In HVAC a variable speed drive is a speed control system for electric motors. The variable speed drive (VSD) or variable frequency drive (VFD), among other names (adjustable-frequency drives (AFD), AC drives, micro-drives, or inverter drives). The application of variable speed drives has brought about a new way of engineering buildings and control systems HVAC.
The flow of water and air can now be regulated precisely using VSD’s and state-of-the-art control systems. By combining VSD’s with state-of-the-art control systems, large savings in energy usage can see realization because the exact quantity of flow of water or air can be delivered to satisfy demand.
Demand-based control is energy efficient. VSD’s can be stand-alone or controlled by a building automation system.
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…)
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…)
HVAC Duct Work delivers the conditioned air to the spaces. The Air Handling Duct channels this conditioned air to spaces where it is needed and then a return duct channels the air back to the air handling unit duct for re-conditioning. The return ductwork has a negative pressure while the supply ductwork has positive pressure.
In commercial systems and tight residential homes, it is necessary to add fresh air to this conditioned air so the air remains fresh and healthy for the occupants of the structure. This is required by the mechanical code and often this air comes through ductwork from the outside. (more…)
HVAC Duct Systems - Ductwork systems channel the air to the spaces where it is needed from the air handler. HVAC duct systems also will pull the air from the space and channels it back to the air handler where it needs to be conditioned. In some commercial applications, the area above the ceiling is considered the return duct. All the return air is channeled back to the air handler through the plenum where it is conditioned in the air handler. Part of the conditioning process is the air being passed through an air filter and then an exchanger like a coil or heat exchanger. (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…)
Most air conditioning and heating systems require some form of ductwork. Ductwork channels or directs the air to places in the dwelling where the conditioned air is needed. There are many types of ductwork available. Often times the ductwork can make a big difference in your utility bills. For that reason, it is important that the ductwork is installed correctly by qualified installation technicians. (more…)
This photo shows the air handler blower compartment. This is how the air handler is opened when the blower needs service or repair. The evaporator coil is on top of the blower which makes this an upflow air handling unit. The supply air ductwork will be above the AHU. Since this air handler is installed in a closet then the ductwork is installed in the ceiling and makes this an ideal installation for AC since cool air falls. (more…)
What Type of HVAC System Needed for Sun Porch - We added a 300 sq. ft. of living space to our home as a sun porch. How do we effectively, efficiently heat/cool this space? We’ve been pitched several options. 1) Use existing with a manual duct damper to the new sun porch. 2) same as above but use a zoned approach. Zoned w/auto dampers for main house 1st floor and sun porch plus separate thermostats. 3) HVAC with new units for sun porch (e.g., radiate, forced air, etc) (more…)
Basic Heat Pump Maintenance - A good heat pump maintenance plan will include a thorough check of the refrigeration system, the electrical system, the heat pump controls, and the air filter system of the heat pump. Heat pump maintenance is as important as maintenance on your vehicle. If we fail to take good care of our vehicle then it is more prone to breakdowns whereas if we keep it in good condition with proper maintenance it is more reliable and repairs usually cost less when repairs are needed.
Of course, if you take good care of the heat pump with regular maintenance major repairs will likely never occur and it is possible you will repair free with a good maintenance plan in place for your heat pump. Basic maintenance adds life to the equipment, keeps the equipment running longer adding to the lifespan, and during the overall life will keep the heat pump more efficient.
HVAC Tip - Some people refer to refrigerant as Freon. So when something is wrong with their HVAC system they say, “I have a Freon leak”. Freon is a name trademarked by Dupont for R-22. R-22 is being phased out because it contains chlorine. While Freon will soon be a thing of the past, the name Freon has found its way in our lexicon as a reference to refrigerant, any type of refrigerant.
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In HVAC a variable speed drive is a speed control system for electric motors. The variable speed drive (VSD) or variable frequency drive (VFD), among other names (adjustable-frequency drives (AFD), AC drives, micro-drives, or inverter drives). The application of variable speed drives has brought about a new way of engineering buildings and control systems HVAC.
Air Handler Filter Pressure Sensor - This is a pressure sensor. It tells a maintenance technician if the 
HVAC Duct Work delivers the conditioned air to the spaces. The Air Handling Duct channels this conditioned air to spaces where it is needed and then a return duct channels the air back to the air handling unit duct for re-conditioning. The 
HVAC Duct Systems - Ductwork systems channel the air to the spaces where it is needed from the 
Most air conditioning and heating systems require some form of ductwork. Ductwork channels or directs the air to places in the dwelling where the conditioned air is needed. There are many types of ductwork available. Often times the ductwork can make a big difference in your utility bills. For that reason, it is important that the ductwork is installed correctly by qualified installation technicians. 
This photo shows the air handler blower compartment. This is how the air handler is opened when the blower needs service or repair. The evaporator coil is on top of the blower which makes this an upflow air handling unit. The supply air ductwork will be above the AHU. Since this air handler is installed in a closet then the ductwork is installed in the ceiling and makes this an ideal installation for AC since cool air falls. 
What Type of HVAC System Needed for Sun Porch - We added a 300 sq. ft. of living space to our home as a sun porch. How do we effectively, efficiently heat/cool this space? We’ve been pitched several options. 1) Use existing with a manual duct damper to the new sun porch. 2) same as above but use a zoned approach. Zoned w/auto dampers for main house 1st floor and sun porch plus separate thermostats. 3) HVAC with new units for sun porch (e.g., radiate, forced air, etc) 