Air Conditioning System (Part 2)

By : Rafikullah Deraman,

Lecturer JKA, Polisas

Learning Outcome: At the end of this lesson, student should be able to:

• Differentiate types of air conditioning system

• Calculate the size of air-conditioner systems

• Window unit, are sufficient when cooling a single room or

small space.

• If you do choose a window unit, it is extremely important

that they are sized for the area being cooled.

• Capacity for cooling load is between 6000- 32,000 BTUH

• Under sizing a unit will cause the unit to run constantly

which will drive up your electric bills.

• On the other hand, if the unit is too large it won’t run long

enough to remove humidity.

• High humidity can cause poor indoor air quality.

RA-10KF-Hitachi

1.0hp Window Type Air Conditioner,

Cooling capacity: 9,010 BTU/h

Product in the Market

Advantages

• They are relatively inexpensive

• Easy to install Disadvantages:

• Higher noise levels

• Physical appearance( typically unattractive)

• Lower efficiency

• Limited cool up to two rooms

• Poor constant temperatures

Win

do

w U

nit

Split Unit

4 indoor air-handling units c/w Single unit outdoor

Split U

nit

A split-system air conditioner splits the hot side from the cold side of the system, as in the diagram below. Outdoor unit: The outdoor unit contains a compressor and a condensing coil filled with refrigerant. Indoor unit: The indoor unit is made up of a coil and blower which is located inside

RAS-S10CC - Hitachi 1.0hp Wide Deluxe Air Conditioner, Cooling capacity: 10,110 BTU/h RAS-S13CY - Hitachi 1.5hp Deluxe Air Conditioner, Cooling capacity: 12,020-12,090 BTU/h

RAS-S18CAM 2.0hp Deluxe Wide Air Conditioner‚ Cooling capacity: 17,410 -17‚750 BTU/h

RAS-24CE9G 2.5hp Deluxe Wide Air Conditioner, Cooling capacity: 24,060 BTU/h

Advantages: • Flexibility and size. Since they are small units, they can easily be installed. More so, their flexibility is perfect for warming and cooling of rooms. Most of the models of split types encompass 4 indoor air-handling units, which are connected to a single unit placed outdoors. These 4 indoor air-handling units are able to cool down and heat up 4 rooms or zones.

Advantages: Easier to install • most of split types can be quickly and easily

installed. • a window or wall opening is not required to

install split ac units. • The indoor unit can be placed on the floor,

hung on wall brackets or mounted on the ceiling. The outdoor unit is obviously installed outside of the buildings.

Advantages: Easy maintenance • The split ac units system should be

maintained on a regular basis (at least twice a year).This will ensure that it always runs at its optimum performance levels, in terms of both power and efficiency.

• Easily maintained on the basis that they will normally have a filter which is washable.

• A regular maintenance will also ensure the longevity of the split ac units system.

Advantages: Quiet operation • The split ac units system is very quiet in

comparison to other air conditioning systems.

• The minimization of noise is importance in rooms which require a peaceful environment

Advantages: Cost effective • With regards to the initial cost of purchasing split

ac units it may be prudent to note that four indoor units can operate from one outdoor unit.

• The running costs of the split ac units are also cost effective. Split ac units are extremely energy efficient.

• Energy efficiency ensures that the split ac units do not work any harder than is ultimately required, thereby minimizing electrical energy consumption on an on going basis.

Advantages: Simple control

The Split ac units are simple to operate and are

therefore suitable for every and any individual

considering the purchase of an air conditioning

system.

Disadvantages: 1. Sometimes the indoor and outdoor unit fan becomes

noisy.

2. Each unit or group of units has a filter, compressor and

refrigeration pipework that needs periodic maintenance

and possible re-charging.

3. Units have course filters therefore filtration is not as

good as with AHU’s.

4. The installation may require long runs of refrigerant

pipework which, if it leaks into the building, can be

difficult to remedy.

Disadvantages: 5. Not at robust as central plant.

6. The majority of room air conditioners just recirculate air in

a room with no fresh air supply although most

manufacturers make units with fresh air capability.

7. Cooling output is limited to about 9 kW maximum per unit;

therefore many units would be required to cool rooms with

high heat gains.

Package Unit

The package unit refer to the components namely

The compressor

The cooling coil

The condenser

The evaporator

are all packaged, designed and matched up by the

manufacturer to form a complete system.

Usually used for medium and large installation air

conditioning system.

Cooling load capacity between 24,000 to 360,000 BTUH

Used with and without a ducting system.

Model Nominal

Tons

Height

(in.)

Width

(in.)

Length

(in.)

Capacity

Cooling-

BTUH

SEER

TCY024G 2 29 36 56 24,000 14.00

TCY030G 2.5 29 36 56 30,600 14.00

TCY036G 3 29 36 64 36,000 14.10

TCY042G 3.5 29 36 64 41,500 14.00

TCY048G 4 33 45 65 49,000 14.40

XL1400 SINGLE PACKAGE AIR CONDITIONER

Model Nominal

Tons

Height

(in.)

Width

(in.)

Length

(in.)

Capacity

Cooling-

BTUH

SEER

TCY024F 2 29 36 56 24,000 12

TCY030F 2 1/2 29 36 56 30,000 12.3

TCY036F 3 29 36 64 36,000 12

TCY042F 3 1/2 29 36 64 41,500 12

TCY048F 4 33 45 65 48,000 13.05

TCY060F 5 33 45 65 60,000 12.4

XL1200 SINGLE PACKAGE AIR CONDITIONER

Advantages :

1. A packaged unit saves precious space. Especially

in an office that probably has limited space.

2. Low installation cost

3. Simple operation- trained man power is not

required.

4. Possible to switch off unit catering to unoccupied

spaces thereby avoiding wastage

5. Less plant room space required.

Disadvantages: 1. Limitations on air flow and filtration levels

2. Smaller compression and hence higher kW/ton

consumption.

3. Operating sound levels can be quite high.

4. Limitations on the amount of fresh air intake.

Cen

tral Plan

t Systems

Central Plant Systems

• Central air conditioning is used for cooling big buildings, houses, offices, entire hotels, gyms, movie theatres, factories etc.

• A central air conditioning system is comprised of a huge compressor that has the capacity to produce hundreds of tons of air conditioning.

• Cooling big halls, malls, huge spaces, galleries etc. is usually only feasible with central conditioning unit

Cen

tral Plan

t Systems

• There is a plant room where large compressor, condenser, thermostatic expansion valve and the evaporator are kept in the large plant room. They perform all the functions as usual similar to a typical refrigeration system. However, all these parts are larger in size and have higher capacities.

• The chilled is passed via the ducts to all the rooms, halls and other spaces that are to be air conditioned.

Cen

tral Plan

t Systems

Cen

tral Plan

t Systems

1. Cooling tower 2. Plant room 3. AHU room 4. Air conditioning room

1) Plant Room:

• The plant room is a important components.

• These include the compressor, condenser, thermostatic

expansion valve and the evaporator or the chillier.

• Piping required to connect these parts

2) Air-Handing Unit (AHU) Room

• The air handling units are installed in the place called air

handling unit rooms.

• The air handling units comprise of the cooling coil, air

filter, the blower and the supply and return air ducts.

Components:

• The chilled water flows through the cooling coil.

• This cooled air passes over the air filter and is passed by the

supply air ducts into the space which is to be air conditioned.

• The air handling unit and the ducts passing through it are

insulated to reduce the loss of the cooling effect.

3) Air Conditioned Rooms:

• These are the rooms or spaces that are to be air conditioned.

• At the top of these rooms the supply and the return air ducts

are laid. The supply air ducts supply the cool air to the room

via one set of the diffusers, while the return air ducts absorbs

the hot return air from the room by another set of the diffusers.

• The hot return air enters the air handling unit, gets cooled and

again enters the room via supply duct to produce air

conditioning effect.

4) Cooling Tower: • The cooling tower is used to cool the water that absorbs

heat from the compressor and the condenser.

• When water flows through these components some water

gets evaporated, to make up this loss some water is also

added in the cooling tower.

• The cooling tower is of evaporative type. Here the water is

cooled by the atmospheric air and is re-circulated through

the compressor and the condenser.

AHU

Cen

tral Plan

t Systems

Cen

tral Plan

t Systems

ADVANTAGES : 1. Noise in rooms is usually reduced if plant room

is away from occupied spaces.

2. The whole building can be controlled from a

central control station. This means that optimum

start and stop can be used .Also time clocks

can bring air conditioning on and off at

appropriate times.

3. Maintenance is centralised in the plant room.

Plant is easier to access.

DISADVANTAGES:

1. Expensive to install a complete full comfort air-

conditioning system throughout a building.

2. Space is required for plant and to run ductwork

both vertically in shafts and horizontally in ceiling

spaces.

3. Individual room control is difficult with central

plant.

Air Conditioning Size

The cooling capacity of room air conditioners is

measured in BTUs, or British Thermal Units, per

hour.

To figure the size unit you need, measure the

space you're trying to cool and find it on this chart.

To estimate square footage, multiply the length of

the room by the width. (A room that's 10 feet by 20

feet, for example, has 200 square feet in it.

To cool this area Size air conditioner

100 to 150 square feet 5,000 BTUs per hour

150 to 250 square feet 6,000 BTUs

250 to 300 square feet 7,000 BTUs

300 to 350 square feet 8,000 BTUs

350 to 400 square feet 9,000 BTUs

400 to 450 square feet 10,000 BTUs

450 to 550 square feet 12,000 BTUs

550 to 700 square feet 14,000 BTUs

700 to 1,000 square feet 18,000 BTUs

1,000 to 1 400 square feet 24,000 BTUs

Table

When looking for the correct size air conditioner, keep these

suggestions in mind, as well:

• If the room is heavily shaded, you can reduce the BTU

capacity by 10%

• If the room is very sunny, you should increase the BTU

capacity by 10%

• If more than 2 people regularly occupy the room, add 600

Btu for each additional person

• If the unit is for a kitchen, increase the capacity by 4,000

Btu/Hr.

Thank You