Footprint (inches): 17.5, 21, and 24.5 (w) by 40 (h)
Serviceability features: System Sentryâ„¢ control board features self-diagnostics and a nonvolatile memory to retain the last five trouble codes even when power is interrupted. Large, 1.5-inch blower door sightglass makes viewing diagnostics easier, the company says. Slide-out blower makes cleaning and service quick. Accessible igniter and flame sensor help simplify service and inspection. Can be installed as two-pipe system, bringing combustion air in from outdoors.