AHU VS RTU
AHU stands for Air Handling Unit while RTU is an acronym for Rooftop Unit. An RTU is a type of AHU and as such is there any difference between the twoAHU vs RT? There are no differences between an AHU and an RTU except for the fact that an RTU is placed on the rooftop.
The Air Handling Unit is a huge metal box, which helps in conditioning and circulating the air to create an ideal atmosphere. The AHU consists of components such as heating elements, cooling elements, blower or fan, filters, mixing chambers, vibration isolators, humidifiers, heat recovery devices and controls. All these components are also present in an RTU as it is only a type of AHU. Three types of AHUs are available in the market. The Mall Air Handlers and Make Up Air Units are the other two types of AHU.
The Roof Top Unit is an outdoor AHU. As the RTU is mounted on the roof, this removes the concern about creating extra space or room for fitting it as is the case for the other types of AHU. As the Unit is fitted on the rooftop, one should have more care as it is exposed to the weather. The RTU box is made of aluminum sheets or galvanized steel with a coating of corrosion resistance materials. All the components like the fan, motor, damper actuator linkages, water valves and controls are installed inside the box.
Both the RTU and the AHU function in the same manner. They sucks air from the room and pass it through cooling coils. After this the cold air is discharged into the room. The moisture in the air is condensed as it passes through the cooling coils.
Summary
- An RTU is a type of AHU.
- AHU stands for Air Handling Unit and the acronym RTU means Rooftop Unit.
- The Roof Top Unit is an outdoor AHU.
- As RTUs are mounted on the roof, there is no concern about creating extra space indoors for it as would be the case for the other types of AHU.
- As the RTU is fitted on the rooftop, one should have more care as it is exposed to the weather.
- Both the RTU and the AHU function in the same manner. They suck air from the room and pass it through cooling coils.
- The AHU and RTU consists of components such as heating elements, cooling elements, blower or fan, filters, mixing chambers, vibration isolators, humidifiers, heat recovery device and controls.
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Whats up with the picture?
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Not accurate…
There is a HUGE difference between the two…
Air Handling units (in your basement) blow air over a coil… that’s it.
The coil might have chilled water, or refrigerant, or glycol etc… but the Air Handling Unit doesn’t care… It never cools the fluid, only the air.
The fluid in the coil is cooled from a separate equipment called a Condensing Unit. (outside your house)
If you take an Air Handling Unit, and a Condensing Unit, and you put them in the same metal enclosure, and directly interconnect them, THAT’s an RTU. RTU’s cool the air by blowing it over (through) a coil filled with cooled refrigerant. It also circulates the refrigerant to an INTERNAL condensing unit with all the parts needed for THAT process, and rejects the heat from the refrigerant to the outside air. Then it returns the cooled refrigerant back to the coil and repeats.
RTU’s are always outside.(in order to reject heat to the outside)
AHU’s usually are inside, with piping that runs out to a condensing unit. But, can be mounted on a roof. (roof mounted AHU and RTU are NOT the same)
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Scott, Thank you for clearing the absolute confusion this article has caused me. as an ambitious fresh HVAC engineer, I wish I could talk to more straight-to-point people like you. cheers!
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Pardon my ignorance. So an air handler is always installed inside a house. Some air handlers are connected to say a heat pump system (condenser unit) that’s outside with a line set full of refrigerant that comes into the house and connects to the air handler where a blower blows air onto the coil within the air handler to heat or cool the air which gets blown into the ducting of a house to heat/cool the house. The out door heat pump either rejects the heat or the cool outside. With an RTU it’s basically a condenser unit plus air handler. It rejects the heat from inside the building our and replaces it with cool air. Can it also heat the air going into the building in the winter months? Sorry I’m really really new to the HVAC side only really been specialized in hydronics. Please let me know your thoughts.
Thank you 🙂
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