Keep It Clean
According to HVAC contractors who are well-versed in motor maintenance, the most basic — and vital — tip is to prevent dirt.
“There aren’t many tips for most furnace motors,” said Dennis Muravez of McClelland Air Conditioning Inc. (Chico, Calif.). “Most newer furnaces have direct drive motors and the motors do not have oil ports.
“The No. 1 tip is to keep the air filter clean. This will prevent the motor from getting dirty.”
Mark Norenberg of Air Comfort of Kentucky (Louisville, Ky.), agreed. “Most motors die because they are full of dirt,” he said. “Dirt is the one thing that is responsible for most of the component failures in our industry. Either the motor or the wheel or both get full of dirt. Not changing the filter frequently enough, leaky duct joints, and other less-than-best-practice activities are what allows dirt accumulation to happen.”
Muravez also suggested some other maintenance tips. “Clean the motor and blower wheel if it is dirty,” he said. “Check the capacitor condition and if the blower wheel is out balance, replace the blower wheel. An out-of-balance blower wheel will take out the motor bearings.”
HVAC contractor Travis Seeger of Chesterfield Service (Chesterfield, Mo.) said that keeping the motor clean is an absolute necessity. “Cleanliness is next to godliness,” he said. “If it is dirty, vacuum it out or use a small paint brush with the vacuum to get the little stuff.
“Also, check the bearings on the motor — they should be free and smooth. Test amp draw with blower door and filter in place. If running close to or over max amps, test system static pressure. Duct problems are very common, even in systems we have serviced for years. Customers change things sometimes and create duct deficiencies.”
Follow a Routine
It’s also a smart idea to establish and follow a routine checklist for motor maintenance. Paul Sammataro of Samm’s Heating and Air Conditioning (Plano, Texas) shared the following list:
1. Ensure there is adequate duct design and return/static pressure.
2. Clean the filter.
3. Clean the evaporator coil.
4. Ensure there is a balanced/secure wheel.
5. Clean the blower wheel.
6. Check for a good run capacitor.
7. If it is a replacement motor, check for proper specifications for system, e.g., amp draw, horsepower, and rpm.
8. Oil/lubricate if applicable but don’t over lubricate.
9. Ensure proper/secure electrical connections.
10. Ensure a proper and secure motor mount.
Check the Bearings
In addition to all routine maintenance tips, motor bearing protection is a key to lengthening motor life, according to Adam Willwerth of Electro Static Technology.
“By allowing motors to run at less than full speed, these variable frequency drives [VFDs] can yield energy savings of 20 to 30 percent, but they also induce currents that can damage bearings and shorten motor life,” he said.
“The resulting repair costs can wipe out any savings from their use. To make HVAC systems sustainable as well as energy-efficient, a reliable method of bearing protection is required. Operations and maintenance costs can account for 60 to 80 percent of a facility’s lifecycle costs. When HVAC equipment does not have to be repaired or replaced as often, that percentage drops significantly. VFDs hold the promise of sizable energy savings, but without effective, long-term bearing protection, those savings could be wiped out by high maintenance costs.
“For example, diverting bearing currents safely to ground extends motor life and ensures the reliable, long-term operation of VFD-driven motor systems, locking in energy savings to make these systems sustainable and truly green.”
According to Joliet Technologies and ABB Inc., a VFD is “basically a computer and power supply. And the same safety and equipment precautions you’d apply to a computer and to a power supply apply here.” According to the manufacturers, VFD maintenance requirements fall into three basic categories:
• Keep it clean,
• Keep it dry, and
• Keep the connections tight.
Following these tips should help to ensure long life for the motors you install and maintain, which in turn should lead to long-term, satisfied customers.
Publication date: 01/16/2012