Maximizing temperature differences

Heating · Mid- and High-Efficiency Furnaces · printed page 133 (PDF page 134)

Book index entries

Gas – Maximizing Temperature Differences Gas Furnace – Maximizing Temperature Differences High Efficiency Furnace – Maximizing Temperature Differences Maximizing Temperature Differences in High Efficiency Gas Furnaces Temperature Differences in High Efficiency Gas Furnaces Condensing Gas Furnaces Furnace – Condensing Gas Furnace – Condensing

Text in the illustration

in most high efficiency furnaces, heat is transferred from the coolest exhaust products to the coolest house air
this maximizes the temperature differential from beginning to end of the heat exchanger for the best flow of exhaust gases and also maximizes heat transfer to the house air
supply plenum
combustion air
hot house air
primary heat exchanger
exhaust gases
exhaust vent
secondary heat exchanger
cool house air
house air blower
induced draft fan

Generated explanation

The illustration shows a high-efficiency gas furnace with a burner, serpentine primary heat exchanger, secondary heat exchanger, and house air blower below. Arrows trace combustion gases through the primary exchanger and then through the secondary exchanger to an induced draft fan and exhaust vent. Cool house air encounters the secondary heat exchanger first, then passes upward over the primary exchanger toward the hot-air supply plenum. This arrangement places the coolest exhaust products next to the coolest house air to maximize temperature differences and heat transfer along the heat exchanger path. A separate downward arrow identifies combustion air entering near the burner.

Components

gas burner primary heat exchanger secondary heat exchanger house air blower induced draft fan exhaust vent combustion air inlet supply plenum furnace cabinet