Window and through-wall units
Room air conditioners come in two forms: unitary and packaged terminal PTAC systems. Unitary systems, the common one room air conditioners, sit in a window or wall opening, with interior controls. Interior air is cooled as a fan blows it over the evaporator. On the exterior the air is heated as a second fan blows it over the condenser. In this process, heat is drawn from the room and discharged to the environment. A large house or building may have several such units, permitting each room be cooled separately. PTAC systems are also known as wall split air conditioning systems or ductless systems. These PTAC systems which are frequently used in hotels have two separate units (terminal packages), the evaportive unit on the exterior and the condensing unit on the interior, with tubing passing through the wall and connecting them. This minimizes the interior system footprint and allows each room to be adjusted independently. PTAC systems may be adapted to provide heating in cold weather, either directly by using an electric strip, gas or other heater, or by reversing the refrigerant flow to heat the interior and draw heat from the exterior air, converting the air conditioner into a heat pump. While room air conditioning provides maximum flexibility, when cooling many rooms it is generally more expensive than central air conditioning.

Evaporative coolers
In very dry climates, evaporative coolers are popular for improving comfort during hot weather. This type of cooler is the dominant cooler used in Iran, which has the largest number of these units of any country in the world, causing some to referring to these units as "Persian coolers."  An evaporative cooler is a device that draws outside air through a wet pad, such as a large sponge soaked with water. The sensible heat of the incoming air, as measured by a dry bulb thermometer, is reduced. The total heat (sensible heat plus latent heat) of the entering air is unchanged. Some of the sensible heat of the entering air is converted to latent heat by the evaporation of water in the wet cooler pads. If the entering air is dry enough, the results can be quite comfortable; evaporative coolers tend to feel as if they are not working during times of high humidity, when there is not much dry air with which the coolers can work to make the air as cool as possible for dwelling occupants. Unlike air conditioners , evaporative coolers rely on the outside air to be channeled through cooler pads that cool the air before it reaches the inside of a house through its air duct system; this cooled outside air must be allowed to push the warmer air within the house out through an exhaust opening such as a open door or window.

These coolers cost less and are mechanically simple to understand and maintain.
An early type of cooler, using ice for a further effect, was patented by John Gorrie of Apalachicola, Florida in 1842. He used the device to cool the patients in his malaria hospital.

Portable air conditioners
Portable air conditioners (or PACs) are moveable units that can be used to cool a specific room in a home and do not require permanent installation. Warm air in the room is drawn in through inlets on the portable air conditioner. The air is circulated through the unit and is cooled by evaporator coils with refrigerant running through them and then blown out through the front. Remaining hot air in the unit is expelled and vented through the back with an exhaust hose. All portable air conditioners require exhaust hoses for venting.

Single Hosed Units
A single hosed unit has one hose that runs from the back of the portable air conditioner to the vent kit where hot air can be released. A single hosed portable air conditioner can cool a room that is 475 sq. ft. or smaller and has at most a cooling power of 12,000 BTUs.

Dual Hosed Units
Dual hosed units are typically used in larger rooms. One hose is used as the exhaust hose to vent hot air and the other as the intake hose to draw in additional air (usually from the outside). These units generally have a cooler power of 12,000-14,000 BTUs and cool rooms that are around 500 sq. ft. The reason an intake hose is needed to draw in extra air is because with higher BTU units, air is cycled in large amounts and hot air is expelled at a faster rate. This creates negative air pressure in the room, and the intake hose stabilizes the room's air pressure.

Split Units
Portable units are also available in split configuration, with the compressor and evaporator located in a separate external package and the two units connected via two detachable refrigerant pipes, as is the case with fixed split systems. Split portable units are superior to both single and dual hosed mono-portable units in that interior noise and size of the internal unit is greatly reduced due to the external location of the compressor, and no water needs to be drained from the internal unit due to the exterior location of the evaporator.

A drawback of split portable units compared with mono-portables is that a surface exterior to the building, such as a balcony must be provided for the external compressor unit to be located.

Unlike window ACs the split AC does not have an option of exchange of indoor and outdoor air.

Heat and Cool Units
Some portable air conditioner units are also able to provide heat by reversing the cooling process so that cool air is collected from a room and warm air is released. These units are not meant to replace actual heaters though and should not be used to cool rooms lower than 50 °F (10 °C).

Central air conditioning
Central air conditioning, commonly referred to as central air (U.S.) or air-con (UK), is an air conditioning system which uses ducts to distribute cooled and/or dehumidified air to more than one room, or uses pipes to distribute chilled water to heat exchangers in more than one room, and which is not plugged into a standard electrical outlet.

With a typical split system, the condenser and compressor are located in an outdoor unit; the evaporator is mounted in the air handler unit. With a package system, all components are located in a single outdoor unit that may be located on the ground or roof.

Central air conditioning performs like a regular air conditioner but has several added benefits:

    * When the air handling unit turns on, room air is drawn in from various parts of the building through return-air ducts. This air is pulled through a filter where airborne particles such as dust and lint are removed. Sophisticated filters may remove microscopic pollutants as well. The filtered air is routed to air supply ductwork that carries it back to rooms. Whenever the air conditioner is running, this cycle repeats continually.

    * Because the condenser unit (with its fan and the compressor) is located outside the home, it offers a lower level of indoor noise than a free-standing heat pums unit.

Mini (Small) Duct, High Velocity
A central air conditioning system using high velocity air forced through small ducts (also called mini-ducts), typically round, flexible hoses about 2 inches in diameter. Using the principle of aspiration, the higher velocity air mixes more effectively with the room air, eliminating temperature discrepancies and drafts. A high velocity system can be louder than a conventional system if sound attenuators are not used, though they come standard on most, if not all, systems.

The smaller, flexible tubing used for a mini-duct system allows it to be more easily installed in historic buildings, and structures with solid walls, such as log homes. These small ducts are also typically longer contiguous pieces, and therefore less prone to leakage. Another added benefit of this type of ducting is the prevention of foreign particle buildup within the ducts, due to a combination of the higher velocity air, as well as the lack of hard corners.

from:wiki

An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle. In construction, a complete system of heating, ventilation, and air conditioning is referred to as "HVAC." Its purpose, in a building or an automobile, is to provide comfort during either hot or cold weather.

In 1758, Benjamin Franklin and John Hadley, professor of chemistry at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids such as alcohol and ether, could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to "quicken" the evaporation; they lowered the temperature of the thermometer bulb down to 7 °F (−14 °C) while the ambient temperature was 65 °F (18 °C). Franklin noted that soon after they passed the freezing point of water (32°F) a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a quarter inch thick when they stopped the experiment upon reaching 7 °F (−14 °C). Franklin concluded, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day".

In 1820, British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital in Apalachicola, Florida. He hoped eventually to use his ice-making machine to regulate the temperature of buildings. He even envisioned centralized air conditioning that could cool entire cities. Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making machine. His hopes for its success vanished soon afterward when his chief financial backer died; Gorrie did not get the money he needed to develop the machine. According to his biographer Vivian M. Sherlock, he blamed the "Ice King", Frederic Tudor, for his failure, suspecting that Tudor had launched a smear campaign against his invention. Dr. Gorrie died impoverished in 1855 and the idea of air conditioning faded away for 50 years.

Early commercial applications of air conditioning were manufactured to cool air for industrial processing rather than personal comfort. In 1902 the first modern electrical air conditioning was invented by Willis Haviland Carrier in Syracuse, NY. Designed to improve manufacturing process control in a printing plant, his invention controlled not only temperature but also humidity. The low heat and humidity were to help maintain consistent paper dimensions and ink alignment. Later Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time air conditioning came to be used to improve comfort in homes and automobiles. Residential sales expanded dramatically in the 1950s.

In 1906, Stuart W. Cramer of Charlotte, North Carolina, was exploring ways to add moisture to the air in his textile mill. Cramer coined the term "air conditioning", using it in a patent claim he filed that year as an analogue to "water conditioning", then a well-known process for making textiles easier to process. He combined moisture with ventilation to "condition" and change the air in the factories, controlling the humidity so necessary in textile plants. Willis Carrier adopted the term and incorporated it into the name of his company. This evaporation of water in air, to provide a cooling effect, is now known as evaporative cooling.

The first Heat pump and refrigerators employed toxic or flammable gases like ammonia, methyl chloride, and propane which could result in fatal accidents when they leaked. Thomas Midgley, Jr. created the first chlorofluorocarbon gas, Freon, in 1928. The refrigerant was much safer for humans but was later found to be harmful to the atmosphere's ozone layer. Freon is a trademark name of DuPont for any chlorofluorocarbon (CFC), hydrogenated CFC (HCFC), or hydrofluorocarbon (HFC) refrigerant, the name of each including a number indicating molecular composition (R-11, R-12, R-22, R-134A). The blend most used in direct-expansion home and building comfort cooling is an HCFC known as R-22. It is to be phased out for use in new equipment by 2010 and completely discontinued by 2020. R-12 was the most common blend used in automobiles in the United States until 1994 when most changed to R-134A. R-11 and R-12 are no longer manufactured in the United States, the only source for purchase being the cleaned and purified gas recovered from other air conditioner systems. Several non-ozone depleting refrigerants have been developed as alternatives, including R-410A, known by the brand name Puron. The most common ozone-depleting refrigerants are R-22, R-11, and R-123.

Innovation in air conditioning technologies continue, with much recent emphasis placed on energy efficiency and improving indoor air quality. As an alternative to conventional refrigerants, natural alternatives like CO2 (R-744) have been proposed.

from:wiki

Air leakage, or infiltration, occurs when outside air enters a house uncontrollably through cracks and openings. Properly air sealing such cracks and openings in your home can significantly reduce heating and cooling costs, improve building durability, and create a healthier indoor environment. It is unwise to rely on air leakage for ventilation because it can't be controlled. During cold or windy weather, too much air may enter the house. When it's warmer and less windy, not enough air may enter. Air infiltration also can contribute to problems with moisture control. Moldy and dusty air can enter a leaky house through such areas as attics or foundations. This air in the house could cause health problems. The recommended strategy in both new and old homes is to reduce air leakage as much as possible and to provide controlled ventilation as needed.

The purpose of the project was to build a low energy and low cost prefabricated house without compromising the comfort. Due to the overall reduced energy consumption in low energy houses the proportion of the heat required for DHW increases from 30% to 40%. This sets new requirements for a heating system. In this residence there are two air to water heat pumps : one for heating (from October to April) and the other for DHW (DHW; all year round).
The former uses outdoor air and the latter indoor exhaust air as its heat source. The SPF of the 4.6 kW heat pump for space heating is 3.0. If auxiliaries such as fans for heat recovery and standby losses of the water heater are considered as well the SPF drops to 2.0.

Heat pumps in residential and commercial buildings
Heat pumps for heating and cooling buildings can be divided into four main categories depending on their operational function:
·         Heating-only heat pumps, providing space heating and/or water heating.
·         Heating and cooling heat pumps, providing both space heating and cooling.
The most common type is the reversible air-to-water heat pump, which either operates in heating or cooling mode. Large heat pumps in commercial/institutional buildings use water loops (hydronic) for heat and cold distribution, so they can provide heating and cooling simultaneously.
·         Integrated heat pump systems, providing space heating, cooling, water heating and sometimes exhaust air heat recovery.
Water heating can be by desuperheating only, or by desuperheating and condenser heating. The latter permits water heating when no space heating or cooling is required.
·         Heat pump water heaters, fully dedicated to water heating.

They often use air from the immediate surroundings as heat source, but can also be exhaust-air heat pumps, or desuperheaters on air-to-water and water-to-air heat pumps . Heat pumps can be both monovalent and bivalent, where monovalent heat pumps meet the annual heating and cooling demand alone, while bivalent heat pumps are sized for 20-60% of the maximum heat load and meet around 50-95% of the annual heating demand (in a European residence). The peak load is met by an auxiliary heating system, often a gas or oil boiler. In larger buildings the heat pump may be used in tandem with a cogeneration system (CHP).

In residential applications room heat pumps can be reversible air-to-air heat pumps (ductless packaged or split type units). The heat pump can also be integrated in a forced-air duct system or a hydronic heat distribution system with floor heating or radiators (central system).
In commercial/institutional buildings the heat pump system can be a central installation connected to an air duct or hydronic system, or a multi-zone system where multiple heat pump units are placed in different zones of the building to provide individual space conditioning. Efficient in large buildings is the water-loop heat pump system, which involves a closed water loop with multiple heat pumps linked to the loop to provide heating and cooling, with a cooling tower and auxiliary heat source as backup.

from:china-heat-pump|heat pump

 

• Conserve Water. Your biggest opportunity for savings is to use less hot water. In addition to saving energy (and money), cutting down on hot water use helps conserve dwindling water supplies, which in some parts of the country is a critical problem. A family of four each showering five minutes a day can use about 700 gallons per week-a three-year drinking water supply for one person! Water-conserving showerheads and faucet aerators can cut hot water use in half. That family of four can save 14,000 gallons of water a year and the energy required to heat it.

• Insulate Your Existing Water Heater. If your electric water heater was installed before 2004, installing an insulating jacket is one of the most effective do-it-yourself energy-saving projects, especially if your water heater is in an unheated space. The insulating jacket will reduce standby heat loss-heat lost through the walls of the tank-by 25-40%, saving 4-9% on your water heating bills. Water heater insulation jackets are widely available for around $10. Always follow directions carefully when installing an insulation jacket.

• Insulate Hot Water Pipes. Insulating your hot water pipes will reduce losses as the hot water is flowing to your faucet and, more importantly, it will reduce standby losses when the tap is turned off and then back on within an hour or so. A great deal of energy and water is wasted waiting for the hot water to reach the tap. Even when pipes are insulated, the water in the pipes will eventually cool, but it stays warmer much longer than it would if the pipes weren??t insulated.

• Lower the Water Heater Temperature. Keep your water heater thermostat set at the lowest temperature that provides you with sufficient hot water. For most households, 120 F water is fine (about midway between the "low" and "medium" setting). Each 10 F reduction in water temperature will generally save 3-5% on your water heating costs. When you are going away on vacation, you can turn the thermostat down to the lowest possible setting, or turn the water heater off altogether for additional savings. With a gas water heater, make sure you know how to relight the pilot if you're going to turn it off while away.

When comparing the performance of heat pumps, it is best to avoid the word "efficiency" which has a very specific thermodynamic definition. The term coefficient of performance (COP) is used to describe the ratio of useful heat movement to work input. Most vapor-compression heat pumps utilize electrically powered motors for their work input. However, in most vehicle applications, shaft work, via their internal combustion engines, provide the needed work.

When used for heating a building on a mild day, a typical air-source heat pump has a COP of 3 to 4, whereas a typical electric resistance heater has a COP of 1.0. That is, one joule of electrical energy will cause a resistance heater to produce one joule of useful heat, while under ideal conditions, one joule of electrical energy can cause a heat pump to move much more than one joule of heat from a cooler place to a warmer place.

Note that when there is a wide temperature differential, e.g., when an air-source heat pump is used to heat a house on a very cold winter day, it takes more work to move the same amount of heat indoors than on a mild day. Ultimately, due to Carnot efficiency limits, the heat pump's performance will approach 1.0 as the outdoor-to-indoor temperature difference increases. This typically occurs around −18 °C (0 °F) outdoor temperature for air source heat pumps. Also, as the heat pump takes heat out of the air, some moisture in the outdoor air may condense and possibly freeze on the outdoor heat exchanger. The system must periodically melt this ice. In other words, when it is extremely cold outside, it is simpler, and wears the machine less, to heat using an electric-resistance heater than to strain an air source heat pump . (Geothermal heat pumps are dependent upon the temperature underground, which is "mild" all year round. Their COP is therefore always in the range of 3.5–4.0).

In cooling mode a heat pump's operating performance is described as its energy efficiency ratio (EER) or seasonal energy efficiency ratio (SEER), and both measures have units of BTU/(h·W) (1 BTU/(h·W) = 0.293 W/W). A larger EER number indicates better performance. The manufacturer's literature should provide both a COP to describe performance in heating mode and an EER or SEER to describe performance in cooling mode. Actual performance varies, however, and depends on many factors such as installation, temperature differences, site elevation, and maintenance.

Heat pumps are more effective for heating than for cooling if the temperature difference is held equal. This is because the compressor's input energy is largely converted to useful heat when in heating mode, and is discharged along with the moved heat via the condenser. But for cooling, the condenser is normally outdoors, and the compressor's dissipated work is rejected rather than put to a useful purpose.

For the same reason, opening a food refrigerator or freezer heats up the room rather than cooling it because its refrigeration cycle rejects heat to the indoor air. This heat includes the compressor's dissipated work as well as the heat removed from the inside of the appliance.

The COP for a heat pump in a heating or cooling application, with steady-state operation, is:

 

 The COP increases as the temperature difference, or "lift", decreases between heat source and destination. The COP can be maximised at design time by choosing a heating system requiring only a low final water temperature (e.g. underfloor heating), and by choosing a heat source with a high average temperature (e.g. the ground). Domestic hot water (DHW) and radiators require high water temperatures, affecting the choice of heat pump technology.

from:wiki

According to the second law of thermodynamics heat cannot spontaneously flow from a colder location to a hotter area; work is required to achieve this.

Since the heat pump uses a certain amount of work to move the heat, the amount of energy deposited on the cold side is less than that taken from the hot side. Conversely, for a heat engine, the amount of energy taken from the hot side is greater than the amount of energy deposited in the cold heat sink since some of the heat has been converted to work.

One common type of heat pump works by exploiting the physical properties of an evaporating and condensing fluid known as a refrigerant.
A simple stylized diagram of a heat pump's vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor.

The working fluid, in its gaseous state, is pressurized and circulated through the system by a compressor. On the discharge side of the compressor, the now hot and highly pressurized gas is cooled in a heat exchanger, called a condenser, until it condenses into a high pressure, moderate temperature liquid. The condensed refrigerant then passes through a pressure-lowering device like an expansion valve, capillary tube, or possibly a work-extracting device such as a turbine. This device then passes the low pressure, (almost) liquid refrigerant to another heat exchanger, the evaporator where the refrigerant evaporates into a gas via heat absorption. The refrigerant then returns to the compressor and the cycle is repeated.

In such a system it is essential that the refrigerant reach a sufficiently high temperature when compressed, since the second law of thermodynamics prevents heat from flowing from a cold fluid to a hot heat sink. Practically, this means the refrigerant must reach a temperature greater than the ambient around the high-temperature heat exchanger. Similarly, the fluid must reach a sufficiently low temperature when allowed to expand, or heat cannot flow from the cold region into the fluid, i.e. the fluid must be colder than the ambient around the cold-temperature heat exchanger. In particular, the pressure difference must be great enough for the fluid to condense at the hot side and still evaporate in the lower pressure region at the cold side. The greater the temperature difference, the greater the required pressure difference, and consequently the more energy needed to compress the fluid. Thus as with all heat pumps , the energy efficiency (amount of heat moved per unit of input work required) decreases with increasing temperature difference.

Due to the variations required in temperatures and pressures, many different refrigerants are available. Refrigerators, air conditioners , and some heating systems are common applications that use this technology.

In HVAC applications, a heat pump normally refers to a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building. In the cooler climates the default setting of the reversing valve is heating. The default setting in warmer climates is cooling. Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. As such, the efficiency of a reversible heat pump is typically slightly less than two separately-optimized machines.

In plumbing applications, a heat pump is sometimes used to heat or preheat water for swimming pools or domestic water heaters.

In somewhat rare applications, both the heat extraction and addition capabilities of a single heat pump can be useful, and typically results in very effective use of the input energy. For example, when an air cooling need can be matched to a water heating load, a single heat pump can serve two useful purposes. Unfortunately, these situations are rare because the demand profiles for heating and cooling are often significantly different.

from:wiki|heat pump

• Chengda Air to Water Heat Pumps
• Chengda is a professional manufacturer of refrigerating and heating products,gathering much experience on refrigeration and heating for about twenty yeas. Now we develop the new generation products which are ecological high efficiency to match the world wlde topic of energy saving.

• A good solution for energy saving
• Chengda air to water heat pump is anew generation heat pump product developed with the advanced heating technologies. The heat pump utilizes the energy from surrounding air and converts the energy to the hot water for house heating and domestic hot water supplying. The whole range of this heat pump is completed and strictly tested with our European partners, to make sure the best efficiency and quality to European market. especially for cold areas. With wide running temperature range from -15℃ to 40℃，keep supplying the warm water from 35℃ to 60℃(max), making you warm and comfortable life.

• A good solution for energy saving
• Chengda air water heat pump is anew generation heat pump product developed with the advanced heating technologies. The heat pump utilizes the energy from surrounding air and converts the energy to the hot water for house heating and domestic hot water supplying. The whole range of this heat pump is completed and strictly tested with our European partners, to make sure the best efficiency and quality to European market. especially for cold areas. With wide running temperature range from -15℃ to 40℃，keep supplying the warm water from 35℃ to 60℃(max), making you warm and comfortable life.
• All main components from our world-known manufacturing partners such as Copeland, Siemens, Danfoss, Wilo. All products offer maximum efficiency together with total reliability and manufactured to the highest quality standard.

• Outstanding performance
  • High efficiency and energy saving
  • R407C refrigerant
  • Maximun outlet water temperature up to 60℃
  • Stepped fan motor
  • Expansion valve keeps the most suitable refrigerant flow in any case
  • Water flow protection, high/low pressure protection, outlettemp protection etc, keeping the system safety.

• High Quality and reliability
  • stainless steel plate heat exchanger with maximum permitted pressure 40 bar
  • 100% stainless water circuit
  • Microprocessor control and error alarm and display
  • Compact design, easy installation and maintenance
  • World-known brand compressor, pump and main components

 

Main components

Flexible installation

 heat pumps are suitable for many different heating systems to heat the house or produce hot water.

• Connected with an exist boiler or replace the old electric/gas/oil heater.
• Installed for house heating and hot water supplying.
• Installed together with a solar heating system.
• Installed for swimming pool heating (closed water circuit)