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Lance Waterbarger's Fall Maintenance Secrets Heat Exchanger
Nashville Interstate AC Service's technician, Lance Waterbarger, reveals how he checks the heat exchanger in an 11-year-old York HVAC dual-fuel furnace in the basement of a customer's home. There is much talk these days about stainless steel heat exchangers and the customer was interested in knowing the type and condition of the heat exchanger.
During a fall maintenance check, the customer asked "Does this unit have a stainless steel heat exchanger?" Lance described ways to peer in to check. With the HVAC turned off, move the wires to get to the high limit sensor, and remove it, leaving a small hole. Using a camera, take a picture through the hole. Check to see if there are any cracks in the cells or if there are signs of rust. If so, pull out the blower motor and look up into the heat exchanger. Lance pulled out the high limit switch revealling a slot large enough to insert his iPhone. He took a photo which showed the heat exchanger is galvanized steel and is in good condition.
Why Checking the Heat Exchanger is so Important
Cool air from the return air ducts is forced by the blower to go past the heat exchanger where the air is heated up. The heat exchanger is the transfer point where heat from hot flue gases - but not the gasses themselves - warms your indoor air supply. The furnace’s heat exchanger heats up and cools down throughout each use. Being metal, it also expands and contracts during this process. Over time, this can cause splits or cracks in the unit due to metal fatigue. If the heat exchanger is cracked, deadly combustion gasses, such as carbon monoxide, could leak into the house. Carbon monoxide is odorless and colorless, and its accumulation inside the house could cause death to all occupants. In addition to dangerous health consequences, even small cracks in a heat exchanger can cause interior pressure changes, affecting how well the furnace burns, and how well your furnace heats. Just one more reason why fall maintenance checks are so important.