Furnace Blower Motor Capacitor Sizing

Smith century dl1056 1 2 hp 1075 rpm 3 speed 115 volts6 5 amps 48 frame sleeve bearing direct drive blower motor.

Furnace blower motor capacitor sizing.

This unit has a variable speed motor that operates in an operating range configuration. A furnace usually uses a run capacitor to maintain a relatively constant voltage supply to the blower motor. It is difficult to find a 40kbtu furnace that can move 1000 cfm at a reasonably high static. Box type note icon none operating range blower table.

Your furnace uses a lot of energy so to supply the extra energy needed to power the blower gas furnaces have a capacitor. Central air conditioners and heat pumps use capacitors. You must replace it so your air conditioner or heat pump continues to work properly. This chart shows the blower details for a 120 000btu furnace.

Divide the start up energy requirement in joules of the motor by x to arrive at the capacitor size needed in farads. If you re concerned that your furnace capacitor isn t operating properly you can test it by following a few simple steps. How to read your capacitor voltage and mfd for a replacement capacitors are rated by the. A bad or faulty capacitor can exhibit many signs and symptoms.

If the furnace is receiving power turn up the thermostat and see whether the blower motor starts within the next few minutes. Before checking the capacitor make sure the fuse controlling the furnace is flipped to the on position. The blower motor in your furnace blows hot air through the ducts and into your home. Here is an example of a furnace blower motor on amazon.

The start up energy of the motor is found either in its documentation or written on the motor itself. Example furnace blower motor on amazon a o. You can see the listing description the specifications are listed for the motor. You simply measure the current amps of the motor start winding coming off of the capacitor and multiply it times 2652 on 60hz power 3183 on 50hz power and then divide that number by the voltage you measure across the capacitor.

A capacitor keeps an electrical charge on standby to provide it to the motor when it first turns on. The capacitor will be located close to the blower motor since it is there to help the blower motor run and have wires coming from it. Problem indicators what you can do. If not the capacitor or the blower motor is not functioning properly.

To answer this question the panel door to the furnace will need to be removed. The blower then moves the warmed air into and through the ductwork in your house. Over time a capacitor will wear out. Assuming a start up energy of 0 00033 joules you obtain 0 33 divided by 66 1 which equals 5 0 times 10 6 farads.

Its capacitor works like a battery and stores the energy needed by the blower to work properly. But with a bad capacitor your blower cannot function well and may put your family s comfort at risk.