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Installation
WARNING
Hazardous Gases and Flammable
Vapors!
Failure to observe the following instructions could
result in exposure to hazardous gases, fuel
substances, or substances from incomplete
combustion, which could result in death or serious
injury. The state of California has determined that
these substances may cause cancer, birth defects, or
other reproductive harm.
Improper installation, adjustment, alteration, service
or use of this product could cause flammable
mixtures or lead to excessive carbon monoxide. To
avoid hazardous gases and flammable vapors follow
proper installation and setup of this product and all
warnings as provided in this manual.
WARNING
Explosion Hazard!
Failure to properly regulate pressure could result in a
violent explosion, which could result in death, serious
injury, or equipment or property-only-damage.
When using dry nitrogen cylinders for pressurizing
units for leak testing, always provide a pressure
regulator on the cylinder to prevent excessively high
unit pressures. Never pressurize unit above the
maximum recommended unit test pressure as
specified in applicable unit literature.
Access holes are provided on the unit as illustrated in to
accommodate a side or bottom pipe entry on 20–75 ton
units and in on 90–130 ton units.
Following the guidelines listed below will enhance both the
installation and operation of the furnace.
Note: In the absence of local codes, the installation must
conform with the American National Standard Z223-
1a of the National Fuel Gas Code, (latest edition).
1. To assure sufficient gas pressure at the unit, use
14, p. 41
as a guide to determine the appropriate gas
pipe size for the unit heating capacity listed on the unit
nameplate.
2. If a gas line already exists, verify that it is sized large
enough to handle the additional furnace capacity
before connecting to it.
3. Take all branch piping from any main gas line from the
top at 90 degrees or at 45 degrees to prevent moisture
from being drawn in with the gas.
4. Ensure that all piping connections are adequately
coated with joint sealant and properly tightened. Use a
piping compound that is resistant to liquid petroleum
gases.
5. Provide a drip leg near the unit.
6. Install a pressure regulator at the unit that is adequate
to maintain 7" w.c. for natural gas while the furnace is
operating at full capacity.
40
Important: Gas pressure in excess of 14" w.c. or 0.5
Gas Valve Damage!
Failure to follow instructions below could result in
gas valve damage from incorrect gas pressures,
irregular pulsating flame patterns, burner rumble, and
potential flame outages.
Use a pressure regulator to properly regulate gas
pressure. DO NOT oversize the regulator.
Failure to use a pressure regulating device will result in
incorrect gas pressure, which can cause erratic
operation due to gas pressure fluctuations as well as
damage the gas valve. Oversizing the regulator will
cause irregular pulsating flame patterns, burner rumble,
potential flame outages, and possible gas valve
damage.
If a single pressure regulator serves more than one
rooftop unit, it must be sized to ensure that the inlet gas
pressure does not fall below 7" w.c. with all the
furnaces operating at full capacity. The gas pressure
must not exceed 14" w.c. when the furnaces are off.
7. Provide adequate support for all field installed gas
piping to avoid stressing the gas train and controls.
Explosion Hazard!
Failure to follow safe leak test procedures below
could result in death or serious injury or equipment or
property-only-damage.
Never use an open flame to detect gas leaks. Use a
leak test solution for leak testing.
8. Leak test the gas supply line using a soap-and-water
solution or equivalent before connecting it to the gas
train.
9. Check the supply pressure before connecting it to the
Table
unit to prevent possible gas valve damage and the
unsafe operating conditions that will result.
Note: Do not rely on the gas train shutoff valves to
isolate the unit while conducting gas pressure/
leak test. These valves are not designed to
withstand pressures in excess of 14" w.c. or 0.5
psig.
Connecting the Gas Supply Line to the
Furnace Gas Train
Follow the steps below to complete the installation between
the supply gas line and the furnace. Refer to
43
through , for the appropriate gas train configuration.
1. Connect the supply gas piping using a "ground-joint"
type union to the furnace gas train and check for leaks.
2. Adjust the inlet supply pressure to the recommended 7"
to 14" w.c. parameter for natural gas.
psig will damage the gas train.
NOTICE
WARNING
Figure 23, p.
RT-SVX072D-EN
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