Bill McCullough

Director ERV Products

Dallas, TX

1. ERV Definition & Benefit

2. Indoor Air Quality

3. Energy Efficiency

4. ERV Technology & Operation

5. Stand-Alone ERVs

6. Compact ERVs

TOPICS

An Energy Recovery Ventilator:

Recovers the Energy from the

airstream discharged from

a building and transfers this energy

to the incoming air used for

Ventilation.

What is an ERV?

In Twenty-One Words…

ERV Operation

A Picture Is Worth a Thousand Words…

96º F Outside Air for

Ventilation

81º F Tempered Air Into

Building

Incoming Ventilation Air Temperature Reduced by 15º

89º F

Exhaust Air from

Building

75º F

Exhaust Air from

Building

ERV Operation

A Picture Is Worth a Thousand Words…

-1º F Outside Air for

Ventilation

47º F Tempered Air Into

Building

Incoming Ventilation Air Temperature Increased by 48º

22º F

Exhaust Air from

Building

72º F

Exhaust Air from

Building

• Energy Savings

• Improved Indoor Air Quality

• Code Compliance

• Utility Rebates

Benefit of ERVs

70% Energy Recovery

ERVs Typically

Recover About 70%

of the Energy

Exhausted from

Buildings

25% HVAC Load Reduction

On new construction, ERVs

can typically reduce the

ERVs Reduce HVAC

Load by Up To 25%

on New Construction

Energy Recovery

Frequently Used Here

• Schools

• Assisted Care Facilities

• Retirement Facilities

• Gyms & Fitness Clubs

• Pet Care & Boarding • Office Buildings

• Health Care

• Restaurants

• Theatres

• Retail Space

Energy Recovery

Technologies

Types of Air-to-Air Energy Recovery

Plate Exchangers – Sensible Recovery With Limited Latent Recovery

– Typically Less Than 50% Effective

– Airstream Separation When Exhaust Pollution is A Concern

– Exchangers Tend to Get Very Large And Heavy in Larger CFM’s

Types of Air to Air Energy Recovery

Rotary Wheels

– Highest Sensible and Latent

Recovery

– 60 – 80% Effective

– Most Compact in Larger CFM’s

– Easy to Maintain

– “Self” Cleaning

Typical Rotary Enthalpy Wheel

Segmented

Thinner

Cost Effective

Permanently Bonded Type

A Silica Desiccant

Vapor Transfer

No Condensate

Low Frost Temperature

Rotary Enthalpy Wheel Maintenance

• Wheels Slide Out for Service

• Pie Segments on Wheel Can be Removed Individually for Easy Cleaning

• Rinse With Tap Water

• Tougher Dirt Soak in Dishwashing Soap

Adjustable

Motor Support

Wheel Pie

Segment

Silica Will Not Wash Away

Brand new wheel

After 3 years in a smoking

environment and 6 washes

Polymeric Frost Considerations

Vapor State = Low Frost Threshold

Frost Threshold Depends on Return/Exhaust Air Humidity and

Temperature

Example of Rotary Wheel ERV

Configured without Frost Control

ERV in Winnipeg:

Ordered Without

Low Ambient Frost

Control Kit

This ERV Wheel Is NOT Damaged

Typical Rotary Wheel Performance Data

Customer Benefit:

Improved IAQ & Code Compliance

• “Ventilation for Acceptable Air

Quality” - ASHRAE Standard 62.1

• Specific CFM Quantity Requirement

• Classrooms Generally 15 CFM Per

Occupant

• CO2 Space Limitations

• Occupant Health and Well Being

• Productivity

• Loss Time

ASHRAE 62.1

Classes of Air

Class Contaminant

Concentration

Sensory-

Irritation

Intensity

Odor Maximum Air

Leakage

1 Low Low Inoffensive Not Specified

2 Moderate Mild Mildly

Offensive

10%

3 Significant Significant Offensive 5%

4 High High High 0%

ASHRAE 62.1

Classes of Air

Class Examples

1 Offices, Public Assembly Spaces

2 Gym, Pet Shops, Restaurants

3 Daycare Sickroom, General Mfg

4 Paint Fumes, Laboratory Fumes

AHRI Standard 1060

for Air-to-Air ERVs

AHRI Standard 1060

for Air-to-Air ERVs

Certified Ratings for Heat Exchanger

The following certification program ratings are verified by test:

1. Sensible Effectiveness at 100% Summer, 75% Summer, 100% Winter, and 75%

Winter, %

2. Latent Effectiveness at 100% Summer, 75% Summer, 100% Winter, and 75%

Winter, %

3. Pressure Drop at 100% airflow laboratory ambient conditions, in H2O

4. Exhaust Air Transfer Ratio (EATR) at three pressure differentials, 0.00 in H2O

and two more within the scope of the program

5. Outdoor Air Correction Factor (OACF) at three pressure differentials, 0.00 in

H2O and two more within the scope of the program

AHRI Standard 1060

for Air-to-Air ERVs

Exhaust Air Transfer Ratio

per AHRI 1060

EATR: The tracer gas concentration

difference between the Leaving Supply

Airflow and the Entering Supply Airflow

divided by the tracer gas concentration

difference between the Entering

Exhaust Airflow and the Entering

Supply Airflow at the 100% rated

Airflows.

Expressed as a percentage.

Outdoor Air Correction Factor

per AHRI 1060

OACF: The ratio of the Entering Supply

Airflow to the measured (gross) Leaving

Supply

Accordingly, OACF is used to size the

fans.

Customer Benefit:

Energy Efficiency & Code Compliance

• “Energy Standard for Buildings” -

ASHRAE Standard 90.1 • Except Low-Rise (3 stories or fewer) Residential Buildings

• Covers Efficiency Standards for Windows, Lighting, Water

Heating, Power Distribution, and HVAC

• ASHRAE 90.1 2010 = Minimum 50%

• ASHRAE 189 = Minimum 60%

What is ASHRAE 189? • Stretch Standard for Energy Efficiency

• Currently Being Specified for Some Government

Buildings

• Requires Even More Energy Recovery

– As Low as 10% Outside Air Requires Energy Recovery

in Some Cases

Minimum Effectiveness Requirements

Widespread Adoption of ASHRAE 90.1

http://www.energycodes.gov/adoption/states

ASHRAE 90.1 2010 Zones

Climate Zones and ERV Requirements

ASHRAE 90.1 2007: Requires energy

recovery if system air is greater than 5,000

CFM (12.5 tons) and outside air is more than

70%.

ASHRAE 90.1 2010: Significantly expands

requirement as shown below:

5 X the

requirement

of previous

standard

Type of ERVs

Primary ERV Configuration Types

Unitized (Bolt-On) Stand-Alone

Compact ERV

Outdoor

Down Discharge

Side-By-Side

Over / Under

Types of Stand Alone ERVs

OVER

X

UNDER

S

I

D

E

X

S

I

D

E

OVER

X

UNDER

S

I

D

E

X

S

I

D

E

Indoor

Side-By-Side

Over / Under

Compact ERV

Configuration: Stand Alone Ducted

A/C Unit ERV

Supply Duct

ERV Return Duct Balancing Dampers

Stand Alone ERVs - Ducting

Configuration: Ducted into RTU

Balancing

Damper

A/C Unit ERV

ERV Supply Duct

ERV Return Duct RTU

Return

Stand Alone ERVs - Ducting

Compact ERV Installation

Alternate Outside Air Entry

Alternate Room

Air Entry

Typical ERV Selling Proposal

Current Scenario

(11) 25-ton High Efficiency RTUs $150,000

Total 1st Cost $150,000

With ERVs and High Efficiency Equipment

(11) 20-ton High Efficiency RTUs $125,000

(4) ERVs $39,000

Total 1st Cost $164,000

ERV Electricity Savings $23,000

•

Total Annual Savings $23,000

Payback 7 Months

*Based on ERV operation in Kansas City, MO

ERV Case Study: Creative Solution for VRF

Systems

• This four-story building (43,000 sq. ft) specified a Variable

Refrigerant Flow (VRF) system within the building’s

heating and cooling system.

Tahlequah City Hospital - Medical Office Building in Oklahoma

ERV Case Study: Jobsite Problems

• High temperature and high humidity in the

summer

Taxed VRF System May Cause Uncomfortable

Conditions

Due to low winter temperatures, additional

heaters might be required to supplement VRF

units

Limited Installation Space for Conventional Large ERVs

ERV Case Study: Solution – Compact Indoor ERV

2 Compact ERVs Per Floor - 8 Total in

Building

Reduced Incoming Temperature and

Humidity Enough to Ensure Comfortable

Conditions in the Summer

• Raised Incoming Temperature Enough to Prevent Need for Supplemental

Heat

• Low Profile, So It Fit in Available Ceiling Space

ERV Case Study: Results

Initial Equipment Cost Savings - $22,400

Estimated Cost Of Purchase and

Installation Assuming that each of the

64 VRF Units Needed Supplemental Heat

Energy Savings Delivered Directly From the

ERVs Pre-Conditioning the Fresh Air - $8,500

/ Annually

8 ERVs Cost Less Than $30k Installed

Examples of ERV Options

• Low Ambient Kit - By Means of Temperature

Sensors the Intake Blower is De-energized

Momentarily When Frost Conditions are Sensed,

and the Blower is Re-energized After the

Exhaust Air Has Warmed the Wheel

• Motorized OA Damper - Closes the Outside Air

Damper When the ERV Is Not Operational (Outdoor

models only)

ERV Options

• Airflow Measurement – Electronic

Fan-inlet Air Measurement Station

Utilizes Thermal Dispersion

Technology Combined with Low-

Pressure Drop Aerodynamic

Sensors to Measure the Airflow

ERV Options

• Pressure Sensor - Provides a Static

Reading Across the Intake Air Side of

the ERV Wheel So Airflow Can Be

Measured

“Economizer Mode” -

Stop, Start, Jog –

When the Fixed Wheel ERV

is Used This Option Stops

the Wheel When Outside

Conditions Exist Where

Recovery is Not Desired,

and the Wheel is “Jogged”

on a Timer to Prevent Dust

Buildup on the Wheel.

Standard ERV Options

Utilizes a Controller that Will

Control the Unit Based on

Temperature and Humidity.

• VFD Control – ERV Blower Speed is Controlled by

VFDs, Which Allows the Building Pressure to be

Control Based on a Variety of Inputs

• Sensible Only Wheel – Allows Moisture To Pass

Through Energy Wheel

• BACnet Controls – Allows Real Time Monitoring and

Controls of Some Functions of ERV

ERV Options

• Disconnect with GFCI (Ground Fault Circuit

Interrupter)

• – ERV is Equipped with a Properly Sized

Disconnect, and a GFCI Plug is Provided (Must Be

Field Wired)

• Filters – Located at Intake and/or Exhaust Air

• Dirty Filter Sensor – Sends 24 Volt Signal When

Filters Need Replacement

ERV Options

• Hinged Access Panels – Easy Access to Inside of

ERV.

• Rotation Sensor – Sensor Provides a 24 Volt

Feedback Signal Should the Wheel Not Rotate as

Required, and Signals Both a Motor Failure and a

Belt Failure

ERV Options