All installations and services must be performed by qualified service personnel.

2.The return air opening may be located in the top, the center or (ideally) the bottom of the closet door, or side wall.

: Do not obstruct any return air openings, including the return grille on the furnace. To do so may cause the furnace to activate the high temperature limit and shutdown, or it may cause asphyxiation.

3.The cross-sectional area of the return air duct leading into the closet (when located in the floor or ceiling) shall not be less than 250 square inches.

4.The total free area of openings in the floor or ceiling registers serving the return air duct system must be at least 350 square inches. At least one register must be located where it is not likely to be covered by carpeting, boxes, furniture, or any other objects.

5.Materials located in the return duct system must have a flame spread classification of 200 or less.

6.Pans made of a non-combustible material having 1 inch upturned flanges are to be located beneath openings in a floor, return air, duct system.

7.Wiring materials located in the return air duct system must conform to Article 300-22 of the latest edition of the National Electrical Code, NFPA 70.

8.Gas piping shall not be located in, or extend through, the return air duct system.

9.Refer to section G. COMBUSTION AIR for additional combustion air requirements.

G. COMBUSTION AIR

The furnace requires the proper amount of combustion air be available to combust the fuel cleanly and efficiently. An inadequate combustion air supply can result in unsafe and erratic operation of the burner, sooting of the combustion chamber and the heat exchanger, and possibly, offensive fuel odors. The combustion air intake must provide an adequate source of combustion air to the appliance. Refer to part 5.3 of the National Fuel Gas Code, ANSI Z223.1 / NFPA 54- 1999, or latest edition for application specific combustion air requirements.

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Thermo Products OMC-70, GMC-85 service manual Combustion AIR
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GMC-85, OMC-70 specifications

Thermo Products has built a reputation for delivering top-notch heating and cooling solutions, and the GMC-85 and OMC-70 models are no exception. These high-efficiency gas furnaces are designed to meet the diverse needs of homeowners while prioritizing energy savings and comfort.

The GMC-85 model is known for its impressive efficiency ratings, operating at an AFUE (Annual Fuel Utilization Efficiency) of up to 85%. This means that a significant portion of the fuel consumed is converted into usable heat, making it an economically sensible option for heating your home. Additionally, it features a multi-speed blower motor, which allows for better air circulation and consistent heating throughout the living space. This model also includes a durable heat exchanger crafted from high-quality materials, ensuring longevity and reliability in performance.

On the other hand, the OMC-70 furnace offers a slightly lower AFUE rating of 70%, but it shines in certain areas such as cost-effectiveness and straightforward installation. Its reputation for reliability is bolstered by its rugged design and construction that can withstand the rigors of various climates. The OMC-70 also includes a standard efficiency motor, contributing to reduced energy consumption while delivering appropriate heating requirements for smaller spaces.

Both models utilize advanced technology aimed at improving user convenience and efficiency. Features such as electronic ignition systems enhance reliability by eliminating the need for a pilot light, while also providing a quick and efficient startup process. Furthermore, each unit can be easily integrated with smart thermostats, allowing homeowners to manage their heating needs remotely for optimized performance.

Noise reduction is another characteristic that sets these models apart. Both the GMC-85 and OMC-70 employ sound-dampening technologies to ensure quieter operation, providing a peaceful environment for families.

In summary, Thermo Products' GMC-85 and OMC-70 furnaces present excellent options for homeowners looking to achieve comfort and energy efficiency. With their durable construction, advanced technology, and features geared toward enhancing user experience, these models provide reliable heating solutions suitable for various needs and budgets. Investing in either of these products translates to improved energy savings and consistent warmth, making them popular choices in today's competitive market.
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