9
7. The stack should be installed in such a manner that access to the appliance is not
obstructed. Do not support the weight of the stack on the flue connection of the heating
section.
8. Approved methods must be followed when putting the stack through walls, floors, roofs,
etc.
9. Any exhaust stack shall have a minimum of at least 36" clearance to combustible
material.
10. The pressure measured with a manometer at the test port in the burner compartment
must not exceed the "Maximum Overfire Positive" pressure on positive fired duct
furnaces.
11. Gravity Venting Adjustment: The flue draft should be adjusted at the damper of the
burner fan when the duct furnace is operating on high fire.
12. Power Venting Adjustment: The flue draft should be adjusted at the damper of the
induced draft (I.D.) fan when the duct furnace is operating on high fire.
2.8 Gas Installation
FOR YOUR SAFETY
Do not store or use gasoline or other flammable vapors and liquids in the
vicinity of this or any other appliance.
1. Installations must be in accordance with the requirements of authorities having
jurisdiction. Emergency manual shut down valve should be provided upstream of piping
to duct furnace and labeled for quick identification. Color-coding of pipe may be required
and is recommended. Carefully check the duct furnace rating plate for the fuel type,
supply pressure and input rating.
2. Gas supply pressure, higher than 14"w.c. (3.5kPa), requires an additional field installed
gas regulator. Install the high-pressure gas regulator and relief valve (if supplied), in the
gas line to the duct furnace. The high-pressure regulator and relief valve should be, if
possible, mounted at least 5 to 10 feet upstream from the appliance regulator on the
duct furnace. Run the gas line to the duct furnace and mount these items so as not to
interfere with or hinder access to the duct furnace or any of its components.
3. The gas line to the duct furnace should be taken off the top of the main gas line. An
approved drip leg with screwed cap should be installed at the bottom of the vertical drop
in the gas line to the duct furnace.
4. If not provided with vent limiters, vent the main gas appliance regulator, the pilot
regulator, and the gas pressure switches to the outdoors. The high-pressure regulator
relief valve and normally open vent valve (if supplied) must be vented to atmosphere
separately from all of the components in accordance with applicable codes. Vent lines
should terminate outside the building with a turndown elbow and fly screen.
