Air Handler Equipment DDC Controllers – These controllers will control an air handler once the wiring is completed. The panel is freshly mounted and waiting for the technician to run the piping and pull the wire from the control points. Other points, such as outside air, temperature sensors in piping or ductwork, flow meters, actuators, or other control points can be terminated to these controllers and the data collected from those input points can be networked over the entire building automation system through the communication trunks. (more…)
BAS DDC Learning | HVAC - HVAC Building Automation Systems (BAS) or Direct Digital Controls (DDC) is pretty much one and the same. Basically described BAS and DDC are combining air conditioning, heating, ventilation, lighting, electrical loads, security systems, and life and safety systems to a computer and complex algorithms for better control over the systems. (more…)
DDC Control Module for an Air Handling Unit – This is a direct digital controls control module for an air handler that serves some VAV boxes in office spaces for a Data Center. This DDC control module includes analog and digital inputs and analog and digital outputs to handle all the control functions necessary to control the devices and components on a large commercial air handler. (more…)
Alerton BTI DDC Controller Building Automation - This is the main DDC controller for Alerton. It communicates with all the other controllers in the field serving the building automation system and connects those systems with a computer or modem. (more…)
DDC Programming Logic Symbols 1 - DDC programming in HVAC Control can be rather complex especially to those who don’t understand software or programming. Some software and hardware manufacturers utilize symbols to build their logic programs for HVAC DDC control. Some of these logic blocks are rather complex but others are very simple. (more…)
DDC Programming Logic 3 - DDC control logic blocks have practically an unlimited way of arranging the blocks for HVAC control. Below is an example of a line of logic blocks arranged for static pressure control of a VAV air handler supply fan using a variable frequency drive. This same arrangement could also be used for static pressure control using a bypass damper instead of a VFD. (more…)
Programming DDC Logic 2 - The analog network input is similar to an analog input except this input is not hardwired to the local controller but on a remote controller in the network. It is very important that the communication works effectively for this analog network input to work. An example of this is the outside air temperature which is hardwired to a DDC controller in the penthouse of a multistory building.
The building engineer only wants the boilers to fire if the outside air temperature is less than 55° F. Instead of having an outside air temperature device hardwired to the boiler controller an analog network input can be placed into the boiler controller program and linked to the outside air temperature reading which is in the penthouse controller where the outside air temperature thermistor is hardwired. This saves devices and wires necessary for optimum control.
Air Handler Filter Pressure Sensor - This is a pressure sensor. It tells a maintenance technician if the air filters are dirty and clogged. The pressure control is a low static pressure switch to trip the unit if the mixing box drops below the setpoint pressure. The pressure the switch is calibrated to.
In addition, the low static pressure sensor protects the fan and the ductwork including dampers from damage. If the economizer damper and the return air damper would fail closed (or another possible scenario) that would cause the unit to pull negative pressure in the mixing box. (more…)
York VAV Air Handlers | HVAC Zoning - This York air handling unit serves several VAV boxes and runs on a static pressure control set point determined by a DDC program. This program has a static pressure control setpoint and sends a signal to the variable frequency drive to speed up or slow down the blower to maintain the proper static pressure control setpoint. When the VAV boxes need more air the drive speeds the air handler blower up.
When the VAV boxes need little the drive slows the blower down. The VAV boxes are controlled by a thermostat in their respective zones.
HVAC Tip - According to studies done by the Department of Energy, 50 percent of the heat loss experienced in the average home occurs through the ceiling. That makes a lot of sense since heat rises. You can reduce that heat loss (heat gain in the summer months) by adding another layer of insulation in the attic. That will hold more heat in our homes for a longer period of time which means the furnace will cycle less. That means you are going to save money. A lot more money than another layer of insulation costs. Additionally, having an attic fan controlled by a thermostat installed in your attic will remove a lot of heat in the summer. This will help you, in addition to having more insulation, reduce heat gain from the attic in the summer.
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Air Handler Equipment DDC Controllers – These controllers will control an air handler once the wiring is completed. The panel is freshly mounted and waiting for the technician to run the piping and pull the wire from the control points. Other points, such as outside air, temperature sensors in piping or ductwork, flow meters, actuators, or other control points can be terminated to these controllers and the data collected from those input points can be networked over the entire building automation system through the communication trunks. (more…)
DDC Control Module for an Air Handling Unit – This is a direct digital controls control module for an air handler that serves some VAV boxes in office spaces for a Data Center. This DDC control module includes analog and digital inputs and analog and digital outputs to handle all the control functions necessary to control the devices and components on a large commercial air handler. 
Alerton BTI DDC Controller Building Automation - This is the main DDC controller for Alerton. It communicates with all the other controllers in the field serving the 
Air Handler Filter Pressure Sensor - This is a pressure sensor. It tells a maintenance technician if the 
York VAV Air Handlers | HVAC Zoning - This York air handling unit serves several VAV boxes and runs on a static pressure control set point determined by a 