DDC Outside Air Economizer System | HVAC Control

DDC Outside Air Economizer System | HVAC Control  economizer dampers

DDC Outside Air Economizer System

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. Introducing outside air into the building not only makes common sense it is also required by the Mechanical Code in commercial applications. This is required mainly for health reasons as it rids the building of volatile organic compounds and CO2 which is naturally produced by humans. Large concentrations of CO2 can build-up inside the building and needs to be vented as too much CO2 negatively affects human health. It is therefore, important that along with the intake of outside air into the building there needs to be an exhaust air damper to maintain good building pressure. Negative pressure inside a building is bad as it causes infiltration moisture issues which leads to mold and mildew. Too much pressure also creates its own problems so it is important, with an outside air damper system, to monitor and maintain building pressure. Enthalpy wheels add to the efficiency of a good economizer system. (more…)

IAQ Ventilation Basics | HVAC Indoor Air Quality

IAQ Ventilation Basics - Indoor air pollution can be reduced and possibly eliminated by taking corrective action using a defined plan. The first step is called an IAQ audit and often requires the services of both a HVAC Test and Balance (TAB) Company and an industrial hygienist. First of all it must be determined where the source of pollution is coming from and then steps taken to eliminate it. Vapor barriers and foundation sealant can often be the source of indoor air pollution but other areas need to be studied to ensure they are not allowing pollution into the structure. Other types of pollutants are carbon dioxide (produced by people), moisture, tobacco smoke, carbon monoxide, formaldehyde, ozone, and other volatile organic compounds (VOC’s) which cause issues with health and safety of the buildings occupants. After the source of the pollutants is determined then a plan of action can be implemented to ensure these issues are corrected. There are different levels of IAQ that range from very thorough to just a cursory look at the building and the buildings HVAC systems.


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