The heating ventilating and air conditioning (HVAC) systems are a technical and critical part of any inspection. Like plumbing and electrical, the initial work should have been done by a licensed trade person. In the South, the air conditioning half of the system is almost always present as part of the central HVAC system. It is important to understand and inspect the HVAC components as a system. The HVAC components not only supply heating and cooling to the house, but they are also a critical part of the health of the home. We will discuss these aspects as we examine each HVAC component. It is also important for the inspector to be sure the customer is comfortable with the system’s function as the inspection proceeds. Remember, the customer may have never had air conditioning, gas heat, a heat pump heating system or replaced a furnace filter before. All these areas should be discussed with the customer to prevent future questions and relieve some buyer anxiety.
As standards dictate, the location of the HVAC units must be identified and the areas of the home that are supplied conditioned air by these units. For our discussions, “conditioned air” will mean circulated air that has either been heated or cooled. Depending on the size and layout of the house there may be one or multiple HVAC units. Each unit must be inspected. A determination should also be made on which part of the house each unit serves. Particular attention must be given to finished basements and additions. It is not uncommon for a finished basement to not be connected to a central HVAC system. This discovery can be unwelcomed information to a prospective buyer and more unwelcomed to the inspector if it was missed during the inspection. The air handling section of the HVAC system can be located in the attic, basement, garage, crawlspace, outdoors or in a closet. The location of these units can also provide a separate set of conditions that impact the operation of the units and the air supplied to living spaces. Consider the hot attic we talked about in a previous article or a wet crawlspace. We will discuss the health and operational aspects of these locations later.
For the ease of understanding we are going to discuss the heating and cooling functions separately. Many components, like the thermostat, are common to both the heating and the cooling cycle. It is the only HVAC control that should be needed to operate both functions of the system. Its operation, location and general condition should be considered. The thermostat may be the first indication the house has a heat pump heating system. Heat pumps may not always be able to keep the house warm during some of those cold January days when the sun is not shining and the wind is blowing. A thermostat for a heat pump system will have an additional setting called emergency heat. As the name implies, it is an added electric heater that can be used to supplement the heat pump during those times when the heat pump alone can’t quite keep the house at the desired temperature.
The type of fuel is also noted. In this part of the country the heating fuel is usually natural gas but could also be electricity or propane gas. Home heating oil or kerosene has been used in the past but most of those systems have been replaced with gas or electric heat. Remember our first article when we discussed the buried fuel tank in the yard? The gas supply piping to these devices also has to be inspected for proper installation and leaking.
The distribution of the conditioned air to and from the air handler section of our system is the area most apt to hide problems. In an ideal system, the same air gets recycled through the supply and return ducts. If ducts are not properly sealed, ambient air can be draw into the system. If the furnace is located in a hot attic or damp moldy crawlspace that air is being drawn into the system and delivered to the living space. Properly operating ducts and vents are important to the health of the house. In many cases where mold or high humidity is noted in the house the cause is an improperly operating HVAC system. The supply and return vents should also be checked to assure sufficient air flow. Duct work and metal plenums have to be checked for Asbestos. Using Asbestos tape to seal duct work was an accepted practice before the health effects were known.
With gas heating we also have to deal with combustion air and venting. Finishing a basement can result in enclosing the gas furnace. If specific accommodations have not been taken, the enclosed gas fired devise may not have sufficient air to support proper combustion. In some older homes with basements it is not uncommon to find a gas fired water heater and furnace in the laundry area, all of which has been enclosed. This is a double problem. Not only do we not have enough combustion air, when the clothes dryer starts, it takes air in the room, heats it, blows the hot air through the wet clothes and is blown outside. This can cause the furnace/water heater vent to back draft and draw combustion gases into the laundry room to replace the exhausted air. Not a good situation. Luckily, most combustion air deficiencies can be easily and inexpensively corrected. Talk it through with the inspector.
The type, location and condition of the system’s air filter also have to be noted. Air filters have to be replaced or washed periodically. A clogged filter can slow air movement that greatly affects the efficiency of the unit. If sufficient air does not flow over the air conditioning coil, the A/C unit can freeze and stop working. Standards also require the inspector to note the age, size of the furnace and its general condition. The inspector has to note excessive rust, neglect and the general operating condition of the units. It is the results of these observations that may prompt the inspector to recommend service by a qualified HVAC technician.
The air conditioning components are located outside and in most cases on the top of the furnace. The size and age of the outside unit has to be determined along with its general operating condition. The A/C unit because of its function, removes humidity from the inside air. Keeping the interior at the proper relative humidity is essential to preventing mold growth in this climate. It is in this role that the A/C unit plays an important part in the health of the home and its occupants. Not all home inspectors may be trained for this type of analysis.
The adequacy of the A/C units cannot always be determined but the inspector can produce a rough estimate of recommended A/C tonnage based on the amount of square footage being supplied with conditioned air. Care must always be taken when finished basements are connected to the central HVAC system. Was the size of the basement furnace and A/C system sized to accommodate the finished basement or was some of the conditioned air simply stolen from the unit only sized to cool the first floor? During colder times of the year the inspector will not turn on the A/C function for fear of the cold damaging the unit. As with the heating components, the general condition and operating condition will determine if the units need servicing.
The next article will deal with the Interior and our search for clues to structural issues.
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