second saturdays: cenergy hvac
TRANSCRIPT
Outside the Box
Introduction to Quality Installation ofHigh Efficiency Heating and Cooling Systems
• Common Installation Issues Impacting Performance
• Pressure Measurement and Diagnostics
• Temperature Measurement and Diagnostics
• Equipment vs. System Performance
• Finding a Professional
• Conclusion - Next Steps
Outside the Box – Introduction to Quality Installation of High Efficiency HVAC Systems
Overview
The House IS a System
INSULATION
SHELL TIGHTNESS
DUCT SYSTEM
CONTROLS
COMBUSTIONAPPLIANCES
VENTILATIONSYSTEMHEATING AND
A/C
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
HVAC Efficiency - It’s All About the Installation
1. Equipment Sizing / Selection – Manual J is the ANSI standard for sizing residential equipment
2. Duct Design / Sizing – On average, duct systems are grossly undersized and restrict airflow significantly
3. Duct Leakage – Delivering air to its destination is critical, but sealing ducts is often more complicated than it might appear
4. Filter Type and Size – Improperly sized filters, or filter types other than what the designer assumed can wreak havoc on the system’s airflow
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
HVAC Efficiency - It’s All About the Installation
5. Equipment Setup – Equipment today is complex and requires great attention to detail in its setup, configuration, and control system(s)
6. Air Balancing – Ensuring the right amount of air is delivered to each room improves comfort and can help reduce utility costs
7. Combustion Efficiency – Maximizing the delivered heat out of the fuel purchased requires more than what is included in a typical “swap the box” replacement
8. Multi-Speed / Staged Equipment – Advanced technology means even more setup is required to operate properly
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
How Do Contractors Size Equipment?
Survey Results (FSEC - 489 HVAC Contractors)
– Software Represents Manufacturer’s Software
– Other is primarily use of a “Short Form” or Utility Method
Common Installation Issues Impacting Performance
Central Iowa Sizing Results - Heating
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Central Iowa Sizing Results - Cooling
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Cooling Sizing to Load - TOTAL Summary (100 Home Sample)
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
Btu
h Design Cooling
Manual J Max Size
Installed (Output)
STATE OF THE INDUSTRY
Nine out of ten HVAC systems cannot operate properly or efficiently without
being repaired first.
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Load
Central Iowa Results – Installed Efficiency
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Load
Central Iowa Results – Installed Efficiency
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
The national average shows HVAC systems deliver only 57% of the
equipment rated BTU into the building
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Good news! After appropriate renovations, the average HVAC system can deliver over 90% of
the equipment rated BTU into the building
6.2%
System BTU Loss of equipment rated capacity
SOURCE: NCI Certified Contractor Survey 11-05 to 2-06
System BTU Delivery of equipment rated capacity
93.8%
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Less than 3% of service agreements
include the duct system…
SO WHO’S CHECKING IT?
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
How heavy is “standard” air?
Training room Length x Width x Height
Room cubic Feet x .075 pounds = the weight (in lbs) of the air in this room
A typical fan has to move about 90 pounds of air per minute. That’s 5400
pounds per hour.
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
So, where do we start?
Evaluate the System, not just the Box…
Static Pressure – Helps us know if the system is delivering the right amount of air
System Temperatures – Helps us understand the impact (gain / loss) of the duct system
Common Installation Issues Impacting Performance
© 2009 ESI, Inc.
Static Pressure is a lot like blood
pressure.
It’s the first, quick test of an HVAC system’s “circulation.”
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
Static Pressure is the amount of resistance the fan must overcome to move air throughout the system
Pressure is measured using a manometer
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
Like blood pressure, static pressure that is too high or too low can cause problems!
Fewer than 6% of contractors even check static pressure!
Supply +.19”
+ Return -.31”
Equals .50”Add
The most common static pressure rating for
residential equipment is .50” of Total External Static
Pressure
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
-.34” +.41”
What is the system return static pressure? _______
What is the system supply static pressure? _______
What is the system total external static pressure? _______
What’s wrong with this system?
.50” rated fan
-.34”
+.41”
.75”
Total Static Pressure too high – airflow will be low
Total External Static Pressure Challenge
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
A pressure drop is the difference
between two readings…
We measure pressure
drops to help troubleshoot
airflow restrictions
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
Pressure drop is measured by
subtracting the pressures on both side of a system
component
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
1. FILTERS – Dirty filters or incorrectly-sized filters will have a higher pressure drop
2. COILS – Dirty coils, or newer higher-efficiency coils will have a higher pressure drop
3. DAMPERS – Dampers that are not operating properly or are too restrictive will have a higher pressure drop
4. ACCESSORIES – Basically, anything that is added into the air stream or is part of the duct system will have a pressure drop associated with it
Pressure Drops
Pressure Measurement and Diagnostics
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
Coil Pressure Drops - Example
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
Filter Pressure Drops - Example
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
Top 10 Static Pressure Repairs
1. Filters are the number one cause of poor Indoor Air Quality in this country today. If the fan can’t move the air, the V in HVAC doesn’t occur.
2. Clean cooling coils. Inspection alone does not verify the coil is clean. Measure coil pressure drop. Average 14 SEER coil drop = .32”
3. The duct sizes typically used across the US are far too small. Adding an additional large return duct to relieve high static pressure.
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
Top 10 Static Pressure Repairs
4. Poor duct installation is next. Straighten ducts, improve duct suspension, lengthen the radius of elbows, replace duct transition, the list goes on and on.
5. Damaged ducting. Cable guys, phone repair techs and alarm system installers have little idea of their impact on duct system performance.
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
Top 10 Static Pressure Repairs
6. Aging ducting. How long does flexible ducting last in a 140 degree attic?
7. Duct systems designed for older, less efficient systems. In most areas of the country, ducts are significantly undersized.
8. Inadequate fan capacity. With today’s coils and filter pressure drops, ask for a variable speed or higher static pressure rated fan.
© 2009 ESI, Inc.
Pressure Measurement and Diagnostics
Top 10 Static Pressure Repairs
9. Outdated, rule-of-thumb duct design methods.
10. Restrictive registers and grilles. Consider replacing with good quality commercial grilles.
© 2009 ESI, Inc.
When measuring equipment ∆t is the difference between the temperature entering and exiting the equipment.
When measuring system ∆t is the difference between the temperature entering and exiting the system – or average
return grille temperature minus average supply register temperature.
∆t = Delta t (The difference between two related temperatures)
Measuring Temperature Change
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
Equipment ∆t
For Heating
Exiting 120°
Entering - 70°
Equipment ∆t 50°
For Cooling
Entering Temperature
-Exiting Temperature
Equals Equipment ∆t
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
For Heating
Return Grille 75°
Supply Register - 115°
System ∆t only 40°
For Cooling
Supply Register Temperature
-Return Grille Temperature
Equals System ∆t
System ∆t
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
Percent of System BTU Duct Loss or Gain
Let’s take a look at system performance.
This quick test and calculation offers a snapshot of system performance by taking only four temperature measurements and working a short formula.
Gather the following four temperature measurements.
1. The temperature entering the equipment
2. The temperature exiting the equipment
3. A typical supply register air temperature
4. A typical return grille air temperature
Page 119
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Page 119
Next, subtract to find the equipment delta t, and subtract to find the system delta t. The divide as shown in the formula below.
Percent of System BTU Duct Loss or Gain
System Loss or Gain Formula
System Loss % =Equipment Temperature Change
Duct System Temperature Loss
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Tem
per
atu
re D
iagn
osti
cs a
nd
Rep
airs
Page 119
Percent of System BTU Duct Loss or Gain
Heating Example:
Duct System Temperature Loss = 15°
Equipment Temperature Change = 60°
Cooling Example:
Duct System Temperature Gain = 9°
Equipment Temperature Change = 18°= 50% System Gain
= 25% System Loss
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Heating Mode
67°
117° 102°
72°
Equipment ΔT 50° System ΔT 30° Return Duct Loss 5° Supply Duct Loss 15°
Duct Loss Example (Sensible BTUs)
What would the supply register temp be if there
was no duct loss?
122º
Page 120
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Return Grille Temp =
Return Plenum Temp =
Return Duct Loss =
72°
Duct Loss Example (Sensible BTU)
67°
5°
Supply Reg Temp =
Supply Plenum Temp =
Supply Duct Loss =
102°
117°
15°
Heating Mode – Use Data from Previous Drawing
Return Duct Loss + Supply Duct Loss = Total Duct Loss
5° + 15° = 20°
Total Duct Loss / Equipment ΔT = % Duct Temp Loss
20° / 50° = 40%
Page 121
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Duct Loss Challenge (Sensible BTU)
Heating Mode69°
119° 102°
73°
Equipment ΔT °System ΔT ° Return Duct Loss ° Supply Duct Loss °
50
17
294
What would the supply register temp be if there
was no duct loss? ____ 123º
Page 122
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Return Grille Temp =
Return Plenum Temp =
Return Duct Loss =
73°
Duct Loss Example (Sensible BTU)
69°
4º
Supply Reg Temp =
Supply Plenum Temp =
Supply Duct Loss =
102°
119°
17°
Heating Mode – Use Data from Previous Drawing
Return Duct Loss + Supply Duct Loss = Total Duct Loss
17° + 4° = 21°
Total Duct Loss / Equipment ΔT = % Duct Temp Loss
21° / 50° = 42%
Page 123
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Duct Loss Challenge (Sensible and Total BTU)
Cooling Mode
70° DB
Equipment ° ____
System ° ____
Ret. Duct Loss ° ____
Sup. Duct Loss ° ____
ΔT ΔH
62.4° WB76° DB
63.8° WB
66° DB58.1° WB
60° DB56.2° WB
Page 125
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Duct Loss Challenge (Sensible and Total BTU)
Cooling Mode
70° DB
Equipment °
System °
Ret. Duct Loss °
Sup. Duct Loss °
ΔT
62.4° WB76° DB
63.8° WB
66° DB58.1° WB
60° DB56.2° WB
16
4
6
6
Page 125
Tem
per
atu
re M
easu
rem
ent
& D
iagn
osti
csT
emp
erat
ure
Mea
sure
men
t &
Dia
gnos
tics
Return Grille Temp =
Return Plenum Temp =
Return Duct Loss =
70°
Duct Loss Example (Sensible BTU)
76°
6º
Supply Reg Temp =
Supply Plenum Temp =
Supply Duct Loss =
66°
60°
6°
Cooling Mode – Use Data from Previous Drawing
Return Duct Loss + Supply Duct Loss = Total Duct Loss
6° + 6° = 12°
Total Duct Loss / Equipment ΔT = % Duct Temp Loss
12° / 16° = 75%
Page 126
Duct Location
• Inside Conditioned Space is Preferred
• Attic/Crawl Space locations require significant duct insulation strategies
• Sometimes ducts that seem like they are “inside” are really more connected to outside
• Ducts in an unfinished basement often require duct insulation
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
Duct SealingLeaky Ductwork Costs U.S. Consumers an Average
of $5,000,000,000 per Year
– Leaky Ducts Can Cause Enormous Performance Penalties
– Leaky Ducts Inside the Envelope are Important Too - Sometimes You Only Think They’re Inside
– Comfort Can be Extremely Difficult to Achieve With Leaky Ducts
– Leaky Returns Can Introduce Dirt, Dust, Insulation Fibers, etc Into the System
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
Duct Sealing
Types of Sealants– Duct Mastic - Can be Used Easily on New Home
Ducts or Accessible Existing Home Ducts– Aerosol Sealants - Seal Ducts from Inside Out– Foil Tape - Difficult to Install Properly, and Falls
Off Over Time– Silicone - Expansion / Contraction Tends to
Break Down Seals Over Time
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
Duct Sealing - DANGER
Sealing Ducts May Not Always Help Solve Problems…
If the Ducts are Already Too Small,
What Happens When You Seal Them?
Before Sealing, You Need to Be Sure That the System Can Afford It!
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
System Temperature DefectsREPAIR
Add additional duct insulation or relocate ducts into conditioned space
Repair or replace ducts. Tighten joints, seal ducts
Seal joint between boot and register to stop infiltration from unconditioned area.
DEFECT
More than 3 degrees of thermal loss through the duct system
Duct airflow loss
Temperature change at grille
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
System Temperature Defects
REPAIR
Repair duct system. Test, adjust, and balance the HVAC system
Repair or replace equipment AND duct system. Do not just “swap boxes”
DEFECT
More than 3° difference between room temperatures
Damaged or inadequate equipment or accessories
Temperature Measurement and Diagnostics
© 2009 ESI, Inc.
Component vs. System Testing
Traditional Service and Installation Practices Require Component-Level Testing Only
• Component-Level Testing = “Perfect World” Testing
*Perfect-World Testing Merely Makes a Statement About Potential Efficiency
• System-Level Testing = “Real World” Testing
*Real-Word Testing Measures the Actual, Installed Efficiency
Equipment Performance vs. System Performance
© 2009 ESI, Inc.
BENEFITS OF ADDRESSNG THE SYSTEM
1. Equipment Change Only: BTU PER THERM 54,720 2. Equipment & Renovation: BTU PER THERM 86,4003. Renovation Only: BTU PER THERM 72,000
© 2009 ESI, Inc.
Equipment Performance vs. System Performance
GETTING THE BEST VALUE
Quality Installation is critical to maximizing Installed Efficiency!
Replacement with high efficiency equipment typically has little impact on utility consumption. In fact, sometimes customers have reported an increase in natural gas consumption.
The primary reason for this is that newer furnaces require 50% more airflow than older furnaces and duct systems are typically significantly undersized. Without considering the entire system, the great new equipment may not even have a chance to work properly!
© 2009 ESI, Inc.
Equipment Performance vs. System Performance
The Tale of Two Systems100k BTU Output Furnace Replacement
Current Annual Heating Cost = $1353 (60% Installed Eff.)
• Replace Unit Only w/ 95% AFUE
• Installed Eff. Decreased to 57%
• Reduced Heating Bill by $173/yr
• $5,000 Cost
• $1,500 Tax Credit
• $450 Utility Incentive
• Total Investment = $3,050
• Payback = 17.6 years
• Est. Equipment Life = 15 years
• ROI over Life of Equip. = $2,595
• Residual Return After Payback = ($455)
• Replace Unit + Duct Renovation
• Installed Eff. Increased to 89%
• Reduced Heating Bill by $597/yr
• $7,000 Cost
• $1,500 Tax Credit
• $450 Utility Incentive
• Total Investment = $5,050
• Payback = 8.5 years
• Est. Equipment Life = 15 years
• ROI over Life of Equip. = $8,955
• Residual Return After Payback = $3,905
© 2009 ESI, Inc.
Equipment Performance vs. System Performance
Conclusion - Next Steps
Finding a Professional-ASK QUESTIONS!
-How do you size equipment?-How will you design/re-design my duct system?-Do you check static pressure?-How will you maximize my SYSTEM’S efficiency?
-Work with an Energy Rater with HVAC expertise-Focus your efforts “Outside the Box” as well-Accept that the House is a System
© 2009 ESI, Inc.
Thank You for Attending Today’s Session!
Questions?
Conclusion - Next Steps