I have some $5 Navy surplus humidistats with both NO and NC terminals. Some
line-voltage thermostats do too. For constant-temp dehumidification, we might
put one $80 AC in a window and one in the basement and wire the window AC
to the close-on-rise contact of Grainger's $16 2E158 SPDT thermostat and
the other to the close-on-fall contact and run the common to Grainger's $60
2E574 (Honeywell H46C1166) "dehumidification control."

Nick