How DDC Status Works – DDC and Status – Is the Device On or Off
This is a current switch sometimes referred to as a CT switch.
The basics of DDC include learning about the status of a fan or a compressor or pump. How does a DDC controller read the status of the device it is monitoring? There are several ways to prove a device is running and some pros and cons of each type of device used to monitor on or off status.
This is a basic DDC guide or reference to help a person understand the basics of DDC status and how it works. When one learns how DDC status works they can improve their troubleshooting skills.
Too many maintenance technicians and others including HVAC technicians don’t understand DDC systems or building automation systems and are therefore crippled when it comes to troubleshooting DDC systems.
High Performance HVAC hopes to change that and help HVAC techs and HVAC maintenance staff learn the basics of DDC systems including how DDC status works. Once someone understands the basics about DDC a light will turn on and they will see that DDC is not really rocket science.
Air Conditioner Squirrel Cage Blower | HVAC blower motors move the air through the system. The blower motor is sized based on the amount of air flow necessary for the system. This blower motor is the supply fan for the supply air in a large commercial York AHU. An AC and heatingforced air system is sized based on load. The load factors include heat loss and heat gain, number of people in the building, types of rooms served, factoring in heat produced by equipment such as computers and other heat producing equipment. (more…)
Grounding and Bonding Electrical Systems | NEC Code - National Electrical Code Article 250 is all about grounding and bonding as represented in this photo where electrical systems are grounded and bonded to the buildings steel structure.
There are many different rules in the NEC (National Electrical Code) pertaining to grounding and bonding because grounding and bonding are important for safety reasons. Electricity will take the path of least resistance so if there is a short in the system the grounding system will be the path for the electricity instead of the motor or load that experiences the short. (more…)
Air Handler Smoke Detectors NFPA - Installing duct smoke detectors or smoke detectors in air handlers are not ideal for the protection of life and property in the event of a fire or smoke condition. The NFPA and mechanical codes cover smoke detectors. (more…)
York Variable Frequency Drives VFDs | HVAC Control - Variable Frequency Drives or VFDs have added a whole new dimension to energy efficiency and control. These drives, or VFDs, are hooked up to two different York VAV air handlers that have two three-phase motors a piece. (more…)
HVAC Tip - HVAC Preventive Maintenance: Just like a vehicle needs preventive maintenance, HVAC systems need a regular maintenance schedule. Having maintenance performed on your air conditioning and heating systems now can help you avoid costly repairs in the future. Air Conditioning and heating preventive maintenance also pays for itself by making the unit more efficient, safe, and reliable. Often, a technician can spot a ten dollar part that needs replacing now where if it is let go and not replaced, can cost you hundreds of dollars more in the future. The old phrase is true, "pay me a little now, or a lot later." I see it every day. Basic maintenance on condensers and air handling units will save you money in the long run. If your local heating and cooling company offers maintenance agreements look into getting one for your home or business. Typically, companies offering maintenance agreements waive overtime charges for after hours or emergency calls and offer you reduced prices on parts. That is in addition to performing preventive maintenance twice annually.
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York Variable Frequency Drives VFDs | HVAC Control - Variable Frequency Drives or VFDs have added a whole new dimension to energy efficiency and control. These drives, or VFDs, are hooked up to two different York VAV air handlers that have two three-phase motors a piece. 