Installation & Service Manual
3 Gas connections
12.If adjustment is necessary, remove the regulator cover screw on the gas valve. Note: If the gas valve under adjustment is located on a manifold assembly monitored by an igniter, the unit may shut down and recycle when the regulator cover screw is removed. This is normal.
13.Turn the regulator adjustment screw “clockwise” to raise the regulator gas pressure. Turn the regulator adjustment screw “counterclockwise” to lower the regulator gas pressure.
14.Replace the regulator cover screw and make sure it is tight for proper operation.
15.Read the value on the manometer/magnahelic and compare it to the values in TABLE- 3E.
16.Repeat this adjustment procedure for each gas valve as necessary to adjust to the proper manifold gas pressure.
17.Remove hoses, replace and tighten plugs and caps when complete.
18.Replace top front upper jacket access panels and control panel door in reverse order.
19.If proper ignition and burner operation is not achieved after checking gas supply pressure, see Cleaning and Maintenance, page 58 for Combustion Air Fan Adjustment. Follow the procedure to adjust the combustion air fans as necessary.
Figure 3-4_Measuring manifold gas pressure
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| REGULATOR |
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| CHAMBER |
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| ADJUSTMENT |
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MANIFOLD |
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| (UNDER CAP |
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PRESSURE |
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| SCREW) |
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INLET | TEE |
OUTLET |
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MANOMETER |
| GAS |
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| TO BARBED |
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| VALVE |
| FITTING | ||
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| CONTROL |
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| KNOB |
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TABLE 3E
Net Manifold Pressure
Regulator Pressure Less
Front Chamber Pressure
MODEL | Nat. Gas | LP |
497 - 747 | 1.8'' w.c. | |
987 - 2067 | 1.2'' w.c. | |
4.6'' w.c. |
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