Anthony Perry's Inspections checks every furnace. Most home inspectors can not see the complete heat exchanger and we will advise you to have the heat exchanger check by a contractor if we see any rust. If there is a crack in the heat exchanger it will let carbon monoxide into the home. If this happens we advise you to have the furnace replaced. Only about 30% of a home's heating system is reviewed by the local gas provider if they are called out for a seasonal start-up. This leaves 70% of the review of the heating system to the homeowner or possibly to untrained personnel.
Heater venting systems are a major concern every winter in every part of the country. During earthquakes, like the ones in Southern California, vent systems can become separated, especially the horizontal connector pipes associated with floor furnaces, allowing the potential for fire, or fumes to escape in unwanted areas possibly resulting in illness, fire or even death.
Floor furnaces can be dirty, prohibiting combustion air needed to allow for proper flame causing soot and the potential for aldehydes and allowing CO into the home.
If the property you are considering has a floor furnace be sure to ask the home inspector to fully review the vent system under the house.
Forced air heating units atop roofs may have loose or leaking gas lines A homeowner may not realize there is a problem even though there may be higher gas bills. Roof mounted units may have damaged supports or other related problems.
Forced air heating units mounted in closets can be another potential for problems. Units today are required to be secured and mounted over the return air hole and tightly sealed. If not properly placed and caulked this will interfere with the flow of natural combustion air affecting the flame and cause venting gases, or carbon monoxide, to flow into the home via the ducts. Some closets furnaces were found to have shifted up to four inches off the return air hole after the Southern California earthquakes. Heater compartment (or closet) doors need to be sealed and should latch tightly if the return air register is within 10 feet of the door. Upper and lower combustion air openings located inside the closet should be clear of debris and obstructions, allowing combustion air to flow. Obstructions such as insulation can inhibit proper air flow causing the heater to burn improperly. Missing fire blocks below the lower combustion air vents can allow the venting process to reverse causing , again, the heater to burn improperly and vent gases and aldehydes into the home through the ducting system.
Wall furnaces have a high potential for cracks in the heat exchangers. Ask your home inspector to review closely with a mirror and flashlight. The home inspector cannot always see a crack in a heat exchanger but may be able to locate those that are visible or suspect. The unit may need to be cleaned before lighting the pilot. You may also wish to ask the home inspector to review carefully the venting system in the attic crawl spaces when the inspector checks this area.
Watch out for the home which has been occupied by the same owner for years. The heating system may not meet today's safety standards and would typically, after and inspection by the gas supplier, be "red-tagged" until replaced or repaired. This could be uncomfortable for a new homeowner if the weather is extremely cold and the repair cost is out-of-pocket.
The Gas Company or provider usually offer a no-charge safety inspection to their customers. It is highly recommended to have this performed regardless if you had the home inspected. A diligent inspection of the heating system, venting system, and a careful review of heat exchangers can possibly save a life or prevent loss by fire.
Remember, even if you have a home inspection get the furnace cleaned, serviced by certified by a Professional Contractor. The heat exchanger is hidden and a home inspector can not see the complete heat exchanger unless it is taken apart or special equipment is used. Have the furnace cleaned and checked every year. The image below shows why a home inspector would have a herd time inspecting a heat exchanger, Remember if the heat exchanger should rust out then you will have carbon monoxide in the home. "Do Not Take Chances" Install a Carbon Monoxide Detector in you home.