RT-SVX34V-EN
33
Installation Piping
General Requirements
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.
All internal gas piping for YC* rooftop units are factory
installed and leak tested. Once the unit is set into place, a
gas supply line must be field installed and connected to the
gas train located inside the gas heat compartment.
Access holes are provided on the unit as shown in Figure
15, p. 18 to accommodate side panel entry. 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 to
determine the appropriate gas pipe size for the heating
capacity listed on the unit's nameplate.
If a gas line already exists, verify that it is sized large
enough to handle the additional furnace capacity.
2. Take all branch piping from any main gas line from the
top at 90 degrees or side at 45 degrees to prevent
moisture from being drawn in with the gas.
3. 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.
4. Provide a drip leg near the unit.
NOTICE
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.
5. Install a pressure regulator at the unit that is adequate
to maintain 7" w.c. for natural gas and 11" w.c. for LP
gas while the unit is operating in the "High Heat" mode.
6. A minimum inlet gas pressure of 7" w.c. for natural gas
and 10" w.c. for LP gas is required at the low gas
pressure switch while operating in the "High Heat"
mode. If inlet gas pressure is too low, furnace may fail
to ignite.
Note: Gas pressure in excess of 14" w.c. or 0.5 psig
will damage the gas train.
WARNING
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.
7. Leak test the gas supply line using a soap-and-water
solution or equivalent before connecting it to the gas
train.
8. Pressure test the supply line before connecting it to the
unit to prevent possible gas valve damage and the
unsafe operating conditions that will result.
Note: Do not rely on 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 for the 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. Provide adequate support for the field installed gas
piping to avoid stressing the gas train and controls.
3. Adjust the inlet supply gas pressure to the
recommended 7" for natural gas or 11" w.c. for LP gas
while operating in "High Heat" mode.
Table 11. Specific gravity multiplier
Specific Gravity Multiplier
0.5 1.1
0.55 1.04
0.6 1
0.65 0.96
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