I am replacing the baystat239a t-stat with a programmable honeywell th6220d for my heat pump with aux heat, want to be sure of correct wire hook up

be sure to tag each colored wire as you take it off
example=red to r
=white to w
=green to g
this is very important
then the install instructions for the honewell should guide you

almost forgot,, be sure to kill the power at breaker to the furnace before starting

Thanks, programing the t-stat for the type of system (2heat/1cool) was a bit challenging, but once it was completed, it seems to be online and pumping cool air.