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

No

After fuel valve opens, does the burner ignite?

For the GMC, measure gas supply pressure at inlet to gas valve. Is it at least 4.5" W.G. for natural gas or 11" W.G. for L.P. gases? For the OMC, is oil present in the fuel line at the valve?

Yes

No

Check the fuel supply. Open all manual shutoff valves serving the unit.

Purge any air in the fuel line.

Are the ignition electrodes

No

Reposition to

 

positioned correctly?

 

correct location.

Yes

Yes

 

 

Does the burner stay

No

lit past proof of flame

 

check?

 

 

 

 

 

Yes

Check for blocked or severely worn burner nozzle (OMC) or burner orifice (GMC). Clean or replace as required.

 

 

Yes

 

 

 

 

 

 

 

 

 

 

 

On the GMC, measure supply &

 

 

manifold pressures. Are they

 

 

constant over time and within the

No

allowable ranges? On the OMC,

 

 

is the oil tank full of fuel? Is the

 

 

fuel clean without contaminates?

 

 

 

Is the fuel filter dirty?

 

 

 

 

 

 

 

 

 

 

 

 

On the GMC, adjust supply pressure to 4.5" W.G. for natural & 11" W.G. for LP gases. Adjust manifold pressure to 3.5" W.G. for natural gas or 10" W.G. for LP gases. If gas pressure fluctuates, a pressure regulator may be required or gas piping may be too small for flow. On the OMC, add or replace fuel and fuel filter. Also, check flame sensor (GMC), cad cell (OMC) for proper operation.

Does the fan timer

energize the circulating air blower after the 56 second time delay?

Yes

No

Check settings on fan

timer against those

on connection

diagram. Is blower

still inoperable after time delay with fan timer set correctly?

Yes

Measure voltage on the circulating air blower terminals. Is it 120 VAC?

Yes

Does blower wheel

spin freely?

Yes

 

 

Check wiring to

 

 

 

 

 

 

blower. If okay,

 

No

 

set fan selector

 

 

 

switch to manual.

 

 

 

 

 

 

If fan operates,

 

 

 

replace fan timer.

 

 

 

 

 

 

 

 

Check for blower wheel

 

No

rubing against housing

 

or motor shaft spinning

 

freely. Adjust or replace

 

 

 

as necessary.

 

 

 

 

Is blower motor

capacitor functioning

properly?

Yes

Replace motor

No

Replace blower motor capacitor.

35

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Thermo Products OMC-70, GMC-85 service manual Yes Does the burner stay
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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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