The coil is usually made of copper tubing with aluminum fins, but some manufactures use aluminum tubing. Its purpose is to transfer heat as rapidly as possible. Pressure inside the coil can exceed 400 psi., during extremely warm weather conditions. The cleaner it is kept, the better it transfers heat. Rinsing with a garden hose occasionally when the unit is not running will help keep it operating efficiently. After many years of use it may be necessary to put special chemicals on to clean it.

The condenser fan moves air across the coil to increase the transfer of heat. It is critical to the system. Obstructing the flow of air will not only reduce efficiency but can lead to compressor failure. Keep debris and objects away from the coil and fan to allow maximum air flow. Some condenser fan motors have sealed bearings, others need lubrication. Damage to the fan can occur if removed improperly. Have a qualified serviceman handle the lubricating if needed.

Electronic air cleaners will usually operate at 95% efficiency, allowing little or no dust to pass through. The dirtier they get, the lower the effectiveness, so clean grids are a must. Before removing the screens and grids for cleaning, it is imperative to shut the power off and wait a few seconds to allow the grids to lose the static charge. They are dishwasher safe as long as they fit inside. If not, sloshing around in a tub of hot soapy water will loosen dirt that can be blasted off with a garden hose.

Extreme caution must be taken when handling to protect the grids and the person handling them. The plates are very sharp, and can cut like razor blades. The fine wires stretched across the grids are delicate and crucial to proper function. Proper spacing between the grids is important. Do not bend or distort them.

If the grids are not completely dry when installing them, do not turn the power back on; damage to the power pack can occur as the water will short the grids out. If in doubt about the dryness, leave the power switch off for a day or two; the air flow will take care of any residual water. Arrows one the grids will display the correct direction for air flow. Improper installation will render them useless. If the air cleaner was installed correctly in the return air duct by the original HVAC mechanic, air flow will be going from the duct toward the appliance. The arrows should do the same.

Furnace mounted units can be by-pass, steam, mist, wick, and powered. Some mount in the ductwork while others are attached to the plenums on the furnace. Whatever the model, mineral deposits from the water will reduce the effectiveness of the humidifier. Be sure to turn the water and humidistat off before servicing.

Special chemicals can be used to clean mineral deposits, but one of the safest is vinegar. A 50% mixture of vinegar and water will usually dissolve or help clean away deposits. If the humidifier has a drum with a belt, replacement of the belt at the beginning of the heating season can be the easiest fix if the water has a high mineral content. If the humidifier has screens or is the wick type, some corrosion can occur as well as build up.

Heat pumps and electric furnaces usually have steam humidifiers to increase output. They are line voltage powered and must be unplugged or disconnected before servicing to avoid injury. With the exception of some mist type humidifiers, all have a reservoir. Stagnant water sitting in the reservoir during the off season can be a breeding ground for bacteria. Turn the water off and clean the humidifier if possible when heating season has ended.

Other than mineral deposits, the most common problem is sediment in the water supply. The float inlet valve has a tiny hole that easily clogs. The float is usually made of plastic, and if cracked will fill with water and sink. The valve will be stuck open and the reservoir will overflow. Use caution when scraping deposits off the float. If the deposits cannot be removed, replace the float or it will sink and cause an overflow.

Routine maintenance includes; monthly filter replacement or washing the electronic air cleaner grids when in constant use, cleaning the humidifier if so equipped, and an annual tune up of the burner.

An oil burner tune up includes a nozzle and filter replacement, heat exchanger and smoke pipe cleaning, and a fuel to air mixture adjustment. Since the mixture adjustment requires the use of special instruments to meet federal standards, it is best left to a professional to obtain peak efficiency.