UNIT 29 Upgrading Heating, Ventilation

and Air Conditioning (Part I)

The power used in running a building's Heating, Ventilation and Air Conditioning (HVAC) is quite substantial, so any measures to improve its efficiency will save energy and cash. An upgrade of the HVAC system can be carried out by replacing the old worn components with modern, more efficient units.

Components of a Typical HVAC System: Ducting, Air Handling Unit (AHU),Filters, Attenuators, Humidifiers and De-humidifiers, Volume Control and Fire/Smoke Dampers, Air Distribution Diffusers, Air Return Grills, Air Handling Unit. Depending on the requirement of hot air or air conditioning, hot water or chilled water can be supplied to the coils. Alternatively, a heat pump can be used with an evaporator / condenser supplying the hot or cold medium. Excessive noise due to the air being circulated through the ducting is both annoying and distracting to the workforce. To mitigate the noise, attenuators (baffles or silencers) are fitted to the ducting.The fans or blowers draw the air through heating/cooling coils, circulating it through the supply and return ducting.

Suction and Discharge Filters. Suction filters are on the return ducting into the AHU; these remove any dust, smoke or other undesirable particles or fumes before the air enters the heating/cooling coils and fan chambers. Discharge filters remove any remaining particles before the air is recirculated again.

High and low humidity can cause problems not only to employees working in the environment, but also the building’s structure: steel, composites, and wood. However, in the HVAC system the humidity in the air can be controlled by a humidistat or de-humidistat. The dehumidifier can have antibacterial/ultraviolet treatment against the growth of bacteria/organisms in the condensed water storage tray.

Diffusers and Grilles. Diffusers, being designed to slow the discharge velocity of the air, are normally located in the room’s ceilings. This is to ensure the air is distributed evenly and in the required direction into the rooms and offices of the buildings. These are set into the ceiling; the louvers are automatically adjustable or fixed, directing the air into the return ducting. The return ducting is run back to the discharge plenum, through the return filter, then back into the air handling unit, completing the system circuit. Volume control dampers are incorporated into the ducting to control the quantity and velocity of the air flow. Fire and smoke dampers and can also be installed that shut automatically in the event of a fire. These dampers need to be reset manually. The heating and cooling coils can be supplied by hot or chilled water; or a heat pump can also be used.

Electric Motors. Air circulating fan electric drive motors are a classic example of overrating, so the first thing to check is the rating plate against the design requirement in the original specification. This will tell you if you can downgrade the motor output. If the system has been operating for a long time, 10-15 years for example, fitting variable speed motors is a worthwhile investment. This will allow the speed of the fan to be altered to suit changing conditions in the system. This has been reported to achieve savings in energy of up to 50% and, if the existing switchboard and wiring are retained, even more savings can be made, ensuring a short pay-back period.

Read and memorize the active vocabulary to the text:

Active Vocabulary

1. running (здесь) эксплуатация; функционирование

2. substantial существенный, значительный; большой

3. upgrade изменение в соответствии с более высокими или современными требованиями

4. Air Handling Unit агрегатная вентиляционная или воздухоприготовительная установка; блочный кондиционер

5. attenuator аттенюатор; ослабитель

6. de-humidifier влагопоглотитель (аппарат), осушитель

7. diffuser диффузор, воздухораспределительный плафон

8. grill вентиляционная решётка, (воздухо)-распределительная решётка

9. heat pump тепловой насос

10. to mitigate смягчать; уменьшать

11. discharge filter выхлопной фильтр

12. humidistat гигростат, регулятор влажности воздуха

13. velocity скорость, вектор скорости

14. adjustable регулируемый, устанавливаемый, передвижной, приспособляемый

15. plenum воздухораспределительная камера

16. volume control damper клапан регулирования расхода воздуха

17. to incorporate внедрить, смонтировать, установить

18. in the event of в случае

19. to reset вновь устанавливать; восстанавливать; повторно включать, запускать

20. to downgrade понижать

21. output производительность; выработка; выпуск

22. switchboard распределительный щит

CONTROL TESTS

TEST I

Decide whether these statements are true or false:

1. a). An upgrade of the HVAC system can be carried out by using fans, evaporating the refrigerant and converting it back to a gas.

b). An upgrade of the HVAC system can be carried out by using diffusers, designed to slow the discharge velocity of the air.

c). An upgrade of the HVAC system can be carried out by replacing the old worn components with modern, more efficient units.

2. a). Discharge filters remove the heat from the air before being discharged by the fans to the building.

b). Discharge filters remove any remaining particles before the air is recirculated again.

c). Discharge filters remove excess moisture from ventilation air.

3. a). Suction filters remove any dust, smoke or other undesirable particles or fumes.

b). Suction filters remove cool and humidity in all or part of a building.

c). Suction filters remove refrigeration conduction media such as water, air, ice, and chemicals, referred to as refrigerants.

4. a). In the HVAC system the humidity in the air can be controlled by modern screw or scroll compressors.

b). In the HVAC system the humidity in the air can be controlled by the fans, evaporating the refrigerant gas.

c). In the HVAC system the humidity in the air can be controlled by a humidistat or de-humidistat.

5. a). The dehumidifier can have antibacterial / ultraviolet treatment against the growth of bacteria.

b). The dehumidifier can introduce and distribute cool outdoor air when appropriate.

c). The dehumidifier can have a circulator to move water through the distribution system.

Match words in columns A and B (synonym match):

A B

1. substantial a). suspended b). essential

c). institutional d). ornamental

2. upgrade a). support b). foundation

c). difference d). modernization

3. to carry out a). to perform b). to shrink

c). to rely d). to distort

4. to annoy a). to irritate b). to indicate

c). to leak d). to test

5. to distract a). to stabilize b). to recommend

c). to divert d). to bear

6. to retain a). to transfer b). to increase

c). to form d). to preserve

7. manually a). usually b). by hand

c). normally d). annually

8. to ensure a). to guarantee b). to flow

c). to vary d). to follow

9. worthwhile a). seasonal b). rewarding

c). differential d). maximum

10. to alter a). to depend b). to excavate

c). to transform d). to pour

TEST III

Select the best possible answer out of the choices from the list to the statements (multiple choice):

1.Depending on the requirement of hot air or air conditioning, …

a. the optimum amount of air is admitted and extracted from the rooms.

b. hot water or chilled water can be supplied to the coils.

c. the heat pump is used to cool the air by dissipating the heat from the building.

2. To mitigate the noise, …

a. volume control dampers are incorporated into the ducting.

b. one can downgrade the motor output.

c. attenuators are fitted to the ducting.

3. Diffusers, being designed to slow the discharge velocity of the air, …

a. are normally located in small private dwellings.

b. are normally located in the room’s ceilings.

c. are normally located in large commercial buildings.

4. Fire and smoke dampers and can also be installed …

a. that constantly monitor the temperatures and pressures of the air.

b. that removes the heat from the air before being discharged.

c. that shut automatically in the event of a fire.

5. A heat pump can be used with an evaporator / condenser, …

a. supplying the hot or cold medium.

b.which is suitable for large buildings provided there is the ground-space to locate the buried pipe loops.

c. to cool the air by dissipating the heat from the building back into the ground through the geothermal loops.

TEST IV