5. Gas Supply and Piping

CARBON MONOXIDE POISONING, FIRE AND EXPLO- SION HAZARD

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

Furnace operating with the wrong fuel result in death,

personal injury and/or property damage.

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 rat- ing 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 in- put. Changing of burner orifices MUST be done by a qualified ser-

vice technician. See section on changing orifices or following page.

Alternate 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

SupplyPressure

FIRE HAZARD

Failure to properly set input pressure can result in

death, personal injury and/or property damage.

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

1, Supply pressure can be checked using the 1/8" NPT port on 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

Pressures

Below

2000'

Gas

Supply

Pressure

 

Manifold

 

Pressure

Type

Recommended

Max.

 

Min.

 

 

Natural

7"

14"

 

4.5"

3.5"

LP

11"

14"

 

11"

10"

 

Important

Note:

 

 

With Propane gas, the rated input is obtained when the BTU content is 2,500 BTU per cubic foot and manifold pressure set at 10" W.C.

If Propane gas has a different BTU content, orifices

MUST be changed by licensed Propane installer.

Measured input can NOT exceed rated input.

Any major change in gas flow requires changing burn- er orifice size.

Gas Supply Pressure

Gas supply pressure should be within minimum and maximum values listed on rating plate. Pressures are usually set by gas sup- pliers.

Manifold Gas Pressure Adjustment

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

FIRE OR EXPLOSION HAZARD

Failure to turn OFF gas at shut off before connecting

manometer can result in death, personal injury and/or

property damage.

Turn OFF gas at shut off before connecting manometer.

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 and remove adjustment screw cover on gas

valve. Turn counterclockwise to decrease pressure and clockwise to increase.

4.For altitudes up to 2000', set pressure to value shown in Table 6, ± 0.3" water column.

5.Connect manometer to the tapped opening on the outlet side of gas valve. Use manometer with a 0-15" min. water column range.

6.Turn gas ON, fire the furnace and remove adjustment screw cover on gas valve.

7.Turn counterclockwise to decrease pressure and clock- wise to increase.

8.SetpressuretovalueshowninTable6. Refertolmportant Notes in Table 6. Pressure is also listed on furnace rating plate.

9.When pressure is set, replace adjustment screw cover on gas valve.

10.Replace the burner compartment door.

E_

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Sears N9MP2 Alternate Btuh Input RatingsUSA Only, SupplyPressure, Gas Supply Pressure, Manifold Gas Pressure Adjustment

9MPD, N9MP1, N9MP2 specifications

The Sears N9MP2, N9MP1, and 9MPD are prominent models in the realm of residential heating systems, specifically designed to provide efficient and effective heating solutions. These models are part of Sears' commitment to quality and innovation, making them a popular choice among homeowners seeking reliability and performance.

The N9MP2 is a high-efficiency multi-speed gas furnace that boasts an impressive AFUE (Annual Fuel Utilization Efficiency) rating. This feature allows the furnace to convert a significant portion of fuel into usable heat, which effectively translates to lower energy bills for homeowners. The unit is equipped with a two-stage gas valve that provides increased comfort by adjusting the heating output based on demand, ensuring an even temperature throughout the home.

The N9MP1, like its counterpart, is known for its reliability and efficiency. It offers a single-stage operation that is ideal for homes needing consistent heating without the necessity for the more complex stages present in two-stage systems. This model also has a good AFUE rating, making it a cost-effective solution for families looking to reduce their heating expenses. Its design is tailored for easy installation and maintenance, allowing homeowners to keep their heating systems running at optimal performance without hassle.

The 9MPD model takes a step further with its advanced technology integration. It features a sophisticated control board that allows for easier diagnostics and enhanced system management. The 9MPD is also designed with quiet operation in mind, employing advanced sound-reduction technologies to minimize noise levels during heating cycles. Homeowners will appreciate the peace and quiet it brings, particularly in shared living spaces.

All three models are equipped with high-quality insulation and specialized heat exchangers that enhance their thermal efficiency. Additionally, they are designed with safety features such as automatic shut-off systems and robust flame rollout protection, ensuring a safe heating experience.

In terms of characteristics, these models are generally constructed with durable materials, designed to endure harsh weather conditions while providing consistent heating. They can be connected to various home automation systems, which adds to their appeal for tech-savvy consumers.

In conclusion, the Sears N9MP2, N9MP1, and 9MPD represent a comprehensive lineup of reliable, efficient, and technologically advanced heating systems suitable for contemporary homes. Their dedication to performance ensures that homeowners enjoy a warm and energy-efficient environment throughout the chilly seasons.