HVAC Preventive Maintenance 101
Subject of the day is heating & air conditioning, specifically, preventing those uncomfortable periods of time between your frantic phone call & waiting on your contractor of choice to show up to fix your air conditioning system this summer.
Many times, that phone call can be prevented.
“Murphy’s Law” number one; “if anything can go wrong, it will.” We should add an addendum to that saying “it will go wrong on the hottest, most humid day of the year.” Let’s use last summer as a prime example. Our air conditioners are expected to work, on a worst case 95 degree day. Here’s an example of a NOAA blog last summer:
“The heat wave in Atlanta continues. Today’s high temperature of 103 degrees recorded at 12:46 PM at Hartsfield-Jackson airport beat the previous record of 101, set back in 1980.”
To use a simple analogy, your air conditioning system needs to be maintained much like your car or truck; run it too long without proper care, catastrophic problems occur. Air conditioning can be reduced to one phrase, the transfer of heat. If your system cannot transfer heat properly, the result is less conditioned air or cooling. There are simple steps that a good mechanical contractor can take to help with heat transfer.
Dirty condenser coils need to be chemically cleaned. When an outdoor condenser coil becomes contaminated with dirt or grime, it cannot provide adequate heat transfer resulting in higher system pressures and lower efficiencies. As the dirt accumulates, the rest of the system needs to work harder to satisfy the set point indoor temperature. The compressor is the most expensive component of your air conditioning system. With dirty coils, lack of heat transfer raises the internal pressure of the compressor resulting in lower efficiencies and ultimately, premature failure. Higher operating pressures can also promote the reduction of lubrication in the compressor, much like the oil in your car. Once this happens in an air conditioning system, acid forms in the lines contaminating the system. One additional characteristic of poor lubrication of the compressor is noise, everybody hates a noisy condenser!
With your indoor coil or evaporator coil, improper care can result in not only lower efficiencies but also contaminated air. The indoor evaporator coil produces condensation when warm, humid air is blown over it. During the summer, your evaporator coil stays moist most of the time promoting growth of mold and bacteria. Cleaning and sanitizing these areas are critical for efficiencies and indoor air quality. In addition, the area that collects the condensation, or drain pan, must be sanitized with a time released chemical or tablet that eliminates the growth of these contaminates. When the drain line gets clogged, the repair bill may include drywall, carpet and furniture!
The HVAC industry has many products that address these cleaning issues. A popular product line is Nu-Calgon which manufactures Nu-Brite using an alkaline, foaming cleaner instead of the harsh acidic cleaner to clean the coils. Other products on the market include system conditioners, lubricants, flushes, insulators; the list is endless.
Studies have proven the impact of dirty coils on energy costs. The Carrier Corporation conducted a study on systems ranging from three to sixty tons. A typical five ton system with moderately dirty coils uses 8,100 KW hours per season in contrast to a clean coil using 5,500 KW hours during the same season resulting in a 32% more efficient system operating with clean coils.
In addition to system efficiencies and indoor air quality, the advantage of a proactive preventive maintenance program is system reliability. A service technician skilled in his trade can identify many potential problems and parts before they fail. There is a fine line between proactive part replacement and theft. As a homeowner, business owner or building manager, you may not know the difference between a contactor and capacitor; trust in your HVAC contractor is critical; choose one with years of experience in the industry, good reviews on-line and are listed with your city’s Better Business Bureau.
Other key areas that must be addressed during a preventive maintenance visit include clean air filters, drive belt wear & alignment, motor amps & draws, proper refrigerant charge, wiring connections, gas pressures, safety switches and air flow. These are just a few items on an inspection report you must request from your contractor.
Extend equipment life, reduce cost of ownership, lower operating costs, minimize down time and increase reliability. !
Other organizations to further develop your HVAC knowledge include: www.ashrae.org, www.comfortinstitute.org & www.energystar.gov.
Steve Lackley is the Operations Manager at Estes Heating & Air, Mechanical Division located in Atlanta, GA. You can contact Steve at slackley@estesair.com.