Variable speed sounds pretty self-explanatory, right? The speed can be varied, and one can choose a specific speed from a range of options to tailor the pumping frequency to their desired specifications. However, there’s a lot more than what meets the eye. When we compare variable speed pumps to traditional single-stage or two-stage pumps, the benefits are innumerable.
According to Golden Rule PHC, single-stage means these air conditioning (AC) or heating pumps only have one setting of running at 100% power. They typically turn off when the desired temperature is met and jump back up to their 100% capacity when they are needed again. Similarly, two-stage can typically switch between 65% capacity and 100%, but only those two. Variable speed pumps, also called VFDs, have several settings of power, ranging from 20% to 100%.
How they work
Variable speed pumps have a mind of their own. They automatically regulate how much flow a fan or pump generates, whether that’s water, glycol, refrigerant, or other heat transfer medium. Whether airflow from a fan, hot water through a boiler pump, or refrigerant through a compressor, VFDs speed change both saves energy and adjusts energy transfer rate at any given point in time. VFDs control of the motor speed can be adjusted by simply sending a speed signal to the device, or by measuring temperature change, or pressure change across different types of systems. This helps regulate heat transfer more efficiently.
Pumps, for example, typically start at around 50% power and slowly shift up their power until they meet their mark at the desired temperature or pressure. Once this temperature is reached, they slow down to a lower setting and run constantly, turning off only when mild temperatures no longer require their use for longer periods.
How they save money
It’s easy to picture these variable speed drives being financially inefficient since they are initially more expensive than traditional pumps and they are constantly running. However, they can save several hundreds of dollars a year due to the reduction of energy they utilize, and they have significantly longer lifespans.
At 50% capacity, variable speed pumps use 75% less energy than traditional pumps use running at 100% power. They also don’t need to be constantly started up. As previously mentioned, traditional pumps turn off when they meet their temperature mark. When they are needed again, lock rotor amps are spiked up and an influx of energy is required to get things moving again. Variable speed pumps have initial soft starts that don’t require this spike of energy, and they don’t need to be constantly started and stopped.
Other benefits
Not only do variable speed pumps save money, they also keep the air cleaner. Since the air is constantly being filtered and circulated, more bacteria, mold and allergens are removed from the air, protecting you more effectively during flu and allergy seasons. These pumps also maintain humidity levels better and reduce the amount of cold or hot spots that result from frequent starting and stopping. Finally, they are significantly quieter than traditional pumps. Running at a lower capacity means they don’t produce as much noise, audible evidence of energy savings.
Variable speed pumps are important for everything in HVAC, and everything in HVAC works better with variable speed. Motors, fans and compressors all benefit in energy savings and functionality when the speed can be reduced from the traditional constant full power.
To learn more about variable speed pumps and how you can incorporate them into your HVAC experience or purchase variable speed equipment, contact Northrich Co. at 216-581-4750 or go to www.northrich.com.