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


hey guys Paul here from the engineering
mindset calm in this video we’re going to be looking at the differences between
chillers AHU’s and RTU’s coming up how to recognize each of the
units the basics of how each unit works the differences between each unit and
where to locate them Before we jump into the content of today’s video I just want
to take a moment to thank our partners over at dan Foss for sponsoring this
video since we’re discussing air-conditioning
systems is worth mentioning that Dan Voss have solutions that can help you
increase efficiency and bring your system in line with refrigerant
regulations across all types dan Foss have a deep understanding of chillers
air handling units and rooftop units and they’ve a broad portfolio of parts to
help you enhance performance and reduce your energy costs find out more about
their air conditioning solutions at Air Conditioning.danfoss.com so first of
all let’s take a look at chillers Cheers 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 water cooled the term water or air called just tells the engineer how
the chillers condenser is rejecting heat from the building but don’t worry we’re
going to cover how both these work in just a moment
water-cooled chillers are typically located in the basement 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 water and pushes this around the
building to air handling units and fan coils these units circulate the air
around the local space as well as the building the air is M forced across the
heat exchangers containing the chilled water which extract C unwanted heat
before the air is distributed throughout the building the unwanted heat that is
extracted from the air collects in the chilled water loop which is pumped back
to the chiller where it will transfer over to the
chillers condenser via a refrigerant loop the condenser absorbs this heat and
then dumped this into the condenser water loop and this runs between the
chillers condenser and the cooling tower up in the
the cooling tower will force ambient air across the condenser water to extract
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 water cooled chiller water-cooled chillers are
typically used on large commercial properties with high cooling loads you
can tell if a building has a water cooled chiller because it will need a
cooling tower which is typically located on the roof there will usually be more
than one chiller and cooling tower and it’s not uncommon to have at least two
or three even more just for redundancy as well as variations in cooling demand
now we’ve covered this system in great detail previously in our videos there’s
some links on the screen now or if you want to learn more you can see the
description below air-cooled chillers air-cooled chillers are typically
located on the roof of the building or outside say in the carpark the
air-cooled chillers also generate chilled water which is pumped around the
building to air handling units as well as phone call units etc in order to cool
the building and pick up unwanted heat the air is forced to circulate around
the building and local space and will pass across heat exchanges within the
air handlers and fan coil units this unwanted heat is a gain transferred over
to the condenser of the chiller from the evaporator it is transferred via a
refrigerant which loops between the evaporator and the condenser and is
forced by the compressor the difference with this type of chiller
he said the fan blows air 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
located outside because they need access to a lot of ambient air in order to
reject the heat this type of chiller can usually be found on medium to large
commercial property 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 covered this in great
detail in previous videos there’s a link on-screen now for that or see the video
description below to learn more a haeju’s and RT use air handling it’s
and rooftop units now these two systems both serve a very similar purpose and
they can even look fairly alike both of these are used to disrobe
air around the building and will contain fans to achieve this they will both take
in fresh ambient air and clean this for a filter before heating or cooling the
air to suit the demands within the building the main difference between
these two is how the air 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 units are also referred to AHU’s for short
AHU’s are typically located inside the building though you can find these
in the rooftop plant rooms and it’s becoming more common to find these more
robust weather-tight AHU’s sitting out in the open on the roof to free up
space within the building their purpose is to distribute air around defined
areas within the building sometimes one ahu will supply the whole
building but it’s common in newer buildings that have multiple smaller eh
use feeding different parts to provide a better indoor environment as well as
resulting in energy savings AHU’s typically do not have their
own cooling system built in instead they will be connected to a central plant
water or air cooled chiller occasionally they will use some sort of split AC unit
and you can also find is connected to district cooling networks they choose
are connected to ductwork which provides a defined route for the air to travel
around the building in a simple form an H you will use a fan to suck in fresh
ambient outside air which will then pass through some filters to remove any dust
and dirt it will then pass through the cooling and heating coil heat exchangers
which as discussed are typically fed from central plant units once the air
has passed over these coils it will be pushed out around the building another
set of ductwork will be collecting the warm used air from these rooms and will
bring this back to the ahu via another fan this fan will then eject the air
from the ahu and the building and there are many different setups for this and
again we’ve covered this in detail in previous videos there’s a link on-screen
now where you can watch that or see their video description below are to use
rooftop units these units are always located on the roof as the name suggests
they are very common in shops and small commercial properties and are popular
because they are simple compact self-contained all-in-one HVAC units
the purpose is to distribute conditioned air around defined areas within a
building are to use are also connected to ductwork which provides a defined
route for the conditioned air to travel along are to use typically have their
own inbuilt refrigeration system to provide cooling only but they can also
contain a heat source such as a gas fired heater or an all-electric heat
pump RTu has all the components within the rooftop unit this contains a
number of dampers to control the flow of air and can allow air recirculation if
conditions are right the unit will also contain filters to clean the air as well
as heating and cooling coils and at least one central fan the refrigeration
system is also connected to the back or the side of the unit and this is used to
control the temperature the fresh ambient air is sucked in via the fan and
passes across the dampers and then passes through the filters to remove any
dust and dirt before its temperature is adjusted in the heat exchanger the fan
then pushes this out into the building to condition the space another duct will
collect the warm used air from the rooms and will distribute this back to the
rooftop unit will be ejected or recirculated if that option is available
and the conditions are right ok guys that’s it for this video but before I
close this out I just want to say another special thanks to our sponsor
den Foss one last time don’t forget to check out their broad portfolio of air
conditioning parts and solutions by heading over to air conditioning Danfoss
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