Operations & Maintenance: Heating and Cooling
Heating systems in individual dwelling units
- Turn off pilot light in summer. For gas boilers and furnaces without an electronic ignition, the pilot lights should be shut off at the end of the heating season and relit at the start of the next beating season. During non-heating months, a lit pilot light on a gas furnace, boiler, or space heater is a source of energy waste. Installation of electronic ignition, which automatically shuts off and relights the pilot light according to demand, should be considered.
- Clean and adjust burners. Burners on gas or oil furnaces or boilers should be regularly cleaned and adjusted to ensure maximum efficiency. When burners have clogged openings or are in need of adjustment, they are less efficient. A burner is in need of adjustment if any of the following applies: the flame edge touches the combustion chamber, the tip of the flame is orange, fiery droplets are present in the flame, or there is smoke above the chimney. On oil burners, a microscreen filter added at the burner may reduce the chances of clogging.
- Change/clean filters on forced-air systems. Filters on individual forced-air systems should be changed or cleaned bi-monthly by maintenance staff. Disposable filters should be replaced using a type recommended by the equipment manufacturer, and permanent filters should be cleaned according to manufacturer's instructions. Clean air filters improve the performance of heating systems by removing impurities from the supply air. When the filter is dirty, the fan requires more energy to force air through the clogged filter.
- Inspect equipment for worn or damaged parts. Periodic inspection should be made to identify worn or damaged gaskets, casings, linkages, and other parts of stationary and moving equipment. Worn or broken parts should be repaired or replaced with parts specified by the manufacturer.
- Lubricate equipment. Equipment such as blowers, motors, fans, and bearings should be lubricated on a regular basis, according to the manufacturer's manual and using the lubricant specified. Proper lubrication reduces wear and tear on equipment and enhances its performance.
Central boilers and furnaces
- Turn off pilot light in summer. For gas boilers and furnaces without an electronic ignition, the pilot lights should be shut off at the end of the heating season and relit at the start of the heating season. During non-heating months, a lit pilot light on a gas boiler or furnace is a source of energy waste. Consider installing electronic ignition, which automatically shuts off and relights the pilot light according to demand.
- Clean and adjust burners. Burners on furnaces and boilers should be regularly cleaned and adjusted to ensure maximum efficiency. Burners are less efficient when they have clogged openings or are in need of adjustment. A burner is in need of adjustment if any of the following applies: the flame edge touches the combustion chamber, the tip of the flame is orange, fiery droplets are present in the flame, or there is smoke above the chimney.
- Check and adjust fuel-to-air ratios. In boilers and furnaces, the fuel-to-air ratio is the proportion of fuel provided to the quantity of combustion air. A qualified maintenance staff person or service person should periodically check this ratio by examining stack temperature and levels of carbon dioxide and oxygen in the flue gases. Too little air causes incomplete combustion, while too much air results in excess air being heated and exhausted up the stack. The proper ratio is necessary to achieve maximum efficiency. The ratio can be adjusted using the controls that determine the maximum of air to fuel.
- Calibrate and adjust controls. For boilers and furnaces, controls on the burners should be periodically adjusted to ensure that they are operating correctly. Proper settings can be found in manufacturer's equipment manuals. These controls also should be calibrated (adjusted for accuracy) from time to time.
- Clean fireside of boiler or furnace. In boilers and furnaces, the fireside surface (the side on which combustion occurs) should be cleaned monthly during the heating season. Because soot on the fireside surface acts as an insulator and reduces heat transfer, keeping these surfaces clean can significantly increase boiler or furnace efficiency. The manufacturer's manual should be consulted for recommended cleaning method (for example, with a brush, chemical, or detergent).
- Remove scale buildup on heat exchanger and waterside of boiler. The heat exchanger and waterside surface of boilers should be cleaned to remove scale buildup. Scale buildup is formed from minerals in the boiler water. It decreases heat transfer, which reduces boiler efficiency. Removal of scale buildup should be done when the boiler is shut down for maintenance. The boiler water can be chemically treated to reduce future scale buildup if scale buildup is a problem.
- Operate only as many boilers as needed at one time. In a multi-boiler installation, only those boilers needed to fulfill heating needs at a given time should be operating. Running backup boilers at night can be avoided with the installation of a remote alarm system that alerts maintenance staff of the need to start up a second boiler to meet heating needs.
- Clean oil strainers. For oil-fired boilers and furnaces, oil strainers should be cleaned on a regular basis to maintain proper flow rate of oil to the burner. A clogged strainer reduces the flow of fuel oil to the burner, resulting in a fuel-to-air ratio that is too low, causing boiler inefficiency. Damaged oil screens should be replaced.
- Clean nozzle or rotary cup on burner. For oil-fired boilers and furnaces, fuel oil must be broken up into a fine mist by a rotary cup or nozzle in order to burn efficiently. If cups are dirty or nozzles are clogged, oil cannot burn efficiently and smoke and soot can result. Consult burner maintenance instructions for guidance in cleaning cups and/or nozzles.
- Preheat fuel oil. For oil-fired boilers and furnaces, oil should be preheated to the recommended temperature to ensure the proper viscosity (density) at the burner head. The recommended temperatures are 135 degrees for No. 2 oil, 185 degrees for No. 4 oil, and 210 degrees for No. 6 oil.
Central heating distribution systems
- Reduce thermostat settings in unoccupied areas. In unoccupied areas such as storage rooms, boilers rooms, and other unoccupied spaces, the thermostat should be kept at 55 degrees to save energy in the winter.
- Keep radiators and hot air registers clean and unobstructed. Radiators and hot air registers in dwelling units and common areas should be kept clean and at least a foot away from curtains, sofas, and other objects.
- Operate vents in hot water radiators and baseboard units. On hot water radiators and baseboard units, manual vents should be opened at least once a year at the beginning of the heating season to allow trapped air to escape.
- Check and repair air vents and steam traps. On single-pipe steam systems, vents that are stuck in the closed or open position should be repaired to allow proper operation of radiators. On two-pipe steam systems, steam traps should be checked to ensure that they are operating properly and are not stack open or shut.
- Balance steam distribution. In many steam-heated multifamily buildings, the worst source of inefficiency is in uneven heating. In order to adequately heat some units, other units have to be overheated, forcing residents to open their windows for relief. If there is an automatic balancing system, the system should be checked and adjusted. If there is not an automatic balancing system, the valves on the steam risers and the air vents on the radiators should be adjusted to control balance.
- Lower steam pressure. In boilers with steam distribution systems, the steam pressure should be reduced to the lowest level required for heating needs. When steam pressure is maintained at a level that is higher than necessary, fuel is wasted. Steam pressure can be reduced by adjusting the pressure control. It should be gradually reduced to the lowest level that will satisfy heating needs in all the dwelling units. During hours of low demand and warm weather, steam pressure can be further reduced.
- Monitor make-up water consumption. In steam heating systems, water must be added periodically. Sudden increases in the make-up water consumption indicate that there are leaks in the system that should be repaired.
- Replace steam traps. Steam traps on radiators in steam-heated buildings should be replaced every five years or so.
- Check heating elements, controls, and fans on electric distribution systems. Electric heating elements, controls, and fans should be checked using manufacturer maintenance instructions. All heater elements, contacts, and terminals should be tight.
- Keep air registers open. Air registers that provide heating and cooling to conditioned spaces should be kept in the open position with heat pump systems. Closing or blocking off registers can impair the system's performance.
- Lubricate fan motors and adjust blowers and drive belt. Fan motors should be lubricated and the blower unit and drive belts adjusted according to manufacturer's instructions.
- Clean coils. Indoor heat exchanger coils should be cleaned with a vacuum or brush when dirt builds up. Outdoor coils must be free from shrubs or other items that may impede air flow and should be cleaned periodically with a garden hose.
- Turn off cooling systems in unoccupied common areas. Air conditioning should be turned off in unoccupied areas and in office areas after hours.
- Clean or change air filters. Air filters should be cleaned or changed monthly during the cooling season, depending on whether they are disposable. Air filters are located in the air handler, behind the grille of return registers, or adjacent to the blower in the main return air duct. Dirty filters block air flow and decrease cooling efficiency.
- Clean evaporator coils. Evaporator coils should be cleaned every three to five years. Dirty evaporator coils result in inefficient cooling and shorten the life of the blower and compressor. Evaporative coils in packaged air conditioners and window units can be reached by removing an access panel. Coils can be cleaned with a bristle brush to loosen and remove dirt.
- Clean condenser coils. The condenser should be cleaned whenever dirt accumulates. If the condenser gets too dirty, the compressor can burn out. Condensing coils can be cleaned with a bristle brush to remove loose dirt. A garden hose can be used to flush the dirt out from the inside out. Caution should be used to avoid damaging the coils.
- Clean blower. Blowers should be cleaned when dirt accumulates on blower blades because dirt reduces their ability to blow air over the condenser coils. Before cleaning the blower, the power should be shut off to the air conditioner at the circuit breaker or main switch. To access the blower, a plate in the blower housing may need to be removed. The blower can be cleaned with a brush and a vacuum cleaner.
- Maintain chillers. On systems with chillers, any leaks in chilled water piping should be repaired. The temperature of the chilled water should be raised to the highest temperature possible without lowering effectiveness of the chiller.
- Maintain evaporative coolers. On evaporative cooling systems, the damper for the air intake duct should be closed before the heating season and opened for the cooling season. The entire cooling water loop should be cleaned and flushed on a monthly basis to avoid fishy or musty odors. Cooler sumps should be completely emptied at the end of the cooling season to remove sediment and microbial growth. Filters should be cleaned and replaced frequently.
For more ways to reduce energy costs, see PHECC's Energy Conservation Measures.