In our recent blog article, Improving Indoor Air Quality in Today’s Restaurants, we discussed how well-designed, properly regulated ventilation systems with higher amounts of fresh air and frequent replacements of stale air are recommended to improve overall indoor air quality (IAQ). As a follow-up, this article digs in a little deeper by exploring how maximizing and maintaining IAQ with Dedicated Outdoor Air Systems (DOAS) ensures a safe, comfortable environment for guests and staff – vital to the survival of restaurants today.

DOAS are specifically engineered to improve IAQ by introducing large amounts of fully conditioned outside air into the building for the ultimate in temperature and humidity control. Not all DOAS units are created equal or come equipped with the same critical design features out of the factory. It's important to be aware that any DOAS unit being used has basic features in place to safeguard its efficiency and effectiveness. While installing a DOAS unit in your operation can be a wise investment, it is worthwhile to understand the difference between what features come standard in the cost of a base unit versus which elements a manufacturer may charge extra for as upgrades.

Accurex DOAS units are engineered to arrive with several standard design elements that not only protect the unit, but also improve performance for optimum IAQ, including:

• Painted (powder coated) finish on the unit housing, improving corrosion resistance
• Injected foam insulation on housing and base, maximizing thermal efficiency and reduced noise
• Ultra-quiet condenser fans, reducing unit noise by up to 12dB
• Inverter scroll compressors, providing precise modulation
• Precise airflow control, ensuring the unit is working as designed

Protecting And Enhancing the Performance of Your Investment DOAS units must withstand harsh weather and environmental conditions. Heat, cold, wind, snow, rain, and air pollution all burden the DOAS housing and components if not adequately protected. In more extreme cases, these conditions can cause problems inside of the unit, decreasing performance, which can directly impact IAQ.

Two primary features that protect against this abuse are having a painted exterior finish on the DOAS housing and an injected foam insulation on the entire unit, sealing the interior cabinet from the effects of variable temperatures.

• Powder Coated Exterior Finish A rusting or peeling finish can create more issues than just poor aesthetics. A proper finish seals the metal, protecting it against chalking and corrosion. Accurex provides DOAS with Permatector^™ protective coating. This coating receives salt spray testing that simulates years of continuous abuse from corrosive conditions. The finish can withstand the most severe environments, maintaining the integrity of the cabinet and its components within.
• Injected Foam Insulation The insulated interior cabinet of a DOAS unit does more than protect the components against temperature extremes that may affect performance. The two-inch foam insulation provides R-13 protection, which reduces the amount of exterior condensation and maximizes thermal efficiency for greater tempering performance.
  The injected foam installation method ensures insulation goes into all the possible crevices of the cabinet frame to eliminate voids in the insulation. Manufacturers using foam panels for insulation cannot guarantee their DOAS units are void-free. Injected foam insulation adds extra strength and rigidity to the cabinet and improves noise reduction, making for quieter operation.

  Both protection features come standard on the Accurex DOAS model XRV to help ensure the longevity and performance of every unit. We also offer these additional options that can be configured to match your exact needs and further enhance the performance and efficiency of the unit. 

• Ultra-Quiet Condenser Fans DOAS units can produce noise, but manufacturers that prioritize customer satisfaction understand the importance of minimizing sound pollution. To achieve this goal, units are incorporated with sound reduction features, such as ultra-quiet condenser fans, as a key design aspect. These specialized fans are specifically engineered to reduce noise levels by up to 12 decibels, resulting in a more peaceful and comfortable environment.
  Ultra-quiet condenser fans also allow for normal conversation even when standing next to the unit while it is operating, which gives for more freedom in placing units on rooftops without concern for code violation or building occupants complaining of excessive noise.
  

Inverter Scroll Compressors Some manufacturers use conventional digital scroll compressors on their DOAS units. While digital scroll compressors can handle the requirements of a DOAS, inverter scroll compressors offer better efficiency, particularly at part-load operation – meaning anytime the unit is running in demand control modes or at more mild outdoor temperature conditions than it was designed for. The inverter scroll compressor also delivers smooth cooling control based on the level of demand. Additionally, digital scroll compressors generate much more sound than the inverter scroll compressor until it reaches full load.

Precise Airflow Control As variations in site conditions and duct runs can impact DOAS performance, incorporating an airflow monitoring system helps maintain optimal indoor air quality and ensures the units are functioning at peak levels. Accurex DOAS have an option to include a stand-alone airflow monitoring system that can be configured to your exact needs to deliver proper ventilation along with meeting LEED requirements. This important feature also reduces troubleshooting time and improves effectiveness in addressing issues like dirty air filters and clogged coils.

In addition, the direct-drive backward-inclined plenum fans with factory mounted Variable Frequency Drives (VFDs), standard on Accurex DOAS, provide precise airflow control via modulating fan speed, which also eliminates belt losses and added maintenance. VFDs control and automatically adjust the speed of the motor and fan, balancing the fresh air supply in cooking spaces.

Maximizing indoor air quality is essential for creating a safe and comfortable environment for staff and guests. A DOAS unit functioning at its optimal level with properly equipped features

can ensure and confirm peak performance, while also properly protecting and extending the lifespan of the equipment. Additional customizable options, based on your specific design needs, can also be incorporated to further enhance efficiency, and maximize comfort for your specific operation.

For more information on how you can achieve long-term IAQ with our Accurex Dedicated Outdoor Air Systems and what options and accessories are available to match your exact needs, connect with an Accurex expert, here.