The liquid enters the evaporator coil at a temperature lower than in standard cooling operation. This lower temperature increases the latent capacity of the rooftop unit. The refrigerant passes through the evaporator and is turned into a vapor. The air passing over the evaporator coil will become colder than during normal operation. However, as this same air passes over the subcooling coil, it will be slightly warmed, partially reheating the air.

Subcooling mode operates only when the outside air temperature is warmer than 40_F. A factory-installed temperature switch located in the condenser section will lock out subcooling mode when the outside temperature is cooler than 40_F.

The scroll compressors are equipped with crankcase heaters to provide protection for the compressors due to the additional refrigerant charge required by the subcooling/reheat coil.

 

When in subcooling mode, there is a slight decrease in system

 

total gross capacity (5% less), a lower gross sensible capacity

 

(20% less), and a greatly increased latent capacity (up to 40%

551B,C

more).

 

 

 

C06135

Fig. 42 ---Perfect Humidityt Normal

Design Cooling Operation

C06136

Fig. 43 ---Perfect Humidity Subcooling

Mode Operation

C06137

Fig. 44 ---Perfect Humidity Hot Gas

Reheat Mode Operation

Hot Gas Reheat Mode

When the humidity levels in the space require humidity control, a hot gas solenoid valve (specific to hot gas reheat mode only) will open to bypass a portion of hot gas refrigerant around the condenser coil. (See Fig. 44.)

This hot gas will mix with liquid refrigerant leaving the condenser coil and flow to the subcooling/reheat dehumidification coil. Now the conditioned air coming off the evaporator will be cooled and dehumidified, but will be warmed to neutral conditions (72_F to 75_F) by the subcooling/reheat dehumidification coil.

The net effect of the rooftop when in hot gas reheat mode is to provide nearly all latent capacity removal from the space when sensible loads diminish (when outdoor temperature conditions are moderate). When in hot gas reheat mode, the unit will operate to provide mostly latent capacity and extremely low sensible heat ratio capability.

Similar to the subcooling mode of operation, hot gas reheat mode operates only when the outside air temperature is warmer than 40_F. Below this temperature, a factory installed outside air temperature switch will lockout this mode of operation.

See Table 34 for the Perfect Humidity adaptive dehumidification system sequence of operation.

SERVICE

!WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could cause personal injury or death.

When sevicing unit, shut off all electrical power to unit and install lockout tag.

Step 1 —Cleaning

Inspect unit interior at the beginning of heating and cooling season and as operating conditions require.

Evaporator Coil

1.Turn unit power off, tag disconnect. Remove evaporator coil access panel.

2.If economizer or two-position damper is installed, remove economizer by disconnecting Molex plug and removing mounting screws.

3.Slide filters out of unit.

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Bryant 551B, 551C installation instructions Cleaning, Evaporator Coil
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551C, 551B specifications

The Bryant 551B and 551C are two highly efficient air conditioning units designed to provide optimal comfort in residential settings. Known for their reliability and performance, these models are part of Bryant's esteemed line of heating and cooling solutions.

One of the standout features of the Bryant 551B is its two-stage cooling system, which allows for better humidity control and increased comfort. This ensures that homeowners can enjoy consistent temperatures while reducing energy consumption. The unit operates quietly, thanks to its noise-reducing technology, making it an ideal choice for bedrooms and living spaces.

On the other hand, the Bryant 551C builds upon this foundation with its variable-speed compressor. This technology allows the unit to adjust its cooling output according to the specific needs of the home. This results in seamless operation and even greater energy efficiency. Both models also incorporate Bryant's advanced control capabilities, which allow users to monitor and adjust settings remotely via smart devices, adding a layer of convenience and modernity to home climate control.

With an emphasis on durability, both the 551B and 551C feature a galvanized steel cabinet that protects against weather-related damage. The powder coat finish further enhances their resistance to rust and corrosion, ensuring a long lifespan and minimal maintenance.

Another significant characteristic of these units is their excellent Seasonal Energy Efficiency Ratio (SEER) ratings. The 551B boasts a SEER rating of up to 16, while the 551C takes it even further with ratings exceeding 20. This efficiency not only translates to lower energy bills for homeowners but also contributes to a reduced carbon footprint, making these units environmentally friendly options.

Both models are also designed to operate with eco-friendly refrigerants, aligning with modern energy standards and regulations aimed at reducing greenhouse gas emissions.

In summary, the Bryant 551B and 551C are exemplary choices for homeowners looking for reliable, efficient, and high-performing air conditioning solutions. With features such as two-stage and variable-speed compressors, advanced smart technology, and robust construction, these models stand out in the competitive HVAC market. They promise a comfortable indoor environment along with significant energy savings, making them a wise investment for the future.
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