Dual Duct System

The dual duct system is another means of providing varying air temperatures to different rooms in the same building. There is no water circulation to peripheral discharge units with terminal reheaters or coolers. This simplifies the plumbing installation as heating and cooling elements for each duct are located in the plant room. However, the system is space consuming and adequate provision must be made in suspended ceilings or raised flooring to accommodate both distribution ducts. The system is most energy economic when heating and cooling elements operate individually.

Variable Air Volume (VAV)

The VAV system has a central air-processing unit to produce air at a specified temperature and relative humidity. The conditioned air from the main unit is conveyed in ductwork to ceiling diffusers which incorporate thermostatically controlled actuators. These can change the air volume to suit each room load. In a large room, several of these VAV ceiling units may be controlled by one room thermostat.


Depending on the state of the air on entering a spray washer, it can be humidified or dehumidified. Humidification in the presence of moisture is understandable, but dehumidification is less easy to comprehend. It occurs when the spray is at a lower temperature than the air and the dew point of the air.

Data Centers Cooling Systems

In a data center, the HVAC system energy consumption is dependent on three main factors: outdoor conditions (temperature and humidity), the use of economization strategies, and the primary type of cooling consider the following:

Flexible Duct Calculator

Flexible Duct Calculator based on four different methods. Based on Friction Loss, Based on Duct Diameter, Equivalent Rectangular Duct, Equivalent Round Duct Diameter. Also table of Maximum Recommended Supply Velocity.

Air Change Cfm Calculator

The rate at which air is exchanged (in the premises) represents another method of measuring ventilation capacity & effectiveness. Air exchange rate is typically expressed in Air Changes per Hour – “ACH”. Air changes per hour can be estimated by determining the total air supplied to, and removed from, the premises “total air exchange” or the outdoor (fresh) air supplied to, and removed from, the premises “outdoor air exchange”.

Air Conditioner Btu Calculator

This calculator is used to determine the capacity of room Air Conditioner. An air conditioner is a system or a machine that treats air in a defined, usually enclosed area via a refrigeration cycle in which warm air is removed and replaced with cooler air.

Solar Geometric Angles

Solar Geometric Angles are all critical to the calculation of solar energy on any given surface at some orientation. To calculate the energy balance across any time scale with respect to the incident solar radiation, you must know the geometric relationships that define the spherical realities of planetary motion relative to the sun for specific tilted surfaces on the planet.

Interactive Psychrometric Chart

The aim of this web app is to create an interactive psychrometric chart on which you can project a range of comfort metrics as well as mapping weather data or room air conditions calculated using EnergyPlus. You can add or remove lines for a range of different metrics or highlight them individually to assist with dynamic explanations or presentations.

Hvac Load Calculations

The accurate calculation of heating and cooling loads is essential to provide a sound bridge between fundamental building design decisions and an operating building. If loads are substantially underestimated, occupants and users will likely be hot or cold. If loads are substantially overestimated, equipment will be oversize (usually wasting money, reducing efficiency, increasing energy consumption, and often imperiling comfort).

Three-Way Control Valves

Three-way valves provide for variable flow through the coil while maintaining somewhat constant flow in the system. While three-way valves are most commonly used where constant fluid flow is desired, in reality they will not result in constant flow no matter which plug style is selected.

Two-Way Control Valves

The control valve is possibly the most important component of a fluid distribution system because it regulates the flow of fluid to the process under control. In HVAC systems, control valves are primarily used to control the flow of chilled water, hot water, and condenser water, the subject of this section.

Psychrometric Processes

The different psychrometric processes are discussed, Sensible Cooling Sensible, Heating Cooling and Dehumidification, Sensible Heat Factor (SHF), Heating and Humidification, Cooling and Humidification, Heating and Dehumidification.


Knowing the principles of Psychrometry which is the study of the properties of mixtures of air and water vapour. Atmospheric air is a mixture of many gases plus water vapour.

Solar Angles

The Solar angles are important factors to improve the power conversion efficiency. To determine the angle of incidence θ between a direct solar beam and the normal to the surface, the surface azimuth ψ and the surface-solar azimuth γ must be known.

Characteristics Of Solar Radiation

Solar energy is the result of electromagnetic radiation released from the sun by the thermonuclear reactions occurring inside its core. All of the energy resources on earth originate from the sun (directly or indirectly), except for nuclear, tidal, and geothermal energy.

Mortgage Calculator

Mortgage calculators are a great tool for anyone looking to finance a HVAC project. With a mortgage calculator online, you can quickly and easily calculate the monthly payment and amortization schedule related to your project. This can help you determine the best financing option for your project and make sure you are getting the best deal. With a mortgage calculator, you can also compare different loan options and find the one that best fits your needs. With a free mortgage calculator, you can save time and money by quickly and accurately calculating the monthly payment and amortization schedule related to your HVAC project.

Weather Design Conditions (ASHRAE)

Search weather stations as published in ASHRAE Handbook. information used for design, sizing, distribution, installation, and marketing of HVAC and dehumidification equipment, as well as for other energy-related processes in residential, agricultural, commercial, and industrial applications.