Choosing a replacement motor for your heating or cooling system is
easier than you think. This technique is usually followed to use a
universal style motor than it is using an exact manufacturer
replacement. The advantages of using a universal style replacement
is the cost.OEM motors are usually very expensive and hard to get in
some cases. Older systems manufacturer motors can be obsolete and
the process for choosing a replacement is the same.
Is the unit a gas furnace or
Remember a heat pump has a 2 parts - the outside heat pump and the
inside air handler.
Choose a category
Gas furnaces - Blower motor 115 Volt
Air Handler - Blower motor 230 Volt
Heat Pump - Condenser Motor 230 Volt
A/C Conditioner - Condenser Motor 230 Volt
What is the Hp or horse
power rating? - Look on the existing motor tag for the information.
Some universal motor have a range of horse powers.
What is the speed? -Look
on the existing motor for the information.
A mult-speed motor will only have the highest RPM rating labeled on it.
It is common for motors in furnaces to have 1 to 4 speeds with each of
the lower speeds running a lower RPM.
Frame Size - Look on the
existing motor for the information.
The frame size is the motor physical dimensions and every motor has an
assigned frame size.
Most residential HVAC systems use the following frame sizes
42 - Used mostly on ac and heat pump condenser fan motors
48 - Most commonly used frame size for blower and condenser motors
56 - not so common
What is the shaft size?
Usually 1/2" diameter.
How many speeds does my motor have?
Look at the electrical tag on the motor to find out.
These are the most commonly used.
If the tag is missing or
unreadable, then count the wires going to the motor.
5 wires = 4 speed
4 wires = 3 speed
3 wires = 2 speed
2 wires = 1 speed
direction does the motor turn? CCW or CW (counter clockwise or
This can be confusing if you do not know from what end of the motor to
look. Face the shaft away from you and rotate the fan in the
proper direction. If is is CCW, then the direction is CCWLE
and CWLE for clockwise direction. Universal style motors have an
option to reverse the direction of rotation so rotation is not a worry.
How is the current
1. Belly Band - The motor has what is known as a belly
band around it with mounts that screw or bolt to the blower fan housing.
2. Mounts of Ear mounts - are a permanent part of the motor that
screw or bolt to the blower fan housing.
3. Independent Mounts - The mounts attached to the side of the motor and
then screw or bolt to the blower fan housing - very common for Rudd & Rheem models
4. Flex Mount - the motor has a frame that mounts around the
entire motor - very common for Trane and American Standard models.
5. Stud Mounts - The motor is mounted using threaded studs that
are part of the motor - most condenser fan motors are mounted this way.
You can replace the belly band, ear
mounts, and flex mounts with the a universal belly band mounting kit.
You now have enough information to
choose a replacement motor. Give us a call with your info.