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HVAC FAQ

What Size Air Conditioner do I Need

Air conditioner capacity is commonly measured in tonnage, and each ton contains approximately 12,000 BTUs of cooling output. Major manufacturers offer units in half-ton increments to address a wide variety of building configurations.

Until the late 1990s, most HVAC contractors used a version of the square-feet-per-ton formula, which was modified for different regions of the country. Unfortunately, this sizing method is very inaccurate and doesn’t account for the quality of the building’s materials or workmanship.

In 1987, the Air Conditioning Contractors of America (ACCA) developed a series of complex calculations designed to determine the exact cooling load requirements for a building and each of its rooms. Known as Manual J, this comprehensive formula includes important criteria such as building orientation, insulation, perimeter tightness, windows, duct leakage and local weather patterns. Quality HVAC contractors always run a complete set of Manual J load calculations before selecting the size of the air conditioning equipment.

What do SEER, MERV and All Those Air Conditioner and Heating Ratings Mean?

Efficiency ratings provide an easy way to compare the relative performance of different brands and models of HVAC equipment. The most frequent air conditioner questions relate to efficiency ratings and their impact on utility costs.

SEER: The Seasonal Energy Efficiency Ratio (SEER) was created by the EPA and the Department of Energy. In essence, an air conditioner’s SEER rating is a reflection of how much electricity the unit uses to deliver each BTU of cooling output. Relative efficiency between two machines can be calculated by dividing the difference in SEER rating by the lower rated SEER number. A higher SEER rating is always indicative of more efficient operation.

In climates that have severe summer heat, it is always important to locate the extended efficiency ratings when comparing two different machines. Higher ambient temperatures degrade performance, and the capacity of two units with identical SEER ratings may differ dramatically when subjected to typical local outdoor conditions.

AFUE: The Annual Fuel Utilization Efficiency (AFUE) rating is used to compare the operational cost of different furnace brands and models. Expressed in percentages, the rating is a direct measurement of the ratio between energy consumed and energy produced. A furnace with an 80 AFUE rating exhausts 20 percent of the energy is consumes as waste gas and turns 80 percent into usable heat.

MERV: The Minimum Efficiency Reporting Value (MERV) was introduced in the late 1980s by AHRAE as a way to compare the effectiveness of different styles of central heating and AC filters. Particles of different sizes are introduced into a sealed test chamber, and the filter is rated according to its capture percentage. A higher MERV rating is indicative of a more efficient filter.

HSPF: The Heating Seasonal Performance Factor (HSPF) is a heat pump specific rating that measures the efficiency of the unit in heat mode. The HSPF rating number is derived from measuring thermal output from the appliance relative to the watt-hours consumed. A higher HSPF rating is indicative of greater heating efficiency.

How do I know if I Have an Existing Warranty of my Furnace, Air Conditioner or HVAC System?

To determine if an existing furnace, air conditioner or heat pump is still under warranty, it is important to locate the unit’s model and serial numbers. For split systems, the air handler and condensing unit will each have a separate identifying model and serial number. Look for a tag attached to the equipment that includes a variety of pertinent information including the mechanical and electrical specifications.

The installing contractor usually maintains detailed records for every system they install. If the warranty information is unavailable locally, the manufacturer will have a record of the installation date and the remaining time left on the warranty.

Most major HVAC equipment manufactures in the U.S offer a minimum five year limited warranty on parts and the compressor. However, if the equipment is under ten years old, it is still worth checking to see if there is any remaining warranty coverage on the unit. Some manufacturers offer a standard 10 years parts and compressor warranty, especially on their high-end equipment.

It is worth noting that standard equipment warranty terms rarely cover labor costs.

When Replacing an Outdoor Unit Should the Indoor Unit Also be Replaced?

In order to secure a replacement job at a lower cost, an unscrupulous contractor may recommend replacing a condensing unit while leaving the existing furnace, air handler and coil intact, especially if the failure is compressor related.

A mismatched evaporator coil and condensing unit will most often result in a substantial reduction in efficiency and capacity. The Air Conditioning and Refrigeration Institute (ARI) provides data that contractors use to verify the compatibility of different coils and condensing units.

Since all new condensing units use R-410A refrigerant, it is important to verify that the indoor coil was designed to accommodate the higher pressure of the new refrigerant. Connecting an R-410A condenser to an R-22 coil will void the manufacturer’s warranty and seriously damage both components.

Which Kind of System is Better: Ductless, Heat Pump or Central Air Conditioning?

HVAC equipment is manufactured in a variety of configurations designed for different applications. The relative value of each system is primarily based on the application, local climate, efficiency expectation and personal preference.

  • Split Systems: Split system air conditioners are characterized by the inclusion of a separate condensing unit and air handler or furnace. The primary advantage of a split system is its low noise level since the condensing unit is located outdoors, usually away from the living area. Split systems also offer the highest efficiency ratings for any central appliance.
  • Heat Pumps: Heap pumps include a reserving valve that allows the refrigerant to flow in either direction, which provides the unique advantage of delivering both heating and cooling from a single unit. In the heating mode, a heat pump is most effective in climates that have mild winters where the temperature rarely reaches the freezing point.
  • Ductless Split Systems: Ductless air conditioners eliminate the need for an air distribution network. Each system includes an outdoor condenser and at least one indoor cabinet that contains an evaporator coil and fan. The indoor enclosure can be hung on an interior wall or installed in the ceiling. Since there is no need for ductwork, ductless split systems are extremely versatile, quiet and energy efficient.
  • Package Units: Package units are installed on rooftops when ground space is unavailable or at a premium. The evaporator coil, condensing coil, blower and compressor are all included in a single unit. Package units are available in a variety of configurations including straight AC, heat pump and gas/electric.

How long do Air Conditioning Units Last?

This is a very common air conditioner FAQ, but there are many factors that affect the service life of HVAC equipment. In general, most systems last from 12-15 years, but performance and longevity are affected by the build quality of the unit, the ductwork, the original system design and the frequency of regular maintenance.

Clogged filters, dirty coils, duct obstructions and greater resistance adversely impact performance and force the system to work harder to satisfy the indoor load. The accumulated runtime hours can cause additional wear on critical parts and result in a premature failure. Poorly designed systems either short cycle or do not have the capacity to meet the thermostat call. In either condition, the additional stress typically shortens the system’s lifecycle.

Modern HVAC equipment is complex, and every major manufacturer includes routine maintenance as provision of their warranty coverage. Regular service keeps air conditioning systems operating at peak performance and helps extend the life of the equipment.

How can I Improve Indoor Air Quality and Circulation?

In order to enhance energy efficiency, modern homes are built to virtually eliminate perimeter leakage. As a result, a variety of unhealthy contaminants can become trapped inside the indoor environment. In fact, the EPA has categorized poor indoor air quality (IAQ) as one of the five most urgent environmental issues.

Whole-house ventilators provide a controlled pathway for the introduction of a specific amount of fresh air according to ASHRAE standard 62.2. Regular air exchange helps remove accumulated indoor pollutants and can improve the performance of exhaust fans and clothes dryers. In climates that experience extreme weather, energy recovery ventilators can help adjust the temperature of the incoming fresh air to closely match the indoor environment.

When used in conjunction with filtration, remediation and duct cleaning, a fresh air ventilation system plays an important role in a comprehensive indoor air quality strategy.

What’s the Best Thermostat Setting for my Air Conditioner?

Since indoor comfort is a matter of individual preference, there is no specific thermostat setting that can be considered the “best.” The fuel costs associated with raising or lowering the thermostat temperature are dependant on a variety of factors including the SEER rating of the unit, weather conditions and the construction quality of the building.

In general, the cost of air conditioner operation can be lowered by about two percent for every degree the thermostat is raised. For many homeowners, the balance between comfort and the cost of electricity is an ongoing dilemma. However, if an air conditioner is struggling to maintain a reasonable temperature, it is important to verify the temperature drop between the return and supply sides of the system. The air exiting the supply duct should always be at least 15 degrees cooler than the air entering the return duct.

Programmable thermostats offer features that allow the user to raise the temperature while the building is unoccupied and gradually lower the temperature just before they return. When used properly, a programmable thermostat can save up to 20 percent on monthly cooling costs.

Why Does My Air Conditioner Turn On and Off?

Air conditioner operation is a function of the thermal load in the living area and the thermostat setting as established by the user. The actual mechanical operation of the unit begins when a sensor in the thermostat registers a temperature that is above the established threshold. A relay is activated, and the refrigeration cycle is initiated.

Refrigerant enters the compressor as a form of low-pressure gas. The action of the device squeezes the refrigerant and transforms it into a high-pressure gas. As it flows into the condensing coil, a forced-air fan removes a substantial amount of heat energy and disperses it into the outdoor environment.

With the heat removed, the refrigerant is converted into a high-pressure liquid as it leaves the condenser. While flowing into the evaporator coil, the liquid passes through an expansion valve, which is a metered orifice. This process creates a pressure drop, and the refrigerant becomes a low-pressure liquid.

The blower inside the air handler pulls warm indoor air across the evaporator coil, and the heat energy is absorbed by the refrigerant. The resulting cooler air is pushed through the ductwork back into the living area. The saturated refrigerant is transformed into a low-pressure gas, and the cycle repeats itself. Once the thermostat call is satisfied, the relay disengages and the unit shuts off.

Equipment that is oversized will turn on and off too frequently, which can result in poor humidity control and inadequate air movement. Undersized air conditioners may run continuously and never satisfy the thermostat call when the outdoor temperature is extreme.

Why Does My Air Conditioner Leak Water?

The production of water is a normal byproduct of the refrigeration cycle and cooling process. Dehumidification helps keep the living area more comfortable by transferring moisture from inside the home and depositing it outdoors.

A properly functioning air conditioner collects water in a drain pan near the evaporator coil. Through gravity, the water flows down a tube known as a condensate pipe that eventually exits the home. Water that puddles near the air handler should be addressed immediately. The most common drain-related problems include:

  • Cracked Drain Pan: Many evaporator coils include a plastic drain pan, especially those produced by third-party manufacturers. The most common source of a water leak is a cracked drain pan. Cracks can develop over time but happen most frequently during the manufacturing process or during shipping.
  • Clogged Condensate Pipe: Water that drains from the coil can be contaminated with dirt or other debris from the recycled air. Over time, an obstruction can form in the drain pipe. Standing water in the pipe or pan can also lead to mold growth. A clogged drain will force the water to accumulate in the drain pan and eventually overflow.
  • Cracked Condensate Pipe: A cracked condensate pipe can create a serous condition, especially if the leak is coming from inside a wall. If water marks appear on an interior or exterior wall, a licensed plumber or HVAC contractor should be called immediately.
  • High Humidity: When the air inside a home is saturated with moisture, condensate can build up on the interior surface of the ductwork and air handler. A dehumidifier is recommended for areas that have excessively high summer humidity levels.

Why Does My Air Conditioner Keep Freezing Up?

An air conditioner that freezes up may require service from an air conditioning specialist. There are two common conditions that usually lead to an iced coil.

Low Refrigerant: A system that is low on refrigerant will cause the evaporator to become too cold, which degrades the efficiency of the energy exchange and eventually begins to build ice. The ice serves as an insulator that continues to affect performance until the system stops functioning completely. In this condition, it is important to check the liquid and suction lines for leaks before adding additional refrigerant.

Insufficient Airflow: Clogged filters, inadequate fan speed and obstructed ductwork can all restrict the air flow across the indoor coil. When the volume of air falls below a certain threshold, energy transfer is affected, and the system begins to freeze up. Filters should be inspected and changed monthly, especially high efficiency models, and a service technician can test the fan and check for ductwork obstructions.

Do You Provide Freon Replacement?

Low refrigerant is one of the most common problems affecting air conditioner performance. Homeowner HVAC FAQ often include issues relating to refrigerant. As part of any maintenance or repair service, we always check the refrigerant level to verify the charge is adequate to maximize system efficiency.

When the system is low on refrigerant, it is important to check the refrigerant lines, compressor and coils to locate any possible leaks in the system. An air conditioner that is low on refrigerant will cost more to operate and have to work harder to meet the indoor load. The R-22 refrigerant used in older system is damaging to the environment, so it is important to fix refrigerant leaks as soon as they are discovered.

What are the Benefits of an Air Conditioning Tune-Up?

A preseason tune-up will help improve system efficiency and enhance indoor comfort. Factory trained and NATE certified technicians perform a variety of important services designed to identify small problems before they can escalate into catastrophic failures.

On a seasonal basis, our techs will test and inspect a variety of vital air conditioning components including circuit boards, contactors, the fan motor, the blower, defrost controls and the compressor. We also check the system’s refrigerant charge, change the filters and clean the coils.

For homes with central heating systems, we inspect and test the heat exchanger, ignition system, burners and the combustion chamber. We also test the venting system and confirm the operation of the safety controls.

After completing the regular service, we rebalance the registers for proper airflow and calibrate the system to the manufacturer’s original specifications.

What Does Duct Cleaning Do?

A poorly maintained air distribution system can degrade indoor air quality and adversely affect the performance of a home’s heating and air conditioning system. Regular duct cleaning helps remove a variety of pollutants that can become trapped indoors and continually circulated through the HVAC system.

An industrial strength vacuum is attached to the ductwork, and the extreme negative pressure removes a significant quantity of accumulated dirt and debris. The technician then uses mechanical brushes or a compressed air whip to dislodge any material that remains adhered to the interior duct surface.

Duct cleaning helps eliminate obstructions that reduce airflow and negatively impact system performance. Buildings with clean ductwork provide superior indoor comfort and lower energy costs. Over time, more efficient operation can help reduce the wear and stress on vital system components, which can extend the lifecycle of the equipment.

Airborne contaminants can irritate respiratory conditions, especially in young children and the elderly. Duct cleaning removes a variety of pollutants including mold spores, fungi, animal dander and pollen. After the process is completed, homes smell fresh and require less cleaning maintenance.