246653-YTG-E-0108

SUPPLY AIR DRIVE ADJUSTMENT

At unit start-up, the measured CFM may be higher or lower than the specified CFM shown in Figures 22, 23, and 24. To achieve the specified CFM, the speed of the drive may have to be decreased or increased by changing the pitch diameter (PD) of the motor sheave as outlined below:

Failure to properly adjust the total system air quan- tity can result in extensive blower damage.

Before making any blower speed changes review the installation for any installation errors, leaks or undesirable systems effects that can result in loss of air flow.

Even small changes in blower speed can result in substantial changes in static pressure and bhp. Bhp or amp draw of the blower motor will increase (see table) by the cube ratio of the blower speed. Static pressure will increase by the square ratio of the blower speed. Tables 26, 27 and 28 are for reference only. All blower speed changes must be made by qualified personnel with strict adherence to the fan laws.

Example:

A 30-ton unit was selected to deliver 12,000 CFM with a 20 HP motor and a 856 RPM drive, but the unit is only delivering 11,000 CFM per Figure 23.

Use the equation to determine the required PD for the new motor sheave (12,000 CFM / 11,000 CFM) x 6.7” = 7.31”.

Use the 30-ton table to select a Browning 2B5V74 which will increase the speed of the unit's drive and its supply air CFM 109%.

New drive speed =

1.091 x 856 = 933 RPM

New supply air =

1.091 x 11,000 = 12,000 CFM

Re-use the existing belts and blower sheave.

New motor BHP = (speed increase)3 x estimated motor BHP at original start-up with 11,000 CFM and 856 RPM = (1.091)3 x 11.0 BHP = 1.2986 x 11.0 BHP = 14.3 BHP New motor amps = (speed increase)3 x measured motor amps at original start-up with 11,000 CFM and 856 RPM.

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Johnson Controls Unitary Products

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York Y34, Y33, Y32 manual Supply AIR Drive Adjustment, Example
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Y32, Y34, Y33 specifications

The York Y33, Y32, and Y34 series represents a significant advancement in rooftop packaged units designed for commercial HVAC applications. These models are known for their reliability, energy efficiency, and innovative features that cater to diverse climate control needs.

The York Y33 series introduces modern features aimed at maximizing comfort and reducing energy costs. Its sleek design and compact size make it a versatile option for various applications, including retail spaces, office buildings, and industrial facilities. One of the standout features of the Y33 is its variable-speed compressor technology. This allows the unit to adjust its cooling output based on real-time demand, resulting in notable energy savings compared to traditional single-speed units.

The Y32 model builds upon the strengths of the Y33, offering enhanced capabilities for large commercial spaces. It incorporates advanced controls and building management system (BMS) connectivity, enabling seamless integration into existing infrastructure. The Y32 is designed with a focus on ease of maintenance and serviceability, featuring accessible components that streamline repair processes.

The York Y34 series emphasizes environmentally friendly practices, utilizing low-GWP refrigerants that minimizes its impact on the environment. It also boasts improved heat exchangers that increase efficiency and performance. The Y34’s design minimizes noise levels, making it ideal for applications where quiet operation is paramount, such as schools and healthcare facilities.

All three models share several key technologies, including fan and motor designs that optimize airflow while reducing energy consumption. Additionally, the series features enhanced insulation, significantly improving thermal performance and reducing the risk of condensation-related issues.

In summary, the York Y33, Y32, and Y34 models represent a commitment to innovation in commercial HVAC systems. Their combination of advanced technology, energy efficiency, and user-friendly design makes them suitable for a variety of applications while promoting sustainability and operational cost-effectiveness. Investing in these units not only supports optimal indoor climate control but also aligns with the growing demand for eco-friendly solutions in today’s commercial landscape.
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