8
NOTE:
In addition to the required clearances to combustible materials, a minimum of 24 inches service clearance must be available
in front of the unit.
TOP
BOTTOM
SIDE
SIDE
SIDE
TOP
BOTTOM
Upflow
Counterflow
Horizontal
Figure 1
A furnace installed in a confined space (i.e., a closet or utility room) must have two ventilation openings with a total minimum free
area of 0.25 square inches per 1,000 BTU/hr of furnace input rating. Refer to Specification Sheet applicable to your model for
minimum clearances to combustible surfaces. One of the ventilation openings must be within 12 inches of the top; the other opening
must be within 12 inches of the bottom of the confined space. In a typical construction, the clearance between the door and door
frame is usually adequate to satisfy this ventilation requirement.
E
XISTING
F
URNACE
R
EMOVAL
NOTE:
When an existing furnace is removed from a venting system serving other appliances,
the venting system may be too large to
properly vent the remaining attached appliances.
The following vent testing procedure is reproduced from the
American National Standard/National Standard of Canada for Gas-
Fired Central Furnaces ANSI Z21.47, CSA-2.3 latest edition Section 1.23.1.
The following steps shall be followed with each appliance connected to the venting system placed in operation, while any other appliances connected to the venting
system are not in operation:
1. Seal any unused openings in the venting system.
2. Inspect the venting system for proper size and horizontal pitch, as required by the National Fuel Gas Code, ANSI Z223.1
or the Natural Gas and Propane Installation Code, CSA B149.1-05 and these instructions. Determine that there is no
blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.
3. As far as practical, close all building doors and windows and all doors between the space in which the appliance(s)
connected to the venting system are located and other spaces of the building.
4. Close fireplace dampers.
5. Turn on clothes dryers and any appliance not connected to the venting system. Turn on any exhaust fans, such as range
hoods and bathroom exhausts, so they shall operate at maximum speed. Do not operate a summer exhaust fan.
6. Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so appliance shall
operate continuously.
7. Test for spillage from draft hood appliances at the draft hood relief opening after 5 minutes of main burner operation.
Use the flame of a match or candle.
8. If improper venting is observed during any of the above tests, the venting system must be corrected in accordance with
the National Fuel Gas Code ANSI Z223.1/NFPA 54 and/or National Gas and Propane Installation Code CSA B149.1-05.
9. After it has been determined that each appliance connected to the venting system properly vents when tested as
outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas burning appliance to their
previous conditions of use.
