The ML180UH series units are classified as fan−assisted Category I furnaces when vertically vented according to the latest edition of National Fuel Gas Code (NFPA 54 / ANSI Z223.1) in the USA. A fan−assisted Category I fur- nace is an appliance equipped with an integral mechanical means to either draw or force combustion products through the combustion chamber and/or heat exchanger. The ML180UH is not approved for use with horizontal venting. NOTE − Use these instructions as a guide. They do not su- persede local codes. This furnace must be vented accord- ing to all local codes these installation instructions, and the provided venting tables in these instructions

The venting tables in this manual were extracted from the National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are provided as a guide for proper vent installation. Proper ap- plication, termination, construction and location of vents must conform to local codes having jurisdiction. In the ab- sence of local codes, the NFGC serves as the defining doc- ument.

Refer to the tables and the venting information contained in these instructions to properly size and install the venting system.

Use self−drilling sheet metal screws or a mechanical fas- tener to firmly secure the vent pipe to the round collar of the flue transition. If self−drilling screws are used to attach the vent pipe, it is recommended that three be used. Drive one self−drilling screw through the front and one through each side of the vent pipe and collar. See figure 23.

Install the first vent connector elbow at a minimum of six inches (152 mm) from the furnace vent outlet. See figure 23.

Venting Using a Masonry Chimney

The following additional requirements apply when a lined masonry chimney is used to vent this furnace.

Masonry chimneys used to vent Category I central fur- naces must be either tile-lined or lined with a listed metal lining system or dedicated gas vent. Unlined masonry chimneys are prohibited. See figures 24 and 25 for com- mon venting.

A chimney with one or more sides exposed to the outside of the structure is considered to be an exterior chimney.

An exterior masonry chimney that is not tile−lined must be lined with B1 vent or a listed insulated flexible metal vent. An exterior tile−lined chimney that is sealed and capped may be lined with a listed uninsulated flexible metal vent.

If the existing chimney will not accommodate a listed metal liner, either the chimney must be rebuilt to accommodate one of these liners or an alternate approved venting meth- od must be found.

Insulation for the flexible vent pipe must be an encapsu- lated fiberglass sleeve recommended by the flexible vent pipe manufacturer. See figure 24.

IMPORTANT

Once the venting system is installed, attach the connected Vent" warning sticker to a visible area of the plenum near the vent pipe. See figure 23. The warning sticker is provided in the bag assembly. Or- der kit 66W04 for additional stickers.

WARNING

Asphyxiation hazard. The exhaust vent for this fur- nace must be securely connected to the furnace flue transition at all times.

VENT CONNECTION UPFLOW AND HORIZONTAL POSITION

 

“DISCONNECTED VENT”

 

WARNING

 

STICKER

 

VENT PIPE

 

(min. 6" length)

 

“DISCONNECTED VENT”

 

WARNING

 

STICKER

 

FLUE TRANSITION

 

COLLAR

 

 

FLUE

VENT PIPE

TRANSITION

COLLAR

(min. 6" length)

FIGURE 23

Page 15

Page 14 Page 16
Page 15
Image 15
Lennox International Inc Merit Series Gas Furnace installation instructions Vent Connection Upflow and Horizontal Position
Page 14 Page 16

Merit Series Gas Furnace specifications

Lennox International Inc. is a leading name in the heating and cooling industry, and their Merit Series Gas Furnace embodies the commitment to quality and efficiency that the company is known for. The Merit Series is designed to provide reliable heating in a sustainable manner, making it an excellent choice for homeowners seeking comfort without excessive energy bills.

One of the standout features of the Merit Series Gas Furnace is its efficiency ratings. The units in this series typically boast Annual Fuel Utilization Efficiency (AFUE) ratings of up to 95%. This level of efficiency means that the furnace converts a significant portion of the fuel it uses into heat, ultimately lowering operating costs. Such energy-efficient performance is not only beneficial for the wallet but also promotes environmental sustainability.

The Merit Series also incorporates advanced technologies that enhance its operation. The inclusion of a multi-speed blower motor is a notable feature that provides thoughtful airflow management throughout the home. By adjusting the speed according to the heating needs, the furnace optimizes comfort levels while minimizing noise and energy consumption. Homeowners can enjoy a warm environment without the disruptive sounds often associated with traditional furnaces.

Moreover, the Merit Series comes equipped with durable construction materials designed to withstand the test of time. From the robust heat exchanger to the heavy-gauge cabinet, Lennox focuses on longevity and reliability. This ensures that homeowners can trust their furnace to operate effectively even in the harshest winter conditions.

Safety features are also integral to the design of the Merit Series Gas Furnace. With an integrated Flame Sensor and a built-in safety shut-off system, the furnace ensures that any irregularities in operation are promptly detected and addressed. Such measures provide peace of mind for families using the heating system throughout the cold months.

Installation and maintenance are further simplified with the Merit Series. Its design facilitates easier access for HVAC professionals, allowing for quicker installations and routine service, ensuring that homeowners spend less time and money on upkeep.

In conclusion, Lennox International Inc.'s Merit Series Gas Furnace combines efficiency, advanced technology, and robust construction, making it a top choice for families looking to enhance their home's heating system. With its energy-saving innovations and commitment to reliability, the Merit Series stands as an exemplary option in today’s market.
Top Page Image Contents