How can i marry my honeywell CM921 the the BDR91 relay box?
we have a Honeywell CM921 thermostat and a BDR91 relay box, for the past two years was working fine. However recently the system appears to have stopped recognising eachother. To make the heating work we have to override the system we have to press the green button however the red button continues to flash. Any suggestions or tips would be most welcome.
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