Heating and air conditioning systems have evolved quite a bit in the past decade or so. Inspecting heating and air conditioning has become both easier and more complex with the current trends of higher efficiency and reduction of carbon footprint. It is easier because units are more compact and better designed; more complex because there are additional issues, such as draining condensate, and more numerous options regarding venting and air exchange. There has also emerged a kind of offshoot house inspection service, focused less on facilitating transfer of real estate and more on auditing for energy use and air quality.

Heating, having borrowed air conditioning technology in a sense, is today more significantly different from a decade ago. Using coal, oil, or wood to heat homes is fast becoming obsolete, and the efficiency of both electric- and gas-based furnaces has improved dramatically. Heat pumps, essentially air conditioners in reverse, are much more in fashion. Size has diminished despite elongated heat exchangers for increased efficiency, and venting sideways through the wall is perhaps replacing venting through the roof.

Fundamental Heating and Air Conditioning Concepts

To provide satisfactory inspection services, one must understand the basic operational concepts of these two systems. Traditional heaters work on the principle of increasing sensible heat (changing temperature without changing state) with burners and then dispersing it throughout the target space. Centralized systems use blowers, ducts, and registers to facilitate dispersal. Air conditioners, on the other hand, work on the principle of latent heat, which has more caloric power than sensible heat, but is limited in range. This limitation is usually sufficient for cooling purposes, but the desired range for heat pumps often exceeds what they can produce, requiring a source of backup heat.

When air conditioners are centralized, they often reuse the heater’s blower and distribution. However, cool air is denser than warm air, requiring larger distribution ducts for the same volume. This can be an issue when existing furnaces are retrofitted to accommodate a new cooling system, and is one reason inspectors pay attention to duct size. Other concerns are capacity of the systems, measured in BTUs, and whether the space provides enough draft and/or combustion air to function to capacity. Inspectors also look at complementary aspects such as insulation and condensation control. They might, for instance, point out that electric-powered heaters require roughly twice the insulation of gas-powered ones for equivalent comfort levels.

Servicing Heating and Air Conditioning Systems

Inspecting heating and cooling systems is fairly straightforward and usually uneventful. I get manufacturer and serial number to determine age and life expectancy. I test thermostat control and measure temperature differentials. Almost universally I find that residents ignore the servicing of their furnace by a professional and are satisfied with changing or cleaning the filters every so often. I always recommend periodic servicing, and may suggest that my clients consider having a maintenance or warranty home inspection, particularly if they have high-efficiency units that require more monitoring.

Rarely do I find a problem with sufficient draft or combustion air or with there being enough volume of space surrounding a heat pump for it to operate properly. Sometimes soot stains will alert me to malfunctions with combustion or ducts. Sometimes encrusted frost on an evaporator coil or similar problems will signal the need for repair.

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