Brown's Oil & Air Conditioning

AIR HANDLER

The function of an air handler, which is often installed in an attic, is to distribute cooled air throughout the rooms within a house to be cooled. Its principal components are an evaporator coil which cools the air, a blower fan which distributes the cooled air through ductwork, a blower motor which powers the blower fan, and a blower motor control which in its simplest form is an on/off switch.

BLOWER FAN

The fan in the air handler circulates air over the low temperature evaporator coil to cool the air. It then distributes the cooled air through the air supply ductwork to the rooms in the house to be cooled. The blower fan also suctions warm air through the return air duct back to the air handler where the cycle begins again.

BLOWER MOTOR

Blower motors are installed in the air handler and the condensing unit and are used power their respective blower fans.

BTU

A BTU (British thermal unit) is a measure of heat energy and is defined as the quantity of heat required to raise or lower the temperature of water by 1 degree Fahrenheit.

BTUH

BTUH (British thermal units per hour) is the measure of heat energy or capacity per hour, expressed in BTUs

COMPRESSOR

The compressor is a mechanical pump which is located in the condensing unit. Its function is to increase the refrigerant pressure and circulate the refrigerant starting in a liquid form as it emerges from the condenser, up to the air handler and then back to the condenser to begin the cycle again.

The compressor pump functions by causing a lowering of the pressure on the pump’s intake side, which suctions the refrigerant gas from the air handler, and by causing an increase in the pressure and consequently temperature of the refrigerant gas on the pump’s discharge side. The heated refrigerant is forced under pressure through the condensing coil where the refrigerant gradually changes state from a gas to a liquid by transferring its heat to the surrounding cooler air which is suctioned in by the condensing unit blower fan. This fan simultaneously blows the air warmed by the evaporator coil heat transfer process out of the condensing unit.

CONDENSING UNIT (CONDENSER)

This is the unit of the air conditioning system, normally located on the exterior of the house, which cools the refrigerant, pumps the refrigerant to the air handler in liquid form and suctions it back to the condensing unit in a gaseous form where the cycle begins again. Its principal components are a compressor to compress and raise the pressure of the refrigerant gas, a coil for cooling the refrigerant, a blower fan for circulating air over the coil and dispersing the heat given off by the cooling refrigerant to the outside air. There are also motors to power the compressor and blower fan.

CONDENSER CAPACITY

The capacity of condensers is expressed and measured in “tons” and BTUs. A 1 ton condenser is the equivalent of 12,000 BTUs, which means it has the rated capacity to remove 12,000 BTUs of heat per hour. 1.5 ton and 2 ton rated condensers would therefore be the rated equivalent of 18,000 and 24,000 BTUH respectively.

A simplified calculation to relate 1 ton to 12,000 BTUH is expressed as follows:

1 ton (2000 lbs) x 144 BTUs* per lb divided by 24 hours = 12,000 BTUs per hour

*144 BTUs is the measure of the latent heat of fusion of water( the heat energy gained by or lost by air when water changes from a solid to a liquid or vice versa). The value of 144 has been rounded slightly for convenience so that it yields a rounded value of 12,000 BTUs.

CONTROL

Controls are used to regulate (“control”) the operation of air conditioning (or heating) systems using devises which may incorporate a variety of electrical, mechanical, electronic and temperature and pressure sensing capabilities and functions.

DAMPERS

Dampers are located in ductwork and use movable plates that can be opened or closed to adjust the flow of air to rooms to be cooled.

DRAIN PAN

Condensation of moisture in the air occurs as the evaporator coil in the air handler cools the air blowing over it. A condensate drain pan underneath the evaporator coil collects this moisture which is then piped to an internal or external drain system. A secondary drain pan may be installed underneath the primary in the event of a problem with the primary, and drained to a location where it can alert the homeowner to a possible problem.

DUCTWORK

Ductwork supply ducts are used to pipe cool air from the air handler to the rooms to be air conditioned. It is also used carry warm air through separate return ducts back to the air handler to be cooled.

ENERGY STAR

Energy Star is a Federally sponsored program to encourage energy efficiency and reduce reliance on fossil fuels and environmental damage resulting from such energy production processes. It is organized as a joint undertaking of the Federal government and the private sector to promote energy efficient products designated by the Energy Star label, used to alert the consumer to the energy savings offered by such products.

Qualification for the Energy Star label is based on efficiency standards set by the Federal government (Environmental Protection Agency).

EVAPORATOR COIL

The evaporator coil is located in the air handler and is a system of copper or aluminum tubing, with aluminum fins bonded to the exterior of the tubing to increase the surface area available for absorbing heat. A refrigerant circulates through the tubing. The warm air being blown over the coil causes the refrigerant to change from a liquid form to a gas, and as consequence of that change of state process the refrigerant absorbs heat from the air, thereby cooling it.

The refrigerant is supplied by a condensing unit which is located on the exterior of the house. The condensing unit pumps the refrigerant in liquid form to the air handler through copper refrigerant lines. The refrigerant is in a gaseous state when it leaves the air handler and is piped back to the condensing unit.

EXPANSION VALVE

An expansion valve is a devise which reduces the flow of high pressure refrigerant. Once the refrigerant passes through the expansion valve its pressure and temperature are lowered. The expansion valve is normally located in the air handler. It also one of the two separation points between the high pressure (compressor) side of the refrigerant flow cycle and the low pressure (evaporator) side of the refrigerant flow cycle.

FILTERS

Filters are installed in return air ducts to help prevent dirt from accumulating on the air handler’s evaporator coil, which can reduce the efficiency of the evaporator coil. Filters may be disposable or permanent, and generally need to be replaced and cleaned respectively on an annual basis.

LATENT HEAT

Latent heat is the amount of energy needed to change a substance from one state to another, such as a block of ice into water. When a substance changes from a solid to a liquid, heat energy is absorbed and when it changes from a liquid to a solid, heat energy is released. There is no change in temperature during a change of state.

REFRIGERANT

A refrigerant is a substance which is capable of absorbing and releasing heat. Different refrigerants are selected for use for specific refrigeration applications based on their particular characteristics and their cost. Freon, also referred to as R-22, is the current preferred refrigerant for central air conditioning because its physical properties are well suited for the warm air environment of a central air conditioning system and it is relatively economic. Freon however is damaging to the environment if released into it, because it causes depletion of the ozone layer in the earth’s stratosphere. Because of this production of Freon will gradually be phased out beginning 2010 with a total production and importation ban beginning in 2020.

REGISTERS

Registers are installed at the exit point of ductwork where the air enters rooms to be cooled. They may include grilles, and/or also dampers and air diffusers to control and direct the flow of air.

SEER

SEER is an abbreviation for Seasonal Energy Efficiency Ratio. Central air conditioning systems are rated for efficiency based on the ratio of their cooling capacity measured in Btus divided by the energy (measured in kilowatt hours) required to produce that capacity. For example, a system rated as 11 SEER would provide 11,000 Btus of cooling capacity for each kilowatt hour of energy consumed. The higher the SEER the higher the efficiency.