1. Leave the low voltage link in place
2. Connect power to RX1/L and RX1/N
3. Link RX1/L to RX1/2
4. Connect RX1/3 to boiler room stat terminal 2.
DH, l would follow your advice if RX1 was to drive a motorised valve, else I would refrain from powering up Rx1/ 2 or 3. Often the 3/4 link in boilers has no voltage, 24 volts or 240 volts. In every case better to use voltage free contacts in programmers to 'link' the 'thermostat' point.

