Gas Heat Units (SFH_)
All internal gas piping is
WARNING
Hazardous Gases and Flammable Vapors!
Exposure to hazardous gases from fuel substances have been shown to cause cancer, birth defects or other reproductive harm. Improper installation, adjust- ment, alteration, service or use of this product could cause flammable mixtures. To avoid hazardous gases and flammable vapors follow proper installation and set up of this product and all warnings as provided in this manual. Failure to follow all instructions could result in death or serious injury.
When using dry nitrogen cylinders for pressurizing units for leak testing, always provide a pressure regula- tor on the cylinder to prevent excessively high unit pressures. Never pressurize unit above the maximum recommended unit test pressure as specified in appli- cable unit literature. Failure to properly regulate pres- sure could result in a violent explosion, which could re- sult in death or serious injury or equipment or prop-
Access holes are provided on the unit as illustrated in Fig- ure
Note: In the absence of local codes, the installation must conform with the American National Standard
1.To assure sufficient gas pressure at the unit, use Table 3- 4 as a guide to determine the appropriate gas pipe size for the unit heating capacity listed on the unit's name- plate.
2.If a gas line already exist, 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.
Installation (Continued)
6.Install a pressure regulator at the unit that is adequate to maintain 7" w.c. for natural gas while the furnace is oper- ating at full capacity.
Note: Gas pressure in excess of 14" w.c. or 0.5 psig will damage the gas train.
Failure to use a pressure regulating device will result in in- correct gas pressure. This can cause erratic operation due to gas pressure fluctuations as well as damage the gas valve.
Over sizing the regulator will cause irregular pulsating flame patterns, burner rumble, potential flame outages, and pos- sible 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.
8.Leak test the gas supply line using a
9.Check the supply pressure before connecting it to the unit to prevent possible gas valve damage and the un- safe 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 Figure
1.Connect the supply gas piping using a
2.Adjust the inlet supply pressure to the recommended 7" to 14" w.c. parameter for natural gas.
3.Ensure that the piping is adequately supported to avoid gas train stress.
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