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    Updating Honeywell T40 Thermostat - too many wires?

    Hi, I’m trying to update my old manual Honeywell T40 thermostat to a programmable T40 on a combi boiler. the man in the shop said nice easy swap but once I removed old I found there’s too many wires. I think the T4 only needs 2 but the old T40 has 4. Is it a simple problem to solve or do I...