The National Electrical Code (NEC) and HVAC: The Basics
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)
- Specific branch circuit requirements for HVAC can also be found in Chapter 4 Article 440 – Air Conditioning and Refrigerating Equipment Branch Circuit Conductor Sizing
- Article 424 – Fixed Electric Space Heating Equipment Branch Sizing
- An entire chapter on motors including feeder circuits for motors
Chapter Two of the NEC also covers basic lighting which by code is done by Volt-Amperes per square foot. (Table 220.12) (more…)
DDC Automated Logic M-Stack
DDC Automated Logic M-Stack – This Automated Logic M-Stack provides control for multiple pieces of HVAC equipment and integrates network communication all in one single stack. This direct digital control system is integrated with pnuematic controls. DDC allows automated HVAC control processes to take place and adds higher efficiency to an HVAC system. (more…)
Mechanical Code Book
Home Inspector HVAC Training
Thank you!! I am training to become a home inspector and the info contained on this site is helpful in identifying issues that require a HVAC professional to resolve. Read more…….
You’re welcome! I understand that everything at High performance HVAC is limited and there is so much more to learn about and for me to write about when I get the time for it. Don’t limit yourself to just what is contained on High Performance HVAC as there is so much more to learn as far as HVAC training and learning air conditioning and heating systems. Additionally, some of that knowledge you learn will come with experience so even after studying air conditioning and heating and other areas of home inspecting there is more to learn in the future that only comes with time and experience. (more…)
Thermostat Selection Guide – This article will help you select the right type thermostat for the HVAC system you have installed. (more…)
VAV Air Handler | HVAC Zoning
VAV 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
Motor Controls for HVAC – The Air Conditioning and Heating Thermostat
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, which the average person is familiar with, 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 and circulates air continuously until the user turns the thermostat fan switch to either the off position or the automatic position. When the thermostat fan switch is placed in the automatic position the blower fan will operate automatically based on the temperature setting of the air conditioning and heating thermostat. In most residential systems the air conditioning and heating thermostat is the primary controller for the whole system. (more…)
HVAC Definitions Terms & Acronyms | Heating Cooling – This is a comprehensive list of HVAC Acronyms and HVAC Terms. High Performance HVAC is certain there are more terms and acronyms. If you know of something we missed please email us. Thanks!
HVAC Definitions Terms & Acronyms
VSD or Variable Speed Drives
AC – Air Conditioning or Alternating Current
ACCA – Air Conditioning Contractors Associations
AFUE – Annual Fuel Utilization Efficiency
AHU – Air Handling Unit
AI – Analog Input
AMCA – Air Movement and Control Association
AO – Analog Output
AQS – Air Quality Systems
ASHRAE – American Society of Heating, Refrigerating, and Air Conditioning Engineers
AV – Automatic Air Vent
AWG – American Wire Gage
B – Boiler
BACnet – Computer communication protocol for building automation systems and control networks
BAS – Building Automation System
BI – Binary Input
BMS – Building Management System
BO – Binary Output
BP – Backflow Preventer
BTU – British Thermal Unit
BTUh – Brtish Thermal Units per Hour (more…)
HVAC Definitions – In air conditioning and heating the name HVAC is often used. HVAC stands for heating, ventilation, and air conditioning. Other acronyms less used to describe air conditioning and heating applications is HVACR or heating, ventilation, air conditioning, and refrigeration and HACR or heating, air conditioning and refrigeration. HVAC can be used to also describe the trade HVAC where many technicians and support personal work to install, maintain, and service HVAC equipment. Mechanical and electrical engineers and advanced level air conditioning and heating tradesman have the responsibility to design HVAC equipment and properly ensure it is installed correctly. HVAC and HVACR can include very small refrigerators, air conditioners, and heaters and HVAC can also include very large systems which maintain temperature and comfort factors in large commercial building and industrial settings. (more…)
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).
HVAC 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 lock out of the air conditioner or mechanical cooling.
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