It's true, some crankcase heaters are wired to single pole contactors. The crankcase heater is wired across the open set of contacts, one lead on the line and the other lead on the load side. Power is from the line side of contacts and through the contactor buss via the compressor windings when the contacts are open. When the contacts close, there is zero potential and the crankcase heater is de-energized.
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The "rumor" is the winding in the motor acts as a CCH. I knew their had to be a little truth to it.
There is truth to it but not the way some people imply that simply adding a single pole contractor regardless if it kills common or run and run cap somehow creates heat. It simply does not. Any ammeter will show you that.
Trane was known in the early days to utilize motor windings as cchtr but they used a distinctly different wiring approach to truly accomplish this.