Selection Procedure with 558J*07 Example

SELECTION PROCEDURE (WITH 558J*07 EXAMPLE)

I.Determine cooling and heating loads.

Given:
Mixed Air Drybulb	80_F (27_C)
Mixed Air Wetbulb	67_F (19_C)
Ambient Drybulb	95_F (35_C)
THCLoad	69.0 MBH
SHCLoad	51.0 MBH
Supply Air	2100 CFM
Heating Load	85.0 MBH
External Static Pressure	0.67 in.wg
Electrical Characteristics	230-3-60

II.Make an initial guess at cooling tons.

Refrig. tons	=	THCLoad / 12 MBH per ton
Refrig. tons	=	69.0 / 12 = 5.75 tons

In this case, start by looking at the 558J*07.

III.Look up the rooftop’s THC and SHC.

Table 11 shows that, at the application’s supply air CFM, mixed air and ambient temperatures, the

558J*07 supplies: THCLoad = 73.7 MBH SHCLoad = 54.3 MBH.

IV. Calculate the building Latent Heat Load.

LHCLoad = THCLoad - SHCLoad

LHCLoad = 692.0 MBH - 51.0 MBH = 18.0 MBH

V.Calculate RTU Latent Heat Capacity

LHC = THC - SHC

LHC = 73.7 MBH - 54.3 MBH = 19.4 MBH

VI. Compare RTU capacities to loads. 2

Compare the rooftop’s SHC and LHC to the building’s Sensible and Latent Heat Loads.

VII. Select factory options (FIOP)

Local code requires an economizer for any unit with THC less than 65.0 MBH.

VIII. Calculate the total static pressure.
External static pressure	0.67 in. wg
Sum of FIOP/Accessory static	+0.13 in. wg
Total Static Pressure	0.80 in. wg

IX. Look up the Indoor Fan RPM & BHP.

Table 26 shows, at 2100 CFM & ESP= 0.8, RPM = 1268 & BHP = 1.52

X.Convert BHP (Step VIII) into Fan Motor Heat.

Fan Motor Heat = 2.546* BHP/Motor Eff.3 Fan Motor Heat = 4.8 MBH

XI. Determine electrical requirements

Table 32 shows the MCA and MOCP of a 558J*07 (without convenience outlet) as:

MCA = 32.8 amps & MOCP = 50 amps

Min. Disconnect Size: FLA = 32 & LRA = 72.

558J

LEGEND

THC — Total Heat Capacity

SHC — Sensible Heat Capacity

LHC — Latent Heat Capacity

RPM — Revolutions Per Minute

RTU — Rooftop Unit

BHP — Break Horsepower

MCA — Min. Circuit Ampacity

MOCP — Max. Over---current Protection

FLA — Full Load Amps

RLA — Rated Load Amps

NOTES:

1.Bryant’s selection software saves time by performing many of the steps above. Contact your Bryant sales rep- resentative for assistance.

2.Selecting a unit with a SHC slightly lower than the SHCLoad is often better than oversizing. Slightly lower SHC’s will help control indoor humidity, and prevent temperature swings.

3.Indoor Fan Motor efficiency is available in Table 13---26. Use the decimal form in the equation eg. 80% =.8.

558J specifications

The Bryant 558J is a high-efficiency air conditioning unit that provides outstanding comfort and performance for residential spaces. Engineered with contemporary technology, this HVAC system showcases a blend of innovative features designed to enhance user experience while promoting energy efficiency.

One of the main features of the Bryant 558J is its high Seasonal Energy Efficiency Ratio (SEER) rating, which ensures optimal energy savings while providing consistent cooling throughout the warmer months. This model boasts an impressive SEER that positions it among the top performers in its category, making it an excellent choice for environmentally-conscious homeowners looking to reduce their energy consumption.

The Bryant 558J utilizes advanced variable-speed compressor technology. This means it can adjust its cooling output dynamically based on indoor temperature requirements, which results in improved temperature consistency and quieter operation. Unlike single-speed systems that can be noisy during operation, the variable-speed compressor provides a more tranquil living environment, as it can run at lower speeds for extended periods.

Additionally, the unit is equipped with a durable, all-weather cabinet designed to resist corrosion and withstand the elements, ensuring longevity and reliability. The unit's aesthetic design also allows it to blend seamlessly into most outdoor settings, enhancing curb appeal without compromising functionality.

In terms of installation and maintenance, the Bryant 558J offers user-friendly features. Its compact design makes it easy to install in tight spaces, while the easy-access panel allows for straightforward maintenance and servicing, reducing downtime and improving overall efficiency.

The unit is compatible with smart thermostats, allowing homeowners to integrate modern technology into their HVAC systems. This compatibility empowers users to control their home environment remotely, monitor energy usage, and create personalized schedules that align with their lifestyles.

Furthermore, the Bryant 558J comes with a comprehensive warranty, offering peace of mind to residents investing in a cooling solution. This level of backing evidences the manufacturer's commitment to quality and customer satisfaction.

In summary, the Bryant 558J stands out as a premier air conditioning solution characterized by its high efficiency, variable-speed technology, durable construction, and modern compatibility. Whether for new installations or replacements, this model exemplifies the perfect balance of comfort, reliability, and energy savings, making it a worthwhile investment for any homeowner.