Vav Box Reheat Coil Sizing

If one vav box cannot meet noise criteria consider using two.

Vav box reheat coil sizing. Imho hvac equipment sizing is 90 engineering and 10 art. Compact size and easy access for service saves time and expense in installation rectangular discharge opening is designed for slip and drive cleat duct connection inlet sizes. Our fan powered terminal units available as parallel and series provide operating cost savings through reduced central fan horsepower and use of waste heat recovery. Daikin s single duct vav boxes from 80 to 8000 cfm provide high performance and set the standard in the industry for construction performance and quality.

Usually inlet diameter determines vav box size. Here is my sizing system object c fakepath capture1 png. Allow spare airflow capacity. For example the maximum rating of a vav box for a general office with a desired nc level of 30 should be no more than nc 35.

Summarizes a detailed analysis of vav box control and selection1 and provides vav boxes sizing criteria that will mini mize lcc in typical applications. Trane has developed a computer program to perform these tasks. Vav box selection matters and if mistakes are made they happen at scale due to the high multiples of vav boxes on a project. Vav controls and airflow setpoints figure 1 shows a single duct vav box using pressure independent control logic.

The vav box is supplying air near 55f and not reheating to meet the temperature setpoint. They are specifically designed for precise air delivery throughout the entire operating range regardless of the installed inlet conditions. Zone with its vav box wide open maximum air flow to the zone. Model tss terminals provide variable air volume vav control beyond the typical single duct box.

4 5 6 7. Electric reheat box was selected the minimum cfm would be dependent upon the kw of the electric heater. A one row coil for a size 12 air valve will operate at the above conditions as follows. The following criteria should be embedded considerations by the engineer with each vav box selection.

Here is my sizing zone object c fakepath capture png. It appear that the coil is not being sized for the reheat load and only for whatever exterior load exists which is none. The zones with lesser cooling demand will throttle their vav boxes down as far as their minimum flows and if the air is still too cold will then reheat the air using a hot water or electric resistance coil at each zone. Two or more vav boxes can be controlled with one temperature sensor.