Mechanical Requirements; Duct Connections; Gas Pipe Sizing - Trane FADA Installation & Operation Manual

Duct Connections

Horizontal Discharge Units Only (Model
FAHA)
When attaching ductwork to a horizontal
discharge unit, provide a watertight
flexible connector at the unit to prevent
noise transmission from the unit into the
ductwork. Refer to the Dimensions and
Weights section on pages 13–23 for the
supply air and return air opening
dimensions. All outdoor ductwork
between the unit and the structure should
be weather proofed after installation is
complete.
WARNING!
Hazardous voltage!
Disconnect electrical power source
and remote disconnects before
servicing unit. Failure to do so may
cause death or injury.
WARNING!
Disconnect gas supply!
Before servicing unit, FIRST turn off
the gas supply. Failure to turn off the
gas supply can cause death or serious
injury.
Ductwork Considerations
Install all air ducts according to the
National Fire Protection Association
standards for the "Installation of Air
Conditioning and Ventilation Systems
other than Residence Type (NFPA 90A)
and Residence Type Warm Air Heating
and Air Conditioning Systems (NFPA
90B).
Make duct connections to the curb with a
flexible material such as heavy canvas. If
a fire hazard exists, Trane recommends
using Flexweave 1000, type FW30 or
equivalent canvas. Use three inches for
the return duct and three inches for the
discharge duct. Keep the material loose
to absorb unit vibration.
Run the ductwork as far as possible
without changing size or direction. Do not
make abrupt turns or transitions near the
unit due to increased noise and excessive
FAXA-SVX01B-EN
Installation
static losses. Use elbows with splitters or
turning vanes to minimize static losses.
Poorly constructed turning vanes may
cause airflow generated noise. Check
total external static pressures against fan
characteristics to be sure the required
airflow is available throughout the
ductwork.

Gas Pipe Sizing

Follow the procedure below to size the
gas piping to adequately provide gas
pressure at the gas heater.
1. Find the cu ft/hr by using the formula:
cu ft/hr = Btu/cu ft.
2. Refer to Table I-MR-1. Match "Pipe Run
in Feet" with appropriate "Gas Input -
Cu Ft/hr" figure. Match this figure to the
pipe size at the top of the column. For
example, requires 67 ft (20.4m) run of
gas pipe to connect a 200 MBh gas duct
furnace to a 1,000 Btu/cu ft (0.29) kW)
natural gas supply.
200,000 Btu/cu ft
1,000 Btu/cu ft = 200 cu ft/hr
Using Table I-MR-1, a 1" pipe is needed.
Before making any connections to
GAS
SUPPLY
LINE
3" (76 MM)
MIN.
DRIP LEG
Figure I-MR-1. Gas pipe connection
mechanical
requirements
existing line suppling other gas appli-
ances, contact the local gas company to
make sure existing line is adequate size
to handle the combined load.
Gas Pipe Installation Procedure
1. Install the gas piping in accordance with
applicable local codes.
2. Check gas supply pressure. Each gas
heater must be connected to a gas
supply capable of supplying its full rated
capacity at a pressure not less than 5"
w.c. (1.62 kPa) nor greater than 14" w.c.
(0.5 psi) for natural gas. Size and install
all gas piping in accordance with ANSI
Standard Z223.1-1992 (or latest edition)
National Fuel Gas Code. In Canada, gas
piping should be according to CAN/CGA
B149. See Table I-MR-1 for correct gas
supply piping size. If gas pressure is
excessive on natural gas applications,
install a pressure regulating valve in the
line upstream from the main shutoff
valve for each independent heater.
3. Adequately support the piping to
prevent strain on the gas manifold and
controls.
4. To prevent the mixing of moisture with
gas, run the takeoff piping from the top,
or side, of the main.
A MANUAL SHUTOFF VALVE WITH
1/8" N.P.T. PLUGGED TAPPING,
ACCESSIBLE FOR TEST GAGE
CONNECTION MUST BE INSTALLED
UPSTEAM OF THE GAS SUPPLY CONNEC-
TION TO THE APPLIANCE.
GROUND JOINT UNION
TO CONTROLS
PLUGGED 1/8" N.P.T.
TEST GAGE CONNECTION
33