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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3757
Experience:  City and Guilds qualified plumber
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Thermostat wiring question: * Old mechanical thermostat with

Customer Question

Thermostat wiring question:
* Old mechanical thermostat with 4 wires: L/N/E and switched live
* New programmable thermostat: two sets of connections. First set: L/N. Second set: NO/COM/NC. I have tried two ways of connecting the new thermostat. 1st attempt: L to COM and SL to Normally Open. In this case even the display of the thermostat did not work. 2nd attempt: L to L and N to N. In this case the display does work but the boiler does not fire up. What is the correct way of wiring?
Submitted: 2 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 2 years ago.
Live to liveNeutral to NeutralLink Live to CommonSwitched Live to NO