The Goodman brand GDS8 Multi-Speed Gas Furnace provides effective home heating at an affordable price. Energy efficiency is key to controlling the cost of heating your home. This furnace's 80% AFUE rating means 80 cents of every $1. 00 of heating energy expense warms your home. Some older central heating systems rate at 60% AFUE, meaning only 60 cents of every $1. 00 of heating energy expense warms your home. The remaining 40 cents is lost energy wasteful and expensive. The heart of any furnace is the heat exchanger. Our aluminized-steel tubular heat exchanger has been tested to industry standards. Your Goodman brand GDS8 Gas Furnace uses a multi-speed blower motor and sound- isolated blower assembly to reduce the noise levels common in other furnaces without these features. Add an insulated, heavy-gauge steel cabinet and the result is quiet comfort. The Goodman brand GDS8 Furnace models are designed to minimize nOx emissions.