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A home’s Heating, Ventilating, and Air Conditioning (HVAC) system is very important in providing comfort to the residents. In Michigan, it keeps us warm in the winter and cools in the summer. 98% of the HVAC systems here are gas forced air furnaces and electric central split air conditioning systems. A poorly functioning HVAC system can cause the home to become inhabitable until the system is repaired or replaced. Properly maintained, HVAC systems can last for years. Changing air filters as needed is most important. It’s just like changing oil filters during an oil change. Many landlords change the air filters themselves because their tenants cannot be counted on to change them as needed. I have three HVAC systems, I change or clean the filters as needed. They range 7-28 years old and they all work well. Having seen thousands of HVAC systems over the years, I know what a good system is as well as informing the buyers: “Budget for replacement” is the term I use for older systems.

What does a home inspector look for in HVAC systems? We remove cabinet covers, look at the furnace, thermostat and the distribution system. Where present, we look at the exterior A/C compressor, A/C coils above the furnace, filter, humidifier, water supply pipes, vent pipe, and the condensate pump. We comment on any defects. We run the HVAC systems, with certain restrictions. Air conditioning (A/C) systems cannot be run when the temperature is below 65° due to possible damage. Certain hot water heating, steam, and electric radiant heat systems cannot be operated when the temperature is extremely high.

If the temperatures are favorable, we run the A/C system first. We let it run for at least 15 minutes, I go to the highest level of the house with my infrared thermometer and we measure the supply air temperature. If the system is designed and working properly the supply air temperature will be in the mid to upper 50s. Anything higher we comment by having “…a qualified HVAC contractor further evaluate…”.

We turn the thermostat to heat and raise the temperature. We listen to the system starting up and will comment on any strange sounds. We have a carbon monoxide (CO) detector to detect any measurement of CO. We look at the electric and gas supply lines. Comments are made when something is not operating or is damaged. Common defects are a dirty air filter and a dirty humidifier.

HVAC systems can be divided into two categories: fast acting and not so fast-acting. Generally, gas fired forced air furnaces and central A/C systems are fast-acting. Different comfort levels throughout the day can be programmed into the system thermostats. No need to run it when it is not needed. Generally, gas-fired hot water, steam, and electric radiant heat systems are not so fast-acting. These systems are turned on at the start of the heating season and stay on until the heating system is over. There is no thermostat programming with these systems.

There is no home inspector in Michigan who has seen enough geothermal or oil-fired systems to be an expert, not enough exist here. When we find these systems we still run the system and comment on any defects.

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