in its usual vertical position. This doesn’t deadlock the internal latch.

Everything else works as expected - it locks and unlocks (engages the latch at 180 degrees clockwise, fully retracts just under 90 degrees further) fine, and the internal snib deadlocks the internal handle - what am I missing? Could the slot in the latch body into which the tab/tongue of the lock fits somehow be 180 degrees out of turn?
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If not then turn it through 360° and line them back up, I think what you gain on the deadlocking side you lose on the unlocking side if that makes sense
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For what it is worth, in my opinion, night latches with a deadlock option are potentially dangerous unless they have the option to use a key to unlock them from inside the property.

They strike me as being a poor substitute for a night latch combined with a dedicated dead lock. Personally I would recommend a night latch plus a euro thumb turn, possibly coupled with a keyed deadlock if you plan to be away for a while.

If a fire starts in the middle of the night I want my family/loved ones to be able to escape as quickly as possible without worrying about trying to use/find keys. If someone breaks in to my home via the rear of the property, I don't want them to trash the house looking for keys to exit via the front.

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