We are going to cover
200 years of HVAC
history in 50 minutes
THE MODERN
HVAC SYSTEM
James D. Stoller, P.E., LEED GA
Facilities Engineering
Mechanical Engineer
Purdue University
HVAC Systems
To help you follow the slides – here the “text rules”
1. Black Text: the main points
2. Blue Text: personal superfluous
comments
3. Red Text: questions for audience
participation
4. Yellow Text: hint of the next slide
5. Green (& others) text: I ran out of
colors so I had to use something
different
1
HVAC Systems
To help you follow the slides – here the “text rules”
1. Black Text: the main points
2. Blue Text: personal superfluous
comments
3. Red Text: questions for audience
participation
4. Yellow Text: hint of the next slide
5. Green (& others) text: I ran out of
colors so I had to use something
different
The goal of this presentation
2
Energy Audit Tips
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
You will walk away with 12
specific energy audit tips
In one slide let’s review two centuries:
1600 to 1800
HVAC Systems
A long history of discovery
Leading to today’s HVAC Engineer
Galileo
Fahrenheit
Celsius
Carrier
Fulton
Watt
4
HVAC Systems
Our work is based on energy transfer
The energy we transfer is …
HEAT
5
HVAC Systems
Heat is always moving
Flowing from higher energy (hot)
to lower energy (cold)
Too much heat gain
in the summer
Our Job: Remove
some heat
6
HVAC Systems
Heat is always moving
Flowing from higher energy (hot)
to lower energy (cold)
Too much heat loss in the winter
Our Job: Add some heat
7
HVAC Systems
In America:
What term is used measure heat flow?
BTU (British Thermal Unit)
How does America compare to other countries?
8
HVAC Systems
QUIZ #1 How many countries use IP units?
IP – Imperial Units
Inches, pounds, BTU, etc.
easy to remember if think IP = “Inch Pound”
USA
Myanmar (Burma)
SI – Metric Units
Liberia
I have heard
they are both
moving to SI
Let’s discuss one BTU
Meters, grams, calorie, etc.
Who uses SI units?
The rest of the world
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HVAC Systems
1 BTU = 1 lb of water 1°F
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HVAC Systems
QUIZ #2 If it takes one hour to heat 1 lb of water 1°F the
heat transfer rate would be …
Circle your answer
1 Btu/Hr
1 BTH
1 BTUH
Being well read
engineers understand
Ralph Waldo Emerson
“A foolish consistency is the hobgoblin of little minds”
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HVAC Systems
This helps you understand
the HVAC engineer
“A foolish consistency is the hobgoblin of little minds”
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HVAC Systems
QUIZ #3 What was a favorite treat Washington and Jefferson
served summer visitors?
How could they eat ice cream in the summer of 1700’s?
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HVAC Systems
ICE HARVESTING
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HVAC Systems
QUIZ #4 When one ton of ice melts in one day (24 hours) what
do we call the heat absorbed by that ice each hour?
1 Ton
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HVAC Systems
QUIZ #4
1 Ton = 12,000 Btu/Hr
1 Ton
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HVAC Systems
QUIZ #5
Is there such a thing as one ton of heat?
What did Emerson say?
ICE: Only AC choice for 200 years
No
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HVAC Systems
1865 – Ice cooled bed
1900 –Ice cooled RR sleeper
1905 – Ice cooled church service
1914 – Ice cooled theater
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HVAC Systems
QUIZ #6
What two things killed the ice industry & ushered in
the age of mechanical refrigeration?
1. A couple of warm winters
around 1915
2. Beer
(consistent brewing all year)
Didn’t take long for mechanical
refrigeration to make the jump
from beer to human comfort
The first step in designing an
HVAC system
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HVAC Systems
HEAT GAIN &
LOSS CALCULATION
This is the backbone of HVAC design
In this room from what sources
could heat come?
Lights
People
Equipment
Walls & Windows
Solar
Sum the BTU from all
those heat sources and
you have the heat gain
Starting in the 1920’s how did we get rid of the heat?
20
HVAC Systems
1940 AHU (AIR HANDLING UNIT)
Originally installed in special rooms (NY Stock Exchange, boardroom)
By the 1950s people wanted AC in different rooms
Cooling Coil &
Condensing Unit
SA Ductwork
Heating
Coils
Diffusers
Fan
Filters
RA Ductwork
Grilles
Conditioning multiple rooms required multiple units
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HVAC Systems
1950S MULTIPLE AHUS
DISADVANTAGES
ADVANTAGES
• Everybody gets AC
• Use a lot of energy
You don’t like this, who
can you call for help?
You call the energy
police (auditors)
What is in their energy toolbox?
22
Energy Audit Tips
1.
2.
3.
4.
Look for grossly oversized equipment
Look for leaks in the building envelope
Look for leaks in the ductwork
Set the summer set points as high and the
winter set points as low as possible
5. Verify operating schedule
Let’s return to our AHU discussion
HVAC Systems
1950S MULTIPLE AHUS
DISADVANTAGES
ADVANTAGES
• Everybody gets AC
• Use a lot of energy
• Exterior appearance
(condensing units are
placed on any flat surface)
• Maintenance
• Noise (these things
shake and rattle)
• Floor space
Being engineers we developed a
way to address the problems
24
HVAC Systems
1960 CENTRAL
STATION AHU
Keep your eyes on
these areas
ADVANTAGES
DISADVANTAGES
• Serves many rooms • One zone (who gets
the thermostat?)
• Noise is isolated
• No outside air (the air
• Localized
is stale and stuffy)
maintenance, few
pieces of equipment We know how to
address this problem
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HVAC Systems
1960 CENTRAL
STATION AHU
Relieve OA out of the building
What do our energy auditors
have to say about OA flow?
Bring OA into the building
26
Energy Audit Tips
1.
2.
3.
4.
Look for grossly oversized equipment
Look for leaks in the building envelope
Look for leaks in the ductwork
Set the summer set points as high and the
winter set points as low as possible
5. Verify operating schedule
6. Verify OA flow
7. Verify proper building pressure
Let’s return to our AHU discussion
HVAC Systems
1960 CENTRAL
ADVANTAGES
•
•
•
•
Serves many rooms •
•
Noise is isolated
Low maintenance
Fresh air
STATION AHU
DISADVANTAGES
One zone
Pressure loss in return
air ducts so air can’t
get back to the AHU
We engineers know how to
move the air back to the AHU
28
HVAC Systems
1963 CENTRAL
STATION AHU
Fans are the largest energy
user in the mechanical
system
So what do our energy
auditors have to say about
fan operation?
29
Energy Audit Tips
1.
2.
3.
4.
5.
6.
7.
8.
9.
Look for grossly oversized equipment
Look for leaks in the building envelope
Look for leaks in the ductwork
Set the summer set points as high and the
winter set points as low as possible
Verify operating schedule
Verify OA flow
Verify proper building pressure
Verify SA & RA fan operation
Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
Let’s return to our AHU discussion
HVAC Systems
1963 CENTRAL
ADVANTAGES
STATION AHU
DISADVANTAGES
• Serves many rooms • One zone
• Mechanically cools
• Noise is isolated
in winter
• Low maintenance
• Fresh air
Let’s see how we prevent
• Pressure Control
mechanical cooling in the winter
31
HVAC Systems
1965 AHU W/
ECONOMIZER
A properly operating
economizer can save a lot of
energy
A poorly operating
economizer can either
• Not save much energy
• Waste energy
So what do our energy auditors have
to say about economizer operation?
32
Energy Audit Tips
1.
2.
3.
4.
Look for grossly oversized equipment
Look for leaks in the building envelope
Look for leaks in the ductwork
Set the summer set points as high and the
winter set points as low as possible
5. Verify operating schedule
6. Verify OA flow
7. Verify proper building pressure
8. Verify SA & RA fan operation
9. Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
10. Verify that all economizers are functioning properly
11. Investigate whether OA temp based reset is appropriate
Let’s return to our AHU discussion
HVAC Systems
1965 AHU W/
ADVANTAGES
•
•
•
•
•
•
ECONOMIZER
DISADVANTAGES
Serves many rooms • One zone
Noise is isolated
Low maintenance
Fresh air
Pressure Control
50 years ago how
Economizer
did we give
each room its own temp control?
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HVAC Systems
1966 DOUBLE DUCT
Systems like this were the
preferred design for many
years
What happened in 1973-4
to change this?
OIL EMBARGO!!
ADVANTAGES
•
•
•
•
•
•
•
Serves many rooms
Noise is isolated
Low maintenance
Fresh air
Economizer
Room level control
Flexible
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HVAC Systems
1966 DOUBLE DUCT
ADVANTAGES
•
•
•
•
•
•
•
DISADVANTAGES
Serves many rooms • Uses a lot of
energy
Noise is isolated
Low maintenance
Fresh air
Economizer
Room level control
Flexible
1975 we changed
the
design to save energy
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HVAC Systems
1975 SHUT-OFF
VAV
ADVANTAGES
DISADVANTAGES
• Saves Money
• Poor air quality
• Poor humidity
control
• Poor temperature
control
SICK BUILDING
SYNDROME!!
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HVAC Systems
1975 SHUT-OFF
VAV
ADVANTAGES
DISADVANTAGES
• Saves Money
• Poor air quality
• Poor humidity
control
• Poor temperature
control
1985 we added reheat coils
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HVAC Systems
1980S VAV WITH REHEAT
Been the workhorse for
over 30 years
There is one LARGE
weakness if this system
isn’t controlled properly!
Let’s assume ….
80°F
40°F 60°F
55°F
What is the problem?
How can you fix it?
What do our energy auditors have to say
about simultaneous heating & cooling?
39
Energy Audit Tips
1.
2.
3.
4.
Look for grossly oversized equipment
Look for leaks in the building envelope
Look for leaks in the ductwork
Set the summer set points as high and the
winter set points as low as possible
5. Verify operating schedule
6. Verify OA flow
7. Verify proper building pressure
8. Verify SA & RA fan operation
9. Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
10. Verify that all economizers are functioning properly
11. Investigate whether OA temp based reset is appropriate
12. Trend controls operation to verify proper set-up, coding, &
functionality
Energy Audit Tips
1.
2.
3.
4.
Look for grossly oversized equipment
Look for leaks in the building envelope
Look for leaks in the ductwork
Set the summer set points as high and the
winter set points as low as possible
5. Verify operating schedule
6. Verify OA flow
7. Verify proper building pressure
8. Verify SA & RA fan operation
9. Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
10. Verify that all economizers are functioning properly
11. Investigate whether OA temp based reset is appropriate
12. Trend controls operation to verify proper set-up, coding, &
functionality
Any questions about our 12 Energy Audit Tips?
HVAC Systems