August 1997 Volume 3 Issue 15
No-Cost/Low-Cost HVAC Savings Opportunities
P.E.I. businesses that operate all year long have a significant heating expense. To help you reduce that expense, we have prepared a list of no-cost and low-cost savings opportunities for HVAC (heating, ventilating, and air-conditioning) systems. As you run through the list, place a þ next to any item that seems worth looking into. If you have questions about the savings potential of a particular opportunity, need more details about implementing a corrective measure, or would like a copy of the informative free booklet Energy-Efficient Heating, Ventilating & Air Conditioning, call Ron Estabrooks or Mike Proud at 1-800-236-5193 (toll free).
¨ Don’t overheat or overcool. A few degrees of temperature difference can make a sizable difference in operating cost. Consider establishing maximum and minimum temperatures, and set controls accordingly.
¨ See that ventilation levels are appropriate. Too little ventilation can result in discomfort and health problems. Too much wastes energy and energy dollars. Different areas of a building and different individuals may require different amounts of ventilation; see if these differences can be accommodated.
¨ During occupied periods, maintain humidification at the minimum level which meets the needs of the occupants. Humidification has an energy price; there is no reason to pay more than is necessary.
¨ Reduce building temperature during unoccupied hours. If the temperature of people-occupied spaces is not yet controlled by a 7-day setback thermostat with battery backup, make this modest investment now.
¨ At the end of the working day, eliminate (or drastically reduce) air exchange with the outdoors. While it is essential to maintain indoor air quality when the building is occupied, there is normally no need to bear the expense of ventilating it during unoccupied periods. Install time clocks to shut down the air systems (if doing so would not cause problems) or switch to 100 per cent recirculated air.
¨ Make sure that exhaust fans do not run after hours. Exhaust fans are needed when processes are going on, and should normally be off at other times.
¨ Turn off humidification during unoccupied periods.
¨ Make sure that heating and air conditioning system controls are interlocked so that heating and cooling cannot happen simultaneously.
HEAT DISTRIBUTION OPPORTUNITIES
¨ To maintain proper air flow, replace air filters at appropriate intervals.
¨ See that air and/or water flow rates are not excessive; reduce them if possible. If they can be reduced, do it by reducing fan or pump RPM. (Change pulley sizes, perhaps?)
¨ Repair or replace damaged or missing insulation on heat distribution pipes and ducts. It is also possible that some pipes or ducts which run through unheated spaces were never insulated in the first place. Correct this.
¨ Replace faulty steam traps.
¨ Repair steam leaks.
¨ Check and repair outside air dampers, and adjust damper linkages. Leaky dampers can let in excessive amounts of outside air, raising heating costs. Consider installing edge seals.
¨ Make sure that the system turns off heating/cooling circulation pumps when no heating or cooling is required. If necessary, modify the control system to do this.
¨ Periodically inspect heating and cooling coils in air ducts for accumulations of dust and dirt; if dirty, clean them.
¨ Maintain proper belt tightness and pulley alignment on pump and fan drives. Improper alignment can cause the drive system to absorb up to 10 per cent of the drive energy.
¨ Periodically calibrate controls, and see that system temperatures are correctly set. They should be checked as part of an annual or semi-annual system tune-up.
¨ Check for duct leakage, and repair any leaks.
¨ If your building generates a lot of heat, and your HVAC system is in the cooling mode much of the time, consider switching to “Economizer” controls where outdoor air is used for “free” cooling during part of the year.
BOILER ROOM OPPORTUNITIES
¨ Make sure that the air/fuel ratio is adjusted for maximum combustion efficiency.
¨ Consider using air from near the ceiling of the boiler room for boiler combustion air.
¨ Properly maintain the boilers that are used for building heating. This involves cleaning or replacing dirty or mis-sized fuel nozzles. It also means removing soot from the fire side of the heat transfer surfaces, and removing mineral deposits from the water side.
¨ Control blowdown losses. Excessive blowdown wastes energy. Insufficient blowdown allows sludge to build up in the boiler water. Blow down only to the extent necessary to maintain acceptable water conditions.
¨ Where boiler water is distributed directly to radiators, arrange for outdoor temperature to control the temperature of the water. Quite hot water may be needed for adequate heating in the middle of winter, but not in the spring and fall. Maintaining a high water temperature for the entire heating season wastes energy.
¨ If building heating is uneven, find out why and correct the problem. If the building has cold spots, the tendency is to turn up the thermostat until those areas are comfortable. This overheats the rest of the building and is costly. Sometimes the best approach is to create a separate heating zone with its own thermostat.
¨ Weatherstrip doors and windows, and fix cracks in walls. Air infiltration causes discomfort and wastes energy.
¨ See that each exhaust hood has its own source of make-up air. Unless an exhaust hood has its own make-up air from outside, brought in close to the hood, HVAC-heated building air will be exhausted and energy will be wasted.