pianotuna wrote:
GordonThree,
Which one offers the best protection for the air conditioner?
Sorry, I don't really know that much about the engineering. If you believe the SUPCO information, the E class offers better protection, as it uses both a potential sensing relay versus a thermal resistor.
The thermal resistor (called a PTC) is going to have a heat up / cool down cycle, meaning if your compressor cycles off and back on too quickly (possibly by adjusting the thermostat), the PTC might not be ready, and the compressor will have to start without benefit of the start capacitor.
As I understand it, a potential relay on the other hand senses load on the motor and cuts out once the compressor is up to speed, and is ready to kick in the start capacitor again right away, there is no cool-down.
Supco goes on to explain the downside of a potential sensing relay; if the capacitor is too big for the compressor, the excess capacitance will prevent the relay from sensing that the motor is up to speed, and leave the start windings/capacitor in circuit, risking damage to the motor or capacitor. Supco states the E class start kits have an additional time-delay circuit that will disconnect the cap before it stays in circuit for too long.
The OP's Sure-Start product probably offers the best protection, as it is an active device (the supco are passive). The electronics of the Sure-Start likely monitor the motor and adjust to its needs, rather than a one size fits most solution like the Supco kits. Its wiring is more complicated though, not a simple add-on like the Supco, and the cost is 10x.
I guess one could consider the Supco cheap insurance, and the Sure-Start good insurance :)
