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James D. Stoller, P.E., LEED GA
Facilities Engineering
Mechanical Engineer
Purdue University
THE MODERN
HVAC SYSTEM
We are going to cover
200 years of HVAC
history in 50 minutes
HVAC Systems
1
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
To help you follow the slides – here the “text rules”
5. Green (& others) text: I ran out of
colors so I had to use something
different
HVAC Systems
2
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
To help you follow the slides – here the “text rules”
5. Green (& others) text: I ran out of
colors so I had to use something
different The goal of this presentation
Energy Audit Tips
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
In one slide let’s review two centuries:
1600 to 1800
12.
You will walk away with 12
specific energy audit tips
HVAC Systems
Carrier
Fahrenheit
Watt
Fulton
Galileo
Celsius
A long history of discovery
4
Leading to today’s HVAC Engineer
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)
6
Too much heat gain
in the summer
Our Job: Remove
some heat
HVAC Systems Heat is always moving
7
Too much heat loss in the winter
Our Job: Add some heat
Flowing from higher energy (hot)
to lower energy (cold)
HVAC Systems
8
In America:
What term is used measure heat flow?
How does America compare to other countries?
BTU (British Thermal Unit)
HVAC Systems
9
QUIZ #1
IP – Imperial Units Inches, pounds, BTU, etc.
easy to remember if think IP = “Inch Pound”
SI – Metric Units Meters, grams, calorie, etc.
The rest of the world
USA
How many countries use IP units?
Who uses SI units?
I have heard
they are both
moving to SI
Myanmar (Burma) Liberia
Let’s discuss one BTU
HVAC Systems
1 BTU = 1 lb of water 1°F
10
HVAC Systems
QUIZ #2
Circle your answer
1 Btu/Hr
1 BTH
1 BTUH
If it takes one hour to heat 1 lb of water 1°F the heat transfer rate would be …
“A foolish consistency is the hobgoblin of little minds”
Being well read engineers understand Ralph Waldo Emerson
11
HVAC Systems
“A foolish consistency is the hobgoblin of little minds”
This helps you understand the HVAC engineer
12
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?
13
HVAC Systems
14
ICE HARVESTING
HVAC Systems
1 Ton
When one ton of ice melts in one day (24 hours) what
do we call the heat absorbed by that ice each hour? QUIZ #4
15
HVAC Systems
1 Ton
QUIZ #4
1 Ton = 12,000 Btu/Hr
16
HVAC Systems
No
Is there such a thing as one ton of heat? QUIZ #5
What did Emerson say?
17
ICE: Only AC choice for 200 years
HVAC Systems
18
1865 – Ice cooled bed
1900 –Ice cooled RR sleeper
1905 – Ice cooled church service
1914 – Ice cooled theater
HVAC Systems
What two things killed the ice industry & ushered in
the age of mechanical refrigeration? QUIZ #6
19
1. A couple of warm winters around 1915
Didn’t take long for mechanical refrigeration to make the jump from beer to human comfort
2. Beer
The first step in designing an
HVAC system
(consistent brewing all year)
HVAC Systems
20
This is the backbone of HVAC design
In this room from what sources
could heat come?
Lights
People
Equipment
Walls & Windows
Solar
Starting in the 1920’s how did we get rid of the heat?
HEAT GAIN & LOSS CALCULATION
Sum the BTU from all those heat sources and you have the heat gain
HVAC Systems
Originally installed in special rooms (NY Stock Exchange, boardroom)
Fan
Conditioning multiple rooms required multiple units
By the 1950s people wanted AC in different rooms
21
1940 AHU (AIR HANDLING UNIT)
Cooling Coil & Condensing Unit
SA Ductwork
Filters
Diffusers
Grilles RA Ductwork
Heating Coils
HVAC Systems
ADVANTAGES
• Everybody gets AC
DISADVANTAGES
• Use a lot of energy
22
1950S MULTIPLE AHUS
What is in their energy toolbox?
You don’t like this, who can you call for help?
You call the energy police (auditors)
Energy Audit Tips
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
Let’s return to our AHU discussion
1.
2.
3.
4.
5.
HVAC Systems
Being engineers we developed a
way to address the problems
• Exterior appearance (condensing units are placed on any flat surface)
• Maintenance
• Noise (these things shake and rattle)
• Floor space
24
1950S MULTIPLE AHUS
ADVANTAGES
• Everybody gets AC
DISADVANTAGES
• Use a lot of energy
HVAC Systems
1960 CENTRAL STATION AHU
ADVANTAGES
• Serves many rooms
DISADVANTAGES
• One zone (who gets the thermostat?)
• No outside air (the air is stale and stuffy)
• Noise is isolated
• Localized maintenance, few pieces of equipment
25
We know how to
address this problem
Keep your eyes on these areas
HVAC Systems
1960 CENTRAL STATION AHU
What do our energy auditors
have to say about OA flow?
26
Bring OA into the building
Relieve OA out of the building
Energy Audit Tips
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
Let’s return to our AHU discussion
1.
2.
3.
4.
5.
Verify proper building pressure
Verify OA flow 6.
7.
HVAC Systems
1960 CENTRAL STATION AHU
ADVANTAGES
• Serves many rooms • Noise is isolated • Low maintenance
DISADVANTAGES
• One zone • Pressure loss in return
air ducts so air can’t get back to the AHU • Fresh air
28
We engineers know how to
move the air back to the AHU
HVAC Systems
1963 CENTRAL STATION AHU
29
Fans are the largest energy
user in the mechanical
system
So what do our energy
auditors have to say about
fan operation?
Energy Audit Tips
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
Let’s return to our AHU discussion
1.
2.
3.
4.
5.
Verify proper building pressure
Verify OA flow 6.
7. 8.
9.
Verify SA & RA fan operation
Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
HVAC Systems
1963 CENTRAL STATION AHU
ADVANTAGES
• Serves many rooms • Noise is isolated • Low maintenance • Fresh air
DISADVANTAGES
• One zone • Mechanically cools
in winter
31
• Pressure Control Let’s see how we prevent
mechanical cooling in the winter
HVAC Systems
1965 AHU W/ ECONOMIZER
32
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?
Energy Audit Tips
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
Let’s return to our AHU discussion
1.
2.
3.
4.
5.
Verify proper building pressure
Verify OA flow 6.
7. 8.
9.
Verify SA & RA fan operation
Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
10.
11.
Verify that all economizers are functioning properly
Investigate whether OA temp based reset is appropriate
HVAC Systems
1965 AHU W/ ECONOMIZER
ADVANTAGES
• Economizer
DISADVANTAGES
• One zone
34
• Serves many rooms • Noise is isolated • Low maintenance • Fresh air • Pressure Control 50 years ago how did we give
each room its own temp control?
HVAC Systems
OIL EMBARGO!!
1966 DOUBLE DUCT
ADVANTAGES
• Serves many rooms • Noise is isolated • Low maintenance • Fresh air • Economizer • Room level control • Flexible
35
Systems like this were the
preferred design for many
years
What happened in 1973-4
to change this?
HVAC Systems
1966 DOUBLE DUCT
ADVANTAGES
• Serves many rooms • Noise is isolated • Low maintenance • Fresh air • Economizer • Room level control • Flexible
DISADVANTAGES
• Uses a lot of energy
36
1975 we changed the
design to save energy
HVAC Systems
1975 SHUT-OFF VAV
37
ADVANTAGES
• Saves Money
DISADVANTAGES
• Poor air quality • Poor humidity
control • Poor temperature
control
SICK BUILDING
SYNDROME!!
HVAC Systems
1975 SHUT-OFF VAV
38
ADVANTAGES
• Saves Money
DISADVANTAGES
• Poor air quality • Poor humidity
control • Poor temperature
control
1985 we added reheat coils
HVAC Systems
1980S VAV WITH REHEAT
39
Been the workhorse for over 30 years
There is one LARGE
weakness if this system
isn’t controlled properly!
Let’s assume ….
40°F 60°F 55°F
80°F
What is the problem?
What do our energy auditors have to say
about simultaneous heating & cooling?
How can you fix it?
Energy Audit Tips
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
1.
2.
3.
4.
5.
Verify proper building pressure
Verify OA flow 6.
7. 8.
9.
Verify SA & RA fan operation
Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
10.
11.
Verify that all economizers are functioning properly
Investigate whether OA temp based reset is appropriate
12. Trend controls operation to verify proper set-up, coding, &
functionality
Energy Audit Tips
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
1.
2.
3.
4.
5.
Verify proper building pressure
Verify OA flow 6.
7. 8.
9.
Verify SA & RA fan operation
Verify that all VFDs are in ‘auto’ and controlled & functioning
properly
10.
11.
Verify that all economizers are functioning properly
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