1. Welcome to Field Controls: HRV / ERV Training Duct Systems Part 3
Presenter Guide:
● Three types of duct system designs will be presented in this course. They are the Simplified, Partially Dedicated, and Fully Dedicated system.
● When installing an HRV or ERV in conjunction with a forced-air furnace or Air Handler, you’ll use either the Simplified or Partially Dedicated method.

2. Sign In Information Sheets
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NATE Credit requires a specific sign in sheet
Pass out sign in sheets
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NATE requires a special sign in sheet plus the standard FC sign in sheet
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3. Introduction HRV – ERV Duct Systems Simplified System
Partially Dedicated System
Fully Dedicated System
Design Tips
E. Installation Considerations
F. Test
G. Review and Comments

4. Simplified System
THE SIMPLIFIED SYSTEM
Is also referred to as: the return / return method
The house Supply and Exhaust air streams are connected to the return air duct
Turn to the “Simplified Installation” page 14 in the Instruction Manual

5. Simplified Installation
Return / Return Method
Fresh Air to Inside
DESIGNING THE SIMPLIFIED
● Remember the Simplified system is also called the Return/Return method of installation.
● Stale air is exhausted from the return air of the furnace, and an equal amount of fresh air is replaced back into the return air.
● You’ll find diagrams for all three systems in the Operation and Installation Manuals.
● Turn to the “Simplified Installation Diagrams” in your manual.
ASK: In what type of situations might we use a simplified system?
LOOK FOR: In retrofits, where it’s usually too difficult to get exhaust ducts into the bathrooms and kitchen.
SAY: The HRV must be interlocked with the forced-air system in this type of install.
ASK: Why?
LOOK FOR: The forced-air furnace would exhaust the fresh air. (Refer the class to the cross sectional system image in the Operation and Installation manual)
DO: Refer the class to the interlock relay in the Operation & Installation manual. Explain how the wiring works.
● This is a side view of the Simplified Installation.
● Fresh air enters from the outside weatherhood.
● The fresh air continues through the recovery core and to the return air duct of the furnace.
● The stale air is exhausted to the outside exhaust weatherhood.
● We recommend a Spring-Loaded Backdraft Damper in the exhaust air duct. The Spring-Loaded Backdraft Damper prevents outdoor air from entering through the exhaust weatherhood when the HRV is in Standby and the furnace is operating.
SAY: Now, let’s look at how the air flows throughout the home.
Return Air
Duct
Fresh Air from Outside
Stale Air
from Inside
Stale Air to Outside
HVAC
Equipment
Ventilation System must be electrically interlocked with HVAC Equipment Fan

6. Simplified Installation
● Spring-Loaded Back-draft Damper recommended in exhaust air duct.
The Back-draft Damper prevents outdoor air from entering through the exhaust hood.
When HRV or ERV is in Standby mode and the HVAC system fan is operating.
● HRV / ERV must be interlocked with the forced-air system in this type of install.
ASK:
● Why?
LOOK FOR: Think the statement below is not correct! TB. ( The furnace would bring fresh air in during operation and migrate out in off position.)
● The forced-air furnace would exhaust the fresh air. (Refer the class to the cross sectional system image in the Operation and Installation manual)

7. Simplified Installation
HVAC Equipment
Simplified Installation
● Fresh air enters from the outside intake hood.
● Fresh air travels through the recovery core and into the HVAC equipment return air duct.
● Stale air passes through the recovery core giving up heat / energy and then is exhausted outside.
ASK:
● In what type of situations might we use a simplified system?
LOOK FOR:
● The duct system already exits / retrofits, it’s usually too difficult in getting exhaust ducts into bathrooms and kitchen.
Note: New construction seal all metal ducts with mastic for Energy star 3.0 pressurized duct test

8. Partially Dedicated System
Partially Dedicated System or a hybrid system.
Page 15

9. Partially Dedicated System
Stale Air
from Inside
Fresh Air to Inside
Ask them to explain, How it works
Part of the duct system is piped into key areas
The other part is connected to existing air distribution duct system
Stale exhaust air is taken from bathroom and kitchen areas.
Fresh air is delivered into the existing return duct for central distribution
Fresh air is equally distributed throughout the home
The system must be electrically interlocked with the HVAC system fan.
Return Air
Fresh Air from Outside
Stale Air to Outside
HVAC
Equipment
Page 15

10. Partially Dedicated Installation
A partially dedicated system is typically, installed in new homes.
Exhaust ductwork can be easily installed between studs in the wall cavity.
Explain: (Tell them what you have already told them)
Stale air is exhausted through ducts that draw air from the poorest air quality areas of a home such; washrooms, kitchen, laundry room etc…
Fresh air is delivered to the forced-air system’s return air which delivers the fresh air evenly throughout the home.
SAY:
As with the Simplified system, the interface relay should be connected to the blower motor / HVAC system fan.
ASK:
Why do we connect the interface relay to the HVAC system fan / blower?
LOOK FOR:
Because we’re using the forced-air system to distribute the fresh air evenly throughout the home.
What happens if we don’t connect the relay interface to the furnace blower?
LOOK FOR/DRAW OUT:
If you don’t connect the two, the fresh air will concentrate, coming from only the first return opening and spilling into the room.
Fresh air can only be delivered evenly through the home when the HRV / ERV relay interface is connected to the HVAC system fan / blower. You’ll find instructions for interlocking the HRV / EVR to an air handler or furnace fan / blower in the Operation and Installation manual.
New Construction: Energy Star 3.0 requires the duct system to be pressure tested
Page 15

11. Partially Dedicated Installation
HVAC Equipment
Partially-Dedicated system is preferred for new housing.
Exhaust from poorest air quality areas of the home, such as the bathroom, kitchen and laundry area.
At the same time, fresh air is being delivered into the return air of the central HVAC duct system.
Note: Seal all metal ducts with mastic to pass a pressurized duct test according to Energy Star 3.0

12. Fully Dedicated System
Turn to page 16 in installation instruction manual
Page 16

13. Fully Dedicated Installation
Stale Air from Inside
Fresh Air to Inside
Exhaust from the poorest air quality areas of a home such as; bathrooms and kitchen.
Fresh air is delivered into main living area and bedrooms
Fresh Air Intake
Stale Air Exhaust

14. Fully Dedicated Installation
THE FULLY DEDICATED SYSTEM
Manual dampers must be installed to balance the system

15. Fully Dedicated Installation
DESIGNING THE FULLY DEDICATED SYSTEM
Draw out a system .
This way your less likely to forget things.
It can be simple as demonstrated on the slide
Make a material list for estimating cost
SAY:
Finally, we draw in the supply duct work.
Enter the measured length for each run from the HRV to the termination point. Include all the vertical rises.
And that completes the design for the Fully Dedicated system.

16. Design Drawing Tips Include all branches and connections Design tips:
Minimize duct lengths
Minimize bends
Use 45° elbows instead of 90°
Use “Y” s instead of a Tees
Join the unit and duct system with non-metallic insulated duct 12 inches in length (noise / vibration)
DESIGNING the SYSTEM
SAY: Design tips:
All ducts should be kept as short as possible
Ducts should have as few bends as possible (to maximize airflow)
45̊ elbows are preferable over 90̊ elbows
Use Y tees instead of straight tees whenever possible
Join the HRV or EVR unit and the supply/exhaust duct systems with a short length of non-metallic insulated duct. This only needs to be 12 inches long.
It reduces noise and vibration.

17. 4 - Installation Considerations
Fresh air intake and stale
air exhaust locations
Condensate drainage
Space is conditioned
Not below 60°F
Not above 100°F
Access for service
Maintenance / Cleaning
Say:
Here are 4 things you must look for when deciding where to place an HRV or ERV:
1. Location of the fresh air intake and stale air exhaust locations to the outdoors. (details are covered later in presentation)
2. Locate the drain. Make sure it’s a working drain. Quickly determine the condensate route.
3. Is the space conditioned? (That means that the temperature does not drop below 60°F or above 100° F )
4. Must have access for product maintenance and service (minimum of 25 inches to open the door and service the core)
● Attic installations are not recommended due to the difficulty of meeting all three of those requirements.
However, if an attic space can meet the three requirements, you can install an HRV there.
● Some people have built an insulated shelter, a dog house, around an HRV - ERV in an attic and cut out a hole in the ceiling below to make it a conditioned space.

18. Ducts: Keep duct runs short Minimize 90° elbows 45° elbows preferred
Y’s instead of tees
Rigid duct recommended
Energy Star homes use mastic to seal duct joints
SAY:
Avoid call backs and nuisance problems!
Air flow is maximized when ducts lengths are kept short.
Bends and elbows are minimized
45° elbows are preferred to 90° elbows.
Y’s are utilized instead of tees
Recommend the use of rigid ducting from the HRV/ERV to the living areas of the house (better air flow / less pressure drop)
Metal ducting typically, does not collapse over time like flex duct.
Flexible duct can be used in moderation if necessary.
Energy Star homes seal all duct joints with mastic.

19. Duct Systems Test

20. 1. Flex duct must be stretched tightly and supported properly with appropriate hangers.
True or False
Flex duct must be stretched tightly and supported with appropriate hangers.
True or False
Answer: T

21. 2. Metal duct seams should be sealed
with mastic to pass a Energy star 3.0
pressurized duct leakage test?
True or False
Metal ducts should be sealed with mastic to pass a Energy star 3.0 pressurized duct leakage test?
True or False
Answer: T

22. 3. When installing a HRV or ERV in
conjunction with an existing forced air
HVAC system you will use:
A.  Partially Dedicated Installation Method
B.  Simplified Installation Method
C.  Fully Dedicated Installation Method
D.  Partially Dedicated or Simplified Installation Method
E.  None of the above
Answer: D

23. 4. When installing an HRV or ERV without
a ducted forced air system you will use:
A.  Partially Dedicated Installation Method
B.  Simplified Installation Method
C.  Fully Dedicated Installation Method
D.  Partially Dedicated or Simplified Installation Method
E.  None of the above.
Answer: C

24. 5. Simplified Installation: stale air is
exhausted from the return air of the
ducted HVAC equipment and an
equal amount of fresh air is replaced
back into the return air.
True or False
Simplified Installation, stale air is exhausted from the return air of the ducted HVAC equipment and an equal amount of fresh air is replaced back into the return air.
True or False
Answer:T

25. 6. Another name for a Simplified Installation
A. The Supply Return Method
B. The Return / Supply Method
C. A Partially Dedicated System
D. The Return / Return Method
E. None of the above
Another name for Simplified Installation is the
Answer: D

26. 7. A Simplified Installation does not require
the furnace blower to run continuously or
be electrically interlocked with the HRV
or ERV.
True or False
Answer:   F

27. 8. Partially Dedicated System: stale air is
exhausted from specific locations
(bathroom, kitchen etc) and an equal
amount of fresh air is replaced back into
the HVAC system return air.
True or False
For the Partially Dedicated System stale air is exhausted from specific locations (bathroom, kitchen etc) and an equal amount of fresh air is replaced back into the HVAC system return air.
True or False
Answer: T

28. 9. Install a backdraft damper on:
A.  Partially Dedicated Installation
B.  Simplified Installation
C.  Fully Dedicated Installation
D.  Partially Dedicated and Simplified Installation
E.  None of the above.
Install a backdraft damper on:
A.   Partially Dedicated Installation Method
B.   Simplified Installation Method
C.   Fully Dedicated Installation Method
D. Partially Dedicated and Simplified Installation Method
E.   None of the above.
Answer: D

29. 10. A Fully Dedicated System is normally installed in homes without
a ducted forced air system.
True or False
AFully Dedicated System is normally installed into homes without forced air systems.
True or False
Answer: T

30. 11. On a Fully Dedicated Installation
the supply ducts deliver fresh air to
bathrooms, kitchen, laundry room, etc.
True or False
A Fully Dedicated Installation, supply ducts deliver fresh air to bathrooms, kitchen, laundry room, etc.
True or False
Answer: F

31. 12. Resistance to air flow is called External Static Pressure (e.s.p.)
True or False
Resistance to air flow is called External Static Pressure (e.s.p.)
True or False
Answer: T

32. 13. General installation considerations are
A. Fresh air intake and stale air exhaust locations
B. Condensate drainage
C. Install unit in the conditioned space
D. Provide access for service and maintenance
E. All the above
F. None of the above
Pick all that apply.
Information from slide 17
4 installation considerations
Answer: E

33. 14. Energy Star Homes A. Seal duct joints and fittings with foil tape
B. Seal duct joints and fittings with duct tape
C. Seal duct joints and fittings using screws or rivets
D. Seal all duct joints with mastic
E. All the above
F. None of the above
Pick all that apply.
Information on slide 18 last comment
Ducts
Answer: D
Screws and rivets do not seal they secure connections.
Tape does not seal fittings and seams under .25 inches of water column positive or negative pressure (duct test required for Energy Star homes)

34. 15. Energy Star Homes A. A recognized label for energy efficient homes
B. Require ventilation according to ASHRAE 62.2
C. Require a pressurized duct leakage test
D. Require manual J load calculations
E. All the above
F. None of the above
Answer E.
All the above

35. Questions
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