second saturdays: cenergy hvac

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


© 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


© 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


Central Iowa Sizing Results - Heating


© 2009 ESI, Inc.

Central Iowa Sizing Results - Cooling


© 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.


© 2009 ESI, Inc.

Load

Central Iowa Results – Installed Efficiency


© 2009 ESI, Inc.

The national average shows HVAC systems deliver only 57% of the

equipment rated BTU into the building


© 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%


© 2009 ESI, Inc.

Less than 3% of service agreements

include the duct system…

SO WHO’S CHECKING IT?


© 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.


© 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


© 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


© 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


© 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


© 2009 ESI, Inc.

A pressure drop is the difference

between two readings…

We measure pressure

drops to help troubleshoot

airflow restrictions


© 2009 ESI, Inc.

Pressure drop is measured by

subtracting the pressures on both side of a system

component


© 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


© 2009 ESI, Inc.


Coil Pressure Drops - Example

© 2009 ESI, Inc.


Filter Pressure Drops - Example

© 2009 ESI, Inc.


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.



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.



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.



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


© 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


© 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

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Next, subtract to find the equipment delta t, and subtract to find the system delta t. The divide as shown in the formula below.


System Loss or Gain Formula

System Loss % =Equipment Temperature Change

Duct System Temperature Loss

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Page 119


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

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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

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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%

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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

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Return Duct Loss =

73°


69°

4º

Supply Reg Temp =


Supply Duct Loss =

102°

119°

17°

Heating Mode – Use Data from Previous Drawing


17° + 4° = 21°


21° / 50° = 42%

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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

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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

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Return Duct Loss =

70°


76°

6º

Supply Reg Temp =


Supply Duct Loss =

66°

60°

6°

Cooling Mode – Use Data from Previous Drawing


6° + 6° = 12°


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


© 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


© 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


© 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!


© 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


© 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


© 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.


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.


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.


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

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