x13 or variable speed?

[RickHeatPump]

Living in Alabama (hot and humid), should I get the air handler with the x13 motor (SEER 15.5) or the variable speed motor (SEER 15)?

What is the difference?

[Kevin O'Neill]

VS set to enhanced mode. Dehumidifiers better.

[George2]

VS set to enhanced mode. Dehumidifiers better.

Ditto!

[SoFlaDave]

With single speed condensers i'm actually preferring the x13 motors. Running in med-low speed they do a great job dehumidifying. Maybe not AS good as a variable speed can but i'm in South Florida and have had no excessive humidity issues with them. Assuming a decent price difference between the air handlers I think they're the best bang for the buck.

They also seem to be a bit more hearty then the GE ECM motors are. I've only replaced one x13 motor since they were introduced, but due to nasty electrical fluctuations we tend to go through ALOT of variable speed modules and motors in a year. Of course there are products now that can be added to protect them better, but still.

[ask_eddie]

While most quality units have 10 years parts warranty , here is what to consider down the road. An x13 a few hundred dollars to replace , a true variable speed.... well depending the motor ...."no pricing" . I offered replacing the airhandler for only a few bucks more. But if money or availablitiy are no object down the road.... variable speed all the way !

[RickHeatPump]

Anyone else have a thought on whether to do an X13 or variable speed air handler? All quotes I get are for the x13 until I ask for the variable speed quote. I think I want the VS but it makes me nervous if the repair costs are that much higher on variable speed.

Better dehumidification and slow ramp up speed - what else makes the VS so great?

I've seen "constant airflow" for VS compared to "constant torque" for x13. What does that mean?

[amd]

I've seen "constant airflow" for VS compared to "constant torque" for x13. What does that mean?

Constant airflow blowers ramp up/down to maintain airflow as the static pressure changes.

As the static pressure increases (this appies to centrifugal fans- for axial fans, the opposite it true), the load on the motor and air flow drop off; the x13 compensates (ramps up) little bit the maintain constant torque (think of it as force being applied to turn the blower wheel), but not air flow.

The x13 is better than a standard motor, but not nearly as good as a variable speed ECM.

[beenthere]

With single speed condensers i'm actually preferring the x13 motors. Running in med-low speed they do a great job dehumidifying. Maybe not AS good as a variable speed can but i'm in South Florida and have had no excessive humidity issues with them. Assuming a decent price difference between the air handlers I think they're the best bang for the buck.

While setting an X13 to med low may dehumidify ok. You lose some efficiency on the hotter days when the A/C is already running long enough to have dehumidified the house, and now it needs a higher sensible capacity. With the VS and the right thermostat, you get that efficiency back.