What Differentiates Condensing Gas Furnaces
Posted on January 2, 2014
If your Wichita-area home is 15 years of age or older, it’s likely due for a furnace replacement. You may be pleasantly surprised, however, at recent, more energy-efficient innovations. For example, condensing gas furnaces are radically different from older technology. They are extremely efficient, saving you money while also preserving natural resources. Here’s how they work:
Dual Heat Exchange
Condensing gas furnaces have two heat exchangers, wringing every last bit of thermal energy from combustion. The first heat exchanger transfers heat from burning fuel to the air blowing through ducts in your Kansas home. The second heat exchanger captures exhaust gas heat, transferring it to the airflow. This can take furnace efficiency up to 98 percent—a substantial step up from 20-year-old furnaces that may have only achieved 60 percent efficiency.
The Sum of Its Parts
Condensing gas furnaces have additional advanced technology that earns high AFUE (Annual Fuel Utilization Efficiency) ratings:
- Electronic ignition—This eliminates the pilot light, reducing fuel consumption.
- Variable-speed blower motor—By running slowly but nearly full-time, the blower circulates warmed air continuously and efficiently.
- Dual-vent pipes—One vent is for fresh air intake, the other is for exhausting the condensing gases
- Dual-stage burner gas valve—Two settings allow different capacities for low and high heat demand.
- Heat recovery ventilator (HRV)—This is a useful option, apart from your furnace, to recover heat from return air ducts, mix it with incoming fresh air, and send the mix into the furnace.
Cautions and Contractors
A trustworthy HVAC contractor will not take shortcuts when installing condensing gas furnaces. Such advanced technology does not lend itself to seat-of-your-pants installation. Precise sizing is critical, for example.
Since wringing heat (energy) from exhaust gases condenses the gas back into liquid (and since the liquid is acidic), the vent for exhaust gases cannot run into your existing chimney. Instead, the stainless steel exhaust pipe should pitch upwards to an outside wall, so the condensate can drain back into the furnace and down to a condensate drain line. This line must run to a drain in your home.
For more information on what differentiates condensing gas furnaces, or gas furnace repairs contact us at Comfort Systems.