Homeowners today have an additional choice between a standard furnace and a high-efficiency model. Mid-efficiency furnaces now occupy the range between 80 and 90 percent on the AFUE (annual fuel utilization efficiency) rating scale. In an era of increasing energy costs, most homeowners want to advance from the conventional standard furnace when it’s time to upgrade. Here’s what’s available in the AFUE 80 and above range.
Mid-efficiency furnaces utilize conventional single-stage combustion but incorporate several recent advancements to get more energy savings out of the unit. The heat exchanger is larger and constructed for longer service life. Many mid-efficiency furnaces utilize induced draft combustion and, instead of a standing pilot light, also incorporate electronic ignition. Most also require venting into a ceramic or mortar chimney. In some cases, an existing chimney may need upgrading to accommodate the venting standard.
High-efficiency furnaces above AFUE 90 percent incorporate condensing technology to harvest surplus heat normally lost in combustion gases. A secondary heat exchanger extracts heat released as the gases condense. In addition, high-efficiency models utilize ECM (electronically commutated motor) blowers that run at variable speeds and use only about one-fifth the electricity of a conventional blower. A sealed combustion chamber draws all air for the burner from outdoors through a small inlet pipe, and the cooled combustion gases are exhausted through a similar pipe. The top of the efficiency pyramid – modulating furnaces – also incorporate multi-stage burners that vary output according to the heating requirements of the home.
The economics of choosing between a mid-efficiency and a high-efficiency furnace hinge on the length of the local heating season and the overall energy efficiency of the house. Long winters and an efficient structure are best-suited to provide enough energy savings to pay back the steeper upfront purchase price of a high-efficiency furnace above 90 percent AFUE over the expected service life of the unit.
Serving Dayton and Springfield homeowners since 1978, Ace Hardware Home Services, Inc. provides year-round heating and cooling sales and service. Ask us for more information about the available options for upgrading to a high-efficiency furnace.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems). For more information about furnaces and other HVAC topics, download our free Home Comfort Resource guide.
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