Helpful things to know about
Air Conditioning and Heating


How Your Air Conditioner Cools the Air
Central air conditioners are split systems: an outdoor unit (the condensing unit) and an indoor unit (air handler). The function of an air conditioner is to transport heat from one station to another. The vehicle your system uses to carry the heat is called a refrigerant, commonly referred to as Freon.

The compressor in your outdoor unit changes the refrigerant (or "Freon") into a high temperature, high pressure gas. As that gas flows through the outdoor coil, it loses heat and condenses into a high temperature, high pressure liquid. This liquid refrigerant travels through copper tubing into the evaporator coil. There the refrigerant expands. Its sudden expansion turns the refrigerant into a low temperature, low pressure gas. This gas then absorbs heat from the air circulating in the duct work. The cooled air is then distributed back through your house or place of business. Meanwhile, the heat absorbed by the refrigerant is carried back outside through copper tubing and released into the outside air.

Dirty coils and improper refrigerant levels can cause your system to cool less efficiently than it should. An inefficient system means higher energy bills. It also forces your compressor to work harder than is necessary and can actually shorten the life span of your unit. An annual air conditioning tune-up by a licensed technician includes an inspection of the coils and the checking of your refrigerant charge, to insure that your system is running efficiently. Back


How Your Air Conditioner Dehumidifies the Air
As the warm air circulating through your ducts passes over the evaporator coil, it is quickly cooled and can no longer hold as much moisture as it did at a higher temperature. The excess moisture condenses on the outside of the coils and is carried away through a drain. The process is similar to what happens when moisture condenses on the outside of a glass of ice water on a hot, humid day.

Occasionally, the drain lines may become clogged and your system will not drain properly. This can result in a drain pan overflow, leading to water leaks in your ceiling or walls. An annual air conditioning tune-up by a licensed technician includes an inspection of your draining system. During the inspection, the technician will treat your draining system with an algaecide to retard the growth of algae, which can clog your system.
Back

 

Efficiency Ratings

SEER RATING: Your cooling system efficiency is rated in SEER (Seasonal Energy Efficiency Ratio). This measurement of an air conditioning or heat pump system’s energy efficiency takes into account the cooling efficiency of the system under various weather conditions. SEER is determined by dividing the total cooling provided during warm months (in BTU’s) by the total energy (watt-hours) consumed during the same period. We recommend a minimum SEER of 11.

BENEFITS: A high-efficiency system means lower electric bills month after month. While a high-efficiency cooling and heating system may cost a little more up front compared to a less efficient system, you'll recover the price difference in a very short time. High-efficiency systems also save our energy resources. You'll have the satisfaction of helping to protect our environment. That's a savings benefit us all.
Back


The Importance of a Matched System
Your cooling system consists of an outdoor unit (the condensing unit) and an indoor unit (air handler). These two components are designed to work together as a coordinated team to provide top performance, maximum efficiency, and comfort. Whenever you install a new outdoor unit, you should install a new, equally efficient "matched" indoor unit at the same time. While replacing the outdoor unit only may initially offer you the lowest price, it may prove more expensive over time. When your air conditioning components don't match, your system may still work, but it won't perform at the promised energy efficiency. In fact, your system could be up to 15% less efficient than stated. You may be sacrificing comfort, as well, as a mismatched system may have difficulty keeping up on the hottest days. Finally, if your cooling system's components aren't matched, it could create undue stress on your cooling system, resulting in unnecessary, premature failure.
Back


The Importance of an Annual Cooling Inspection
Would you drive a car year after year without ever changing the oil or taking it to a mechanic for a tune-up? Probably not. Like your car, your cooling and heating systems must be maintained in order to run efficiently and dependably. An annual cooling check-up allows a technician to identify minor problems before they become major ones.

Bob Fox Services performs annual cooling system inspections on both residential and commercial structures. Click here for details on what our Seasonal Inspections covers.
Back


Heat Pumps
By definition, a heat pump is a machine which moves heat. Heat exists in all air at all temperatures down to "absolute zero" (-460° F). In the winter, a heat pump draws heat from the outdoor air and circulates it through ducts into your home. During the summer, it reverses the process and draws heat from your interior air and releases it outdoors. It also dehumidifies the indoor air as it cools it.

Benefits of a Heat Pump System

  • Because a heat pump does not burn fuel, it is safer and cleaner to run than a gas powered furnace.
  • A heat pump provides a more uniform temperature throughout a building. It does not produce a sudden blast of hot air as traditional furnaces do each time they kick on.
  • In the heat mode, heat pumps do not dry out the air the way traditional heaters do. The higher humidity maintained by heat pumps during cold weather provides for a healthier environment.
  • Heat pumps are more efficient and cost less to run than electric furnaces.
  • Because heat pumps are used year round (for cooling as well as heating needs), they cost less per hour of use (cost of purchase and installation divided by total number of hours used per year) than do individual heating and cooling systems, which each sit idle for a good part of the year.

Back

The Heat Pump as an Air Conditioner
The heat pump serves as an air conditioner by absorbing heat from indoor air and pumping it outdoors. The heat pump contains an indoor coil which, in turn, contains a very cold liquid refrigerant. As indoor air passes over the indoor coil, the refrigerant-cooled coil absorbs heat from the air and so quickly cools that air. The cooled air cannot hold as much moisture as it did at a higher temperature. The excess moisture condenses on the outside of the coil, resulting in the dehumidification of the air. The cooled, dehumidified air is then forced (by a fan) into the duct system which, in turn, circulates it throughout the building.

At the same time, the absorption of heat by the refrigerant turns the refrigerant from a liquid into a vapor. A compressor pumps the heat laden vapor through a vapor line to an outdoor coil which discharges the heat extracted from the indoor air. As the heat is discharged, the vapor is cooled and changes back into a liquid refrigerant. The refrigerant is then pumped back through a liquid line to the indoor coil and the cycle is repeated.

In addition to serving as an air conditioner, the heat pump contains a reversal valve which reverses the flow of refrigerant and thus allows the heat pump to serve as a heater during cold weather.

The Heat Pump as a Heater
The heat pump serves as a heater by absorbing heat from outdoor air and pumping it indoors. All air, even cold winter air, contains a certain amount of heat. As the outdoor air passes over the outdoor coil, heat from that air is absorbed by the refrigerant contained inside the coil. This absorption of heat changes the refrigerant from a low-temperature liquid to a low-temperature, low-pressure vapor. The vapor then passes through a compressor where it is compressed into a high pressure, high-temperature vapor. The hot vapor then circulates into the indoor coil. As indoor air passes over the indoor coil, it absorbs heat from the coil. The warmed air is then redistributed through the duct system.
Back

The Need for a Supplemental Heater
As explained above, as outdoor air passes over the outdoor coil, its heat is absorbed by the refrigerant contained inside that coil. The temperature of the outdoor air passing over the outdoor coil is reduced by about 10° F (or 5.56°). This means that even if the outdoor temperature is above freezing (say, 35° to 40° F), the air closest to the outdoor coil will be reduced to below freezing (32° F or 0°). This reduction in temperature will cause the moisture contained in that air to freeze and to form frost on the surface of the outdoor coil. When the coil is iced over, if must be defrosted. Methods for defrosting the coil vary among manufacturers. The most popular method uses a reversal of the refrigerant flow. As in the system described above (The Heat Pump as an Air Conditioner), warm air is absorbed by the refrigerant as it passes through the indoor coil. This raises the temperature of the refrigerant and turns it from a liquid into a vapor. As the hot vapor passes, in turn, through the outdoor coil, it defrosts it. Because the heat pump is operating in a cooling mode (drawing heat from indoors and pumping it outdoors) in order to defrost the outdoor coil, it must be supplemented by a secondary heater. Once all the frost on the outside coil has melted, the defrost controls cause the reversal valve to switch over and the unit returns to its heating mode.

Efficiency Ratings
Heat pumps are assigned two efficiency ratings, a SEER rating based on a unit's cooling efficiency and a HSPF rating based on a unit's heating efficiency.

Cooling Efficiency
The SEER (Seasonal Energy Efficiency Ratio) rating is used to identify the cooling efficiency of both traditional air conditioners and heat pumps. The SEER rating indicates how efficiently the unit utilizes electricity: the higher the rating, the less electricity the unit requires to cool a given area. Heat pumps manufactured today have a SEER rating from 10.0 to about 17.0.
Back

Heating Efficiency
The HSPF (Heating Seasonal Performance Factor) rating is used to identify the heating efficiency of heat pumps: the higher the rating, the less electricity the heat pump uses to heat a given area. Today's heat pumps are generally rated between 6.8 and 10.0 HSPF.

Initial Cost versus Long Term Expense
Generally speaking, heat pumps with the highest SEER and HSPF ratings are more expensive to purchase than their lower rated counterparts. However, because they utilize less electricity, they can actually save you money in the long run. If you are planning to sell your residence in the near future, you may not wish to invest in a unit with a high rating. However, if you plan to be in your home for a while, it may be more cost effective to purchase a more high efficiency unit.

Comfort Features
Some heat pumps come with additional features that provide greater comfort. Two-speed units can run on low-speed (using about 50% of the energy) 80% of the time. Consequently, they use fewer on/off cycles and produce fewer drafts. Likewise, they produce much small temperature swings: only two or three degrees rather than the four degree temperature swing commonly experienced with single-speed units. Finally, the improved air circulation provided by a two-speed unit helps to prevent air "stratification": warm air rising to the ceiling and cold air settling near the floor.
Back



SEASONAL TUNE-UP AND INSPECTION

Spring
1. Test and check operating pressures with gauges.
2. Check voltage and amperage to all motors with meter.
3. Check air temperature drop across evaporator.
4. Check for adequate refrigerant charge and possible leaks.
5. Check evaporator superheat.
6. Lubricate all moving parts.
7. Check belts and adjust tension.
8. Check/clean/change, customer supplied, filters.
9. Check pressure switch cut out settings.
10. Check electrical lock out circuits.
11. Check starting contactor contacts.
12. Check all wiring and connectors.
13. Clean and adjust thermostat.
14. Check that condensate drain is open.
15. Turn exposed dampers to cooling position. (No balancing)

Fall
1. Clean and adjust thermostat.
2. Clean and adjust all safety controls.
3. Vacuum clean burners and controls.
4. Clean and adjust pilot assembly.
5. Adjust burner for efficiency.
6. Check for gas/oil leaks in furnace.
7. Lubricate all moving parts.
8. Check belt and adjust tension.
9. Check/clean/change, customer supplied, filters.
10. Check flue pipe.
11. Shut down central air conditioner.
12. Turn exposed dampers to heating position. (No balancing)
13. Adjust pressure regulator.
14. Check overall performance and operating efficiency of heating system.
15. Check combustion efficiency.
Back

INSPECTION OF EQUIPMENT
1. Visual Check

A. Oil leaks
B. Oil Levels
C. Freon leaks
D. Unusual noises
E. Potential hazards
F. Condition of filters
G. Condition of coils
H. Correct noted discrepancies

2. Hands-on Check

A. Thermostat
B. Drain lines
C. Operating voltages
D. Operation of safety controls
E. Condition and tension of belts
F. Electrical wire and connections
G. Operating temperatures and pressures
H. Bolt/nut and flare connection for tightness
I. Correct noted discrepancies
Back

MAINTENANCE
1. Replace compressor oil, as needed (semi-hermetic only)
2. Lubricate motor/fan bearing and control linkage
3. Clean condenser and evaporator, where applicable
4. Clean heat exchanger, where applicable
5. Check overall functional operation of equipment

SYSTEM CHANGE-OVER

SPRING:
1. Heat shut down: Air Conditioning start-up

A. Inspection/Maintenance of heat and air conditioning system
B. Secure heating for summer
C. Fill water tower, where applicable
D. Start up air conditioning unit
E. Leak check freon system, with electronic leak detector

FALL:
1. Air conditioning shut-down: Heat start-up

A. Inspection/Maintenance of air conditioning and heating system
B. Secure air conditioning units for winter
C. Drain and clean water tower, where applicable
D. Start-up heating system and check operation

Priority Emergency Service - Should you have a breakdown, our technician will respond to your call as a priority situation. We provide emergency service 24 hours a day, 365 days a year.

Parts Replacement or Repair - Whether a contract holder or not, Bob Fox Services can replace or repair the parts on your furnace, air conditioner, humidifier or electronic air cleaner, or can install for you a new system.
Back

System Diagram

Back to top