I am currently using a Weil-McLain Gold sealed combustion boiler for heat (with old Cast Iron radiators) and last year 2 years ago installed a seperate central AC system. I would like to change my a/c outdoor unit to a heat pump, but am looking for a thermo. or other controller that will kill the heat pump and use the boiler when the temp. is too low. Any suggestions or companies to look at? I currently use Aube Technologies thermostats.