The dampers straight across are outside air dampers or make-up air coming from an energy recovery unit. According to the mechanical code, commercial buildings require a certain amount of fresh air from the outside to maintain good IAQ for the occupants.
An energy recovery unit allows it to be conditioned before being introduced into the building. Other methods include using enthalpy calculations to open economizer dampers and/or CO2 control of the dampers. (more…)
Economizer Systems and HVAC Control - Direct Digital Controls Systems in HVAC control have taken leaps and bounds in the last few years. Especially so in being user-friendly, ease of designing systems, troubleshooting system problems, and increasing efficiency over the older energy management systems. When discussing the increasing efficiency of systems the idea of economizing always comes up. (more…)
Rooftop Economizer CO2 | HVAC Control – This damper is part of a free cooling system for a rooftop economizer. It is part of an economizer damper system that allows free outside air cooling when the outside air temperature and humidity are ideal. This economizer also works on CO2 control so that if the CO2 levels inside the space rise above a set point the economizer damper opens allowing fresh outside air into the building while venting the air laden with CO2 to the outside. (more…)
Home Inspector HVAC Training - Thank you!! I am training to become a home inspector, and the info contained on this site helps identify issues that require an HVAC professional to resolve. (more…)
Energy Recovery Wheels | HVAC Enthalpy & Heat - As the cost of energy rises engineers are looking for ways to improve and increase energy efficiency. Aside from HVAC equipment with higher energy efficiency rates, improving structures for less heat loss and heat gain, and building automation systems giving the equipment precision control for the
better efficiency of the equipment, there are other ways to increase energy efficiency inside buildings. One of the ways to increase energy efficiency inside buildings is to add energy recovery wheelsto the economizer systems. A US Department of Energy study concluded energy recovery wheels can save over 15% of the energy used in commercial HVAC applications.
DDC Outside Air Economizer System - Outside louvers allow the DDC control system to open dampers and introduce fresh air into the building. Building automation system, or the energy management system as it is sometimes called, monitors outside air temperature and humidity and based on a calculation and opens the outside air dampers when this calculation determines a precise set point. (more…)
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…)
HVAC Inspections Commissioning - How often have you heard someone complain about inspectors or code officials whose job it is to inspect mechanical, electrical, plumbing, and other trades work for safety and quality workmanship?
One could argue that workmanship or even design can be horrible even if the work passes a code inspection. However, chances are if the trades have any integrity they want the job to look good whether it is for the inspector or whether it is for pride and quality of work. (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…)
Chapter Three NEC and HVAC - Chapter Three in the NEC covers Wiring Methods which includes how the wiring is supposed to run, the conduit for wiring, outlets, junctions, and switch points, and a host of other topics about the proper way to run wiring.
HVAC Technicians will be familiar with piping support as is required in the Mechanical Code and electricians must follow some of the same rules when running conduit and add support for the conduit. (more…)
HVAC Tip - A thermocouple is commonly used in standing pilot gas furnaces and water heaters are technically referred to as a copple element and produces millivolts when heat is applied to the tip. This millivoltage is necessary to keep the pilot valve inside the gas valve open. If the pilot flame goes out, the thermocouple stops generating millivolts. Without the millivolts, the valve closes thus preventing gas from escaping when there is no flame. Thermocouples fail because of oxidation. It is recommended that you keep the pilot lit throughout the year to prevent excess oxidation. The thermocouple can be found in many different types of gas furnaces, gas logs, and gas water heaters. Learn How to Test a Thermocouple with a Multi-Meter
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