When a furnace maintenance is performed a combustion analysis should be performed to identify any problems that couldn't be found by a visual inspection. You want to know what the Carbon monoxide level your furnace is producing as well as the oxygen/CO2 levels and stack temperate. The analyzer will also give you a calculated efficiency rating with the information the analyzer receives. You should have >100ppm of Carbon monoxide output during normal operation of your gas furnace. When you have higher numbers or CO numbers increasing during operation their is a problem with the furnace the technician should then find the cause of. This is just a brief explanation I'm trying to get across to those who get their furnace maintained and to those who don't! Check to see if anyone in the company has a NCI certification for carbon monoxide/combustion analysis.
Furnace Service Company
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.