A lot of people do not know that a UPVC door – or door that has a euro or oval cylinder in it should never have a set of keys left in the back. If you do a couple of things could go wrong – firstly if somebody comes with another key and tries to unlock the door from the other side inevitably you will break the barrel. This is because the lock barrel does not understand how when one side is engaged the other side trying to engage at the same time. This is too advanced for a cylinder and breaks it .So if you have somebody else in your household that also has a key to the door or maybe children or partners – make everybody aware that once you unlock the door you need to take your keys out! This morning I attended as a Locksmith Manchester to a property in Didsbury for a lady who had exactly this problem. She had unlocked the door knowing her son was coming home. He arrived and tried to unlock the already unlocked door, and ending up locking it again and actually snapping is key in the barrel. So we ended up changing the barrel for the lady and all was okay again however it was an expensive lesson to learn.
So remember if you leave a key in the back of a lock you risk a the barrel breaking or your key snapping in the lock. Remove your keys and hang them somewhere out of sight.