Replacing old Honeywell thermostat with Meross MTS200

[newbie2022]

I need some help with figuring out how to wire the new thermostat.

The old one has 3 wires (red, blue and yellow) as soon on image "old_wires.jpg"

I have attached the wiring diagram of the old thermostat "old_wiring_diagram.jpg" and the wiring diagram of the new thermostat "new_wiring_diagram.jpg"

What's the right way to connect the new thermostat?

It is going to control a Worcester Greenstar 15Ri boiler.

 

[ericmark]

Red to L with a link to com, blue to neutral, yellow to NO.

However seems with reference sensor this is designed for under floor heating.