CONNECTING THE VENT - Continued
Typical Installation Using
Class “B” Vent Pipe
1.Adequate clearances around floor furnace.
2.Draft Diverter 6” from combustibles.
3.Adequate clearances around vent pipe.
4.Horizontal vent pipe sloping upward 1/4” per foot.
5.Pipe supported with metal straps.
6.Adequate height of vent system.
7.Listed vent cap.
If more than one gas appliance is vented through a common vent system, the vent should be increased in size to accommodate the increased load. Consult your local code or the tables in the latest edition of NFPA54/ANSI.Z223.1 for the correct size. If no local codes apply, use the following alternate method for sizing a vent connected to more than one appliance. The effective area of the vent must be not less than the area of the largest vent connection plus 50 percent of the areas of additional draft hood outlets.
The homeowner appreciates neatness in workmanship and the neat installation usually functions better than the sloppy one. Double check your work to verify that all clearances around the floor furnace and vent system are adequate and that the vent system is installed to code or pipe manufacturers specifications. See Figure 10.
FIGURE 10
GAS SUPPLY AND PIPING
The gas piping system must meet the requirements of local codes or the specifications of the servicing gas supplier. It must have adequate capacity to supply the floor furnace and any other appliance within the home with enough gas to maintain the full rated capacities without excessive pressure drop when all appliances are operating at full rate.
GAS PIPE SIZES - CAPACITY - *NATURAL GAS
Length of | INSIDE PIPE DIAMETER |
| |||
Pipe - Feet | 1/2” |
| 3/4” | 1” |
|
|
| ||||
1 0 | 132,000 |
| 278,000 | 520,000 |
|
2 0 | 92,000 |
| 190,000 | 350,000 | Capacity |
3 0 | 73,000 |
| 152,000 | 285,000 | B.T.U. |
4 0 | 63,000 |
| 130,000 | 245,000 | Per Hour |
5 0 | 56,000 |
| 115,000 | 215,000 | Input |
6 0 | 50,000 |
| 105,000 | 195,000 |
|
*Based on heating value of 1,000 btu per cubic foot (specific gravity of 0.6) @ 0.5 PSIG and a pressure drop of 0.3 inch water column.
GAS TUBING AND PIPE SIZES - CAPACITY - *L.P. GAS
Length of | **Copper Tubing | **Steel Pipe |
|
| ||
Pipe/Tubing | Outside Diameter | Inside Diameter |
|
| ||
Feet | 1/2” | 3/4” | 1/2” | 3/4” |
|
|
1 0 | 92,000 | 329,000 | 275,000 | 567,000 |
|
|
2 0 | 62,000 | 216,000 | 189,000 | 393,000 | Capacity | |
3 0 | 50,000 | 181,000 | 152,000 | 315,000 | B.T.U. | |
4 0 | 41,000 | 145,000 | 129,000 | 267,000 | Per Hour | |
5 0 | 37,000 | 131,000 | 114,000 | 237,000 | Input | |
6 0 | 35,000 | 121,000 | 103,000 | 217,000 |
|
|
*Undiluted Liquefied Petroleum Gas @ 11 inches water column inlet pressure. Based on a pressure drop of 0.5 inches water column. **Copper tubing must comply with limitations of NATIONAL FUEL
GAS CODE reference 2.6.3 metallic tubing.
***Steel pipe should be of at least standard weight (Schedule 40).
Support the piping or tubing at regular intervals with metal pipe strapping. See chart below.
Nominal Steel | Spacing of |
Pipe Size | Supports |
|
|
1/2” | 6’ |
3/4” or 1” | 8’ |
|
|
Nominal size of | Spacing of |
tubing O.D. | Supports |
|
|
1/2” | 4’ |
5/8” or 3/4” | 6’ |
|
|
Where local conditions include earthquake, tornado, unstable ground or flood hazards, give special consideration to increased strength and flexibility of piping supports and connections. Consult local authorities for recommendations.
All unused openings in the piping system must be securely closed
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