Old Programmer was a Danfoss CP715 and the new is a Honeywell ST9400C.
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I had Danfoss FP/CP715-Si which started to freeze every time it switched the CH on, so I replaced it with Honeywell ST9400C which according to the documentation has the same wiring.
I only replaced the programmer installing it on the Danfoss' backplate, but now CH is constantly on regardless the programmers settings.
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Of course if anyone could shed some ideas it would be highly appreciated.