SyndicateHvac.com – Information about Air Handler Checks
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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 can be a part of your furnace and ...
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 can be a part of your furnace and houses the evaporator coils, the blower, and some controls. The air handler can be an upflow, downflow, 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 filter and/or is the biggest register grill in the house. If the return ends in the bottom of the unit it is an upflow air handler. If the return duct ends in the top of the unit it is a downflow air handler. If the unit looks as if it is lying on it's side with the return duct coming in one side the supply ducts going out the other it is a horizontal flow air handler.
Knowing this information can help you find the filter if you have never changed the filter in this unit. Some air handling units 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 air quality in your home but it is essential for the proper operation of the unit itself. The air must be filtered before it reaches the 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 unit becomes less and less efficient and will eventually
Spring maintenance checks to the air handler can help you avoid costly repairs when the heat of summer arrives. A word of caution is advised here before you open the panel. Air Handlers 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 unit. Only a professional should operate the unit with the panels off. Even with the thermostat in the off position the unit has high voltage running into it. Turn the circuit breaker off before opening any panel on your heating and air conditioning equipment. The air handler contains the evaporator, metering device (on most units), the blower, and some controls. The metering device and the controls should be checked by a professional. These components are highly technical and beyond the scope of this site to explain in detail. The evaporator and blower can be maintained by the homeowner as long as safety and common sense are applied.
Checking the Evaporator
The evaporator coil carries refrigerant inside it. This coil and refrigerant, through the heat exchange process, absorbs heat from the air passing through the coils. 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 uninsulated 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 coils to the evaporator. When the unit is running the liquid line should be hot and suction line should be cold. The temperatures of these lines will vary depending on how 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 plenty of air f
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