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This page is for computer room air condition
| computer room air condition |
This page is for computer room air condition |
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How does Air Conditioning work?
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our contact page is a website that can help you find a computer room air condition . |
Welcome to Icecape Limited t/a RAC Kettering A leading and progressive supplier and installer of air conditioning systems at the most competitive prices available. RAC is at the forefront of supplying, installing and maintaining a range of state-of-the-art, high quality and reliable air conditioning systems into the commercial, industrial and domestic sectors.
We provide cooling and heating solutions for BARS, PUBS, CLUBS & RESTAURANTS; SHOPS, OFFICES, WAREHOUSE & FACTORY UNITS; HOSPITALS & SURGERIES; MOBILE HOMES as well as HOUSES, BUNGALOWS AND CONSERVATORIES.
Please browse through our website so that you can fully appreciate the benefits that RAC Kettering can bring to you from a wide selection of advanced technology air conditioning systems to suit your needs and requirements.
Air Conditioning is a process of what we call Heat Transfer. Regardless
of the outdoor conditions we are able to draw on the natural hot or cold molecules
in the atmosphere and use them to heat or cool an indoor air space.
An Air conditioner removes cold molecules from the air outside passes them through
pipe work into your house, office or conservatory and then releases them. At
the same time it removes the heat from indoors and releases it to the atmosphere
outside. By reversing this process we can also heat a house, office or conservatory.
All models, excluding Portables, come with an Inside Unit and an Outside Unit, providing high-efficiency rotary compressors that guarantee refrigerant compression with minimal loss, or a heating efficiency of nearly 300% for each 1kW input giving up to 2.85kW output. So what does all that mean - simply put, it means that the cost control over your interior climatic environment is significantly enhanced in your favour.
Too often, precision air conditioning is only considered when humidity
control is required. If the application does not demand humidity control, comfort
cooling is installed. In fact, the combination of recent economic conditions
and an increasingly competitive market have led to a rise in the number of server
rooms and data closets being served by traditional comfort cooling. These applications
can be air-cooled with a traditional, residential-style split system, or utilize
a cooling only water-source heat pump or a chilled water fan coil unit. These
systems appear attractive to the installer because of their apparent low up-front
costs. However, with some analysis, the cost differences between precision and
comfort cooling systems are not what they first appear. General Applications
ConsiderationsSensible Cooling CapacityThe first thing to consider when comparing
costs of cooling units is the amount of sensible cooling available. Since almost
all of the loads in these rooms are sensible heat, units should be selected
on their sen-sible capacities. The higher latent capacity of comfort units actually
hurts their perfor-mance in this application by unnecessarily lowering the humidity
in the room. In addition, comfort cooling units are usu-ally rated at the ARI
standard of 80 degrees F entering air temperature — not nearly cool enough
for computers and servers. One comfort manufacturer’s two-ton unit actually
de-rates to one ton of sensible cooling when adjusted for a 72 degrees F entering
air temperature. Be sure to compare the cost of units with the same sensible
capacity at the same entering conditions and not just “two-ton versus two-ton.”
A lower tonnage precision air conditioning system will probably match the higher
tonnage comfort unit for most applications.AccessSmall precision ceiling units,
which are designed for one-side only service access and filter replacement,
utilize tight room space more efficiently. Several comfort cooling units require
multi-side access, which restricts where they can be installed and can increase
ducting requirements and cost. One comfort unit actually requires bottom access,
making installation of the code-mandated auxiliary drain pan virtually impossible.Condensate
Pump Power, Drains and Alarms Because of limited above-ceiling space, many small
units require condensate pumps. condensate pumps get their power from
the unit and do not require an additional power feed. Most comfort units require
an additional electrical feed (usually at a different voltage) for the pump,
increas-ing overall installed cost. Also, if a condensate pump detects
an overflow, it shuts off the unit and sends an alarm to the wall-mounted controller.
The comfort cooling pump sends its alarm by overflowing water onto the floor.
Be sure to compare the cost of units at the same sensible capacity at the same
entering conditions . . .
(If the pump is installed in the auxiliary pan with an overflow switch, it will
shut the unit down; however, the owner will not know the unit is off until the
room gets hot.) Finally, since units are internally trapped, the required number
of field solder joints is reduced, further saving cost. Some comfort units actually
have more than one required drain connection, adding addi-tional labor cost.Remote
shutdown Many small server rooms have either an FM200 fire suppression system
or an Emer-gency Power Off (EPO) system. Both of these require the air conditioning
unit to be shut down immediately upon alarm. Units come standard with remote
shutdown contacts. Comfort units must be specially wired to accomplish this
task, increasing the owner’s cost.MonitoringUsually, smaller rooms are
not continuously occupied. Notification of a problem with the unit is very important.
Units come standard with a common alarm con-tact which can be connected to a
variety of alarm or management systems. Since this contact picks up all alarms
within the unit, not just temperature, potential problems (such as a dirty filter
or clogged condensate line) can be found and fixed prior to the room getting
out of control. Continuous Operation and Filtration evaporator fan motors are
designed to run continuously to help eliminate hot spots in rooms and provide
for increased filtration. Ducted units have 4-inch pleated filters as standard.
Even though their fans can be put in the “on” position, comfort cooling
units are designed for intermittent operation and typically do not have the
required motors for continuous duty. Typi-cal comfort cooling filters are 1-inch
throw-away, which can catch large contaminants, but are not very effective in
controlling dust.Air-Cooled Application ConsiderationsLow ambient controls.
Small systems come standard with low ambient controls to -20 degrees F. This
is important since the room will likely require air conditioning regardless
of out-door conditions. Low ambient controls must be added to comfort cooling
systems at an increased cost and generally are rated only down to 0 degrees
F or 20 degrees F. Often this option requires field installation, raising costs
even further.Voltage RangeSince many air-cooled comfort units are actually residential
units, they are designed around a nominal input voltage of 240 Volts. However,
in a commercial building, this voltage usually comes from a three-phase panel,
making the actual input volt-age nominally 208V. This voltage is very close
to being out of range for some of these units. Comfort cooling units are designed
for intermittent operation and typically do not have the required motors for
continuous duty.
Page 4
4One manufacturer lists their minimum volt-age as 207 volts. ’s
small systems are rated at 208/230 to cover the entire range of possible commercial
voltages. Water Cooled Application Considerations. units come standard
with a variety of water-regulating valves pre-installed at the factory. Specifically,
two or three-way valves are available in standard and high pressure ratings
to suit numerous applica-tions. Comfort cooling units require the purchase and
installation of an external valve, adding material and labor cost.Compressorized
Application ConsiderationsHot gas bypassBecause of load uncertainty or future
growth, hot gas bypass is a frequent addition to a small unit. It is standard
on every compressorized Mini-Mate2. Providing hot gas bypass extends
the compressor life by reducing the number of compressor cycles if the load
of the room does not match the unit capacity. This is often the case when simple
room load esti-mates have been made (or when room equipment loads are not operating
at full capacity). Another benefit is enhanced humidity con-trol. As offered
with some microprocessor controls, hot gas bypass reduces the latent (or
dehumidification) capacity of the Mini-Mate2 coil, thus allowing more of the
water vapor to stay in the space. Hot gas bypass warms the evaporator coil and
is an effective means to dry the coil. Yet, during a call for dehumidification,
some controls will disable the hot gas bypass mode, thus providing maximum
latent removal.Chilled Water Application ConsiderationsControl Valves and Controlssome
units come standard with a variety of control valves, including high pressure,
pre-installed at the factory. Comfort cool-ing units do not. Also, since the
thermostat and control valve must be purchased sepa-rately, these items must
be designed and integrated in the field, likely adding relays and wiring. This
not only adds field cost, but increases project management time as sep-arate
orders must be placed and shipments tracked.Starters and Motor Mountingsome
units do not require external start-ers. Most chilled water units require exter-nal
starters, adding material and labor cost. Also, many chilled water units have
the motor “shipped loose” which adds field labor time.ConclusionPrecision
air conditioning systems are designed specifically to cool electronic equipment.
Their high sensible heat ratio and continuous-duty design makes them ideal for
small computer rooms and closets. They also include a number of features that
simplify and reduce installation cost. Consequently, precision cooling units
are almost always a more effective and cost efficient choice.Precision air condition-ing
systems, such as the Mini-Mate2, are designed specifically to cool electronic
equip-ment. Their high sen-sible heat ratio and continuous-duty design makes
them the best choice for small com-puter rooms and closets.
The budget computer room air condition can
be had if you look round. To get the best portable computer room air conditioner ,
shop around and compare each computer room air conditioning unit
from the different sites.
Air Conditioning Systems Unrivalled standards of experience,
professionalism and customer care have combined to establish Icecape Ltd t/a RAC
Kettering as one of the UK's leading distributors of Daikin Air Conditioning
Products and Systems. RAC Kettering has chosen Daikin in 1977 as its first UK
supplier and has since grown steadily to become a major UK Distributor of Air
Conditioning Equipment with special expertise in VRV and Chiller Systems. In
addition to just supplying Daikin Air Conditioning Products, we also operate a
highly professional distribution service and demonstrate our ommitment to fully
back-up our clients by maintaining a well-stocked spare parts department.
Similarly high standards apply to the full pre and after sales support services
provided by RAC Kettering. Clients throughout the UK depend on the expertise of
RAC Kettering whose Sales Engineers operate nation-wide to give a
comprehensive design and support service. This is reinforced with a programme of
specialised product training for client's design and engineering personnel. An
experienced Technical Department assists with any engineering issue and can
provide on-site commissioning and troubleshooting.
What is air conditioning? Throughout the ages, we have sought to improve the
level of comfort offered by our surroundings. In colder regions, we have tried
to heat our dwellings and in warmer climes, to cool them down because if we are
not comfortable, we can neither work nor relax. But thermal comfort vital to our
well being, is subject to three basic influences:
Among these influences, the human factor is somewhat unpredictable. The others can be controlled in order to provide that much sought after feeling of well being. Changing patterns in construction, working practises and internal occupancy levels have created new parameters within which designers must operate. Modern buildings for instance, generate far more heat than their predecessors of say, 50 years ago and there are several reasons for this:
| Solar Infiltration Developments in building technology have also given rise to an increased use of glass - even when solar protective glazing is fitted, solar gains can be considerable. |
| Occupants Increasing numbers of occupants, each generating some 120W/h of heat, are routinely crammed into office areas. |
| Electrical Appliances Computers, printers and photo copiers, all part of the modern offices scenario, also generate substantial heat loads. |
| Ventilation Introducing the outside air into a building also introduces its temperature something of a problem if it's 30ºC outside! |
The principles of air conditioning are based around the transportation of
heat from one place to another and the medium generally used to effect
transportation is refrigerant. Refrigerant is used because it evaporates at very
low temperature. Physics shows that the evaporation of a substance (change of
phase) requires considerable energy.
The low boiling point inherent in
refrigerant enables it to be used at relatively low temperature, such as room
temperature. When a liquid refrigerant evaporates it absorbs heat from its
surroundings which therefore, cool down. Evaporation causes the refrigerant to
change from liquid to gas (phase change), at which point it contains
considerably more energy (heat) than in its liquid state the maximum amount
possible, in fact. If the refrigerant is to be reused, this heat must be
released, preferably at a point where it is no longer required. Once again,
physics shows that when a substance condenses, it releases much of the energy it
carries thus the refrigerant must be condensed. This requires its pressure to be
increased in order to raise the condensation temperature above that of the heat
exhaust point. This operation is carried out by a compressor. Once returned to
its fluid state, the refrigerant can absorb heat again. But its pressure is now
too high, as is its condensation point and also its evaporation
temperature. The problem is overcome by use of an expansion valve which
allows the pressure to fall, thereby reducing the evaporation temperature to its
original level. At this point the cycle can recommence. Manipulation of the
refrigerant pressure enables heat to be absorbed from an area of lower
temperature and released to an area of higher temperature with the corresponding
result of cooling or heating.
Air conditioners are part of our lives and we enjoy their comfort everywhere.
In shops, restaurants, offices, hotels ¦it's hard to imagine life without them.
Air conditioning provides you with pure cool air when it's hot outside. But what
about winter, and those cooler periods during spring and autumn? This is when we
need heating. Not cooling. ...heating in the winter The
ideal solution to this problem is the Heat pump. It cools when it's hot, and
warms when it's cold. The choice is yours, at the push of a button. Comfort and
well being all year round. A simple principle developed to perfection
Air conditioning works like your refrigerator, which removes heat
continuously from the cabinet and discharges it into the kitchen. You can feel
this 'free' heat by touching the coil on the back of your refrigerator. In
summer, the heat pump extracts heat from the warm air in your home and pumps it
outside. Your home stays comfortable and cool. In winter, it's the reverse.
Natural heat in the outdoor air - even when it's freezing - is extracted and
moved indoors. Wonderful warmth when you need it. Comfort that costs
less Three kilowatts of heat for each kilowatt of electricity used.
Heat pumps are up to three times more economical than conventional gas fired or
electric heating systems. Installation costs are lower too. With just one system
for cooling in summer and heating in winter, you save on equipment
outlay.
If we look for AIR CONDITIONING in Collins English Dictionary it states:
"A system or process for Controlling the Temperature and sometimes the Humidity and Purity of the air"
Controlling the Temperature is being able to Heat and Cool. Not only cool. The air that we breathe is made up of 3 major components all capable of carrying energy (heat):
1) The component molecular constituents of air: Oxygen (23%), Nitrogen (76%), Carbon Dioxide (< 1%) and Inert Gases (< 1%).
2) Moisture or Water Vapour: Water vapour is present in the air at all times, the quantity present being dependent upon the air temperature. The higher the air temperature the higher the water vapour (quantity).
3) Airborne Particulate: These are the suspended impurities within the air from either industrial or natural pollution such as Pollen, Dust, Smoke, Germs… etc.
As air is the only media that encompasses the whole of our body, we need to condition this air to provide comfort.
The action we need to take is:
1) Control Temperature (Heating & cooling) which entails adding energy (heating) or removing unwanted energy (cooling). General comfort conditions range between 20 - 25 °C in the UK.
2) Control Humidity (moisture content in the air), either Humidify (add moisture) when dry, which can result in dryness of skin, dry throat and encourages static built-up) or de-humidify (remove moisture) when the amount of moisture in the air is high, which can result in breathing discomfort. Comfort humidity is generally between 30-70 % RH (Relative Humidity) for the UK.
3) Provide Ventilation to provide the necessary Oxygen for breathing and dispelling carbon dioxide, Odour,dust, smoke etc. General Ventilation requirement ranges between 5 - 18 litres per second per person.
4) Provide Filtration to clean outside and inside air by removing dust, pollen, etc. Dust in dry air combined with dryness (lack of moisture in the air) is the main cause of static shocks. Lack of ventilation and filtration combined with the lack of maintenance is the main causes of Sick Building Syndrome (SBS). Therefore air conditioning encompasses HEATING, COOLING, HUMIDITY CONTROL, VENTILATION, FILTRATION.
There are many different methods of achieving comfort conditions (Heating, Cooling, Humidity Control, Ventilation & Filtration).
1) Heating and Cooling (which should be treated as one entity) are the most important parts of the Air conditioning system. Heating (adding energy): Is achieved through electrical energy input, Natural Gas Boilers, Oil Boilers and Reverse Cycle Refrigerant Heat Pump. Transfer of this energy from source to the air-conditioned space can be via air circulation (Air systems), via water circulation (Water systems) or via refrigerant (Extended Direct Expansion systems). Cooling (absorbing/removing heat): This is the reverse of heating i.e. transferring unwanted energy/heat (generated by lights, computers, people, solar heat gains through glass, structure heat gains, ventilation heat gains, etc.) from inside to outside. The transfer method is via the same media as heating transfer: Air systems, Water systems or Extended Direct expansion systems. Statement: 95% of cooling systems (air, water or Extended Direct Expansion (EDX)) use Refrigerant (vapour compression cycle or VCC) in the heat rejection process, as Refrigerant is the most efficient media and has the advantage of having a boiling temperature of -40°C (water =+100°C) and an energy carrying capacity 10 times more efficient than water and 50 times more efficient than air.
2) Ventilation which can be: A part of the whole air conditioning system, (in the case of Air Systems) where Air is also used to transfer energy. Or an independent system mainly to provide ventilation (in the case of Water Systems and EDX). However, outside air needs to be treated (heated and/or cooled and filtered) to meet indoor temperature conditions, especially in extreme winter conditions and not so extreme summer conditions. Statement: Utilising ventilation in mid season to control temperature can also provide an acceptable energy efficient solution. This is more the case in outer city areas and areas of low level, internal energy gain. Ventilation can represent a high percentage of building energy consumption, especially in centralised systems. Modular systems are more controllable, run only where needed and easily added to when requirements change.
3) Filtration is an integral part of any air movement device; the level of it depends on the type of equipment selected to provide the other parts of the air conditioning system. It can also be added to an existing system or stand-alone (e.g. electrostatic) Dependent on the application (Public Houses, etc) and special requirements (Hospitals, etc). Statement: There may be applications where due to capital cost implication, excessive ventilation (oversized) is applied to overcome the above special requirements at the expense of running cost. Localised filtration is more possible these days at low cost rather than over sizing the ventilation system
Air conditioning is to control the temperature in the main, control the humidity and clean the atmosphere that we live in. To control the temperature we have to add heat (energy) when cold and remove heat (energy) when warm. This energy has to be transported from outside to inside (Heating) and from inside to outside (Cooling). There are three main methods to transfer this energy: Air Systems, Water Systems and Refrigerant Systems. Air Systems: This where we use the air to carry the energy from inside to outside and vice versa. The use of Air Handling Units (AHU) or Roof Top Packages (RTP) to condition the air (Temperature, humidity sometimes), filter and refresh the air and send it through ductwork to the occupied space where the conditioned air will heat or cool the space as required and return via return air ducts back to the AHU or RTP. Air Handling Units contain a cooling coil (connected to a chiller or condensing unit) a heating coil (connected to boilers or electric heaters) filters and circulating fan(s). Roof Top Packages contain refrigerant cooling cycle, heating coils (connected to boilers or electric heaters), filters and circulating fan(s).
Water Systems: In these systems water is used to carry the energy from inside to outside and vice versa. The use of a chiller (on roofs or plant rooms) to cool the water which would be circulated via circulating pumps to the occupied space where it will be passed through fan coils (terminal units) which circulate room air over the coil, hence absorbing unwanted heat. The use of boilers (in plant rooms) to heat the water (separate circuit from cooling) which would be circulated via circulating pumps to and back from the occupied space where it will be passed through the same fan coil which circulate room air hence adding heat to the space. Water Systems only control the temperature. Filtering of the air is normally carried out through the indoor fan coils (terminal units). Ventilation is normally carried out through a separate system with a range of AHU and ductwork distribution system (smaller than air systems) which can be localised to the air-conditioned space.
Refrigerant Systems (Known as Extended Direct Expansion or DX Systems): In these systems refrigerant is used to carry the energy from inside to outside or vice versa. The use of outdoor condensing units (can be reverse cycle heat pump for heating) cool the refrigerant and sends it through refrigeration small bore pipe work to indoor fan coils (terminal units) where it will expand to lower the temperature of the refrigerant in the pipe, hence room air when circulated over the coil will lose its unwanted heat. Heating is achieved via the same outdoor unit by reversing the cycle or utilising a third pipe to carry hot refrigerant to the indoor unit to provide heating. Filtering of the air is normally carried out through the indoor fan coils (terminal units). Ventilation is normally carried out through a separate system with a range of AHU and ductwork distribution system (smaller than air systems) which can be localised to the air-conditioned space.
The basis of most (more than 95%) air conditioning systems is the ' vapour compression cycle". The media (vapour) is Refrigerant (hydrochlorofluorocarbons - HCFC or hydrofluorocarbons - HFC) which is non-toxic, non-explosive and non-corrosive. These Refrigerants have a boiling point of aprox. Minus 40°C which means that even if the air (outside or inside) temperature is as low as minus 39°C it still has heat to be absorbed by refrigerants.
The vapour compression cycle requires four components:
1) The compressor: To raise the pressure of low-pressure low temperature gas to high-pressure high temperature gas. There are many types of compressors; the most common are Reciprocating, Rotary, Scroll, Screw and Centrifugal.
2) The Condenser: To change the state of high-pressure, high temperature gas to high-pressure, high temperature LIQUID. This is achieved by passing ambient air (known as air-cooled) or water (known as water-cooled) over the condenser tubes.
3) The Expansion Device: The purpose of the device is to change the state of the refrigerant from high-pressure, high temperature liquid to low pressure low temperature saturated liquid. This is achieved by passing the liquid through an orifice.
4) The Evaporator: To absorb the heat from room air or water, which in
the case of a chiller is circulated around the evaporator coil. This will change
the state of low-pressure, low temperature saturated liquid to low pressure,
low/medium temperature gas. These components are common to the
vast majority of domestic refrigerators and appear in slightly different forms
in 95% of air conditioning and refrigeration systems, Domestic, commercial or
industrial. This vapour compression cycle if reversed (condenser
becomes evaporator and visa versa) can now absorb heat from outside and transfer
it to inside, hence saving energy. This is called Reverse Cycle Heat Pump. Energy
savings can be as high as 4 to 1 (for every kW input we get 4 kW output).
| our contact page . For a budget computer room air condition or a computer room air condition in England, Scotland and Wales visit our contact page now. |
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computerroomcooling@rackett.freeserve.co.uk