Air Handling Units

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HVAC Air Handler Quickpage jump links:

Air Handler Basics

Air Handling/Air Conditioning Unit Spring Maintenance

Checking the Air Handler Evaporator

Air Handler Related Links

Air Handler Basics

The Air Handler pages offers residential commercial HVAC advice and maintenance tips with york air handling units, trane air handler, and carrier air handlers, and all air handling unit brands brands in particular. It really doesn't matter what brand of air handling unit you have, many air handlers operate in the same manner and have the same components and we will show the air handler basics on the air handlers pages. Enjoy.

An air handler is usually located in the garage, a closet, or in the attic (unless you have a package unit then the air handler is incorporated in the system). It is essential to any air conditioning unit and heating forced air system. All air conditioning units need an air handler or way to handle air. It can be a part of your furnace and houses the evaporator coils, the blower motor, and some HVAC controls. The air handler can be an up flow air handler, down flow air handler, or horizontal flow AHU (air handling unit). To determine which one you have follow the return duct. The return duct should originate where you put the HVAC filter and/or is the biggest register grill in the house. If the return ends in the bottom of the unit it is an up flow air handler. If the return duct ends in the top of the unit it is a down flow air handler. If the unit looks as if it is lying on its side with the return duct coming in one side the supply ducts going out the other it is a horizontal flow air handler.

Horizontal Flow Air Handler

Knowing this information can help you find the filter if you have never changed the filter in this air handling unit on many types of air conditioning units. Some air handling units (AHU's) have the filter inside. If there is no filter in the return register or grill then the filter is either in the return duct somewhere or in the air handler itself. Filtering the air is not only important for the indoor air quality in your home but it is essential for the proper operation of the air handling unit itself. The air must be filtered before it reaches the evaporator coils or heat exchanger inside the air handler. If it is not then there will be a build up over time of dust and debris that get sucked into the return. This build up clogs off the evaporator coil and causes the heat exchanger to operate at higher than normal temperatures. The air handling unit becomes less and less efficient and will eventually fail to cool or heat the home. Besides, a good air conditioning units filtering system can improve indoor air quality. HVAC preventive maintenance on your air handler includes maintaining good filter maintenance schedules. Carrier air handling units are no different that York Air Handlers and they need a basic preventive maintenance schedule to prevent premature breakdowns and to keep the air handling unit operating at peak efficiency.

The air handler can be a Carrier Air handling Units, York Air Handlers, Trane Air Handler Units, or any one of numerous other brands but they all perform the same function. All air handlers deliver air through the HVAC ductwork system.

The Air Handler moves air through the evaporator coils for conditioning

Air Handler Spring Maintenance Checks: Cleaning the Evaporator Coils

Large York Commercial Air Handling Unit

Spring maintenance checks to the air handler can help you avoid costly AC repairs (heating repairs in winter) when the heat of summer arrives. An air handling unit is essential to any air conditioning units and requires some preventive maintenance attention. A word of caution is advised here before you open the panel. Air Handling Units have high voltage running into them and there is a shock hazard. Before you remove the panel make sure the power is turned off to the air handling unit. There are times when I, as a certified heating and air conditioning technician, have to operate the air handling unit with the air handler panels off. Only an HVAC professional should operate the air handler unit with the panels off. Even with the thermostat in the off position the air handling unit has high voltage running into it. Turn the circuit breaker off before opening any panel on any heating and air conditioning equipment including air handlers. The air handler contains the evaporator, metering device (on most units), the blower motor, and some electro-mechanical controls for HVAC control. The metering device and the electro-mechanical controls should be checked by an HVAC professional. These air handler components are highly technical and beyond the scope of this site to explain in detail. The air handler evaporator and air handler blower motor can be maintained by the homeowner as long as safety and common sense are applied.

Large air handlers being installed in a commercial building.

Checking the Air Handler Evaporator

The evaporator coil inside the air handler unit carries refrigerant inside it. This coil and refrigerant, through the heat exchange process, absorbs heat from the air passing through the coils inside the air handler. The heat causes the refrigerant inside the evaporator coils to boil and change state. The refrigerant, where it enters the coil, is mostly a liquid. By the time it reaches the end of the coils it should have absorbed enough heat to change it from a liquid to a vapor*. On the outside of the air handler there are two copper lines. One large and insulated line, and one small and un-insulated line. The large line is the suction line. This line carries the vapor (refrigerant) back to the compressor in the condensing unit. The small line is called a liquid line. This line carries liquid (refrigerant) from the condensing unit coils to the evaporator. Click here to see the refrigeration cycle. When the unit is running the liquid line should be hot and suction line should be cold *(Unless it is a heat pump in the heating mode). The temperatures of these lines will vary depending on how

Place your mouse over the up flow air handler for component explanations

hot the house is inside and the ambient temperature outside the home. A big problem most people encounter with the evaporator coils is blocked coils. The coils are plugged with dust, dirt, and other debris, there is a duct collapsed somewhere, or there are too many supply vents closed off in the home. For the evaporator to work properly and efficiently the coils must be clean and have a measured amount of air flow (the amount of air flow required for your evaporator coil inside the air handling unit depends on the tonnage of the system. More precise, 400 CFM's equal one ton or 12,000 BTU's). Thus, the necessity of a good filter to filter all the particles from the air before it reaches the coils. Coils operate below the dew point when the air conditioner or heat pump cooling cycle is on. This will make the evaporator coil wet so when the dust makes contact with the evaporator coil it will often stick to the evaporator coil. Over time this will cause a build up and eventually the HVAC system will stop cooling. With improper air flow across the evaporator coils there is no heat exchange process. The coils will freeze and ice will form on them. Another cause of ice forming on the evaporator coil is a low refrigerant charge. If the evaporator coils are clean and they are icing up, you need to call an HVAC professional to check the air handling unit.

High Performance HVAC

For an explanation of the asterisk* and in depth information see air handlers page two.

Air Handler Related Links

Air Handler Units Page 2 | Air Handler Units Components Page 1 | Air Handler Units Components Page 2 | Air Handler Units Components Page 3 | ECM Variable Speed Blower Motors | High Performance HVAC Home | Air Handler Top

Air Handler Reviews

Amana Air Handler Reviews | Bryant Air Handler Reviews | Carrier Air Handler Reviews | Goodman Air Handler Reviews | Heil Air Handler Reviews | Lennox Air Handler Reviews | Rheem Air Handler Reviews | Trane Air Handler Reviews | York Air Handler Reviews

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