Air For Combustion; Checking The Draft - A.O. Smith FPS 75 Technical Information

FPS/FPSE/FPD TECHNICAL TRAINING AND SERVICE WORKBOOK
AIR FOR COMBUSTION
Checking for
Draft
On initial start up, check for the correct draft on the Power Shot. To check the
draft, place a smoke stick directly in front of the inlet air damper while the heater
is firing. A properly operating system will draw the smoke into the inlet air damper
as shown in the right illustration. The illustration on the left shows a negative
To check for a negative condition close all windows, outside doors, and fireplace
dampers. Turn on all exhausting appliances, including kitchen draft hoods,
clothes dryers, furnaces, bathroom vents, etc. Open all inner doors between
these appliances and the Power Shot.
Once all appliances are on and inner doors open, open the inlet air damper on
the Power Shot when the heater is not firing. Using your hand, check for air
movement. If air is being blown back into the room, a negative pressure condition
exists.