Vav box reheat coil sizing software

Variable air volume box with hot water reheat hvac zoning. A variety of accessories are available to tailor this unit to specific applications including those with stringent requirements for noise levels, temperature, and energy efficiency. Vav terminals provide a measured quantity of conditioned air to a space, in response to a control signal from a thermostat or room sensor. In one case, the software correctly activated the reheat coil when the vav box damper reached its minimum stop and the zone temperature was. First, the program performs a psychrometric and analysis to determine. This limit is active only when the zone thermostat requests heating and the. Vav controller flow calculation constants 3 key concepts about flow calculation constants a flow calculation constant is referred to as the flow multiplier in variable air volume vav controller applications created with hvac pro software.

Some variable air volume boxes also have a heat source inside the box. Performance selection data hot water heating coils non fan powered units b76. In one case, the software correctly activated the reheat coil when the vav box damper reached its minimum stop and the zone temperature was still below the setpoint. Coils are available with the total capacity divided into one. If a zone is satisfied for cooling temperature, it is possible that the internal heat gain is not adequate to offset the room heat loss lights may be off, people may not be in the room. Weve had a lot of request fr a demo of out teams selection software, so we made it this weeks titus timeout. Vav box reheat guidelines revised 050102 vav box reheat. The air flow rate used for reheat coil sizing is reported with other component sizing information as reheat coil sizing air volume flow rate. Sizing of the reheat coil, calculation of the reheat coil load, and calculation of the reheat coil heating water flow rate are dependent on several factors. Nailor 3000 and 3100 series terminal units are among the most versatile vav boxes on the market, providing easy hvac system integration with diverse control packages. Vav controllervariable air volume vav controller 5 1 2fintroduction the variable air volume vav controller is an electronic device for digital control of single duct, dual duct, fan powered, and supplyexhaust vav box configurations. The thermostat and the controller will also turn on the heat whenever the temperature in the space falls below the set point, as determined by the thermostat and pre. The means and selection of parameters for this reheat leads to much of the. Peak loads and airflow rates for all spaces and zones served by the system.

The means and selection of parameters for this reheat leads to much of the complexity and questions in selecting and specifying vav terminals. Q the amount of heat transferred to or from the fluid btuhr m mass flow rate of the fluid lbhr cp. Vavbox selection, code conformance hpac engineering. How vav boxes work hvac commercial zoning stepbystep. The system will consist of rooftop units with chilled water coils and preheat coils, chillers, boiler, pumps etc, with vav boxes serving the classrooms and offices. Cfm 140 100 300 400 500 600 710 800 925 heating capacity mbh air side pressure drop in w. In trying to size the preheat coil, my intent is maintain a minimum discharge air from the unit around 55 degrees f and do heating in the spaces with reheat coils in the vav boxes. Carrier hap hourly analysis program softwares hvacr.

Here is the part ive never seen, all the hot water reheat coils are located in the high side duct work about two feet before the inlet of each vav box. Model tss terminals provide variable air volume vav control beyond the typical single duct box. If you know a rep that sells vav boxes you could figure out what size box has a reheat coil similar in size, give him a gpm and cfm, and he could tell you how many btus. Quiet type with dissipative silencers and hospital grade boxes are also available. The heat source in many variable air volume boxes are typically electric but can also be a hot water coil. Daikin offers a variety of vav terminal boxes to meet your system needs. Yes,100% outside air,chiller with hot water reheat. Understanding the userdefined sizing option for hap air. The 35e single duct unit provides cooling only or cooling with reheat to meet most application requirements.

Frames are constructed of 20 gauge galvanized steel. Turns out,bad zv head,not opening,letting just cold air through. Hot water coils are attached to the terminal unit as standard. The program provides features for quickly designing fan coil, wshp, gshp and vrf systems in batch runs. The unit is designed to allow maximum flexibility in configuration and control. Accessories for the single duct with a water coil include access doors in the coil section upstream and downstream of the water coil.

Reverted the initial changes related to removing reheatmult term, the. Variable air volume vav controller technical bulletin. Vav controls and airflow setpoints figure 1 shows a single duct vav box using pressure independent control logic. Performance selection data hot water heating coils. Heating airflow is determined from the userentered or default vav minimum. The vav box is supplying air near 55f and not reheating to meet the temperature setpoint. These units are generally applied in coolingonly vav zones that require no heat during occupied hours. Unlike custom air handlers, the fin spacing, circuiting, and tube spacing are fixed for vav box coils. Vav reheat system downstairs in the suite it has your typical vav boxes with pneumatic thermostat, damper actuator, velocity controller and hw reheat valve. However, as the zone temperature rose and the damper lifted off its minimum point, the reheat coil wasnt deactivated.

Heating can usually be provided by use of reheat coils or thermostatic baseboard. I usually see in the sequence of operation that when heating is. Electric heat coil capacity is rated in kilowatts kw. Pressure independent controls use two cascading control loops. The advanced variable air volume vav system design guide design guide provides a powerful new resource for heating, ventilation, and air conditioning hvac designers. If local zone heat is necessary it can be provided either remotely for example, perimeter heat or by terminal. Variable by volume varitrane single duct vav trane. The variable air volume vav box model mqthi5 is our high performance single duct air terminal product line. Reheat coil sizing appears to be broken for normal action vav added on 20506. Brass coil hookup kits xylem applied water systems.

Heating coil selection if required first, determine the amount of heat required to meet space and downstream duct heat losses from a load calculation. Smartphone devices have the ability to make vav and reheat selections for. The supply air temperature must be low enough to meet the cooling load in the zone having the greatest load. Hvac design overview of variable air volume systems.

What distinguishes a variable air volume system from other types of air delivery systems is the use of a variable air volume box in the ductwork. Teams is a windows based engineering design tool allowing applicationbased selection of grilles, registers, diffusers, vav terminals, and fan coils for. Coils must fill from lower tube and discharge from upper tube. Designed to control the flow of conditioned air into an occupied space, single duct terminal units can be used in almost any application. Normally carriers hourly analysis program hap is used to automatically determine sizing requirements for hvac systems such as supply and ventilation airflow rates, and coil capacities. Vav with electric heater ter electric heater electric heating coils are applied on vav terminal units as terminal reheat devices. There are several equations that can be used in conjunction withthe colmac coilpro selection softwareprogram to speed the process of sizing coils. This air may be tempered with a reheat coil, plenum air, or both.

The load calc on the room should have already been done, basically you size the vav and reheat based upon the load of the space, so a load calc software would help a lot. Teams is a windows based engineering design tool allowing applicationbased selection of grilles, registers, diffusers, vav terminals, and fan coils for commercial hvac systems. Berg, mechanical engineer, colmac coil manufacturing, inc. Our vav units can also be configured with heating options like electric and hot water, factoryassembled piping packages, and control options like analog electric, pneumatic, and consigned. It appear that the coil is not being sized for the. Once you determine the load requirements then choosing the proper size vav and reheat is fairly easy but basically a couple rules of thumb for typical office space are. Vav system faults filterfancoil and vav box sections. Heating coil selection section of the system checksums report. Designed for cooling only, cooling with reheat, heating only or heatcool changeover applications. Using vendorfurnished software for vavbox selection streamlines the design process and provides answers to many sizing questions. Also lists sizing data for zone reheat coils, mixing box fans and supplemental heaters. Vav piping packages as well as hl, hp, vf, and vl fan coil unit packages are factory assembled and shipped loose for field installation and wiring. For dx fan coils, wshps and hydronic fan coils this report lists detailed airflow and coil sizing data for all fan coil or wshp units. Cooling mode air enters the mixing box of the air handler from both the cabins return air, ra.

The carnes hot water coil is available on vav units as an optional accessory. Rooms can optionally be grouped under vav boxes as well zones. The algorithms as implemented in the laboratory software correctly. The vav concept may vary according to the vav box locations, air temperature controls and types of heating elements. The cooling coil is controlled by a controller setpoint specified for the cooling coil. Vav systems can be used for interior or perimeter zones with a common fan system, air temperature control, and reheating devices. The variable air volume box or vav box is a commercial solution to adding multiple zones to large buildings vav boxes offer zoning solutions so that separate zoning demands or temperature selections can be maintained in different areas of the building. Singleduct terminal units control the volumetric flow of supply air to the space to maintain the zone temperature at setpoint. Teams dynamically calculates a range of products that will operate at userspecified conditions, allowing the design engineer to pick the best fit for the application.

The reheat option is either a water coil, or an electric heater. Fan section an illustration of this unit and the vavreheat system is shown on the following page. Standard kits are available for use with all of our balance and flow limiting valves, and nonstandard. The teams installation includes all of the titus air distribution selection software suite of products. Can somebody give me a good explanation why typically when you size heating coils in vav systems either reheat coils for vav boxes or in the vav ahu is it customary to size the coil for about 50% of the maximum cooling airflow rate. Heating air with a steam coil or a hot water coil is an example of sensibly heating air. Coil hookup kits have been shown to reduce ordering and installation time and help reduce field problems. Understanding the userdefined sizing option for hap air systems. Rectangular discharge opening is designed for slip and drive cleat duct connection.

Titus timeout podcast how to use teams to select vav boxes. Sizing data is provided for central cooling and heating coils, preheat and precool coils, fans, humidifiers, terminal reheat coils, cav and vav air terminals, fan powered mixing boxes, perimeter baseboard units. For sensible heating or cooling, the following equation holds true. The most basic vav box consists of an enclosure with a small air valve damper that regulates the. Other common terms for this constant are kconstant or pickup gain. All vh fan coil unit packages are factory assembled, installed, and wired. They also offer improved space comfort and flexibility for a wide variety of hvac applications. It appear that the coil is not being sized for the reheat load and only for whatever exterior load exists which is none. Compact size and easy access for service saves time and expense in installation. Reheat provides a model for single duct constant volume systems with reheat that satisfy the cooling load in a zone by changing the inlet air temperature with a reheat coil. When selecting a coil, one can pick only one independent variable, with different parameters for increasing the number of rows, gpm, etc. The 35e unit is among the most versatile singleduct products on the market, offering a compact design with diverse control packages. Vav pid wrh 100 vav pid wrh 125 vav pid wrh 150 gpm 2nd row coil gpm 3rd row coil gpm 4th row coil.

There are 6 different calculation paths included in both programs. Following is a listing of several of these equations, a description of where they come from, and examples of how they. It used to be 2 separate rooms,each with their own stat, and controller in the ceiling,just outside the rooms. They are specifically designed for precise air delivery throughout the entire operating range, regardless of the installed inlet conditions. Useful equations when sizing coils with coilpro introduction there are several equations that can be used in conjunction with the colmac coilpro selection software program to speed the process of sizing coils. Titus hvac engineering innovative air distribution. It presents brand new information on fan selection and modeling and provides the most current recommendations on vav airside system design. Note that if an electric reheat box was selected, the minimum cfm would be dependent upon the kw of the electric heater.