Difference Between AHU and RTU (With Table)

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ATU and RTU are air heating units. To be precise, RTU is a type of ATU. Their function is to circulate purified air inside the building. The difference lies in their mounting type. The indoor inits are already safe since they are kept inside the building but consume space. The outdoor units are robust but need proper care to function properly in weather conditions.

Hence it is known the different kinds of units. They have different internal constructions and need to be handled accordingly.

AHU vs RTU

The difference between AHU and RTU is that RHU is a type of AHU that is placed on the rooftop and is only suitable as an outdoor unit. AHUs are of three different kinds, one of which is RTU. Rest are indoor setups. Hence all RTUs are AHUs but all AHUs are not RTUs.

AHU is defined as a device that is used to circulate and control the air in a building. It has a process of heating, ventilation as well as air conditioning. This process is abbreviated as the HVAC system. It set the temperature to an ideal degree which is 55 degrees Fahrenheit or, 13 degrees Celsius.

On the other hand, RTU is a subtype of AHU. It is mounted on the rooftop. It needs extra care since it is exposed to all the air and weather conditions. All its components are packaged as a single unit and are fixed in the roof. It is also a type of HVA equipment.

Comparison Table Between AHU and RTU

Parameters of DifferenceAHURTU
AbbreviationIt is the short form for an air handling unit.It is the short form for a rooftop unit.
Mounting TypeIt can be mounted indoor as well as outdoor.It can only be mounted outdoor.
ProcessThey have condensation pipes attached to them.They reject the heat to the outside directly.
Set upMost of the AHUs are placed indoors and they take up the extra place.RTUs are set up outdoor hence they do not take up any inside space.
ProtectionNormal ATUs do not need extra care since they are already kept inside the building.RTUs do not need extra care since they are exposed to strong weather conditions.

What is AHU?

AHU means air handling unit. The function of AHU is to re-condition and circulate the air to create an optimum or temperature, and is a huge metal box, which is connected o the ductwork. The main function of AHU is to collect the outside air, pass it through the condensation unit and then supply the fresh and purified air to the building.

The ductwork henceforth channels the conditioned air through an indoor structure. At the end of the process, it returns the fresh and purified air to the room. They are used for commercial purposes.

They are extensively used with HVAC systems. It is the abbreviation of heating, ventilation, and air-conditioning. The box comprises various components such as heating and cooling elements, a fan or a blower, humidifier, mixing chambers, filters, vibration isolators, and devices for heat control.

ATUs can be indoor or outdoor units, depending on their type. there are three types of air handling units. They are rooftop air handler, mall air handler, and makeup air handler. The first one is an outdoor unit whereas the rest two are indoor units.

What is RTU?

RTU stands for rooftop unit. It is a type of air handling unit which is mounted on top of the roof. They have all the components as one unit and that is why often referred to as packaged air conditioners. They are more compact and budget-friendly.

They are used for commercial purposes. Mostly found on the roofs of small buildings and shops to provide air conditioning. They are small, compact, and user-friendly, all-in-one setup of HVAC units. Their purpose is to circulate conditioned air throughout the building. the whole setup is done outdoor hence it does not consume any extra space inside the building.

The units are connected to the ductwork. It provides a well-set path for the conditioning process. They are more robust and need more care as compared to other kinds of AHUs. This is because it has to deal with the sun and extreme weather conditions. hence it needs to be weather-proof.

The compact unit includes components such as the condenser, fans, evaporating coil, condenser, and compressor. The evaporating coil and fan are not separated from the condenser and compressor. The function is very simple. It keeps the building warm during winter and cools during summer, by regulating its temperature.

Main Differences Between AHU and RTU

  1. The main difference between AHU and RTU is that all RTUs are AHUs but all AHUs are not RTUs. AHU can be outdoor or indoor units whereas RTUs are only outdoor units. They are mounted on top of the roof.
  2. AHU is the abbreviation for air handling units whereas RTU is the abbreviation for rooftop units.
  3. Most of the AHUs are placed inside the building and they take up the extra place. On the other hand, RTUs are set up outdoor hence they do help in space management.
  4. They have condensation pipes attached to them to carry out the condensation process for the collected air. RTUs reject the heat to the outside directly.
  5.  The common ATUs do not need extra care since they are already kept inside the building. However, RTUs do not need extra care since they are exposed to strong sun and all kinds of weather conditions.

Conclusion

Air handling devices have the same working principle. However, its construction may differ depending on the type they can be indoor units or outdoor units. RTU is a type of outdoor AHU. The only difference is in their mounting type. They are fixed on the top of the roof. This is why they need to be water-resistant and more robust. They need to fight strong Sun and extreme weather conditions.

It consists of a mixing chamber that controls the inside versus outside air.  The main aim is to regulate and circulate fresh air to the building that improves the quality of the air and maintains hygiene. The room air is circulated. This in turn results in noticeable energy saving.

References

  1. https://www.sciencedirect.com/science/article/pii/S0306261919320616
  2. https://www.sciencedirect.com/science/article/pii/S0378778818302305
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