Regarding your post, Every technician performs a maintenance differently. Today's modern furnaces really don't require as much maintenance as older style systems did. For instance: Older furnaces had drive belts, pulleys and motors with oil ports.Today's blowers are direct drive no belts, no pulleys, sealed bearing motors no oiling required. All of the new modern technology cuts the maintenance time in half if not more. Today's equipment has multiple safety's in place so that in case of a failure the system will shut down. non serviceable control boards or (Brains) monitor system functions. Unlike oil systems, the maintenance on a gas system can possibly be completed in less than half the time. I'd say 20 to 30 minutes is about right unless a service issue arises. In the 30 minute time span, the doors can be removed, system components can be visually inspected, the flame can be inspected and co test can be performed for spillage and vacuum of the combustion area can be performed if needed. The air filter should be checked and the humidifier can be activated. Remember that probing into a perfectly functioning system can be detrimental to its lifespan. My advice is change you air filter, keep the area around the equipment free of dust and try not to store in close proximity to the heating plant. Be sure you have an updated quality carbon monoxide detector in your home. Regarding the crack in your heat ex-changer, If the heat ex-changer had a crack in it, the system it should have been shut down right then and there. Be aware that Carbon monoxide may be entering your living space due to that crack. Have a knowledgeable company come back and do a CO test in your home at the supply vents and use a scope to check your heat ex-changer for cracks. I hope this helps you. Bottom line, you have to trust the company that you are using. If you feel uncertain about their capabilities, then more than likely, you instinct is correct. Good Luck to you.. Happy Holidays
AAA Heating and Cooling has been the leader in residential and commercial furnace installation, heating services and air conditioning repair for thousands of clients throughout Portland, Beaverton, Hillsboro, Lake Oswego and the surrounding areas for over half a century. As a family-owned Portland, OR business, we offer a variety of services, including the installation of home heating and air conditioning systems, AC and furnace service and repair, duct cleaning as well as a variety of commercial heating and cooling solutions.