Furnace Blower Motor Capacitor Sizing

Here is an example of a furnace blower motor on amazon.

Furnace blower motor capacitor sizing. To answer this question the panel door to the furnace will need to be removed. Its capacitor works like a battery and stores the energy needed by the blower to work properly. Divide the start up energy requirement in joules of the motor by x to arrive at the capacitor size needed in farads. The start up energy of the motor is found either in its documentation or written on the motor itself.

This chart shows the blower details for a 120 000btu furnace. How to read your capacitor voltage and mfd for a replacement capacitors are rated by the. 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. It is difficult to find a 40kbtu furnace that can move 1000 cfm at a reasonably high static.

The blower motor in your furnace blows hot air through the ducts and into your home. You can see the listing description the specifications are listed for the motor. Hvac heating ventilation and air conditioning capacitors store electricity and help compressors and blower motors the systems that distribute hot. How to locate a furnace s start capacitor.

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. Example furnace blower motor on amazon a o. You aproximate sizing of the capacitor is in the range of 4 40 mf and at the motors i have 1 1 2 2 kw the run capacitor is sized between 35 70 uf. 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.

Smith century dl1056 1 2 hp 1075 rpm 3 speed 115 volts6 5 amps 48 frame sleeve bearing direct drive blower motor. If you re concerned that your furnace capacitor isn t operating properly you can test it by following a few simple steps. A furnace usually uses a run capacitor to maintain a relatively constant voltage supply to the blower motor. But with a bad capacitor your blower cannot function well and may put your family s comfort at risk.

If not the capacitor or the blower motor is not functioning properly. Where is a furnace capacitor located. Box type note icon none operating range blower table. This unit has a variable speed motor that operates in an operating range configuration.

Before checking the capacitor make sure the fuse controlling the furnace is flipped to the on position.