It can also be a health hazard. Technicians say a furnace inspection can reveal carbon monoxide leaks, which are hard to detect because the gas is colorless and odorless. Carbon monoxide can lead to headaches, dizziness, nausea and even death. An estimated 500 people die each year, and 15,000 people are taken to emergency rooms, because of exposure.
Inspect your furnace thermostat by first making sure that it’s turned on. Also, ensure that the thermostat switch is turned to “heat” and not “cool”. If your furnace will still not start with the thermostat on, try adjusting the temperature settings to a few degrees higher. Inspect any visible wires for breaks or splits, and make sure your thermostat batteries are not dead. Do not touch any open wires; contact a professional.
As a Carrier dealer, with a wide variety of products to choose from, we can keep your family healthy and feeling comfortable all year long. We carry a complete line of indoor comfort equipment with innovations that raise the standards of comfort and reliability, including air conditioners, heat pumps, gas furnaces, programmable thermostats, humidifiers, ductless split systems, air cleaners, ultra violet lights, ventilators and zoning products. Let the experts at A. Johnson Heating & Air help you customize a solution that's right for you.
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