VAV COOLING Ð In VAV operation, the ®lter and volume controller perform the same functions as in CV operation. The unit-mounted thermostat modi®es control operation as described below.

Refer to Fig. 55. The air enters the low pressure chamber of the volume controller through a ®xed ori®ce. The low pres- sure chamber is connected through a stub ®tting and tube to the unit-mounted thermostat. The thermostat senses room tem- perature, closes its port as the temperature rises, and opens it as the temperature falls. This makes it possible to control the pressure in the low pressure chamber in response to the space temperature. With normal space temperatures, and the thermostat satis®ed, the low pressure chamber valve is open to the atmosphere through the thermostat. The rate at which the valve bleeds air from the low pressure chamber is high in relation to the rate at which air enters through the ori®ce, and the pressure decreases in relation to the high pressure. The high pressure force is stronger than the low pressure force and the bleed valve of the bellows pressure chamber of the controller is held closed. Since no air escapes, the bel- lows pressure becomes equal to the high pressure in the ple- num and the unit damper is closed, shutting off the unit.

As the room load increases, the space temperature in- creases. The thermostat senses this change and starts to close,

raising the pressure in the low pressure chamber of the con- troller. As the low pressure rises, it gradually overcomes the high pressure and opens the bellows pressure-chamber bleed valve, lowering the bellows pressure proportionally. This allows the unit damper to open and gradually increase the ¯ow of conditioned primary air into the space. See Fig. 56.

This process continues until the ¯ow of primary air is suf- ®cient to offset the load, or until the ¯ow level set point of the volume controller is reached (Fig. 57). At this point, the thermostat bleed is closed and the unit is actually operating in CV con®guration. As the load is reduced, the process is reversed and the unit ¯ow decreases proportionally until the unit is shut off when the thermostat is satis®ed (bleed fully open) (Fig. 58). In this manner, the unit normally delivers only the actual amount of primary air needed to offset the existing load.

When the wall-mounted DA thermostat is used in place of the unit-mounted thermostat, variable air volume control op- eration is the same as described above for the unit-mounted thermostat. The only difference is that the wall-mounted ther- mostat does not include the aspiration feature.

Fig. 55 Ð Variable Volume Controls Schematic

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Image 56
Carrier 37HS specifications Variable Volume Controls Schematic
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37HS specifications

The Carrier 37HS is a cutting-edge heating, ventilation, and air conditioning (HVAC) solution designed to deliver exceptional performance and energy efficiency for residential and commercial applications. This unit is particularly favored for its advanced features and reliable operation, making it a popular choice among homeowners and building managers alike.

One of the standout characteristics of the Carrier 37HS is its high Seasonal Energy Efficiency Ratio (SEER), which indicates its ability to provide effective cooling while minimizing energy consumption. This makes it not only cost-effective but also an environmentally-friendly choice, helping to reduce the overall carbon footprint. The unit is equipped with state-of-the-art inverter technology, which allows it to adjust its cooling capacity to match the current demand, thus enhancing comfort while optimizing energy use.

The Carrier 37HS incorporates a high-efficiency scroll compressor that operates quietly and efficiently. This technology enhances the unit's reliability and longer service life while ensuring minimal noise levels during operation, making it suitable for residential settings where tranquility is paramount.

A significant feature of the 37HS is its variable-speed fan system, which enables gradual adjustments in airflow to maintain a consistent and comfortable indoor environment. This not only contributes to enhanced comfort but also reduces wear and tear on the system, further extending its longevity.

Moreover, the Carrier 37HS is designed with advanced air filtration capabilities, utilizing multi-stage filters that capture airborne particles, allergens, and pollutants. This results in improved indoor air quality, making it an ideal choice for those with allergies or respiratory issues.

The unit also boasts user-friendly smart controls, allowing homeowners to monitor and adjust settings remotely via a smartphone app. This feature adds convenience and assists in energy management, ensuring that users can optimize their HVAC system even when they are away from home.

In summary, the Carrier 37HS stands out for its exceptional energy efficiency, quiet operation, advanced technology, superior air filtration, and modern smart controls. These features collectively make it a prime solution for those seeking a reliable HVAC system that delivers both comfort and savings, while also contributing positively to environmental sustainability. Whether for a residential setting or a commercial establishment, the Carrier 37HS is engineered to meet a variety of climate control needs with excellence.
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