SELECTION PROCEDURE (With 579F180 Example)

I DETERMINE COOLING AND HEATING REQUIRE- MENTS AT DESIGN CONDITIONS.

Given:

Required Cooling Capacity . . . . . . . . . . . . . 170,000 Btuh Sensible Heat Capacity . . . . . . . . . . . . . . . . 111,000 Btuh Required Heating Capacity . . . . . . . . . . . . . 200,000 Btuh Condenser Entering Air Temp . . . . . . . . . . 95 F (Summer) Evaporator Entering Air Temp . . . . . . . . . . . . . . .80 F edb,

67 F ewb Evaporator Air Quantity . . . . . . . . . . . . . . . . . . . 4,500 cfm External Static Pressure . . . . . . . . . . . . . . . . . . 0.6 in. wg Electrical Characteristics (V-Ph-Hz). . . . . . . . . . . 460-3-60

Vertical discharge unit with optional EconoMi$er IV required.

edb — Entering dry-bulb ewb — Entering wet-bulb

IISELECT UNIT BASED ON REQUIRED COOLING CAPACITY.

Enter Cooling Capacities table for 579F180300 (page 152) at condenser entering temperature 95 F, evaporator air entering at 4,500 cfm and 67 F wb. The 579F180300 unit will provide a total cooling capacity of 179,000 Btuh and a sensible heating capacity of 117,000 Btuh. For air entering evaporator at temperatures other than 80 F edb, calculate sensible heat capacity correction as required using the for- mula in the notes following the Cooling Capacities tables.

NOTE: Unit ratings are gross capacities and do not include the effect of evaporator-fan motor heat. To calcu- late net capacities, see Step V.

IIISELECT HEATING CAPACITY OF UNIT TO PROVIDE DESIGN CONDITION REQUIREMENTS.

In the ARI Heating Capacities and Efficiencies table (page 12) note that the 579F180300 will provide an output capacity of 243,000 Btuh, which is adequate for the given application.

IV DETERMINE FAN SPEED AND POWER REQUIRE- MENTS AT DESIGN CONDITIONS.

Before entering the Fan Performance tables, calculate the total static pressure required based on unit components. From the given and the Accessory/FIOP Static Pressure table on page 164 find:

External static pressure

0.60 in. wg

EconoMi$er IV static pressure

0.04 in. wg

Total static pressure

 

0.64 in. wg

Enter the Fan Performance table 579F180300 (page 161) at 4,500 cfm and 0.64 in. wg external static pressure. By interpolation, find that the rpm is 1017 and the watts are 1743.

VDETERMINE NET COOLING CAPACITY.

Cooling capacities are gross capacities and do not include indoor (evaporator) fan motor (IFM) heat. Use the watts input power to the motor calculated in Section IV above.

IFM Watts = 1743

Determine net cooling capacity using the following formula:

Net capacity = Gross capacity – IFM heat

=179,000 Btuh – 1743 Watts

Btuh

(3.412 Watts )

=179,000 Btuh – 5947 Btuh

=173,053 Btuh

Net sensible capacity = 117,000 Btuh – 5947 Btuh = 111,053 Btuh

The calculations show that a 579F180300 unit with the standard motor and standard low-medium static drive is the correct selection for the given conditions.

579F180-300

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Bryant 581A/B manual Selection Procedure With 579F180 Example, II Select Unit Based on Required Cooling Capacity

581A/B specifications

The Bryant 581A/B is a sophisticated rooftop unit designed for commercial heating and cooling applications, striking a balance between performance, efficiency, and versatility. This unit is engineered to cater to various building sizes and configurations, making it an excellent choice for businesses seeking reliable climate control solutions.

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Overall, the Bryant 581A/B is a robust solution for businesses seeking efficient, reliable, and flexible climate control. Its combination of advanced technology, durable construction, and user-friendly features make it a leading choice in the commercial HVAC market.