nuair NU0103 Assembly Instructions

OPERATING, MAINTAINING & INSTALLING YOUR LIGHT COMMERCIAL
HEAT RECOVERY VENTILATOR
IMPORTANT –READ AND SAVE THESE INSTRUCTIONS
* LEAVE THIS DOCUMENT WITH THE BUILDING OWNER
Specifications, dimensions and ratings may change without notice
due to ongoing product development and improvements.
For products using controller NU-HRV Rev F manufactured April 2013 or later
NU0103, NU0305, NU0406, NU0508, NU0912, NU1316
NU305, NU500, NU600, NU800, NU1200, NU1600
INSTALLATION AND WIRING MUST BE IN ACCORDANCE WITH CEC, NEC AND
LOCAL ELECTRICAL CODES.
P.O. Box 2758
Windsor, Nova Scotia, B0N 2T0
Ph. 902-798-2261 Fax: [phone]
www.nu-airventilation.com
E-mail: [email protected]

NOTE
Prior to integrating this unit with any other piece of mechanical equipment, i.e. furnace, air handler,
combustion heating appliance, careful consideration must be given to system design and integration to ensure
compatibility and proper operation of both appliances. Do not connect the duct system of your H/ERV to any
clothes dryer or kitchen exhaust fan duct system.
Whether installing this unit as part of an independent system or to integrate it with a central heating/cooling
system, use the procedure in this manual to ensure that the air flows of the H/ERV are balanced. Only a
properly balanced H/ERV will deliver maximum performance and energy efficiency.
Although this document contains guidelines for proper HRV sizing and installation, your ventilation system
should be installed in conformance to the appropriate provincial or state building regulations or National
Building Code and/or ASHRAE “Good Engineering Practices”.
IMPORTANT
PLEASE READ THIS MANUAL BEFORE YOU INSTALL OR SERVICE UNIT
AVOID RISK OF INJURY, ELECTRIC SHOCK AND FIRE HAZARD
DO NOT install this product in an unconditioned space—15º C/59º F ambient temperature is recommended—or in a
space/manner where maintenance and service might a pose risk of personal injury or damage to this product.
For indoor installations only.
If your H/ERV is equipped with a 3-prong plug which will fit an A/C electrical outlet in just one orientation. Do not alter this
plug or its cord in any way. Grip the plug firmly when removing it from an electrical outlet—NEVER unplug this product by
pulling or twisting its power cord.
ALWAYS unplug an H/ERV before you open or remove its cover (door) to clean the inside of the unit or for any other
servicing or repairs.
The cover to this H/ERV is removable to ensure ease of access to internal components during cleaning and servicing.
USE CAUTION when opening or removing the cover of this H/ERV to avoid risk of personal injury or damage to the cover.
NEVER attempt to clean the interior of this H/ERV or its components while the unit is plugged in or running.
ONLY qualified persons should attempt repair or service of any electrical/internal component of this product.
NEVER attempt to repair or service any internal component of this H/ERV while the unit is plugged in or running.
DO NOT use your ventilation system to exhaust flammable fumes or gasses.
ALWAYS contact your Nu-Air representative if you have any questions or comments about the operation or maintenance
of your Nu-Air H/ERV—we are here to help you!
ALWAYS contact your Nu-Air representative if you have any questions or comments about the operation or maintenance
of your Nu-Air H/ERV—we are here to help you!

Contents
1 How the NU-AIR System Works ...........................................................................................................4
2 Features and Operation........................................................................................................................4
3 Installation Instructions..........................................................................................................................4
3.1 Installer’s Responsibilities .............................................................................................................4
3.2 Installation Basics .........................................................................................................................4
3.3 Ductwork .......................................................................................................................................5
3.4 Weather Hoods .............................................................................................................................6
3.5 Port Configurations .......................................................................................................................7
3.6 Mounting and Noise Control .........................................................................................................8
3.7 Drain Connections.......................................................................................................................10
4 Connecting to Other Equipment..........................................................................................................10
5 External Connections..........................................................................................................................10
6 Unit Controls: Operation and Wiring ...................................................................................................11
6.1 ES Series Controls (12 VDC)......................................................................................................11
6.1.1 ES Control Wiring –applicable to all ES series controls ....................................................13
6.2 Winsor Series & Other 24 VAC Control Options.........................................................................13
6.2.1 Terminal Designation/Function ...........................................................................................13
6.2.2 Building Automation and Control Systems..........................................................................13
6.2.3 Standard Dehumidistat (Part # DSTAT-1) & 2-wire switches .............................................14
6.2.4 Windsor Control (Part # WIN-1)..........................................................................................14
6.2.5 Windsor Timer (WIN-20).....................................................................................................14
7 Control Board Status LEDs.................................................................................................................16
8 Selectable Furnace/Air Handler Interlock ...........................................................................................16
8.1 Furnace/Air Handler Interlock Wiring..........................................................................................17
9 Defrost Operation................................................................................................................................18
10 Balancing the System .....................................................................................................................19
10.1 Balancing Procedure: NU0103/NU305, NU0305/NU500, NU0406/NU600................................20
10.2 Balancing Procedure: NU0508/NU800, NU0912/NU1200, NU1316/NU1600............................21
11 Maintenance....................................................................................................................................21
12 Troubleshooting ..............................................................................................................................23
13 Electrical Schematics......................................................................................................................24
14 Warranty..........................................................................................................................................39

1How the NU-AIR System Works
This heat recovery ventilator (HRV) provides fresh air to a conditioned space while exhausting an equal
amount of stale air. Heat energy is transferred from one air stream to the other within a non-contact cross
flow heat exchanger.
Two forward curve blowers work to bring fresh air into the space and exhaust an equal amount of
stale air.
Incoming fresh air is filtered before flowing through the heat exchange core.
Stale, humid air flows through the cross-flow heat exchanger and transfers the heat to the
incoming fresh air.
Warm fresh air is distributed through an independent ductwork system or an existing air distribution
system.
2Features and Operation
These models use microprocessor based control technology.
The standard control configurations of these HRV’s consist of two speed settings selectable from a remote
control. Connection between the HRV and control is achieved through low voltage wiring.
Features include:
Powerful transformer
Intelligent defrost.
Self-resetting fuse to protect the board against mis-wiring.
Motor speed control (NU0103, NU0305, NU0406 only) –Motors can be independently adjusted in
HRV high and low speeds. Optional setting for 220V/50Hz geographic areas.
Fan interlock
3Installation Instructions
3.1 Installer’s Responsibilities
Installers are responsible for the performance of the ventilation system and for ensuring that all codes and
standards are met.
Do not mount the fresh air supply near a source of contaminated air such as automotive exhaust, gas or
propane exhaust or oil tanks.
Combustion appliances such as furnaces and hot water heaters must not draw combustion air directly from
an H/ERV.
3.2 Installation Basics
Before installing a Nu-Air Light Commercial H/ERV for the first time, please read these instructions.

1. Standard Issue Items
The HRV comes equipped with:
Filters
Heat/Energy Recovery Core
Drain Kit
Anti-Vibration straps (NU0103, NU0305)
Anti-vibration Springs, chain & hanging brackets
(NU0406)
2. Other Basic Needs
Control Package Galvanized Duct Flexible Duct Connector
Outside Hoods (2) Duct Fittings Duct Sealer or Tape
Screws Diffusers Duct Hanger
Balancing dampers Air flow measuring device for balancing
3.3 Ductwork
Ductwork
Duct runs should be straight with minimum bends
and elbows. Joints should be tight fitting and
sealed with high velocity, fiber reinforced duct
sealant or good quality duct tape.
RECOMMENDATION: An engineer or other
qualified person should design the duct system
Ducting must be supported according to the
designers’ specified hanger system and intervals.
Ducting from the Weather Hoods
Between the weather hoods and the H/ERV it is recommended to use rigid rectangular ducting equal to or
larger than the collar size of the machine. These ducts should be wrapped with an insulating duct wrap.
The minimum RSI value of insulation should equal that of the local building codes.
HRAI-recommended hood location for residential applications.

3.4 Weather Hoods
Locating the Weather Hoods (Commercial Installations)
Designers should try to locate the hoods in such a way that there is easy access for cleaning purposes.
The H/ERV should be located close to the outside wall(s) containing the hoods, the resulting short duct
lines will minimize airflow losses.
There should be maximum separation between the fresh air and exhaust hoods. Supply hoods should be a
minimum of 36” (inches) above the ground level. Exhaust hoods should be at least 12" (inches) above the
ground level. Fresh air hoods must be min. 10’ away from any other appliance exhaust vent or furnace
vent.
In addition ASHRAE Standard 62-99 recommends the following:
Ventilation systems should be designed to prevent re-entrainment of exhaust contaminants, condensation
or freeze-ups and growth of microorganisms. Make-up air inlets and exhaust air outlets shall be located to
avoid contamination of the makeup air. Contaminants from sources such as cooling towers, sanitary
vents, vehicular exhaust, and street traffic should be avoided.
Locating the Weather Hoods (Residential Installations)
There should be a minimum of 6’ (feet) of separation between the fresh air and exhaust hoods. Supply
hoods should be a minimum of 18 “(inches) above the ground level. Exhaust hoods should be at least 4
"(inches) above the ground level. Holes through the wall should be 1” larger than the collar on the hood.
Fresh air hoods must be 3’ away from any other appliance exhaust vent or furnace vent.
NOTE: Refer to local code requirements.

3.5 Port Configurations
1 - FROM OUTSIDE 2 - TO SPACE 3 - FROM SPACE 4 - TO OUTSIDE
1 & 4 Insulated 2 & 3 Non-Insulated
C or G for NU0103, NU0305, NU0608, NU0912, NU1316 (NU305, NU500, NU800, NU1200, NU1600)
A or E for NU0406 (NU600)
1 - Outside Air (OA) 2 - Supply Air (SA) 3 - Return Air (RA) 4 - Exhaust Air (EA)
1 4 1 3
A C
3 2 4 2
4 1 3 1
E G
2 3 2 4
Collar Sizes (inches)
NU0103/NU305
8 DIA
NU0305/NU500
10X6
NU0406/NU600
14X8
NU0608/NU800
14X8
NU0912/NU1200
14X8
NU1316/NU1600
20X10

3.6 Mounting and Noise Control
NU0103/NU305, NU0305/NU500:
For maximum efficiency, the H/ERV should be installed in a heated area. The HRV is designed to be
hung from the ceiling by way of the anti-vibration straps supplied. Attach rubberized anti-vibration straps
with machine screws provided to the threaded brass insert in the top corners of the cabinet. Avoid
hanging the HRV directly below a bedroom or other quiet area.
Nu-Air EZ System Features: EZ Level, EZ Balance
Included in orders shipped after November 1, 2016

Rev 2.3 July 17, 2017 9
NU0406 –NU1316 & NU600-NU1600:
The H/ERV is designed to be hung from the ceiling by way of
the anti-vibration springs and chain supplied. You will also need
bolt cutters or snips and self-tapping screws. The following
items are included with the H/ERV:
Galvanized suspension bracket (4)
#10-24 x 1/2" machine screw, Robertson socket drive
(16)
Suspension Springs (4)
Double loop suspension chain (20')
Securely fasten the bracket to the HRV with the machine screws
supplied. (A)
Cut the suspension chain into four equal lengths (5' max).
Use a self-tapping screw to fasten the first complete link of
chain to the pre-drilled hole in the bracket. (B)
Hook the chain into the grab slot of the bracket. Note that the
tension of the chain must pull toward the middle of the bracket.
Use the appropriate slot for this effect. ( C )
Attach the free end of the chain to a structurally sound member overhead. This will vary from
site to site.
Form a 5" loop in the chain and hook the vibration isolation spring between the slack. (D)
IMPORTANT: A. Do not rely on the spring to hold up the HRV without chain back up. B.
Flexible duct connector (PRO flex or other) should be used at all four collars of the H/ERV to
isolate vibration.

Rev 2.3 July 17, 2017 10
3.7 Drain Connections
Access to a drain is required to handle the HRV
condensate. Care should be taken to run the condensate
tube where it will not freeze.
For best results, Nu-Air recommends the following steps
be followed when installing drain kits.
1. Apply the O-ring supplied to the flange of each
drain spout. (A)
2. Insert the drain spouts through the holes in the
drain pan. (B)
3. Use the speed nut to tightly secure the drain
spout.
4. Cut two lengths of drain hose long enough to
avoid kinking. (E)
5. Attach the hose to the drain spout by sliding it over the spout until it is tight to the bottom
of the speed nut.
6. Secure the hose to the spout with the plastic tie wraps. (D)
7. Install the tee fitting as shown in the drawing below. (F)
8. Attach the free end of the hose to the left fitting. Repeat for the other side.
9. Use the remaining hose to form a "P" trap and terminate at the top of the tee.
10. Pour water into the drain assembly to form an air seal. This prevents gasses from being
drawn into the HRV.
4Connecting to Other Equipment
In general the H/ERV is not intended to be connected to other equipment or appliances.
Connection with a forced air furnace or air handler is common practice but additional controls
must be in place.
If the H/ERV is used upstream of an air handler or similar equipment (e.g. fresh air into
economizer section), the start-up sequence must be H/ERV first followed by the air handler.
Starting the air handler first, will rotate the H/ERV's fresh air fan backward. If the motor is
unable to overcome the extra load an over amp situation will result.
5External Connections
For electrical hook-up, the H/ERV should be connected to its own circuit using electrical wire
and conduit in accordance with code requirements.
Nu-Air H/ERVs are equipped for remote controls. Options include occupancy, humidity and gas
sensors, timers, off/on/intermittent-on, and low-high switching.

Rev 2.3 July 17, 2017 11
6Unit Controls: Operation and Wiring
Your unit is equipped with 12 VDC and 24 VAC removable terminal blocks. The control logic of the unit
circuit board is such that the most recently used remote control will control the unit. If desired, 12 VDC
and 24 VAC controls may be used in the same installation. Use a 3 mm flat-head screwdriver to connect
wires to the terminal blocks.
6.1 ES Series Controls (12 VDC)
All ES type controls (sold separately) connect
to the 12V (4-wire) removable terminal block.
ES Series Mxand Txcontrols are equipped
with a touch pad and 3 LED’s. The touch pad is used to select
mode of operation or turn the appliance off. The LED’s indicate
the operating mode of the HRV/ERV.
ES controls can be used in any combination and in virtually
any number, and can be wired in series or in parallel. The user
may toggle through and select any function, even if this interrupts
a current mode or cycle.
ES-T1 –20/40/60 Minute Timer
This timer is used to make the unit operate in high speed for 20, 40 or 60 minutes and is typically
installed in bathrooms, kitchens and workspaces. You may toggle between functions or even
cancel a high speed run by tapping the touch pad.
ES-M1 Control
This basic control allows you to select from standby mode, low speed, or high speed. The ES-M1
is ideal for installations where basic ventilation functions are required.
Functions:
No LED: HRV/ERV is OFF
Standby: Unit is in standby, ready for a control signal.
Lo: Unit operates in low speed continuously with high speed override from timers or sensors.
Hi: Unit operates in high speed continuously.
ES-M2 Control
While featuring the convenience of standby and low speed modes, the ES-M2 offers automatic
ventilation with 20 minutes low speed ventilation followed by 40 minutes in standby. Use the
20/40 cycle during times of low occupancy.
Functions:
Selecting operation with ES Controls
is easy: Just tap the touch-pad!

Rev 2.3 July 17, 2017 12
No LED: HRV/ERV is OFF
Standby: Unit is in standby, ready for a command
Lo: Unit operates in low speed continuously
20 Lo/40 Standby: Unit cycles between 20 minutes continuous low and 40 minutes standby.
ES-M3
ES Series units are equipped with a recirculation system that will not recycle bathroom air. The
re-circulation function of the ES-M3 enables you to re-circulate air for 40 minutes of every hour.
In addition to ventilating, this control can be used to cycle air when there is no forced air system
to alleviate stratification and dead zones.
Functions:
No LED: HRV/ERV is OFF
Standby: Unit is in standby, ready for a command
Lo: Unit operates in low speed continuously
20 Lo/40 Rec.: Unit cycles between 20 minutes continuous low and 40 minutes recirculation.
Low and circulation cycles are overridden by a high speed signal from another control.
ES-M4
The ES-M4 control offers the simplicity of the ES-M1, with the added convenience of full-time
recirculation mode.
Functions:
No LED: HRV/ERV is OFF
Standby: Unit is in standby, ready for a command
Lo: Unit operates in low speed continuously
Rec.: Unit operates in full-time recirculation with no outdoor air exchange.4
Low and circulation cycles are overridden by a high speed signal from another control.
M4 can only be used with HRV equipped with recirculation capability: NU0103, NU0305, NU0406, NU0508, NU0912, NU1316
with circulation defrost.
Lumnia ES multi-function digital Wall Control with Dehumidistat
Mounting
MOUNT IN A CENTRAL LOCATION WITHIN THE BUILDING.
FITS A STANDARD 2X3” (NOMINAL) ELECTRICAL WALL BOX (NOT INCLUDED). WHILE YOUR LUMINA WALL CONTROL COMES WITH
A SCREWLESS WALL PLATE, YOU CAN SUBSTITUTE THE FACTORY SUPPLIED WALL PLATE TO MATCH ANY DÉCOR BY USING A FLAT
SCREWDRIVER TO PRY OFF THE ORIGINAL FACE PLATE AND BY REMOVING THE 5 MM SCREWS SECURING FACEPLATE BASE.
DRYWALL ANCHORS MAY BE USED WHERE A WALL BOX IS NOT AVAILABLE.
Wiring
USING A 2 MM FLAT SCREWDRIVER AND 4-CONDUCTOR WIRE, CONNECT THE H/ERV
12 VDC TERMINAL BLOCK TO THE CORRESPONDING TERMINALS LUMINA WALL
CONTROL.

Rev 2.3 July 17, 2017 13
G
A
B
12
UNIT 12 VDC REMOVABLE
TERMINAL BLOCK
ES SERIES CONTROL
+12
B
A
G
See “Lumina Wall Control and Installation Guide” for details.
6.1.1 ES Control Wiring –applicable to all ES series controls
Crossing the +12V/12 and ground (G)
wires might short-circuit and destroy
the ES wall control processor.
Note: If you are using ONLY an ES-T1 to
control your unit, you must connect a jumper
wire between R and SB on the 24V (10-wire)
removable terminal block. In this situation
you can add continuous low speed operation by
connecting a jumper wire between R and LO.
Consult local building code in case a centrally located control with an on/off switch is required.
6.2 Winsor Series & Other 24 VAC Control Options
Windsor Series and other 24VAC controls (sold separately) connect to the 24V (10-wire)
removable terminal block.
6.2.1 Terminal Designation/Function
Normally closed –a dry relay contact paired with I that opens when the HRV is running
I –interlock –a common relay terminal used with NC or NO. See Sec. 8
Normally open - a dry relay contact paired with I that closes when the HRV is running
24 VAC output
24 VAC common return
Timer Light –used only with WIN-20
Timer Switch –used only with WIN-20
Stand By –a closed switch across SB- R makes HRV dampers active, fans are off.
High –a closed switch across Hi-R makes HRV run in high speed
Low –a closed switch across Lo-R makes HRV run in low speed.
6.2.2 Building Automation and Control Systems
The HRV does not communicate with BMS. Dry relay contacts from the BMS can used to enable 3
modes of operation. R-SB, R-Lo, R-Hi. If 2 or mores are called simultaneously, the highest fan speed
results.
NC
NO
C
TL
TS
Hi
LO
I
R
SB

Rev 2.3 July 17, 2017 14
UNIT 24 VAC REMOVABLE TERMINAL BLOCK
NC
I
NO
R
C
TL
TS
SB
Hi
LO
JUMPER WIRE
JUMPER WIRE
PURPLE
PURPLE
DSTAT-1
For intermittent high speed operation, connect Nu-Air PN DSTAT-1,
dedicated (RNC) wall switch, CO2sensor, etc. to R and Hi terminals.
For continuous low speed, connect jumper wire to R and LO
terminals.
Where required, C terminal may be used for controls requiring
external 24 VAC power source.
For two-wire switching, and where local building regulations permit,
Nu-Air recommends a jumper wire between R and SB to engage the
unit in standby mode.
UNIT 24 VAC REMOVABLE TERMINAL BLOCK
NC
I
NO
R
C
TL
TS
SB
Hi
LO
RED
GREEN
BLACK
YELLOW
WIN-1
Choose from the following operating modes:
1. Off
2. Standby
3. Continuous low speed
4. Intermittent high speed
5. Continuous high speed
6.2.3 Standard Dehumidistat (Part # DSTAT-1) & 2-wire switches
The dehumidistat switches the HRV to high speed when the relative humidity of the air around it
exceeds its set point until indoor humidity falls below the set point.
6.2.4 Windsor Control (Part # WIN-1)
The Windsor Dehumidistat Control provides the same humidity control as the Standard
Dehumidistat, with the added functionality of a 3-position switch from which the operator can
select three operating modes. The Constant switch can be engaged for full-time high speed.
6.2.5 Windsor Timer (WIN-20)
Install in bathrooms, kitchens, workstations or other locations where high-speed ventilation
control is needed. The machine will run at high speed for twenty (20) minutes and then return to
its previous operating condition. Timers can be connected in series or parallel.

Rev 2.3 July 17, 2017 15
UNIT 24 VAC REMOVABLE TERMINAL BLOCK
NC
I
NO
R
C
TL
TS
SB
Hi
LO
PWR (red)
LED (yellow)
SWITCH (black)
WIN-20
Win-20 Timer
Up to 6 Win-20 timers may run off of one system.
If using only the Win-20 timer as a means of remote
control, connect jumper wire between R and SB.

Rev 2.3 July 17, 2017 16
7Control Board Status LEDs
The control board is equipped with LEDs which indicate the unit’s current state of operation.
8Selectable Furnace/Air Handler Interlock
You may choose on the unit control board to interlock whenever the HRV/ERV is operating at
any speed, or just high speed. Position 5: interlock at any HRV speed; Position 6: interlock at
HRV high speed only.
CONDITION
LED AND STATUS
NO LED
UNIT/TRANSFORMER IS NOT POWERED
UNIT OFF
Red is off, Green is blinking slow, every 1 s. Also indicates processor is
programmed and running.
STANDBY
Green is OFF. Red led is blinking slow, every 1 s.
EXHCHANGE LOW SPEED
Green ON. Red blinking slow, every 1 s.
EXCHANGE HIGH SPEED
Green ON. Red blinking fast.
DEFROST
Green ON, Red ON. (Appears Yellow)
RECIRCULATION LOW SPEED*
Red led ON, Yellow blinking slow, every 1s.
RECIRCULATION HIGH SPEED*
Red led ON, Green led blinking fast.
One jumper must be present in
jumper range 1-4 and in jumper
range 5-8.
Do not alter jumper set 3.
1 2 3 4 5 6 7 8
(factory setting shown)

Rev 2.3 July 17, 2017 17
8.1 Furnace/Air Handler Interlock Wiring
NC
I
NO
R
C
TL
TS
SB
Hi
LO
UNIT 24 VAC REMOVABLE TERMINAL BLOCK
THERMOSTAT TERMINALS
Y
R
G
W
W
G
R
C
Y
COOLING SYSTEM
FURNACE 24 VAC
NC
I
NO
R
C
TL
TS
SB
Hi
LO
UNIT 24 VAC REMOVABLE TERMINAL BLOCK
THERMOSTAT TERMINALS
Y
R
G
W
W
G
R
C
Y
COOLING SYSTEM
FURNACE 24 VAC
STANDARD FURNACE INTERLOCK
ALTERNATE FURNACE INTERLOCK
If the standard interlocking method has the unwanted
effect of bringing on the AC, i.e. thermostats that do
not isolate “G” from “Y”, use the alternate method
shown above.

Rev 2.3 July 17, 2017 18
9Defrost Operation
Proportional Defrost Cycles
Your unit will adjust defrost frequency and duration, based on outdoor temperature: -5º C (23º F)
-15º C (5º F), -20º C (-4º F) and -27º C (-17º F).
Circulation Defrost:
When outdoor temperature is below -5º C (23º F), a defrost cycle is initiated for a fixed duration.
The fresh air motor will run and the exhaust air motor will shut down. A damper will shut off the
cold supply port, directing ambient air through the core for defrosting. The unit will resume
normal operation for a fixed duration, then the processor will read outdoor temperature and
initiate defrost as necessary. Defrost times and intervals will vary according to temperature
below -5º C (23º F).
Timed Fan Shut-Down Defrost:
The outside air before the core is monitored. When below freezing, a timed defrost cycle is
activated. The supply fan shuts down while the exhaust fan continues to move warm air through
the core. After a predefined temperature based time cycle, the HRV reverts to exchange mode.
NOTE: In circulation defrost mode, this unit will not induce indoor negative pressure nor recycle
exhaust air; rather it will redistribute ambient room air.

Rev 2.3 July 17, 2017 19
10 Balancing the System
Once the H/ERV system is installed, do the following:
1. Close all windows and doors.
2. Turn off any exhaust only systems.
3. To balance the H/ERV, set the machine on high speed.
4. Make a small hole in the supply duct at least 2 feet down stream of the motor. Insert a
Pitot tube in the cross sectional center of the duct.
5. Measure the velocity pressure with a digital manometer or magnehelic gauge.
6. Record the value and repeat the procedure for the exhaust air stream.
7. Use the motor speed control buttons on the side of the unit to reduce airflow until the
velocity pressure equals that of the opposite air stream.
To balance the H/ERV, you will need a device to measure air flow. It is recommended to use
either a magnehelic gauge or a pitot tube air meter (discussed here). Depending on the device
you are using, follow one of the two procedures below:
Digital Manometer & Pitot Tube (Supplied by Others)
Magnehelic Gauge: (Part # 2000-00 –not shown)
1. Disengage one end of the exhaust flexible duct connector in the main duct before any branch
ducts and push the duct back into itself. Insert the flow grid and tape the joint between the
flow grid and ductwork.
2. Set the HRV on high speed. Mount the magnehelic gauge level and plumb. Join the hoses
from the flow grid to the magnehelic gauge. The needle of the magnehelic gauge should read
positively. Switch hose connections if the needle falls below zero.
3. Record reading from gauge. Repeat the procedure for the supply duct.
4. Go back to the duct with the higher reading and adjust the motor speed until the supply air is
equal to the exhaust air reading.

Rev 2.3 July 17, 2017 20
460 Air Meter: (Nu-Air Part #100460).
1. Drill a ¼” hole in both the supply and exhaust ducts on the warm-side of the
machine at least 12” away from the HRV and any elbows, tees, etc.
2. Set the H/ERV on high speed.
3. Take a pressure reading in each duct and record the results.
4. Go back to the duct having the higher reading, and using the motor speed
control buttons reduce the airflow down until the pressure reads to within 10%
of the other air flow.
5. Use tape to reseal the holes.
6. To convert pressure readings to airflow (cfm or L/s) refer to the instructions
and table included with the air meter.
10.1 Balancing Procedure: NU0103/NU305, NU0305/NU500, NU0406/NU600
Balanced air flow between the supply and exhaust air streams is essential to the performance of
an HRV or ERV. Changing motor speeds or balancing is quick and simple with two buttons
recessed slightly into the unit’s cabinet. NO BALANCING DAMPERS ARE REQUIRED. Be
sure to close windows and doors, and turn off all exhaust fans/appliances during the balancing
procedure.
High-Speed Adjustment/Balancing:
1. Use any means to initiate high speed (e.g. ES-M1 control, R—H jumper wire, or 24V
R—H control) may be used. Remove the jumper wires after balancing.
2. Press and hold either the FRESH air or EXHAUST air pushbuttons (not both) for 3
Seconds. Releasing the push-button places the unit in SPEED ADJUST MODE.
3. Now press the corresponding pushbutton to
adjust the fresh air fan or the exhaust fan,
thereby changing the air flow. Each press
will reduce motor speed until the default
minimum is reached, at which point the
motor will return to its peak speed. Allowing
a brief pause between presses (about 0.5
seconds), you will press the adjust button
about 70 times before reaching minimum
speed. During the balancing procedure, you
can switch between adjusting the fresh air
motor or exhaust air motor.
4. To exit balancing/speed adjust mode, stop pressing buttons for 10 seconds. This will
place the unit back in operating mode with the new speeds saved to the circuit board’s
memory.