## Calculating Cost of Electric Defrost Heaters vs. Costs of 2 Fan Motors Running 24/7

Step 1: Operating Costs of the Defrost Heaters

The evaporator coil has 6 face heaters. Each face heater consumes 1,824 watts. There is also one drain pan heater that draws 736 watts.

#### Heater Power:

(6 face heaters x 1,824 watts’/face heater) + (1 drain pan heater x 736 watts/drain pan heater) = 11,680 watts

The defrost clock runs 4 times a day, in 15 minute cycles. That’s a total run-time of 60 minutes a day. We can now use the total watts to calculate the energy consumption in watt-hours.

#### Heater Consumption:

11,680 watts * (1 hour) = 11.68 kWh per day = 355.3 kWh per month

The cost of electricity is $0.134 per kWh, so the true cost of the electric defrost heaters can be determined in the calculations below:

#### Heater operating cost:

355.3 kWh per month x ($0.134/kWh) = **$47.61 per month**

### STEP 2: OPERATING COST OF THE (2) FAN MOTORS RUNNING 24/7

#### Fan motors power:

Volts per motor x Amps per motor x # of motors x Power factor (efficiency) x square root of three (for a 3-phase motor) = 460 Volts * 1 Amps * 2 * 0.83 * square root of 3 = 1,380 kW drawn by the fans

**Fan motors consumption:**

1,380 kW * 30.42 days/month = 1007 kWh per month = 12,089 kWh per year

The cost of electricity is $0.134 per kWh, so the true cost of the (2) fan motors running 24/7 can be determined below:

Fan motors operating cost = 12,089 kWh per year x ($0.134/kWh) = **$134.99 per month**

**THE COST TO OPERATE THE (2) FAN MOTORS IS ALMOST 3 TIMES MORE THAN THE DEFROST HEATERS!**

**THE COST TO OPERATE THE (2) FAN MOTORS IS ALMOST 3 TIMES MORE THAN THE DEFROST HEATERS!**

**For more information on Frigitek™ Electronically Commuted (EC) Motors and Controllers and how Carlisle Energy can save you money, please contact us directly at (714) 684-1766.**

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