2017-11-01
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Most of the year, the volume of outside air may be reduced to about a third of the outdoor air volume at design load. This could result in indoor air quality problems. Separate controls to insure adequate outside air year round do not increase energy costs. Some new VAV systems incorporate these controls.
Economizer
Economizers are controls of the outdoor air designed to save energy by using cool outside air as a means of cooling the indoor space. When the enthalpy of the outside air is less than the enthalpy of the recirculating air, conditioning the outside air is more energy efficient than conditioning recirculating air. Economizers can reduce HVAC energy costs in cold and temperate climates while potentially improving IAQ, but are not appropriate in hot and humid climates.
Cooling Towers
Water is a convenient incubator for microbial growth, with potentially fatal consequences, such as Legionnaires Disease, for building occupants. Periodically monitoring water quality and chemical treatment to prevent microbial growth is essential. Physical cleaning to prevent sediment accumulation and installation of drift eliminators may also be necessary.
Boilers
Fossil fuel combustion boilers provide the potential for contamination with carbon monoxide or other combustion by-products.
Maintain gaskets and breaching to prevent carbon monoxide from escaping.
Maintain the room in which the boiler is located under sufficient positive pressure relative to the outside to prevent back drafting of flue gases. Back drafting occurs when flue gases fail to be drawn up the flue and spill out into the room. Provide combustion air directly from the outside to prevent back drafting. A smoke tube can be used to check for back drafting.
Provide high enough exhaust stacks to prevent re-entrainment into the building, and maintain fuel lines to prevent leaks.
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Glossary
Abbreviations:
Adj.= adjective- имя прилагательное/ прикметник
Adv.= adverb- наречие/ прислівник
Pl.=plural- множественное число/ множина
pp.=past participle- причастие прошедшего времени / дієприкметник
n.= noun- имя существительное / іменник
v.= verb-глагол/ дієслово
| spatial (adj) | пространственный | просторовий |
| air movement (n) | движение воздуха | рух повітря |
| constant temperature (n) | постоянная температура | постійна температура |
| constant fraction (n) | постоянная доля | постійна частка |
| outdoor air (n) | наружный воздух | зовнішнє повітря |
| gaskets (n) | прокладки | прокладки |
| spill out (v) | разливать | розливати |
| Sediment accumulation (n) | накопление осадков | накопичення опадів |
| smoke tube (n) | дымовая труба | димова труба |
Major terms
Constant air volume (CAV)
A system designed to provide a constant air volume per unit time. This term is used in HVAC systems that have variable supply –air temperature but constant air flow rates. Many residential forced-air systems are small CAV systems with on/off control
Variable air volume (VAV) system
An HVAC system that has a stable supply-air temperature, and varies the air flow rate to meet the temperature requirements. Compared to CAV systems, these systems waste less energy through unnecessarily-high fan speeds. Most new commercial buildings have VAV systems.
