Smart Lock - Mortise Lock with Handle (S851)

A mortise lock with a lever handle and a doorbell button on the keypad. It opens by fingerprint, code, card, key or the Tuya app, and the bell on the front means a visitor has something to press instead of hammering on the door.

• Always-On mode, and when to use it
• A doorbell on the panel
• Users and codes
• Fitting the S851 smart lock
• Buy it for Always-On

Always-On mode is the feature worth knowing about. Switch it on and the lock stops asking for authentication, so during the day an office or a shop door simply opens on the handle. Switch it off in the evening and it locks down again.

It takes 50 fingerprints, and cards and codes on top of that, which is enough for a family, a small office or a guest house. Temporary and timed codes are issued from the app, so a cleaner gets a code that stops working on Thursday evening.

Four AA cells run it. Emergency power is Type-C, so the same cable that charges your phone will wake the lock, and two mechanical keys come in the box.

It fits doors from 40 to 120 mm thick, which is a wider range than most, and it is handed on site for a door that opens either way.

Always-On mode, and when to use it

This is the feature that separates the S851 smart lock from the rest of the mortise handles. Switch Always-On mode on and the lock stops asking for authentication, so a shop or an office door simply opens on the handle through the working day. Switch it off in the evening and it locks down again.

Nobody has to badge in and out of a room that is meant to be open, and the door is still a smart lock the moment you want it to be.

A doorbell on the panel

There is a bell button on the keypad itself, so a visitor has something to press rather than hammering on the door. On a solid steel or timber front door that is more useful than it sounds.

Users and codes

It takes 50 fingerprints, with cards and codes on top, which covers a family, a small office or a guest house. Temporary and timed codes are issued from the Tuya or Smart Life app, so a cleaner gets a code that stops working on Thursday evening without anyone standing at the door to cancel it.

Five ways in altogether: fingerprint, code, induction card, mechanical key and the app. The reader is a semiconductor type in the handle ring.

Fitting the S851 smart lock

Door thickness runs from 40 to 120 mm, which is a wider range than most mortise handles manage, and it suits interior doors, wooden doors and security doors. The escutcheon is 65 x 280 mm in aluminium alloy, and handing is set on site so there is no left or right version to specify when ordering.

Four AA dry cells power it. Emergency power is a Type-C port on the underside, so the cable that charges your phone will wake the lock, and two mechanical keys come in the box.

Buy it for Always-On

If you are fitting a shop, an office or a room that stands open through the day, this is the one in the range that handles it properly. Switch Always-On on in the morning and the door opens on the handle; switch it off at night and it is a lock again.

It takes doors 40 to 120 mm, wider than most mortise handles manage, and it is handed on site. Fifty fingerprints, plus cards and codes. Compare the others in smart locks, and the app is at tuya.com.