blower speed?

[rub234]

What is the difference between a 3-4 speed blower, 4-5, and variable?

Thanks.

[coolguysfl]

A multispeed blower is just that- it has multiple speeds. The speed taps are chosen by the contractor to get max circulation as required by the tonnage and duct design.

Variable speed fan motors, also know as ECM are electronically commutated motors and actually controlled by a solid state module that adds horse power to achieve the desired CFM. Overall, they ramp up, and are more efficient. Word to the wise - get the extended warranty, when the ECM fails, it's a painful experience.

The variable speed systems have been embraced to remedy marginally bad duct systems, but be advised in the process of adding HP the SEER evaporates - moral of the story:

Get a good contractor, take his advice.

[duct dr]

Originally posted by coolguysfl

The variable speed systems have been embraced to remedy marginally bad duct systems, but be advised in the process of adding HP the SEER evaporates - moral of the story:

Get a good contractor, take his advice.

I would have to dissagree, variable speed blowers are designed to enhance humidity control, as well as lessen ones power bill. ECM motors are DC volt driven making them more efficient and quieter. I would expect to see the price of ECM modules come down too due to the new X13 motor that Carrier has out. It uses an ECM module on a single speed blower.

[coolguysfl]

Variable speed motors can be employed to assist latent removal if the control system is in place, that is true. In some markets the factory tech reps are discouraging the SUPER dehumidify mode as the TD is so high the AH cabinets sweat and eventually the grills sweat.

To my knowledge, Carrier didn't invent the X13, it's GE's next generation "ECM" that should prove more cost effective.

And yes it's true - the variable speed, ECM technology CAN be quieter IF the duct work is properly sized. If the duct work is not sized for the CFM, the motor will ramp up to the preselected speed by adding HP thus the savings is gone unless the duct design supports it. Rheem recently published data that correlated a 13 SEER (variable speed) applied to a high static system (greater that .5"WC) actually bordered on a 10 SEER after the motor loaded up.

In extreme cases, I've seen duct work blown apart or collapsed after a variable is installed.

ECM's are a good product, when properly utilized.

[duct dr]

You're right cool. I didn't mean that Carrier developed the X13 motor, I just meant that they're using it on new airhandlers. Maybe I should send you a resume.