When a furnace is not designed correctly, it loses or wastes heat and thus requires more energy to keep your home warm. Some furnaces will lose heat through the walls of the furnace cabinet. Energy-efficient furnaces, such as Ruud's full line of state-of-the-art models, will significantly reduce this loss thanks to a blanket of insulation that lines the inside of the cabinet walls.
When most gas furnaces are not in operation, they usually send a steady, wasteful draft of warm household air traveling up the venting system and out the roof. The Ruud Classic® Series and Classic® Plus Lines, with AFUE ratings of 78% and better, feature an induced-draft blower that works in conjunction with a hot surface ignition system.
What this setup does is pull hot gases through the heat exchanger at a constant and controlled rate of flow. As the burner cycles off, the draft blower stops and thus keeps the heated air in the system.
Pilot lights also can waste energy. The electric ignition in many of Ruud's furnaces eliminates the need for a pilot light that constantly burns. This feature alone provides up to 6% higher efficiency. This, in combination with an induced-draft blower, can improve the efficiency of the furnace by over 20%.
Most gas furnaces expel combustion by-products and gases by allowing the warm air to naturally rise. However, on occasion, proper venting of combustion by-products may be limited due to blockages, deteriorated venting systems, malfunctions, or other causes.
The Ruud induced-draft blower maintains a constant draft through the heat exchanger. This assures proper venting of the furnace combustion chamber at all times. Ruud also features a pressure switch which continuously monitors venting. In the event it senses a vent flow restriction, it will automatically shut down the heating system for your safety.
The most efficient furnaces tap the energy of the hot vent gases, which can reach temperatures of 500 degrees Fahrenheit or more. The Ruud Classic Series® 2-Stage 90 Plus gas furnace does this by routing hot gases through a secondary heat exchanger. This step captures the otherwise wasted heat. It is used to preheat the household air and delivers AFUE ratings of up to 95%.