CONTROLS

OPERATING SEQUENCE — 548F036-120 AND 549B036-120

Cooling, Units Without Economizer — When thermostat calls for cooling, terminals G and Y1 are energized. The indoor-fan contactor (IFC), reversing valve solenoid (RVS1) and compres- sor contactor no. 1 (C1) are energized and indoor-fan motor, compressor no. 1, and outdoor fans start. The outdoor-fan motor(s) run continuously while unit is cooling. On 548F090- 120 units, if the thermostat calls for a second stage of cooling by energizing Y2, compressor contactor no. 2 (C2) and revers- ing valve solenoid (RVS2) are energized and compressor no. 2 starts.

Heating, Units Without Economizer (548F036-072 and 549B036-072) — Set system switch at AUTO. or HEAT position. Set thermostat at desired temperature.

When the thermostat calls for heat, the IFC, outdoor-fan con- tactor (OFC), and compressor contactor are energized. The RVS is deenergized and switches position, and the indoor fan, outdoor fan, and compressor are energized.

If the thermostat calls for a second stage of heat, the heater contactor (HC) is energized and starts the electric heaters.

When the space temperature approaches the heating tem- perature set point, heating stages cycle off. The reversing valve solenoid is reenergized.

Heating, Units Without Economizer (548F090-120 and 549B090,120) — Upon a request for heating from the space thermostat, terminal W1 will be energized with 24 v. The IFC, outdoor-fan contactor (OFC), C1, and C2 will be energized. The reversing valves switch position and the indoor fan, outdoor fan, compressor no. 1, and compressor no. 2 are energized.

If the space temperature continues to fall while W1 is ener- gized, W2 will be energized with 24 v, and the heater contac- tor(s) (HC) will be energized, which will energize the electric heater(s).

When the space thermostat is satisfied, W2 will be deen- ergized first, and the electric heater(s) will be deenergized.

Upon a further rise in space temperature, W1 will be deener- gized, and the reversing valve solenoids (RVS1 and RVS2) will be energized.

Cooling, Units With EconoMi$er (548F036-072 and 549B036-

072)— When the outdoor-air temperature (OAT) is above the ECON SP set point and the room thermostat calls for Stage 1 cooling (R to G + Y1), the indoor-fan motor (IFM) is energized and the EconoMi$er damper modulates to minimum position. The compressor contactor is energized to start the compressor and outdoor-fan motor (OFM) and RVS1 (reversing valve sole- noid). After the thermostat is satisfied, the damper modulates to the fully closed position when the IFM is deenergized.

When the OAT is below the ECON SP setting and the room thermostat calls for Stage 1 cooling (R to G + Y1), the EconoMi$er modulates to the minimum position when the IFM is energized. The EconoMi$er provides Stage 1 of cooling by modulating the return and outdoor-air dampers to maintain a 55 F supply air set point. If the supply-air temperature (SAT) is greater than 57 F, the EconoMi$er modulates open, allowing a greater amount of outdoor air to enter the unit. If the SAT drops below 53 F, the outdoor air damper modulates closed to reduce the amount of outdoor air. When the SAT is between 53 and 57 F, the EconoMi$er maintains its position.

If outdoor-air alone cannot satisfy the cooling requirements of the conditioned space, and the OAT is above the MECH CLG LOCKOUT set point, the EconoMi$er integrates free cooling

with mechanical cooling. This is accomplished by the strategies below.

NOTE: Compressor has a 2-minute Minimum On, Minimum Off, and Interstage delay timer.

1.If Y1 is energized, and the room thermostat calls for Y2 (2-stage thermostat), the compressor and OFM are ener- gized. The EconoMi$er damper is maintained at its current position.

2.If Y1 is energized for more than 20 minutes, and Y2 is not energized (whether or not a 2-stage thermostat is used), the compressor and OFM are energized. The EconoMi$er damper is maintained at its current position.

3.If Y1 is energized, and the compressor is already energized (see Step 2) and the room thermostat calls for Y2, the com- pressor continues to operate.

4.If compressor is energized and the thermostat is satisfied, the compressor, the OFM, and IFM are deenergized and the EconoMi$er modulates closed.

When the OAT is below the MECH CLG LOCKOUT set point, the compressors remain off.

Cooling, Units With EconoMi$er (548F090-120 and 549B090,120) — When the outdoor-air temperature (OAT) is above the ECON SP set point and the room thermostat calls for Stage 1 cooling (R to G + Y1), the indoor-fan motor (IFM) is energized and the EconoMi$er damper modulates to mini- mum position. The compressor contactor is energized to start the compressor and outdoor-fan motor (OFM) and RVS1 (reversing valve solenoid). After the thermostat is satisfied, the damper modulates to the fully closed position when the IFM is deenergized.

When the OAT is below the ECON SP setting and the room thermostat calls for Stage 1 cooling (R to G + Y1), the EconoMi$er modulates to the minimum position when the IFM is energized. The EconoMi$er provides Stage 1 of cooling by modulating the return and outdoor-air dampers to maintain a 55 F supply air set point. If the supply-air temperature (SAT) is greater than 57 F, the EconoMi$er modulates open, allowing a greater amount of outdoor air to enter the unit. If the SAT drops below 53 F, the outdoor air damper modulates closed to reduce the amount of outdoor air. When the SAT is between 53 and 57 F, the EconoMi$er maintains its position.

If outdoor-air alone cannot satisfy the cooling requirements of the conditioned space, and the OAT is above the MECH CLG LOCKOUT set point, the EconoMi$er integrates free cooling with mechanical cooling. This is accomplished by the strategies below.

NOTE: Compressors have a 2-minute Minimum On, Minimum Off, and Interstage delay timer.

1.If Y1 is energized, and the room thermostat calls for Y2 (2-stage thermostat), compressor no. 1 and OFM are ener- gized. The EconoMi$er damper is maintained at its current position.

2.If Y1 is energized for more than 20 minutes, and Y2 is not energized (whether or not a 2-stage thermostat is used), compressor no. 1 and OFM are energized. The EconoMi$er damper is maintained at its current position.

3.If Y1 is energized, and compressor no. 1 is already ener- gized (see Step 2) and the room thermostat calls for Y2, compressor no. 1 continues to operate. If Y2 remains energized for more than 20 minutes, compressor no. 2 is energized.

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Bryant 542J manual Controls, Cooling, Units With EconoMi$er 548F036-072 and 549B036
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549B, 548F, 542J specifications

Bryant 542J is a high-efficiency gas furnace that stands out for its reliability and advanced heating technologies. Designed to deliver consistent warmth and comfort in residential settings, it combines innovative engineering with energy-efficient features.

One of the key characteristics of the Bryant 542J is its two-stage heating capability. This means that the furnace can adjust its heat output according to the heating demands of your home. During milder weather, it operates at a lower stage, consuming less energy while still maintaining a comfortable environment. When the temperatures drop, the furnace shifts to its higher capacity, providing the necessary warmth efficiently. This not only enhances comfort but also contributes to lower energy bills.

In addition to its two-stage operation, the Bryant 542J also incorporates a variable-speed blower motor. This technology allows the furnace to adjust the airflow depending on the heating requirements, ensuring an even distribution of warm air throughout the home. The variable-speed blower also operates more quietly than conventional fixed-speed motors, creating a serene indoor environment.

Energy efficiency is a hallmark of the Bryant 542J, boasting an Annual Fuel Utilization Efficiency (AFUE) rating of up to 96.5%. This impressive rating means that a significant portion of the energy consumed is effectively converted into usable heat, resulting in substantial savings on heating costs over time. Furthermore, the furnace is equipped with a sealed combustion system that draws air from outside the home, minimizing energy waste and improving indoor air quality.

Diagnostic features are another highlight of the Bryant 542J, which come equipped with SmartEvap technology. This allows the unit to self-diagnose potential issues, providing homeowners with peace of mind and simplifying maintenance procedures.

Durability is also a key feature of the Bryant 542J. It is constructed with high-quality materials designed to withstand harsh winter conditions, ensuring a long lifespan and reliable performance. Its compact design also allows for flexible installation, making it suitable for various residential layouts.

In summary, the Bryant 542J is more than just a gas furnace; it is a sophisticated heating solution that combines efficiency, comfort, and reliability. With features such as two-stage heating, a variable-speed blower, high AFUE ratings, and advanced diagnostics, it is an excellent choice for homeowners seeking an efficient and effective heating system.
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