Sears N9MP1100F14B1, N9MP2050B12B1 manual Gas Supply Pressure, Manifold Gas Pressure Adjustment

5. Gas Supply and Piping

CARBON MONOXIDE POISONING, FIRE AND EXPLOSION HAZARD.

Failure to follow these instructions could result in

death, personal injury and/or property damage.

Models designated for Natural Gas are to be used with Natural Gas ONLY, unless properly converted to use with LP gas.

NOTE: The rating plate is stamped with the model number, gas

type and gas input rating. In addition, models manufactured for sale in Canada have orifice size information stamped on the rating plate.

Alternate BTUH Input Ratings (USA Only)

The input rating of these furnaces can be changed from the stan- dard input rating to the alternate input rating shown in Table 5, by changing the main burner orifices. NOTE: The input rating ot 80,000 BTUH models cannot be changed from the standard input.

Changing of burner orifices MUST be done by a qualified service technician. See section on changing orifices or following page.

IAIternate Input Ratings, USA ONLY.

BTUH	BTUH	Natural	LP
Standard	Alternate	Gas	Gas
Rating	Rating	Orifice	Orifice
50,000	40,000	#44	#55
75,000	60,000	#44	#55
100,000	80,000	#44	#55
125,000	100,000	#44	#55

Supply Pressure

FIRE HAZARD

Failure to properly set input pressure could result in death, personal injury and/or property damage.

Do NOT set input rating above that shown on rating plate.

1. Supplypressurecanbecheckedusingthel/8 " NPTporton the supply side of the gas valve.

2.Gas input to burners MUST NOT exceed the rated input shown on rating plate.

3.Do NOT allow minimum gas supply pressure to vary down- ward. Doing so will decrease input to furnace. Refer to Table 6 for normal gas supply and manifold pressures.

Gas Supply Pressure

Gas supply pressure should be within minimum and maximum val- ues listed on rating plate. Pressures are usually set by gas suppli- ers.

Manifold Gas Pressure Adjustment

NOTE: Make adjustment to manifold pressure with burners oper- ating.

ELECTRICAL SHOCK HAZARD.

Failure to do so could result in death, personal injury and/or property damage.

Turn OFF power to furnace before changing speed taps.

1.Remove the burner compartment door.

2.With gas OFF, connect manometer to tapped opening on gas valve. Use manometer with a 0 to 15" water column range.

3.Turn gas ON. Operate the furnace by using a jumper wire on

the R to W thermostat connections on the fan board.

4.Remove manifold pressure adjustment screw cover on fur- nace gas control valve. Turn adjusting screw counterclock-

wise to decrease manifold pressure and clockwise to increase pressure.

NOTE: Adjustment screw cover MUST be replaced on gas control valve before reading manifold pressure and operating furnace.

5.Set manifold pressure to value shown in Table 6, Table 7, Table 8 or Table 9.

6.When the manifold pressure is properly set, replace the ad- justment screw cover on the gas control valve.

7.Remove jumper wire from thermostat connection on fan

board. Remove manometer connection from manifold pressure tap, and replace plug in manifold.

8.Check for leaks at plug.

9.Replace the burner compartment door.

44001 102004 [_