Thought swapping these over was going to be simple but the wiring I have does not appear to conform with the conversion data on the website / enclosed instructions - just want to be 100% sure. Instructions say: __ST699 - L - N - 3 - 4 - 5 - - -6 - 7 - 8 ST9400C - L - N - 4 - 2 - nc - - 3 - 1 - nc The trouble is T5 is COM - 2 * Red wires for heating and T8 is COM 1 * Red wire for Hot W so cannot not connect them on the ST9400C. (I have a set of 6 connections, the 2 * NC on the ST699 are 7 & 4) Please could someone clarify ? Many thanks
Are you talking about the wires which link L to 5 and 8? If so, they are not required as the link are made internally on the ST9400C. Wire as follows (ST699 first): L to L N to N 3 to 4 (CH ON) 6 to 3 (HW ON) 7 to 1 (HW OFF) - may not be present on your system.
Yes it is the wires that go on T5 and T8, I had not noticed they are bridged, probably on the back plate I have not removed yet. You are correct there are no wires on T7. I'll wire as you outline. Many thanks for you reply ✨✨✨✨✨
Download the Honeywell wiring app and from the home controls site download wiring guide edition 16 which also includes a trouble shooting guide for beginners. Interesting the wiring guide include information on Opentherm (bus therm), I mostly install modulation controls for heating controls and strip out old dumb on/off systems, so much cleaner and simple compared to birds nest wiring centres.
Hello there, I am about to replace ST699 to ST9400C, but there are only 4 wires coming from the wall and there are interlinking wires between L-6, 3-7 and 5-6. Please find photo attached. Any idea, how to connect these? Many thanks in advance.
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