What is the rooftop package?
روفتاپ پکیج چیست؟
Rooftop package is an equipment for cooling, heating and air filtration. As its name suggests, this unit is installed on the roof and works as an independent and complete unit for cooling and heating the building. Rooftop package is one of the most common air conditioning equipment used in office and commercial buildings, but it is not often used in residential buildings, the reason for which will be explained in the rest of the article. It should be noted that although the dual-purpose model of the rooftop unit is capable of providing heating as well, in Iran it is usually used to produce cool and comfortable air (in fact, it is a combination of a condensing unit and an air conditioner).
اجزای اصلی روفتاپ پکیج
The main components of the rooftop package are the compressor, air-cooled condenser, blower fan, DX coils and air filter, all housed in a large metal body. Of course, there are other components in the rooftop unit, some of their features are:
- A strong body that does not suffer from direct and constant sunlight and wind. In addition, the body should be insulated against the penetration of rain and snow.
- The rooftop package is connected to a ducting system and transfers cool air through the ducts into the building.
- On one side of the body, there is a vent for outside air to enter the package. This compartment is equipped with a cap that prevents rain and snow from entering the unit.
- Some rooftop packages are equipped with dampers to control the volume of air entering and leaving. The position of these dampers can determine the amount of outside air entering.
- Inside the unit and after the air inlet valve, a filter was placed to absorb dust, to prevent dust particles from entering the mechanical equipment, fans and channels. If there is no filter inside the rooftop, due to the deposition of dust from the outside air inside the equipment and channels, the efficiency of the device will decrease and eventually the device will have a major problem.
- In some units, there is also an air humidity adjustment device.
- A number of coils are placed in the rooftop units after the filter. These coils, which can be cold or hot or both depending on the type of rooftop package and its use, are used for cooling or heating the outside air.
- The fan installed inside the unit, which is usually of the centrifugal type, is placed after the coils and draws the outside air into the unit so that the air after passing through the damper, filter and coil enters the channel and spreads inside the building.
- The size of the cooling components of the unit, i.e. fan, condenser, compressor and controllers are usually installed at the back of the unit.
انواع روفتاپ پکیج
Rooftop packages are divided into 4 categories based on the type of air used for cooling.
Rooftop package with 100% fresh air
In this model, which is the simplest type of rooftop unit, the air that undergoes cooling and conditioning is completely supplied from the air outside the building, and the air inside the building is not included in the re-cooling cycle. But usually, to adjust the air pressure inside the building, part of the air is blown to the outside environment through the return channels.
Rooftop package with 100% return air
In some rooftop packages, the return air from the building is used and circulated. In this case, a damper is seen at the end of the return air channel. Using the return air from the building and combining this air with fresh outside air and performing operations on the combination of these two airs reduces the amount of energy consumption. If the unit is dual-purpose and used for heating, this reduction in energy consumption will be very significant in the winter season. The position and degree of opening and closing of the dampers determines the ratio of mixing of these two airs. Of course, it is necessary that a minimum amount of fresh air enters the system from the outside, and the dampers of the outside air will never be 100% closed. Otherwise, the indoor air quality will decrease due to the increase in carbon dioxide concentration and the air will become unhealthy for the people inside the building.
Rooftop package with 100% mixed air
The third type of units is designed in such a way that part of the air returned from the building passes through the damper and circulates, and another part is transferred outside the building. 3 Factors of outdoor air temperature, temperature and carbon dioxide level of the returned air determine the ratio of mixing of the two airs with each other and determine how many percent of the returned air should be transferred outside the building. In these cases, if the outside air temperature is close to the desired temperature of the building, all the volume of returned air from the building is transferred outside and does not circulate.
Rooftop package equipped with heat recovery
After entering the unit, the returned air from the building passes through a filter to get rid of pollution and suspended particles. Then it hits the heat recovery fins and causes the temperature of the fins to change. The heat recovery vanes also rotate towards the top where there is fresh air and cause the temperature of the fresh air to change. In fact, the returning air from inside the building gives its heat or cold to the vanes, and the vanes give this energy to the fresh air. In this method, the fresh air is preheated or precooled and then transferred to the heat transfer coils. This method has a significant effect in reducing energy consumption.
نحوه کار روفتاپ پکیج
- The filtered air (which, depending on the rooftop model described above, can be only fresh air from outside the building or a combination of fresh air and return air from the building) passes over the evaporator coils.
- Inside the evaporator coils, the cold liquid refrigerant is evaporating at low pressure. As a result of heat transfer in the evaporator, the air is cooled and transferred into the building through the channel. On the other hand, the refrigerant turns into steam due to air heat absorption and leaves the coils.
- The vapor refrigerant enters the compressor and its temperature and pressure increase. At this stage, the high-pressure refrigerant and superheat enters the condenser coils.
- Refrigerant heat is absorbed and transferred to the air through the body of the coils and the fins connected to the coils. As a result of this heat transfer, the temperature of the refrigerant decreases and turns into a liquid.
- The liquid refrigerant coming out of the condenser passes through the expansion valve and as a result of the expansion, it faces a decrease in pressure and a further decrease in temperature and again enters the evaporator coils to cool the air.
- Rooftop packages are usually controlled by a simple thermostat. The high refrigeration cycle continues until the building temperature reaches the thermostat setting
- If the rooftop is used to supply hot air in the winter season, it is necessary to transfer hot water from the engine room or the wall package device to the coils of the unit.
کاربرد روفتاپ پکیج
- The filtered air (which, depending on the rooftop model described above, can be only fresh air from outside the building or a combination of fresh air and return air from the building) passes over the evaporator coils.
- Inside the evaporator coils, the cold liquid refrigerant is evaporating at low pressure. As a result of heat transfer in the evaporator, the air is cooled and transferred into the building through the channel. On the other hand, the refrigerant turns into steam due to air heat absorption and leaves the coils.
- The vapor refrigerant enters the compressor and its temperature and pressure increase. At this stage, the high-pressure refrigerant and superheat enters the condenser coils.
- Refrigerant heat is absorbed and transferred to the air through the body of the coils and the fins connected to the coils. As a result of this heat transfer, the temperature of the refrigerant decreases and turns into a liquid.
- The liquid refrigerant coming out of the condenser passes through the expansion valve and as a result of the expansion, it faces a decrease in pressure and a further decrease in temperature and again enters the evaporator coils to cool the air.
- Rooftop packages are usually controlled by a simple thermostat. The high refrigeration cycle continues until the building temperature reaches the thermostat setting
- If the rooftop is used to supply hot air in the winter season, it is necessary to transfer hot water from the engine room or the wall package device to the coils of the unit.
مزایای استفاده از روفتاپ پکیج
Rooftop package units have advantages over split systems, which include:
- Less noise pollution in the building
- Small dimensions and less space required
- Increased efficiency due to the reduction of connections and pipe lengths
- The price is lower than the total cost of buying a chiller and air conditioner
- Easy installation
- Easy repairs
معایب روفتاپ پکیج
In this system, it is not possible to adjust and control the air temperature for each space independently, and this is a major flaw in these units; Because people in different spaces have different temperature needs, for example, if a building has 3 rooms, the comfortable temperature in one of the rooms is 24 degrees, another is 20 degrees, and the other room is 18 degrees. Now, if the temperature of the thermostat is set to the lowest value, then in the rest of the spaces, we have a waste of energy and people’s dissatisfaction. If the average temperature is considered, we also have people’s dissatisfaction and energy waste, and if the thermostat is set to the highest temperature, there is no energy waste, but people in the other two spaces are dissatisfied with the heat of the air. Therefore, rooftop packages are usually used in one-piece spaces (one hall or two parts).
Baredsanat production group started its activity in Isfahan in 2013 in the field of designing and producing all kinds of air conditioning and cooling systems. This collection has the ability to design and produce specialized types of rooftop packages in various capacities, according to the needs of our dear customers. All rooftop packages of this collection are provided with a valid 5-year warranty, including all equipment and accessories, as well as 10-year after-sales service. Some of the rooftop unit equipments are imported, which Baredsanat always tries to supply these equipments from the best and most reliable brands, among which the following can be mentioned:
- Compressor from BITZER Germany, HANBELL Taiwan and COPELAND USA
- Electronic expansion valve from CAREL Italy
- Miniature and thermal switches and device power from the German SIMENS brand
- Condenser fans of axial type and Zilabag, Rosenberg and IBM brands.
All other equipments are made by Bared Sanat company and are of excellent quality and at the level of reputable European brands. The price of Baredsanat rooftop units varies based on the type of capacity and the brand of equipment used. You can contact the experts of the collection to get the exact price.
Compression chiller
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