Alan McIntosh  HVAC Consulting Services

Sample HVAC Operation and Maintenance Instructions

You have made a sizeable and valuable investment in your home. Your heating, ventilation and air conditioning system plays a major role in providing you with a comfortable indoor environment. In order to maintain your investment, your operating efficiency, and your comfort, your heating, ventilating and air conditioning equipment and systems should be properly operated and maintained.

Indoor Temperature

Your home is provided with a programmable thermostat. Programmable thermostats allow flexibility to homeowners because they can be programmed to match your lifestyle. A programmable thermostat will keep you and your home comfortable while you are there to enjoy it, and will change the set point at programmed times to an energy savings level when you are not home. By simply planning your schedule you can enjoy the benefits of personalized comfort and enhanced energy savings.

Set your thermostat as high as comfortably possible in the summer and as low as comfortably possible in the winter. The less difference between the indoor and outdoor temperatures, the lower your overall heating and cooling bills will be.

Chart your weekly habits including wake up and departure times, return home times, and bedtimes, and the temperatures that are comfortable during those times.

• Recommended winter settings are 68°F when at home and awake, 62°F when sleeping or away.

• Recommended summer settings are 78°F when at home, 82°F when away.

• Do not set your thermostat at a colder setting than normal or a warmer setting than normal. Lowering or raising the settings will not cool nor heat your home any faster and could result in excessive cooling or heating cost and, therefore, unnecessary expense.

• Do not place heat producing appliances near your air-conditioning thermostat. The thermostat senses heat from these appliances which can cause the cooling system to run longer than necessary or cause the heating system to turn off prematurely.

When the thermostat is satisfied the heating and cooling system fan will be turned off, thereby, spaces with greater exposure and more or less activity will heat up or cool down at a faster rate than other spaces. If you wish to maintain a more even temperature throughout the house set the fan switch to “On” for constant fan operation. With continuous fan operation the heating and cooling system will cycle on and off, dependant on your thermostat setting, and will provide a more even blend of your homes indoor temperature.

For your comfort, do not turn your heating and cooling system off when the home is unoccupied. When leaving your home set your thermostat no lower than the minimum and no higher than the maximum settings specified above. Your HVAC system is deigned and sized to handle the hourly BTU heat gain and heat loss of exterior surfaces, infiltration, occupants and miscellaneous equipment. When your HVAC system is turned off the mass of interior surfaces and materials rise, or lower, to the space temperature. Your heating and cooling system is not designed nor has the capacity to keep up with the instantaneous heat gain or heat loss in addition with a mass storage of internal heat gain or heat loss.

Air Balance

Air balancing your heating and cooling system plays a major role in maintaining even temperatures throughout your home. Air balancing is achieved through distributing the amount of air produced by the heating and cooling system fan, proportionate to the heating or cooling requirement of each space. 

Each room has a cooling air requirement and a heating air requirement, each being different from the other, depending on the room’s heat gain and heat loss. You have one thermostat to control the temperature of a multitude of spaces.  Since the air system cannot change automatically, your heating and cooling system air distribution system has been air balanced to the average air requirement of each space.

Example 1:        Cooling air requirement 150 CFM, heating air requirement 100 CFM, supply air register setting will be 125 CFM.

Example 2:        Heating air requirement 150 CFM, Cooling air requirement 100 CFM, supply air register setting will be 125 CFM. 

You may have rooms that will either over cool or over heat, and visa versa, depending on many factors i.e. Home orientation, wall surface exposure, window surface exposure, activity, and distance from the temperature controlling thermostat. A temperature variation of 4˚F from room-to-room is considered acceptable. To help maintain even temperatures throughout you home, do not close doors for extended periods of time.

Temperature conditions inside and outside the home change continuously with the sun angle, time of day and activities within the space. With changing conditions comes changing requirements for heating and cooling distribution. Your home has been balanced based upon the requirements of an average block load over time and conditions, therefore air balancing will not meet each and every condition.

If you notice a change or lack of air flow, please check your filter. A dirty filter can reduce and change the dynamics of your design air flow considerably.

Ultimately, you will be responsible to fine tune the air distribution system dependant on your personal requirements, your lifestyle and the season.

Indoor Relative Humidity

Humidity is the amount of moisture or water vapor in the air. You, your family, and your pets produce moisture when you breathe or perspire. Even your indoor plants produce moisture. Every time you or someone in your family boils a kettle of water, cooks, washes a load of dishes, takes a shower or bath, does laundry,  moisture is released into your home’s atmosphere. If your home is closed up, that moisture can build up to the point that condensation can occur.

Experts have developed rules of thumb to help homeowners make decisions regarding humidity levels in their houses. The limits should be used as guides only. Acceptable or comfortable humidity levels will actually vary from season to season, from house to house, and even between rooms in the same house.

Recommended indoor RH: 30% to 50%

Condensation that collects on your windows or other surfaces can eventually cause rot or mold. Condensation occurs when the indoor dewpoint temperature (the absolute amount of moisture in the air) is higher than the specific surface temperature. The colder the surface, the less moisture in the air it takes to cause condensation inside.

To keep window and surface condensation from occurring, it’s important to keep the indoor dewpoint lower than the window temperature.

• Heating, ventilation and air conditioning system(s) should remain on and in automatic operation at all times.

• Bathroom exhaust fans should be switched on during, and remain in operation for at least 30 minutes after bathrooms are used for bathing or showering.

• Laundry room exhaust fans should be switched on during, and remain in operation for at least 30 minutes after using washer and or dryer.

• Kitchen range hood exhaust fan should be switched on during, and remain in operation for at least 30 minutes after cooking.

• Do not seal off windows. Allow window surfaces, and air spaces between windows and window coverings, ventilation. If installing window blinds, provide a minimum 2” spacing between window sill and bottom of blinds, and do not close blinds totally closed.

• Clothes dryer venting needs to be checked on a regular basis to insure against built up of lint. Periodically remove the flexible vent connection and check that the discharge ducting is clear and free of debris. Check the outdoor discharge opening, verify that the discharge is clear and free of lint and debris. Make sure that the flexible vent ducting provides a free flow of air and is connected air tight to both the clothes dryer and vent connection.

General Maintenance

• Your heating, ventilation and air conditioning systems should be inspected and serviced at least twice a year by a qualified technician to insure proper and efficient operation. Once at the start of the heating season and once at the start of the cooling season.

• Dirty filters will reduce air flow and efficiency of your heating, ventilating and air conditioning systems. Air filters should be inspected and changed on a regular basis, preferably at least once a month or more. Filters will be generally located at your furnace or in your return air grille frame.

• Condensate drain lines off the cooling coil and safety pans should be inspected on a regular basis and be kept clear and free of debris to insure proper drainage.

• Cooling coils should also be inspected on a regular basis and cleaned when necessary.

• Outdoor unit condenser coils should be washed out and cleaned on a regular basis.

• Exhaust and makeup air fans should be checked on a regular basis to insure proper operation. Discharge outlets should be kept clear and free of debris.

Warranties

In order to maintain your contractor and manufacturer warranties it is the Homeowners responsibility to operate and maintain the heating, ventilating and air conditioning systems properly and in accordance with the manufacturer’s recommendations.

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Last modified: 03/23/11