honeywell st699

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    Replacing Honeywell ST699 with Tado extension kit

    Hi, first time poster with relatively little knowledge of central heating controllers here ! I've got a Honeywell ST699 controller which controls a Valliant ecoTec Plus 831 combi boiler. The Honeywell is left over from when we had our old boiler and a hot water tank. As the Valliant is a...
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