I am replacing the locks on a property and want to change the deadlock. Firstly there are two depths to the locks: 64 mm (2.5") and 76mm (3") under the same BS3621. After returning the first lock I bought and buying the correct depth (with the same BS3621) the new lock has other subtly different dimensions:
- the body of the lock is taller by a few millimeters (89mm vs 76mm) so it doesn't fit in the hole already there.
- the position of the key hole is a different distance from the door edge by 4mm and is lower by 10mm.
- the deadbolt is taller (36mm vs 30mm) so doesn't fit into the strike plate's smaller recess.
I'm sure there are other things that are different but this is clearly not a standard, or it is a standard that has changed or been narrowed over time.
I tried to look up the old installer / suppler but they've both closed down.
My question is: before I buy the third lock, how do I tell it's going to fit? Clearly BS3621 defines some thing but exact dimensions is not one of them. What can I do? (You can imagine what I think bs stands for right about now)