The NEC and HVAC Chapter Two

The NEC and HVAC Chapter Two – Chapter Two of the National Electrical Code (NEC) covers Wiring and Protection and starts at Branch Circuits, Feeder circuits, GFCI requirements and protection,. An HVAC installer may want to pay attention to branch circuit requirements. Article 220 in Chapter two of the NEC includes calculations for branch and feeder circuits including service calculations. (Table 220.3) (more…)

VAV Air Handler | HVAC Zoning

 VAV Air Handler | HVAC Zoning

VAV Air Handler and HVAC ZoningVAV Air Handlers are ideal for providing zones in a commercial building. Office space typically has several offices and open areas that need to be conditioned for the comfort of the people working in those areas or offices. By installing VAV boxes and zoning the duct work from those VAV boxes these areas and offices can be kept comfortable using a VAV air handler system. Each box can have its own thermostat and that area or office served by that particular VAV box can be maintained and conditioned for the people working in that space. The VAV box will receive its conditioned air from an air handler through a primary duct that feeds air to the VAV box. The VAV box then determines the amount of air to the secondary duct by a damper located in the VAV box. Depending on what the thermostat temperature set point is and the temperature in the space will determine the amount of air flow the space will receive from the VAV box. Additionally, A box with reheat will energize the heat strips or open the actuator for the hot water coil if the set point and room temperatures calls for the reheat to provide heat to the space (If the VAV box is equipped with reheat).

To learn more see our article on How VAV Boxes Work

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Motor Controls for HVAC – Residential Air Conditioning and Heating

Motor Controls for HVAC - Motor controls are necessary to start and stop air conditioning and heating motors automatically or manually. The most common manual motor control for air conditioning and heating is the thermostat. The thermostat starts and stops the blower motor on their home air conditioning and heating system. It is the Fan – Off – Auto switch on the air conditioning and heating thermostat. This switch when placed in the on position turns the blower motor on. It circulates air continuously until the user turns the thermostat fan switch to either the off position or the automatic position. (more…)

Variable Air Volume Systems – Commercial HVAC

Variable Air Volume Systems - Variable Air Volume (VAV) systems are the best way to zone especially in large buildings. A VAV system with the proper controls and set-up will help the building owner realize large savings in energy usage. There are many VAV systems out there set up in different ways. The most common set-up (for DDC) are, of course, usually the cheapest to install. They have an air handler (DX or Chilled Water) which supplies the VAV Boxes with a fixed pressure and temperature of conditioned air. The VAV Boxes have electric reheat which will heat the air if that particular zone calls for heat (it is not uncommon to also find VAV boxes that have hot water reheat although this usually cost more to install but can save in energy costs).

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HVAC Damper Actuator for Economizer Free Cooling

HVAC Damper Actuator for Economizer Free CoolingHVAC Damper Actuator for Economizer Free Cooling

This damper actuator controls a free cooling damper for an economizer. It is part of an economizer damper system which allows free outside air cooling when the outside air temperature and humidity are ideal. In the Fall and the Spring when the outside air temperatures are mild it is unnecessary to run the air conditioning system to cool the building if the system is set up for free cooling. The air conditioning system has duct work running to the outside. When the control system program calls for free cooling the outside air damper opens and the system draws in cool air from the outside. Another damper directs the return air, which originates inside the spaces of the building, to the outside. This brings cool conditioned air into the building while exhausting the warmer air to the outside. Another action that the control program initiates is the lockout of the air conditioner or mechanical cooling.

To learn more about HVAC click here.

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