Cache Mechanical Systems

Energy efficient HVAC systems - 101

Is your A/C, Heating, Refrigeration, or Ventilation system running as efficiently as it should?

Energy efficient HVAC systems not only cost less to operate, they also promote indoor air quality. There are numerous ways to make your HVAC system operate more efficiently. And there are simple cost effective ways to do it. Cache Mechanical Systems can take your existing HVAC and refrigeration equipment and assess which areas have room for improvement. Many times it is noted by our technicians that one or several factors are causing a waste of energy output in an HVAC or refrigeration system. Is such a case, our technicians can coordinate with the owner of the home, business, or building and inform him of his assessment and request that corrective service be performed in order to restore and improve system efficiency. The following are common factors in all HVAC and refrigeration systems that greatly affect the amount of energy consumed by a system:

Fouling

Definition: Dirt and dust buildup which occurs on the surface of A/C coils over time and can cause a loss of energy efficiency and excessive wear and tear on the compressor. Fouling may also lead to problems with indoor air quality and excessive mold buildup.

Figure 1-Clean coil vs. dirty coil

Clean Coil Program. St. Louis: Nu-Calgon, 2007

Effect on efficiency: ‘Operating an A/C unit with dirty coils (fouling) and/or filters and easily consume up to
37% more electricity as compared to an A/C unit with clean coils and filters. For example, consider a 10 ton air conditioning system operating for an average cooling season of 1,500 hours. When the coils are clean, it will cost approximately $1,650 to operate
for the season, given a typical Kw/hr cost and equipment SEER (efficiency). However, when the condenser
coil becomes dirty, the six-month cost of operation escalates to $2,268 . . . a 37% increase.’ Excerpt from Clean Coil Program. St. Louis: Nu-Calgon, 2007

Figure 2- Clean coil savings

Clean Coil Program. St. Louis: Nu-Calgon, 2007

Solution: Coils must be sprayed with an aluminum/nickel safe coil cleaner that is strong enough to break down the buildup. After the chemical reacts with the fouling, it must be thoroughly rinsed with copious amounts of water. Drain pans and drain lines should be cleared of all debris and coil (indoor unit), return plenum, and inside of air-handler should be sprayed with an aluminum/nickel safe sanitizer. Condensate water should be treated to prevent buildup of bacteria that causes foul odor. Fan blades should also be checked for any buildup, as this can cause a decrease in airflow and thus a decrease in efficiency.

HVAC Controls

Definition: Any electronic or mechanical device that controls an HVAC unit by monitoring temperature, air volume, or the level of a specific toxin, which may occur in an indoor environment.

Note: Typically, many commercial buildings have simple on/off type thermostats either being electronic or the simple mercury bulb type.

Figure 3-Zoning & Programmable Thermostat Controls

Effect on efficiency: ‘A typical A/C unit running constantly for one year will generally cost more to operate than the cost of the unit.’ SMACNA National Association. Energy Systems and Management Manual, VA, 1997

Solution: An energy-consuming device uses the least amount of energy when it is turned off. Quality, commercial grade, programmable HVAC controls & thermostats should be installed by a professional to reduce the amount of time the HVAC unit runs during the season. Many businesses with simple on/off type thermostats who rely on their employees to turn the HVAC units off at night may be surprised to find out how often their HVAC unit runs all night while no one is in the building, wasting money and energy.