Installation and Maintenance Manual

Installation: Piping
24 GTND-SVX01B-EN
Category I
Includes non-condensing appliances with negative vent
pressure, like the traditional atmospheric unit heater.
Category II
Groups condensing appliances with negative vent
pressure.
Category III
Appliances are non-condensing and operate with a
positive vent pressure.
Category IV
Covers condensing appliances with positive vent
pressure.
Note: Category II and IV do not apply to equipment
specified within this manual.
When an existing heater is removed or replaced in venting
system, the venting system may not be properly sized to
vent the attached appliances. An improperly sized vent
system can cause formulation of condensate or leakage or
spillage of flue gases.
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 in the National Fuel Gas
Code, ANSI Z223.1 and these instructions. Determine
that there is no blockage or restriction, leakage,
corrosion and other deficiencies, which could cause an
unsafe condition.
3. Insofar as practical, close all building doors and
wi
ndows and all doors between the space in which the
appliance(s) connected to the venting system are
located and other spaces of the building. Turn on
clothes dryers and any exhaust fans, such as range
hoods and bathroom exhausts, so they shall operate at
maximum speed. Do not operate a summer exhaust
fan. Close fireplace damper.
4. Follow the lighting instructions. Pla
ce the appliance
being inspected in operation. Adjust thermostat so
that the appliance will operate continuously.
5. After it has been determined that e
ach appliance
connected to the venting system properly vents when
tested as outline above, return doors, windows,
exhaust fans, fireplace dampers, and any other gas-
burning appliance to their previous condition of use.
6. If improper venting is observed during any of the
a
bove tests, the venting system must be corrected
immediately so that the system conforms with the
National Fuel Gas Code, ANSI Z223.1. When resizing
any portion of the venting system, the venting system
should be resized to approach the minimum size as
determined using the appropriate tables in
Appendix G of the National Fuel Gas Code, ANSI
Z223
.1.
The unit heater shall be connected to a factory built
c
himney or vent complying with a recognized standard, or
a masonry or concrete chimney lined with a lining material
acceptable to the authority having jurisdiction. Venting
into an unlined masonry chimney is prohibited.
The following guidelines apply to all categories to follow:
Do not damper or add heat recovery devices to the flue
piping. Failure to open such a damper prior to operating
the gas unit heater will result in the spillage of flue gas into
the occupied space.
Avoid installing units in areas under negative pressure.
When required, a flue vent fan should be installed in
accordance with the instructions included with the fan.
Vent connectors serving Category I and Category II
heaters shall not be connected into any portion of
mechanical draft systems operating under positive vent
pressure.
Maintain 1-inch (25.4-mm) clearance between the vent
pipe and combustible materials.
Table 5. All unit sizes: Venting categories
Non Condensing Condensing
Negative Vent Pressure I II
Positive Vent Pressure III IV
Table 6. Unit sizes 30–120: Vent systems termination
clearance requirements
Structure
Minimum for
Termination Locations
Door, window or any gravity vent inlet
4 feet below
4 feet horizontally
1 foot above
Forced air inlet within 10 feet 3 feet above
Adjoining building or parapet 6 feet
Adjacent public walkways 7 feet above grade
Electric, gas meters & regulators 4 feet horizontal