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
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
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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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