Air Conditioning Service
Why a Variable Speed Fan Motor is Better
A variable speed fan motor was designed to eliminate the discomforts caused by heating and air conditioning systems cycling on and off. It increases comfort and saves energy.
Variable speed fan motors, will use about one eighth the electricity operating at half-speed than it will use when running at full speed. A variable speed fan motor operates at variable speeds to provide the greatest efficiency while maintaining comfort by allowing the HVAC system to fully perform its job. With a fixed speed fan the HVAC cannot operate at the optimum. Let’s look at the differences in function for a better understanding of operation and benefits.
First, let’s not confuse a variable speed fan motor with say a three speed motor. A three speed motor will have 3 preset speeds for the fan to operate. Containing a circuit board, a three speed motor will operate at the fan speed the circuit board dictates based on the boards ‘analysis’ of the home environment. You receive three set speeds, regardless of whether they are too fast or two slow.
In comparison, a variable speed fan motor can operate at 0 rpm all the way up to full speed. It operates at the rpm its circuitry analysis of your home dictates, be that at 0 rpm, or 5 rpm, or 7 rpm etc… You receive exactly what your home requires and not a single rpm more or less.
HVAC systems have the job of removing heat and moisture from the air. When air conditioning is running, a fixed speed fan runs on its fastest speed all of the time. This results in more heat and less moisture being removed from the air. Fixed speed fans simply can’t be turned down; if you could adjust their speed more moisture would be removed from the air and less heat. A variable speed accomplishes this with the fan running at a slow speed when the air compressor first kicks on allowing the humidity to be extracted from the air. While humidity is being removed, the air conditioning coil cools the air moving over it, causing the blowers speed to increase and sending the cooled and dry air into your home. When a balance is established between humidity and heat loads the fan motor runs at less than high speed. Whereas the typical always-running-on-high-speed fan motor runs at a single high speed, allowing the air to retain humidity and reducing comfort.
With a variable speed fan motor installed, when the AC first kicks on, the fan motor is going to run slow in order to extract the moisture from the air. When humidity is reduced to an appropriate level the air coming from the vent registers will be cooler and the force of air coming out of the registers will be increased. At this point humidity in the air will have been reduced to about 50%.
Humidity makes it harder for air to be cooled, and causes HVAC systems to run more often with fast blowing motors that are incapable of removing humidity properly. Humidity also makes the air temperature feel hotter than it actually is and promotes the growth of mold and mildew as well. A variable speed fan solves most of this problem by limiting the air flow until the moisture is removed from the air. With a variable speed fan this moisture is sent down the drain line where it is will not end up in your duct system to grow mold.
As for potential energy savings, a variable speed fan motor at half speed will have to run 8 hours to equal the same amount of electricity used at full motor speed in 1 hour. The variable speed fan roughly uses slightly less than half of the electricity of a full-speed fan simply because it is able to reduce fan speed and provide just the right amount of circulating air that your home requires.
The variable speed fan motor provides ‘smart fans’, and are able to provide the optimum conditions your home requires for maximum comfort and the most efficient operation of the HVAC system.
If you are interested in installing a variable speed fan in your HVAC system give the certified HVAC specialists at Cypress Heating and Air Conditioning a call. We will be happy to assist you in any of your heating and air conditioning service, repair, or installation needs.