Fig. 13: Sediment Trap Orientation
CAUTION: Do not use Teflon tape on gas line pipe thread. A pipe compound rated for use with gas systems is recommended. Apply sparingly only on male pipe ends.
CAUTION: Support gas supply piping with hangers, not by the heater or its accessories. Ensure the gas piping is protected from physical damage and freezing where required.
Gas Supply Pressure
A minimum of 4 in. WC and a maximum of 10.5 in. WC upstream gas pressure is required under load and no load conditions for natural gas. A minimum of 11 in. WC and a maximum of 13 in. WC is required for propane gas. The gas pressure regulator supplied on the heater is for low pressure service. If upstream
pressure exceeds 14 in. WC, an intermediate gas pressure regulator, of the lockup type, must be installed.
When connecting additional gas utilization equipment to the gas piping system, the existing piping must be checked to determine if it has adequate capacity.
Gas Pressure Regulator
The gas valve pressure regulator(s) on the heater are nominally preset at 3 in. WC for natural gas, and 10.0 in. WC for propane gas manifold pressure. The pres- sure at the gas valve outlet tap, measured with a manometer, while in operation should be 3.0 in. ± 0.3 in. WC (HI), and 1.0 in. ± 0.1 WC (LO) for natural gas and 10.0 in. ± 0.1 in. WC (HI), and 3.5 in. ± 0.1 in. WC (LO) for propane gas. If an adjustment is needed, turn the adjustment screw clockwise to increase pressure or
Model | Input | 3/4” |
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No. | (KBTUH) | N | P | N |
| P | N | P | N | P |
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HD101 | 100 | 105 | 385 | 340 |
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HD151 | 150 | 50 | 180 | 160 |
| 530 | 600 |
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HD201 | 199 | 30 | 95 | 95 |
| 355 | 360 |
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HD251 | 250 | 20 | 50 | 60 |
| 230 | 240 |
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HD301 | 299 | 15 | 35 | 45 |
| 170 | 170 | 550 | 360 |
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HD401 | 399 | 5 | 20 | 25 |
| 80 | 100 | 365 | 210 |
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Natural gas – 1,000 BTUH per ft3, .60 specific gravity at 0.5 in. WC pressure drop Propane gas – 2,500 BTUH per ft3, 1.50 specific gravity at 0.5 in. WC pressure drop
Table G: Maximum Equivalent Pipe Length
18
