Hi all. I am trying to upgrade from an old mechanical stat to a digital programmable one. We got an excelvan BYC17. My question relates to the correct wiring. I just want to make sure I get it right. The old stat had 3 wires plus earth. Red - Live Blue - Neutral Yellow - Neutral (I presume this is the control to turn on boiler when heating is demanded)
The new stat has input for L and N and and output to load L and N and the connection for external sensor (which I'm not going to use)
So I plugged the red and blue to the input and the new stat turns on. I had read somewhere that the yellow wire is obsolete so left it disconnected but when I turned the stat up it clicked on but the heating didn't. So I thought the yellow wire needs to connect to the stat. When I took the multimeter out, the live (via load) read 240v but the neutral still reads 0v. This leads me to think the 240 from the output live is the on signal for the boiler... so do I connect the yellow wire to this output live?
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