Greenheck Fan PVF Location Recommendations, Unit Clearances to Combustible Materials, Venting

Location Recommendations

1.Do not install units in locations where flue products can be drawn into adjacent building openings such as windows, fresh air intakes, etc. Distance from vent terminal to adjacent public walkways, adjacent buildings, operable windows, and building openings shall conform with the local codes. In the absence of local codes, installation shall conform with the National Fuel Gas Code, ANSI Z223.1, or the CAN/CGA B-149 Installation Codes.

2.Building materials that will be affected by flue gases should be protected.

3.Avoid locating in an area where deep snow is likely to accumulate. During the winter months, keep snow clear on the access side of the unit to prevent any blockage of combustion air inlet or flue exhaust openings.

4.Maintain minimum horizontal clearance of 4 feet from electric meters, gas meters, regulators, and relief equipment. In Canada, the minimum clearance is 6 feet.

5.Local codes may supercede any of the above provisions.

6.Be sure that the minimum clearances to combustible materials are maintained.

Unit Clearances to Combustible Materials

Combustion blower discharge must be located 42 in. from any combustible materials.

Venting

1.Do not modify or obstruct the combustion air inlet cover or the combustion blower weatherhood.

2.During the winter months, periodically clear snow from access side of unit to prevent blockage of the inlet and exhaust openings.

3.Do not add any vents other than those supplied by the manufacturer.

Gas Connection

Gas Supply Pressure Requirements

Natural: 6 to 14 in. wg

LP: 11 to 14 in. wg

1.Single furnaces (furnace input 100 to 400 MBH) have a single 3⁄4 inch connection. Double furnaces (furnace input 500 to 800 MBH) have two 3⁄4 inch connections, and triple furnaces (furnace input

1050 to 1200 MBH have three 3⁄4 inch connections.

2.When connecting the gas supply, the length of the run must be considered in determining the pipe size to avoid excessive pressure drop. Refer to a Gas Engineer’s Handbook for gas pipe capacities.

3.A drip leg should be installed in the pipe run to the unit.

4.Install an easily accessible ground joint union and a manual shut off valve (these are required by some local codes) for emergency shut off and easy servicing of the controls.

5.A 1⁄8 inch NPT plugged tap shall be installed immediately ahead of the gas supply connection to the furnace.

6.After gas piping is completed, carefully check all piping connections for gas leaks. Use soap solution or equivalent for testing. DO NOT use a flame or other source of ignition to check for gas leaks.

7.When leak testing pressures above 14 in. wg (1⁄2 psi), close the field installed shutoff valve, disconnect the furnace and its gas train from the gas supply line, and plug the supply line before testing.

8.When leak testing at pressures equal to or less than 14 in. wg (1⁄2 psi) close the field-installed shutoff valve to isolate the unit from the gas supply line before testing.

	Ground Joint Union
From	Gas Cock
Gas	To Controls
	1/8 in. Plugged
	6 in. Trap

Figure 1: Recommended Piping to Controls

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