[bowman1964]

watts rating on a humidifier means little to nothing.i can take one compressor and rate it at 500,600,700 watts .depending on the condensor and evaperator size.
a humidifier is rated with all 3 parts combined.you need to look at the hp load of the comperssor and voltage.for -40 degree temps 1/4 compresor is what you need. a 1/4 hp compressor does not mean it will run at that hp while it running.only when it needs the full load does it runn at 1/4hp.so that 1/4hp compressor only works like a 1/8 or so as the load is needed.so look for hp power ratting if you can.