If your natural gas furnace was installed before 1995, it is very likely only 50-70% efficient. Furnaces after 1995 should be 78% efficient. It’s been only 2 years when the furnaces without pilot lights were introduced. They are up to 95% efficient and can reduce heating costs by up to 40%. This translates into a lot of dollar savings as gas prices have tripled in the last 10 years.
Condensing Furnaces – produce up to 95% AFUE (Annual Fuel Utilization Efficiency) efficiency – they are very energy efficient. The main components are:
- HEAT EXCHANGER: high efficiency furnaces use primary exchanger with 80% efficiency plus a secondary heat exchanger with 15% efficiency.
- FAN SECTION: Often a conventional furnace fan’s AC motor is the largest consumer of electricity in the household. Some newer furnaces use variable speed DC motors which only use about half of the AC motor electricity. (They offer good & quiet performance and high-efficiency: A variable speed motor costs only as much as a 75watt light bulb to operate.
- GAS SECTION: Multi-stage heating: 2-stage or fully-modulating gas valve (clearly better than the old on/off valves). hot-surface ignition is used instead of a pilot light.
- VENTING: new high efficiency furnaces use two-pipe system – brings all the combustion air into the furnace from outside and exhausts the burned gases outside. This does not put the house under a negative pressure and stops conditioned air being used for the combustion process. Houses are vented by means of plastic pipe through the side of the home – PVC 636 or grey CPVC 636 to be used.
- CONTROL SYSTEMS: electronic controls constantly monitor and control system operation; they display a failure code for easy diagnostics of a problem
Note on WARRANTY: make sure you have a 7-10 year warranty + transferable onto a new house owner + some provide free furnace replacement if heat exchanger fails within 10 years
