Leaks around loose fitting joints

Unit 1 HVAC components

1. Introduction

1.1 Read the text title and hypothesize what the text is about. Write down your hypothesis. ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

1.2 What do you know concerning this issue? List your ideas in the table left column "I know".

I know	I have learnt

 

1.3 Do you know answers to these questions? Write down your short answers in the space given after each question.

Are people standards of living the same in different countries? What are some of the rules about changing business cards? Where is it unusual to shake hands whea meeting? Why? Do you know any rules about clothes? Is it OK to discuss business when eating? What does this saying mean: "When in Rome, do as the Romans do"?	What HVAC components are essential to maintain good IAQ?
	What Humidification and Dehumidification Equipment are mentioned?
	What problems can duct leakage cause?
	What is the role of cooling coils?
	Why are higher efficiency filters recommended?
	Why are air filters used?
	What is the principle of exhaust systems?

 

1.4 Circle in the list the words and expressions you know. Write down their translation in table and calculate the percentage of your lexical competence.

1.4 Circle in the list the words and expressions you know. Write down their translation in table and calculate the percentage of your lexical competence.1	coils			efficiency
	drain pans			requirements
	to waste			sloping
	potable			chemicals
	essential			duct
	air dampers			leaks
	air filters			exhaust systems
	to remove			loads

Many HVAC components are particularly important to maintaining good IAQ (Indoor Air Quality). Tips for optimum functioning are listed below.

Coils and Drain Pans

Malfunctioning coils, including dirty coils, can waste energy and cause thermal discomfort. Leaky valves that allow hot or chilled water through the coil when there is no demand waste energy and create thermal discomfort. Cooling coils dehumidify the air and cause condensate water to drip into a drain pan and exit via a deep seal trap. Standing water will accumulate if the drain pan is not properly designed and maintained, creating a microbial habitat. Proper sloping and frequent cleaning of the drain pans is essential to good indoor air quality.

Humidification and Dehumidification Equipment

Potable water rather than boiler water should be used as a source of steam to avoid contaminating the indoor air with boiler treatment chemicals. Wet surfaces should be properly drained and periodically treated as necessary to prevent microbial growth. Duct linings should not be allowed to become moist from water spray.

Outdoor Air Dampers

Screens and grilles can become obstructed. Remove obstructions, check connections and otherwise insure that dampers are operating to bring in sufficient outdoor air to meet design-level requirements under all operating conditions.

Air Filters

Use filters to remove particles from the air stream. Filters should be replaced on a regular basis, on the basis of pressure drop across the filter, or on a scheduled basis. Fans should be shut off when changing the filter to prevent contamination of the air. Filters should fit tightly in the filter housing. Low efficiency filters, if loaded to excess, will become deformed and even “blow out”, leading to clogged coils, dirty ducts, reduced indoor air quality and greater energy use. Higher efficiency filters are often recommended as a cost-effective means of improving IAQ performance while minimizing energy consumption. Filtration efficiency should be matched to equipment capabilities and expected airflows.

Ducts

A small amount of dust on duct surfaces is normal. Parts of the duct susceptible to contamination include areas with restricted airflow, duct lining, or areas of moisture or condensation. Problems with biological pollutants can be prevented by:

Minimizing dust and dirt build-up (especially during construction or renovation).

Promptly repairing leaks and water damage. Keeping system components dry that should be dry. Cleaning components such as coils and drip pans.

Good filter maintenance.

Good housekeeping in occupied spaces. Duct leakage can cause or exacerbate air quality problems and waste energy. Sealed duct systems with a leakage rate of less than 3% will usually have a superior life cycle cost analysis and reduce problems associated with leaky ductwork. Common problems include:

Leaks around loose fitting joints.

Leaks around light Troffer-type diffusers at the diffuser light fixture interface when installed in the return plenum. Leaks in return ducts in unconditioned spaces or underground can draw contaminants from these spaces into the supply air system.

Exhaust Systems

In general, slightly more outdoor air should be brought into the building than the exhaust air and relief air of the HVAC system. This will insure that the building remains under slight positive pressure. Exhaust intake should be located as close to the source as possible. Fan should draw sufficient air to keep the room in which the exhaust is located under negative pressure relative to the surrounding spaces, including wall cavities and plenums.

Air should flow into, but not out of, the exhaust area, which may require louvered panels in doors or walls to provide an unobstructed pathway for replacement air.

The integrity of walls and ceilings of rooms to be exhausted must be well maintained to prevent contaminated air from escaping into the return air plenum. Provisions must be made for replacing all air exhausted out of the building with make-up outside air.

Return Air Plenum

Space above the ceiling tiles is often used as a return air plenum. Strictly follow code which restricts material and supplies in the plenum to prevent contamination and insure that airflow is not interrupted. Remove all dirt and debris from construction activity.

All exhaust systems passing through the plenum must be rigorously maintained to prevent leaks, and no exhaust should be released into the plenum. Avoid condensation on pipes in plenum area. Moisture creates a habitat for microbial growth.

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

 

malfunction (v)	неисправность в работе	несправність в роботі
waste (v)	тратить	витрачати
cause (v)	вызывать	викликати
avoid (v)	избежать	уникнути
leaky valves (n)	подтекающие клапаны	клапани, що підтікають
dehumidify (v)	осушать	осушувати
return valve (n)	обратный клапан	зворотній клапан
clogged coils (n)	забитые катушки	забиті котушки
contaminants (n)	загрязняющие вещества	забруднюючі речовини
airflow (n)	воздушный поток	повітряний потік
wall cavities (n)	полости стены	порожнини стіни
potable water (n)	питьевая вода	питна вода
unobstructed pathway (n)	беспрепятственный путь	безперешкодний шлях
debris (n)	мусор	сміття
louvered panels (n)	жалюзи	жалюзі
leak (n)	утечка	витік