How Chiller, AHU, RTU work – working principle Air handling unit, rooftop unit hvac system

19August 2021

Hey there guys, Paul here from In this video, we’re going to be looking at the differences between chillers, AHUs, and RTUs. Coming up, how to recognize each of the units, the basics of how each unit creations, the differences between each unit, and where to pinpoint them. Before we jump into the content of today’s video, I simply want to take a moment to thank our partners over at Danfoss for patronizing this video.

Since we’re discussing air conditioner organizations, it’s worth mentioning that Danfoss have solutions that can help you increase efficiency and bring your system in-line with refrigerant regulations across all types.

Danfoss have a deep understanding of chillers, air manage contingents, and rooftop cells and have a broad portfolio of constituents to assist you enhance performance and abbreviate your exertion payment. Find out more about their air conditioner solutions at

So first of all, let’s take a look at chillers. Chillers are used to generate chilled or cold water which is pumped around the building to provide air conditioning by collecting unwanted heat.

There are two main types of chillers which are air cooled or ocean cooled. The word water or breeze cooled just tells the engineer how the chiller’s condenser is rejecting hot from the building. But don’t worry, we’re going to cover how both sets of work in just a moment.

Water cooled chillers are often are contained in the vault or the lowest floor of a building. This type of chiller needs a cooling tower to reject the heat from the building. The chiller produces chilled sea and propagandizes this around the building to air hold contingents and love cool units.

These units run the air in various regions of the neighbourhood infinite, as well as the building. The air is then forced across the heat exchangers containing such chilled ocean, which removes the unwanted heat before the breeze is distributed throughout the building.

The unwanted hot that is extracted from the aura collects in the chilled water curve, which is ran back to the chiller where it will convey over to the chiller’s condenser via a refrigerant loop-the-loop. The condenser absorbs this hot and then drops this into the condenser water loop, and this runs between the chiller’s condenser and the cooling castle up on the roof. The chill pillar will thrust ambient aura across the condenser water to remove the unwanted heat and reject this heat out of the building and into the atmosphere. So in this instance, the condenser of the chiller has been cooled by water so it is now a irrigate cooled chiller. Water cooled chillers are typically used on gigantic business belongings with high-pitched cooling loads.

You can tell if a structure has a water cooled chiller because it will need a cooling castle, which is typically located on the ceiling. There will usually be more than one chiller and cooling castle and it’s not uncommon to have at least two or three, even more just for redundancy as well as variations in cooling demand. And we’ve covered this system in great detail previously in other videos. There’s some ties-in on the screen now, where if you want to learn more you can see the description below.

Air cooled chillers, breeze cooled chillers are commonly located throughout the roof of the building or outside say in the car park.

The air cooled chillers also generate chilled water which is spouted around the building to air treatment contingents as well as fan cool components, et cetera, in order to cool the building and pick up unwanted heat. The breath is forced to circulate around the building and regional cavity and will pass across heat exchanges within the air handlers and fan cool gangs. This unsolicited hot is again carried over to the condenser of the chiller from the evaporator. It is gave via a refrigerant, which curves between the evaporator and the condenser and is forced by the compressor. The difference with this type of chiller is that the love blows breeze across the condenser which removes the unwanted heat.

So in this instance, the condenser of the chiller has been cooled by air, therefore it is an air cooled chiller. Air cooled chillers are typically unearthed outside because they need access to a lot of ambient aura in order to better reject the heat. This type of chiller can usually be found on medium to large-scale commercial quality, and there’s an example on-screen now of how these units look in the real-world on the roof of an office.

Again, we’ve comprised this in great detail in previous videos. There’s a join on-screen now for that, or accompany the video description below to learn more.

AHUs and RTUs, breeze cover legions and rooftop cells. Now these two systems both suffice a very similar purpose and they can even glance moderately alike. Both of these are used to distribute air around the building and incorporated in love to achieve this. They will both take up fresh ambient air and clean this through a filter before heating or cooling the air to suit the demands within the building. The main difference between these two is how the breath is heated or cooled and we’ll look at each of these to learn the basics of how they work in just a moment.

Air handling components are also referred to as AHUs for short.

AHUs are typically located inside the building, although you can find these in the rooftop bush areas and it’s becoming more common to find these more robust weathertight AHUs sitting out in the open on the roof to free up space within the building. Their purpose is to distribute air around characterized areas within the building. Sometimes one AHU will supply the whole building. But it’s common in newer constructs to have several smaller AHUs feeding different parts to provide a better indoor environment, as well as resulting in energy savings.

AHUs often do not have their own cooling system built-in. Instead they will be connected to a central weed, water or air cooled chiller. Rarely, they will use some sort of split AC unit and you can also find these connected to district chill networks.

AHUs are connected to duct work, which provides a characterized superhighway for the breath to travel around the building. In a simple form, an AHU will use a devotee to suck in fresh ambient outside aura, which will then pass across some filters to remove any dust and dirt.

It will then pass across the cool and heating loop heat exchanges, which as discussed, are typically fed from central embed forces. Once their air has passed over these scrolls, it is likely to be propagandized out around the building. Another begin of passage labor will be collecting the warm applied breath from these offices and will bring this back to the AHU via another fan.

This fan will then exhaust the breath from the AHU and the building, and there are many different setups for this, and again, we’ve plowed this in detail in previous videos. There’s a connect on-screen now where you can watch that or realise the video description below.

RTUs, rooftop groups, these units are always located throughout the ceiling, as the identify intimates. They are very common in shops and small business owneds and are favourite because they are simple, pact, self-contained, all-in-one HVAC forces. Their purpose is to distribute necessity aura around defined areas within a structure. RTUs are also connected to duct work, which provides a defined superhighway for the conditioned air to travel along. RTUs typically have their own indoor refrigeration system to provide cooling exclusively, but they can also contain a heat beginning such as a gas fired heater or an all-electric heat pump.

RTUs home all the components within the rooftop unit. This contains a number of dampers to control the flow of breeze and can allow air recirculation if preconditions are right. The gang will also contain filters to clean the aura, as well as heating and cooling scrolls and at least one central fan.

The refrigeration system is also connected to the back or the side of unit, and this is used to control the temperature. The fresh ambient breath is sucked in via the devotee and passes across the dampers.

It then guides through the filters to remove any dust and dirt before its temperature is adjusted in the heat exchanger. The love then propagandizes this out into the building to circumstance the seat. Another canal will accumulate the heated employed aura from the rooms and will administer this back to the rooftop unit where it will be ejected or recirculated if that alternative is available and the conditions are right. Okay guys, that’s it for this video. But before I close this out, I exactly want to say another special thanks to our patronize Danfoss one last-place time.

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com. Once again, thanks for watching..

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