Refrigeration and Heating System in Hotels (HVAC) for Lecture Purpose

REFRIGERATION SYSTEM

INTRODUCTION

Refrigeration is cooling of food and beverage stores and wine cellars. Air-cooling and food storage depend on adequate and economical refrigeration systems. Refrigeration is necessary for complete, year-round air-conditioned comfort for hotels. Cooling of an object and the maintenance of its temperature below that of surroundings is called Refrigeration.

                                                            OR

Refrigeration is the science of producing and maintaining a temperature condition in a closed space lower than the surrounding ambiance by removing heat from the space and transferring that heat to another space or substance.

Uses of refrigeration in Hotels

• In hotels and households, food items, both cooked and uncooked, can be preserved for a long time in low temperatures.

• Storage of fruits and vegetables makes it possible to add fresh salads to the menu all year round.

• Storage of fish, meat and other perishables items safely for longer periods is possible due to refrigeration.

• Seasonal food items can be bought from the market in bulk quantity at relatively cheaper price, stored in refrigerated conditions and later used during off season.

• Cooling of desserts and drinks.

TERMS USED IN REFRIGERATION:

• REFRIGERANT – It is the substance used for heat transfer in a refrigeration system. It takes up heat from inside the refrigerator cabinet and releases it to outside atmosphere.

• SENSIBLE HEAT – The heat that is used to raise or lower the temperature of a substance.

• LATENT HEAT – Latent heat is the energy absorbed or released when a substance changes its physical state. Latent heat is absorbed upon evaporation, and released upon condensation to liquid (as in clouds).

• EVAPORATION – It is the process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure.

• CONDENSATION - It is the change of the physical state of matter from gas phase into liquid phase, and is the reverse of evaporation.

• ONE TON OF REFRIGERATION – It means cooling by extracting heat at the rate of 50Kcal/minute or 3000 Kcal/hr

TYPES OF REFRIGERANTS AND USAGE

DESIRABLE PROPERTIES OF REFRIGERANTS

• It should be non poisonous and non irritant.
• It should be non flammable.
• It should be chemically stable.
• It should be non corrosive and should not react with the parts / components of the system.
• It should have no objectionable odour or smell.
• It should be easily and reliably detectable in case of leakage.
• Its LH of vapourisation should be high so that quantity of high refrigerant can be minimized.
• Its cost should be low.
• It should be easily available.

HOW A REFRIGERATOR WORKS

A refrigerator is a common household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the temperature of the room.

Parts of a Refrigerator

If you pour a little rubbing alcohol on your skin, it'll feel cold -- really cold. It isn't refrigerated, so how does this happen? Well, alcohol evaporates at room temperature the way water evaporates at a low temperature in an oven. As it evaporates, it absorbs the heat on the surface of your skin, making your skin cooler. A special coolant called a refrigerant functions in a refrigerator the way alcohol works on your skin, except in a refrigerator, the coolant is trapped inside a series of coils. As it makes a circuit through them, it changes back and forth from a liquid to a gas.

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·         The compressor constricts the refrigerant vapor, raising its pressure, and pushes it into the coils on the outside of the refrigerator.

·         When the hot gas in the coils meets the cooler air temperature of the kitchen, it becomes a liquid.

·         Now in liquid form at high pressure, the refrigerant cools down as it flows into the coils inside the freezer and the fridge.

·         The refrigerant absorbs the heat inside the fridge, cooling down the air.

·         Last, the refrigerant evaporates to a gas, and then flows back to the compressor, where the cycle starts all over.

REFRIGERATION PROCESS

The main components of a refrigeration process are:

1.        Evaporator

2.        Compressor

3.        Condenser

4.        Expansion Valve

EVAPORATOR: In the evaporator the Refrigerant absorbs the heat from the object to be cooled and itself gets heated up. The heat absorbed is the latent heat of vaporisation of the liquid refrigerant and therefore the  refrigerant under goes a change of state i.e. from liquid to vapours without any change in temperature. The vapour refrigerant then returns to the compressor.

COMPRESSOR: The vapour refrigerant is compressed at a very high pressure and temperature. It then passes through the condenser coil.

CONDENSER: While passing through the condenser the refrigerant rejects heat either to air or to surrounding water which gets heated up. The refrigerant condenses to cold liquid state but at high pressure. This high pressure colder refrigerant then passes through the expansion valve.

EXPANSION VALVE: The expansion valve cools down the refrigerant to a low temperature and also reduces the pressure. It can be adjusted to control the temperature and pressure to which the refrigerant goes to the evaporator. The cool refrigerant is now ready to absorb heat from the hot objects while passes through the evaporator.
* Efficiency of Refrigeration System is expressed as Coefficient of Performance (COP) and is defined as the ratio of refrigeration effect produced to the mechanical work done.


REFRIGERATION CYCLE

·         To avoid continuous running of electric motor (motor required to run the compressor) and unnecessary work of compression, thermostatic control is used which senses the set interior temperature and stops the motor from running and when the temperature rises again, the motor restarts and the Compressor starts working again.

·         Compressor is the most expensive part of the refrigeration cycle and its repair is difficult. An inefficient or defective compressor is generally replaced with a new one.

TYPES OF REFRIGERATING UNITS IN HOTEL INDUSTRY

The usual categories of refrigerating units employed in the hotel industry are:

·         Reach – in Units

·         Counter – top or table – top Units

·         Walk – in Units

·         Special – purpose Units

Each of the above mentioned units can have both cooler and freezer sections in them. Some refrigerators are now divided into four zones to store different types of food. They are as follows:
Subzero (up to –18 degree Celsius) - Freezer Section
0 degree Celsius     - Meat preservation Section
5 degree Celsius     - Refrigerator
10 degree Celsius     - Vegetables Section

Reach – in refrigerators

Coolers & Freezers – Capacities of such units are usually expressed in terms of the internal space volume (cubic metre) or in mass (Kg) of material being stored in it.
Typical interior temperature range for  cooler should be 4.4 degree Celsius to 7 degree Celsius and for a freezer should be -15 degree Celsius to -23 degree Celsius.

Counter top units

Small counter top refrigerators are frequently used to facilitate service.
They are usually coolers and have features similar to those of reach-in coolers but of much smaller size usually up to a size of 100 litres only.

WALK – IN REFRIGERATION SYSTEM

As the name suggests, food operators can directly move into such units.
They are much bigger in size and height than walk – in refrigerators.
A typical size would be 4 X 5 X 3 m, or even more, or as lass as having a floor area of 2 sq. m..
They are normally custom built.

Special purpose units

Ice Cream Conservator and frozen food conservator: They are usually “well type” and open vertically through a lid. This minimizes heat loss as cool and heavy air inside cannot escape upward. They are usually maintained at temperatures between -23 to -18 degree Celsius.

Wet Fish Cabinets

They contain deep galvanized drawers in which fish can be embedded in ice. They keep moist storage conditions necessary for maintaining the quality of fish. They are usually maintained at temperatures between 0 to -2 degree Celsius.

SPECIAL PURPOSE UNITS

Display Cabinets: In many hotels, there is a refrigerated display cabinet kept in the dinning for the customers to choose varieties of meats for grilling. They are also used to display bakery products and desserts.

Bottle Coolers: They are used in dinning and are usually in bars. They are constructed in two ways. One is open refrigerated through type and the other is glass front cabinet type withhinged doors or sliding doors.

Ice makers:  Modern ice making machines need only to be connected to a cold water supply line. Water flows over a refrigerated plate and gets converted into a slab of ice. This slab of ice passes over a wire net which is electrically heated and the slab melts along the wire mesh and falls through the square holes as separate small cubes of ice.

CARE AND MAINTENANCE OF REFRIGERATING UNITS

Regular cleaning and maintenance not only makes your equipment work more efficiently, but it also helps it last longer. When parts are worn and dirty, the unit runs more frequently causing more wear and tear on the parts. Eventually, the unit breaks down for good long before it should have.
Preventing these issues is simpler than you think. Call in a qualified refrigeration service company at least twice a year and up to once a month, depending on the load and usage of your equipment, to do the following tasks:

·         Clean evaporator and condenser coils

·         Check lines for condensation

·         Clean fan blades and inspect the fan motor

·         Check integrity of insulation

·         Check for air leaks through cracks, holes, and worn parts like gaskets and seals

·         Lubricate door hinges and handles

·         Check for loose electrical connections

·         Clear drain lines of debris

·         Check temperature and defrost settings and calibrate thermometers

·         Check filters on ice makers

·         Thoroughly clean all ice maker components

FREEZERS – CARE AND MAINTENANCE

·         Check the owner’s manual for your particular unit. There are many different types of freezers, and they can have slightly different care instructions and placement of parts, so make sure that you are familiar with how yours works.

·         Place the freezer in a temperature-stable area. Extreme changes in temperature outside your unit will cause the freezer to work harder at its job, causing strain. It might seem like cold temperatures would help a freezer, but remember that it’s only designed to withstand freezing temperatures on the inside! Also be aware that condenser coils can emit heat, so make sure there is some space for airflow between the freezer and any walls or nearby items.

·         Check the thermostat regularly. Many freezers have a built-in thermostat, but if yours does not, you can use a thermometer. The temperature should be set at 0 degrees Fahrenheit (-18 degrees Celsius), so adjust the controls when necessary. If your unit starts fluctuating on its own, you should get it checked.

·         Check the gasket regularly. The gasket, or seal, of your freezer makes sure that cold air stays in and warm air stays out of the unit. If the seal is damaged or broken, your freezer will leak and its performance will suffer. If you notice damage, get the gasket replaced immediately to save yourself some money on energy consumption.

·         Keep the freezer clean. You can easily clean your freezer with a damp rag and dish detergent. Make sure you reach all of the interior, exterior, and the seals. You can use a spray cleaner to remove tougher spills and deodorizers to remove nasty smells. Frost buildup is normal, and you need to periodically defrost the unit to remove the buildup (see below for more details).

·         Keep the freezer full. For the best results, keep your freezer at least half full of food. This helps stabilize the temperature and keep energy consumption down. It might seem counter-intuitive, but the food retains its temperature easier than plain air when the door is opened.

MAINTAINING CHEST FREEZERS

·         Chest freezers do not have an automatic defrost, so you will have to do it manually. It’s best to do this at least once a year, or whenever half an inch of frost has built up on the walls. Here are the basic steps to defrost your chest freezer:

ü     Remove all food.

ü     Unplug the unit or turn off the thermostat.

ü     Unplug the drain once all ice has melted. Do not scrape away ice.

ü     Wait until the freezer is dry.

ü     Return the plug and turn the unit back on.

ü     Return food once the temperature returns to 0°F. This can take up to 24 hours.

·         Clean the interior twice a year - No need to unplug the refrigerator—that will waste energy. But do move the food to a cooler. Wipe the walls and the shelves using a cloth and a mix of dish soap and water, says Varun Rajasekaran, an engineering manager at Kenmore refrigeration. Rinse and dry thoroughly. To clean the door seal, wrap a credit card in a cloth, dip it in soapy water, and glide it into the grooves. Nix odors with a box of baking soda.

·         Vacuum the condenser coils once a year - Dust keeps the engine from running smoothly. Move the unit to get to coils in the back, or if the coils are located in front, snap off the lower grill. Then unplug and vacuum using the brush attachment. There should be three inches of space between the wall and the unit on the sides, one inch in the rear.

·         Maintain the proper temperature - Ideally that is 0 degrees Fahrenheit. To see how cold your freezer is, leave a thermometer in a cup of vegetable oil in the freezer overnight, says Jill Notini, a spokesperson for the Association of Home Appliance Manufacturers. Still too warm after lowering the setting? Check that cold air isn’t escaping. Stick a dollar bill in the doorjamb, close, and try to slide out the bill. “With a tight seal, you’ll feel resistance,” says Rajasekaran. For optimum efficiency, keep the freezer stocked and away from direct sunlight, a stove, or a dishwasher.

AIR-CONDITIONING & HEATING SYSTEM

INTRODUCTION

The use of building cooling systems in the hotel industry has greatly increased management’s physical plant responsibility. For a hotel building’ it undoubtedly has some type of air-cooling system, even if it is only needed for a month or two during the entire year. Customers expect and demand a comfortable environment. Air cooling reduces the seasonal nature of many lodging and foodservice businesses.

The heart of the HVAC (heating, ventilation and air-conditioning) system is the air-conditioning component. It is most costly component to install. It is greatly affected by building construction techniques and materials. Its air quality output can have very good or very poor effects on employees and customers. Its operating cost can be very high. Its maintenance requirements are generally the highest of all electromechanical systems within the building.

TERMS

There are three terms that describe the systems used to cool air: air-conditioning, air-cooling and refrigerated air.

Air – conditioning

Any treatment of the environment air within a building is air conditioning. Technically, a fan placed in a room to circulate air meets the air-conditioning definition. Filtering air is conditioning air; heating is conditioning the air; cooling, humidifying, or dehumidifying are kinds of air-conditioning. Thus, the process of changing any one of several properties of the air can be correctly classified as air-conditioning.

Air-cooling

Air-cooling is any process that reduces air temperature. There are several air temperature reduction techniques. A fan blowing air over a bucket of ice water can be called air-cooling. Evaporative coolers, or swamp coolers are air-cooling techniques. The evaporative device lowers air temperature and increases the moisture content in the air.

Refrigerated air

Refrigerate air is produced by a mechanical refrigeration cycle. The primary refrigeration systems are vapor compression and absorption cycle. The primary refrigeration systems are vapor compression and absorption cycles. The refrigerated air system is capable of providing cool comfortable air at all times. It is also most costly air-cooling system to install and operate.

HOW AN AIR CONDITIONER WORKS

The machine has three main parts.

 They are a compressor, a condenser and an evaporator.

The job of room air conditioner is move heat from inside the room to the outside, thereby cooling the room. Air conditioners blow cool air into the room by pulling the heat out of that air. The air is cooled by blowing it over a set of cold pipes called an evaporator coil. The evaporator coil is filled with a special liquid called a refrigerant, which changes from a liquid to a gas as it absorbs heat from the air. The refrigerant is pumped outside the room to another coil where it gives up its heat and changes back into a liquid. This outside coil is called the condenser because the refrigerant is condensing from a gas back to a fluid. A pump, called a compressor, is used to move the refrigerant between the two coils and to change the pressure of the refrigerant so that the entire refrigerant evaporates or condenses in the appropriate coils.

The energy to do all of this is used by the motor that runs the compressor.

Maintaining room air conditioner

·         Dry the grill and condenser coil

·         Use a soft brush and a vacuum to remove dust and lint wiper off the grills

·         Bent grills should be straightened.

·         Fan blade- remove dust and lint, wiped off with a soft cloth.

TYPE OF AIR-CONDITIONING
1) Window air-conditioning system
2) Split air-conditioning system
3) Centralized air-conditioning system

4) Package air-conditioning system

1) Windows Air-conditioning System -
Window air conditioners are one of the most commonly used and cheapest type of air conditioners.
To install one of these units, you need the space to make a slot in the wall, and there should also be some open space behind the wall.
Window air-conditioner units are reliable and simple-to-install solution to keep a room cool
while avoiding the costly construction of a central air system.
Better yet, when the summer heat dies down, these units can be easily removed for storage, and you can use the window sill for other purpose.
 
2) Split Air-Conditioning System
The split air conditioner comprises of two parts: the outdoor unit and the indoor unit.
The outdoor unit, fitted outside the room, houses components like the compressor, condenser and expansion valve.
The indoor unit comprises the evaporator or cooling coil and the cooling fan. For this unit you don’t have to make any slot in the wall of the room.
 Further, the present day split units have aesthetic looks and add to the beauty of the room. The split air conditioner can be used to cool one or two rooms.

3) Centralized Air-Conditioning System
The central air conditioning plants or the systems are used when large buildings, hotels, theaters, airports, shopping malls etc. are to be air conditioned completely.
The window and split air conditioners are used for single rooms or small office spaces.
If the whole building is to be cooled it is not economically viable to put window or split air conditioner in each and every room.
Further, these small units cannot satisfactorily cool the large halls, auditoriums, receptions areas etc.

4) Packaged Air-Conditioning System
The window and split air conditioners are usually used for the small air conditioning capacities up to 5 tons.
The central air conditioning systems are used for where the cooling loads extend beyond 20 tons.
The packaged air conditioners are used for the cooling capacities in between these two extremes.
The packaged air conditioners are available in the fixed rated capacities of 3,5, 7, 10 and 15 tons.
These units are used commonly in places like restaurants, telephone exchanges, homes, small halls, etc.

TYPES OF HEATING SYSTEMS

CENTRAL HEAT

Furnaces
A furnace works by blowing heated air through ducts that deliver the warm air to rooms throughout the house via air registers or grills. This type of heating system is called a ducted warm-air or forced warm-air distribution system. It can be powered by electricity, natural gas, or fuel oil. Inside a gas- or oil-fired furnace, the fuel is mixed with air and burned. The flames heat a metal heat exchanger where the heat is transferred to air. Air is pushed through the heat exchanger by the “air handler’s” furnace fan and then forced through the ductwork downstream of the heat exchanger. At the furnace, combustion products are vented out of the building through a flue pipe. Older “atmospheric” furnaces vented directly to the atmosphere, and wasted about 30% of the fuel energy just to keep the exhaust hot enough to safely rise through the chimney. Current minimum-efficiency furnaces reduce this waste substantially by using an “inducer” fan to pull the exhaust gases through the heat exchanger and induce draft in the chimney. “Condensing” furnaces are designed to reclaim much of this escaping heat by cooling exhaust gases well below 140°F, where water vapor in the exhaust condenses into water. This is the primary feature of a high-efficiency furnace (or boiler). These typically vent through a sidewall with a plastic pipe.
       
Boilers
Boilers are special-purpose water heaters. While furnaces carry heat in warm air, boiler systems distribute the heat in hot water, which gives up heat as it passes through radiators or other devices in rooms throughout the house. The cooler water then returns to the boiler to be reheated. Hot water systems are often called hydronic systems. Residential boilers generally use natural gas or heating oil for fuel.

Heat Pumps
Heat pumps are just two-way air conditioners. During the summer, an air conditioner works by moving heat from the relatively cool indoors to the relatively warm outside. In winter, the heat pump reverses this trick, scavenging heat from the cold outdoors with the help of an electrical system, and discharging that heat inside the house. Almost all heat pumps use forced warm-air delivery systems to move heated air throughout the hotel. A ground-source heat pump heats and cools in any climate by exchanging heat with the ground, which has a more constant temperature.

There are two relatively common types of heat pumps:

·         Air-source heat pumps use the outside air as the heat source in winter and heat sink in summer. Ground-source (also called geothermal, Geo Exchange, or GX) heat pumps get their heat from underground, where temperatures are more constant year-round. Air-source heat pumps are far more common than ground-source heat pumps because they are cheaper and easier to install.

·         Whereas an air-source heat pump is installed much like a central air conditioner, ground-source heat pumps require that a “loop” be buried in the ground, usually in long, shallow (3–6' deep) trenches or in one or more vertical boreholes.

DIRECT HEAT

Gas-Fired Space Heaters
This includes wall-mounted, free-standing, and floor furnaces, all characterized by their lack of ductwork and relatively small heat output. Because they lack ducts, they are most useful for warming a single room. If heating several rooms is required, either the doors between rooms must be left open or another heating method is necessary. Better models use “sealed combustion air” systems, with pipes installed through the wall to both provide combustion air and carry off the combustion products. These units can provide acceptable performance, particularly for cabins and other buildings where large temperature differences between bedrooms and main rooms are acceptable. The models can be fired with natural gas or propane, and some burn kerosene.

Electric Space Heaters
Portable (plug-in) electric heaters are inexpensive to buy, but costly to use. They convert electric current from the wall socket directly into heat, like a toaster or clothes iron.

State of the Art Heating
Radiant floor heat generally refers to systems that circulate warm water in tubes under the floor. This warms the floor, which in turn warms people using the room. It is highly controllable, considered efficient by its advocates, and is expensive to install. It also requires a very experienced system designer and installer, and limits carpet choices and other floor finishes: you don’t want to “blanket” your heat source.

CONDITIONS FOR COMFORT AIR MOVEMENT

Temperature - How hot or cold is it? Humans like to be in the range of 70 to 80 degrees, more or less. This is the most obvious of the 4 factors of comfort and gets the most attention.
Humidity - How much moisture is in the air? Forty to sixty percent relative humidity is the ideal range. In addition to decreasing comfort, a relative humidity that's too low or too high increases the likelihood of things like bacteria, mold, dust mites.
Air Movement - Is the air moving across your skin? In the summer, one way that our bodies keep cool is by the evaporation of sweat. A nice breeze or a ceiling fan can keep us comfortable even when the the temperature and humidity are at or above the narrow range we find most comfortable. In the winter, that same air movement will make us uncomfortable.
Mean Radiant Temperature - How hot or cold are the surfaces around you? The cold inner wall surfaces and glass suck heat out of your body because you're radiating heat to them but they're not radiating much back. Another mean radiant hot attic knee wall with mean radiant temperature problem, one of  the 4 factors of comfort temperature problem occurs in bonus rooms, where you have walls with hot attic on the other side. Most of the time those attic knee walls are poorly insulated and thus get very hot. Even if the air temperature in that room is 70 degrees, you may be uncomfortable because the walls keep blasting you with heat.

                                             The two things that most affect our comfort in buildings are the building envelope (insulation and air barrier) and the heating and cooling system. Good insulation, properly installed and in contact with the air barrier and a tight house go a long way to helping. Good HVAC design takes us the rest of the way.

HUMIDITY CONTROL

Humidity is the relative humidity or percent relative humidity, relates two temperatures: Dew point and Dry bulb. Dew point temperature is the temperature at which moisture will start to condense from the air. It is a measure of the latent heat content of the air. And, Dry Bulb temperature is the temperature measured by an ordinary mercury-in-glass thermometer.

The percent relative humidity is a ratio of the amount of moisture contained in a given volume of air (its dew point) to the maximum amount of moisture this air can hold at a given temperature (its dry bulb).

A low relative humidity means that the amount of moisture in the air is small, whereas a high relative humidity means that the air holding a large amount of moisture. Either of these conditions can make you feel uncomfortable. If the relative humidity is high (80 percent or higher), the ability of air to absorb moisture from the body is low. Therefore, one feels too warm during the summer when relative humidity is high. Likewise, a high moisture level can make you feel warmer during the winter when relative humidity is low.

One measure of the relationship between dry-bulb (sensible-heat) and dew-point (latent-heat) temperatures is the Wet-bulb temperature. The wet-bulb temperature is a measure of the total heat content of the air (sensible plus latent heat). 

VENTILATION

Ventilation is the process by which ‘Clean’ air (normally outdoor air) is intentionally provided to a space and stale air is removed. This may be accomplished by either natural or mechanical means. Ventilation is needed to provide oxygen for metabolism and to dilute metabolic pollutants (carbon dioxide and odour). It is also used to assist in maintaining good indoor air quality by diluting and removing other pollutants emitted within a space but should not be used as a substitute for proper source control of pollutants. Good ventilation is a major contributor to the health and comfort of building occupants.

Ventilation is providing a controlled quantity of air to a space or entire building. Generally, a mechanical system consisting of fans, ducts, registers, grill and filters is required.

Ventilation provides a controlled amount of air to a room or building. Ventilation air must be sufficient to eliminate moisture condensation, which can cause slippery floors or unsanitary conditions, within employee work areas. Proper air movement and ventilation will reduce or eliminate these undesirable conditions and will provide a quality room environment.

SELECTION OF AIR CONDITIONING SYSTEM

An air-conditioning system is designed to remove the heat load, expressed in Btu per hour (watts per hour). The heat load factors are:

1.      Transmission and residual heat loads – depends on the interior and exterior temperatures, the heat transmission coefficient, and the surface areas exposed to different temperature. The transmission heat load is based on an average high outside temperature, the design temperature. The residual heat load is the heat contained within the building’s furnishings and structural components.

2.      Solar Heat load

Þ    Glass surfaces

Þ    Non glass surfaces

3.      Occupant heat load – the number of customers, clients, and the number of employees and determine their activity level. The heat load depends both on the number of people and on what they are doing.

4.      Infiltration heat load – the movement of air through window and door frames and the movement of air from the outside to the inside through open doors and windows.

5.      Appliance heat load – operating appliances generate heat, e.g. electric lamps that convert 75 to 95 percent of their electric energy consumption to heat.

6.      Ventilation heat load – the heat removed from air as it is cooled in the air-cooling process. The size and operating cost of the air-cooling system depend on the ventilation heat load. The ventilation heat load depends on the amount of ventilation air, the air properties (relative humidity and temperature) before cooling, and the building cooling requirements.

While Repairing Air Conditioning Unit Employers should:

Ø  Require that all electrical equipment be de-energized before any repairs are performed;

Ø  Provide employees with education and training in the recognition and avoidance of electrical hazards;

Ensure that electrical equipment is installed to meet the manufacturers specifications, and ensure that equipment is restored to the manufacturers specifications before any work is begun.