Pippin Brothers, an Oklahoma provider of heating system repair services, notes on its website that furnace problems are often caused by something other than the furnace itself. Among the most common furnace problems are a failure to heat up, not producing enough heat or higher energy bills. Some of these issues can be easily fixed by a homeowner, others will require expert intervention.
If your furnace fails to heat properly, it could simply be that the thermostat isn't correctly set. You can fix that by ensuring that the thermostat is turned to the "heat" setting, Pippin Brothers notes. It is also a good idea to check your circuit breaker to ensure it hasn't tripped. Pilot light problems, however, should be examined by an HVAC expert. Dirty air filters can inhibit the flow of heat through your home; this can be prevented by changing the filters every three months.
Energy Savers notes on its website that retrofitting an old furnace can improve its efficiency and lower your energy bills. However, a retrofit might not be ideal if your furnace is near the end of its 15- to 20-year lifespan. If you do opt to have your furnace retrofitted, recommended upgrades include installing a programmable thermostat and, for forced-air systems, upgrading the duct work. Other retrofits are specific to furnace types, such as gas-powered or oil-powered.
According to Pippin Brothers, a lack of proper maintenance is the "biggest culprit" with respect to furnace problems. An expert cleaning once a year will help your furnace run more efficiently, in turn saving you money. Upgrading a furnace is an option if the unit is 15 or more years old. While the initial expense can be high, the savings over time can make it a worthwhile investment, Energy Star reports.