Changing Main Burner Orifices, Gas, Heating Value

Table 7. Natural Gas Orifice Size.
					ELEVATION
GAS	Up	2001	3001	4001	5001	6001*	7001*	8001*	9001*
HEATING	to	to	to	to	to	to	to	to	to
VALUE**	2000	3000	4000	5000	6000	7000	8000	9000	10000
(Btu/cu. ft.)	Feet	Feet	Feet	Feet	Feet	Feet	Feet	Feet	Feet
800-849	2.25	2.20	2.15	2.15	2.10	2.05	2.05	2.00	1.95
850-899	2.20	2.15	2.10	2.10	2.05	2.00	2.00	1.95	1.90
900-949	2.15	2.10	2.05	2.05	2.00	1.95	1.95	1.90	1.85
950-999	2.10	2.05	2.00	2.00	1.95	1.90	1.90	1.85	1.80
1000-1049	2.05	2.00	1.95	1.95	1.90	1.85	1.85	1.80	1.75
1050-1099	2.00	1.95	1.90	1.90	1.85	1.80	1.80	1.75	1.75
1100-1149	1.95	1.90	1.85	1.85	1.80	1.80	1.75	1.75	--
1150-1199	1.90	1.85	1.85	1.80	1.75	1.75	--	--	--

*Above 6000 feet, a high-altitude gas conversion kit must be used.

**At standard conditions: 30.0 inches Mercury, 60°F, Saturated.

Table 8. Propane (LP) Gas Orifice Size.
GAS					ELEVATION
GAS	Up	2001	3001	4001	5001	6001*	7001*	8001*	9001*
HEATING*	to	to	to	to	to	to	to	to	to
VALUE	2000	3000	4000	5000	6000	7000	8000	9000	10000
(Btu/cu. ft.)	Feet	Feet	Feet	Feet	Feet	Feet	Feet	Feet	Feet
2500-2550	1.20	1.15	1.15	1.15	1.15	1.10	1.10	1.10	1.05

* Above 6000 feet, a high-altitude gas conversion kit must be used.

SECTION 17. CHANGING MAIN BURNER ORIFICES

WARNING: To prevent electrical shock and gas leaks, turn off electrical power and gas before changing

orifices.

Follow this procedure:

1.Turn off electricity at electrical disconnect switch next to furnace.

2.Turn off equipment shut-off valve in gas supply line just ahead of furnace.

3.Remove three screws holding burner access panel in place. Remove burner access panel.

4.Starting with burner farthest from gas control, remove main burner screws and main burners. Note how burners overlap. Burner farthest from gas control is on top. See Figure 21.

5.Remove original main burner orifices from manifold pipe.

6.Carefully, hand thread new orifices into manifold pipe. Do not cross-thread. Tighten to torque of 50 inch- pounds.

7.Starting with burner closest to gas control, replace main burners and main burner screws. Burner mounting flange of burner farther from gas control overlaps burner-mounting flange of burner closest to gas control.

HP 422690 I manual Changing Main Burner Orifices, Gas, Heating Value

ELEVATION

GAS

HEATING

VALUE**

(Btu/cu. ft.)

SECTION 17. CHANGING MAIN BURNER ORIFICES

Figure 21. Main Burner Removal.

8.Check burner carry-over alignment. Burner carry- overs may touch but not overlap adjacent burner carry- overs. Replace screws .

9.Replace burner access panel using three screws removed in step 3.

10.Open equipment shut-off valve in gas supply line just ahead of furnace.

11.Set room thermostat to highest setting and to heating mode.

12.Turn on electricity at electrical disconnect switch located next to furnace. Furnace will light.

13.Visually check that each burner lights promptly.

14.Check gas input following Section 14, "Checking Gas Input Rate."

15.Reset room thermostat to desired setting.