Viessmann AirflowPLUS User manual

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5680 011 - 23 07/2021
Viessmann AirflowPLUS
Installation, Service and
Operating Instructions
for use by heating contractor
Viessmann AirflowPLUS AH2A series
Hydronic forced air handler
Product may not be exactly as shown
Read and save these instructions
for future reference.
IMPORTANT

Viessmann AirflowPLUS AH2A Installation, Operating and Service
5680 011 - 23
2
Safety, Installation and Warranty Requirements
Safety
2
Please ensure that these instructions are read and understood before commencing installation. Failure to comply with
the instructions listed below and details printed in this manual can cause product/property damage, severe personal
injury, and/or loss of life. Ensure all requirements below are understood and fulfilled (including detailed information
found in manual subsections).
WARNING
Follow the Viessmann maintenance schedule of the boiler
contained in this manual.
Product documentation
Read all applicable documentation before commencing
installation. Store documentation near air handler in a
readily accessible location for reference in the future
by service personnel.
For a listing of applicable literature,
please see section entitled “Important
Regulatory and Installation Requirements”.
Warranty
Information contained in this and related
product documentation must be read
and followed. Failure to do so renders
the warranty null and void.
Licensed professional heating contractor
The installation, adjustment, service and maintenance
of this equipment must be performed by a licensed
professional heating contractor.
Please see section entitled
“Important Regulatory and Installation
Requirements”.
Advice to owner
Once the installation work is complete, the heating
contractor must familiarize the system operator/
ultimate owner with all equipment, as well as safety
precautions/requirements, shutdown procedure, and
the need for professional service annually before the
heating season begins.
Operating and service documentation
It is recommended that all product documentation such as
parts lists, operating and service instructions be handed
over to the system user for storage. Documentation is to
be stored near air handler in a readily accessible location
for reference by service personnel.
WARNING
Inhaling of fiberglass wool materials is a possible cancer
hazard. These materials can also cause respiratory, skin
and eye irritation.
Fiberglass wool materials
WARNING
Appliance materials of construction, may contain toxic
or harmful substances which can cause serious injury
or loss of life and which are known to the State of
California to cause cancer, birth defects and other
reproductive harm. Always use proper safety clothing,
respirators and equipment when servicing or working
nearby the appliance.
The state of California has listed the airborne fibers of
these materials as a possible cancer hazard through
inhalation. When handling these materials, special care
must be applied.
First aid measures
- If eye contact occurs, flush eyes with water to
remove dust. If symptoms persist, seek medical
attention.
- If skin contact occurs, wash affected areas gently
with soap and warm water after handling.
Suppliers of fiberglass wool products recommend the
following precautions be taken when handling these
materials:
- Avoid breathing fiberglass dust and contact with
skin and eyes.
- Use NIOSH approved dust/mist respirator.
- Wear long-sleeved, loose fitting clothing, gloves
and eye protection.
- Wash work clothes separately from other clothing.
Rinse washer thoroughly.
- Operations such as sawing, blowing, tear-out and
spraying may generate airborne fiber concentration
requiring additional protection.

3
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
Safety
General Information
Product Description
Installation
Page
Safety, Installation and Warranty Requirements..............2
Product documentation...........................................2
Warranty...............................................................2
Licensed professional heating contractor...................2
Advice to owner....................................................2
Operating and service documentation.......................2
Fiberglass wool materials........................................2
First aid measures..................................................2
About these Installation Instructions..............................5
Necessary Tools.........................................................5
Important Regulatory and Installation Requirements........6
Codes..................................................................6
Instructing the system user...................................6
Initial start-up........................................................6
Working on the equipment......................................6
Technical literature................................................6
Introduction...............................................................7
Components................................................................7
Features......................................................................8
Equipment Selection and Sizing.....................................9
Compatibility Charts.....................................................9
BeforeSet-up..............................................................11
Minimum Clearances...................................................11
Dimensions.............................................................12
Heating Circuit Pumps.............................................13
Installation...............................................................13
Installation Examples.................................................14
Horizontal installation...........................................14
Vertical installation..............................................15
Proper Piping Practice................................................16
Connecting to the Heating System..............................16
Removing the Blower Shipping Bracket.......................17
Opening the Air Handling Unit....................................17
Panels.....................................................................18
Accessing the Connection Board................................21
Vitodens 100 WB1B Wiring.......................................22
Vitodens 100 B1HA/B1KA Wiring...............................23
Vitodens 100 WB1B Wiring using DHW Connection.....24
HO1B Wiring............................................................25
Control Function.......................................................26
Supply Water Temperature (T1).................................26
Freeze Protection Temperature (T3)............................26
A/C Discharge Air Temperature (T4)...........................26
Remote Return Air Sensor (T5)..................................27
Ambient Sensor (T6).................................................27
Sensor Locations......................................................27
S1 Dip Switch Settings.............................................28
Door Safety Switch..................................................29
Electrical.................................................................30
Thermostat.........................................................30
Power Supply...........................................................31
Control Inputs.........................................................32
Setting Fan Speed....................................................33
Table of Contents

Viessmann AirflowPLUS AH2A Installation, Operating and Service
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4
Startup
Operation
Service
Additional Information
Page
Quick Check.............................................................36
Pre-start Checklist.....................................................36
Startup Procedure....................................................37
Air handlers LED Indications for Temperature...............37
Installing Connection Board........................................38
Installing the Access Panels.......................................38
Indicators................................................................39
Flashing LED............................................................39
Normal Operation......................................................39
Heating mode.....................................................39
Cooling mode......................................................39
Summary............................................................39
External Heat Demand via Switching Contact -
Boilers equipped with HO1B User Interface..................40
Heating System Operation - Vitodens 100 WB1B..........40
DHW Contact for Air Handler - Vitodens 100 WB1B......41
Illuminated Alarm Indicator.........................................42
Home freeze protect............................................42
Temperature sensor failure....................................42
Alarm Relay and LED Fault Codes..............................43
Control LED flash codes.......................................43
Alarm.................................................................43
Checking ECM (DC) Fan Motor Connections.................44
Troubleshooting.......................................................45
Service and Maintenance...........................................49
Checking temperature sensor................................49
Installed sensors..................................................49
Failed sensors......................................................49
Air filter..............................................................49
Circulator...........................................................49
Coils..................................................................49
System Layout 1......................................................50
System Layout 2......................................................51
System Layout 3......................................................52
System Layout 4......................................................53
System Layout 5......................................................54
System Layout 6......................................................55
System Layout 7......................................................56
System Layout 8......................................................57
System Layout 9......................................................58
System Layout 10....................................................59
Electrical Connectors.................................................60
Technical Data.........................................................62
Parts List.................................................................63
Table of Contents

5
5680 011 - 23
Viessmann AirflowPLUS AH2A Installation, Operating and Service General Information
About these Installation Instructions
Take note of all symbols and notations intended to draw attention to potential hazards or important
product information.
CAUTION
Cautions draw your attention to the presence of potential
hazards or important product information.
WARNING
Warnings draw your attention to the presence of potential
hazards or important product information.

IMPORTANT
Indicates an imminently hazardous situation which,
if not avoided, could result in death, serious injury or
substantial product/property damage.
Indicates an imminently hazardous situation which,
if not avoided, may result in minor injury or product/
property damage.
Helpful hints for installation, operation or maintenance
which pertain to the product.
This symbol indicates to note additional information
This symbol indicates that other instructions must be
referenced.
Necessary Tools
Testing/analysis equipment
(Use only calibrated equipment)
HMultimeter to measure 0 - 230V, 0 - 12A AC and
0-100 mA DC
HManometer to measure air pressure 0 to 11 "w.c.
(accurately) (or a non-electric Magnehelic® manometer
may also be utilized)
Cleaning supplies
HPlastic hand brush
HRags
Special items
HPipe joint sealant

Viessmann AirflowPLUS AH2A Installation, Operating and Service
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6
Important Regulatory and Installation Requirements
General Information
Codes
In Canada all electrical wiring is to be done in accordance
with the latest edition of CSA C22.1 Part 1 and/or local
codes. In the U.S. use the National Electrical Code ANSI/
NFPA 70. The heating contractor must also comply with
both the Standard for Controls and Safety Devices for
Automatically Fired Boilers, ANSI/ASME CSD-1, and
the Installation Code for Hydronic Heating Systems,
CSA B214-01, where required by the authority having
jurisdiction.
Instructing the system user
The installer of the system is responsible to ensure the
system operator/ultimate owner is made familiar with the
system functioning, its activation, and its shut-down.
The following topics must be covered:
- Proper system operation sequence.
- Explain the equipment.
- Demonstrate an emergency shut-down, what to do
and what not.
- Explain that there is no substitute for proper
maintenance to help ensure safe operation.
Initial start-up
Initial start-up must be performed by a qualified heating
contractor. Proper completion of the Maintenance Record
by the heating contractor is also required.
Working on the equipment
The installation, adjustment, service, and maintenance of
this air handler must be done by a licensed professional
heating contractor who is qualified and experienced in
the installation, service, and maintenance of hot water
heating equipment. There are no user serviceable parts
on the air handler.
Please carefully read this manual prior to attempting
start-up, maintenance or service. Any warranty is null
and void if these instructions are not followed.
For information regarding other Viessmann System
Technology componentry, please reference
documentation of the respective product.
We offer frequent installation and service seminars to
familiarize our partners with our products. Please inquire.
Ensure main power supply to equipment, the heating
system, and all external controls have been deactivated.
Take precautions in all instances to avoid accidental
activation of power during service work.
The completeness and functionality of field supplied
electrical controls and components must be verified by
the heating contractor. These include low water
cut-offs, flow switches (if used), staging controls,
pumps, motorized valves, air vents, thermostats, etc.
Technical literature
Literature for the Viessmann AirflowPLUS air handler:
- Technical Data Manual
- Installation, Service, and Operating Instructions
- Instructions of other Viessmann products utilized and
installed
- Installation codes mentioned in this manual
Leave all literature at the installation site and advise the
system operator/ultimate owner where the literature can
be found. Contact Viessmann for additional copies.
This product comes with several safety instruction labels
attached.
Do not remove!
Contact Viessmann immediately if replacement labels are
required.

7
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
Introduction
The Viessmann AirflowPLUS AH2A series air handlers
are to be used in conjunction with Viessmann boilers.
The automatic adjustments are made in heating as well
as cooling. This minimizes selecting an oversized heating
appliance just to accommodate the cooling load.
The Viessmann AirflowPLUS AH2A series is always the
right size.
Components
Cabinet
All cabinets have a tough, durable powder coat finish
on satin coat 20 gauge steel.
Heating coils
All heating coils are copper and assembled using no lead
solder. All coils and internal piping conform to ASTM
B-68, B-88 and/or B-743 standards.
High density aluminum fins provide maximum heat
transfer for small coil surface.
Fan and motor
The ECM fan is a wide body dynamically balanced for
extra quiet operation. Multi-directional sleeve bearing
motors allow mounting in any direction for maximum
installation flexibility.
Circulating pump
The internal circulating pump is matched for maximum
performance. All Airflow PLUS air handlers come with
internally mounted pumps for ease of installation.
Check valve
A check valve is built into the circulator to protect against
backflow of water.
Legend
AStandard adaptors (at the rear)
BHeating coil and pump slide out for easy service
CIntegrate pump with check valve
DFibreglass insulation with reinforced foil face and
gasket seals
EFan and controls slide out on rails
FIntegrated filter rack
Product Description

Viessmann AirflowPLUS AH2A Installation, Operating and Service
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8
Product Description
Features
Pump exercise function
If the internal circulating pump has not run in the previous
24 hours, the control will turn the pump on for 1 minute
to flush the lines and heat exchanger. This will help
ensure that the water lubricated pump does not seize
during long periods of inactivity.
Home freeze protection
The Viessmann AirflowPLUS AH2A series air handlers
have an integrated sensor which will help prevent the
home from freezing due to a faulty thermostat. Should
the ambient temperature get too low, the control will turn
the air handler on automatically and maintain the home
at approximately 40°F (4°C).
Note: this feature will only work if the boiler is turned on
and the air handler has power. While in Home
freeze protect mode the alarm relay and red light
will be on. Refer to page 42.
Status and alarm indicators
A bicolor LED indicator is installed in the air handler
housing and is used to indicate alarm, test mode, and
normal operation. The indicator will display temperature
readings of the sensors during normal operation.
Alarms
Should service problems arise the Viessmann AirflowPLUS
AH2A series will notify the user with a housing mounted
LED. Dry contacts are provided on the controller which
can be connected to an external device such as a warning
light or home security system.
Customizing
The heating and cooling features can be field customized
to provide maximum comfort for almost any home or
location. Refer to page 28, 33, 34 and 35.

9
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
Equipment Selection and Sizing
Proper sizing of systems components is crucial for proper
operation;
1. Obtain room by room heat loss and/or heat gain
2. Determine heating water temperature
3. Determine duct layout
Make sure a proper room-by-room heat loss and heat
gain for the dwelling is calculated using Manual J, HRAI,
ASHRAE or other approved sizing method.
Boiler supply water temperature 120°F (28 MBH) 140°F (46 MBH) 160°F (62 MBH) 180°F (72 MBH)
Vitodens 100 B1HA-94  --
Vitodens 100 B1HA-125  --
Vitodens 100 B1KA-125  --
Vitodens 100 B1HE-85  --
Vitodens 100 B1HE-120 
Vitodens 100 B1HE-150 
Vitodens 100 B1HE-199 
Vitodens 100 B1KE-120  --
Vitodens 100 B1KE-199 
Vitodens 222 B2TB-68  --
Vitodens 222 B2TB-125 
Vitodens 200 B2HB-68 -- --
Vitodens 200 B2HB-94 
Vitodens 200 B2HB-125 
Vitodens 200 B2HB-160 
Vitodens 200 B2HB-199 
Vitodens 200 B2HA-285 
Vitodens 200 B2HA-311 
Vitodens 200 B2HA-352 
Vitodens 200 B2HA-399 
Vitodens 200 B2HA-530 
Vitodens 200 B2HE-85  --
Vitodens 200 B2HE-120 
Vitodens 200 B2HE-150 
Vitodens 200 B2HE-199 
Vitocrossal 300 CU3A-94 
Vitocrossal 300 CU3A-125 
Vitocrossal 300 CU3A-160 
Vitocrossal 300 CU3A-57, 199 
Compatibility Charts
Air handler model AH2A-213
Product Description
Note: Compatibility charts do not take into consideration systems using additional heat emitters, DHW load etc.
Ensure the boiler selected meets all of the system requirements for loads generated by additional components.
It is the responsibility of the system designer to ensure proper sizing and equipment selection.

Viessmann AirflowPLUS AH2A Installation, Operating and Service
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10
Compatibility Charts (continued)
Product Description
Boiler supply water temperature 120°F (44 MBH) 140°F (61 MBH) 160°F (83 MBH) 180°F (98 MBH)
Vitodens 100 B1HA-94   --
Vitodens 100 B1HA-125   --
Vitodens 100 B1KA-125   --
Vitodens 100 B1HE-85  -- --
Vitodens 100 B1HE-120   
Vitodens 100 B1HE-150   
Vitodens 100 B1HE-199   
Vitodens 100 B1KE-120   
Vitodens 100 B1KE-199   
Vitodens 222 B2TB-68   --
Vitodens 222 B2TB-125   
Vitodens 200 B2HB-68  -- --
Vitodens 200 B2HB-94   
Vitodens 200 B2HB-125   
Vitodens 200 B2HB-160   
Vitodens 200 B2HB-199   
Vitodens 200 B2HA-285   
Vitodens 200 B2HA-311   
Vitodens 200 B2HA-352   
Vitodens 200 B2HA-399   
Vitodens 200 B2HA-530  
Vitodens 200 B2HE-85  -- --
Vitodens 200 B2HE-120   
Vitodens 200 B2HE-150   
Vitodens 200 B2HE-199   
Vitocrossal 300 CU3A-94   --
Vitocrossal 300 CU3A-125   
Vitocrossal 300 CU3A-160   
Vitocrossal 300 CU3A-199   
Air handler model AH2A-354
Note: Compatibility charts do not take into consideration systems using additional heat emitters, DHW load etc.
Ensure the boiler selected meets all of the system requirements for loads generated by additional components.
It is the responsibility of the system designer to ensure proper sizing and equipment selection.

11
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
Boiler supply water temperature 120°F (51 MBH) 140°F (74 MBH) 160°F (90 MBH) 180°F (115 MBH)
Vitodens 100 B1HA-94  --
Vitodens 100 B1HA-125  --
Vitodens 100 B1KA-125  --
Vitodens 100 B1HE-85 -- -- --
Vitodens 100 B1HE-120  --
Vitodens 100 B1HE-150  
Vitodens 100 B1HE-199  
Vitodens 100 B1KE-120  
Vitodens 100 B1KE-199  
Vitodens 222 B2TB-68  -- --
Vitodens 222 B2TB-125 
Vitodens 200 B2HB-68  --
Vitodens 200 B2HB-94  --
Vitodens 200 B2HB-125  
Vitodens 200 B2HB-160  
Vitodens 200 B2HB-199  
Vitodens 200 B2HA-285  
Vitodens 200 B2HA-311  
Vitodens 200 B2HA-352  
Vitodens 200 B2HA-399  
Vitodens 200 B2HA-530  
Vitodens 200 B2HE-85 -- -- --
Vitodens 200 B2HE-120  --
Vitodens 200 B2HE-150  
Vitodens 200 B2HE-199  
Vitocrossal 300 CU3A-94  -- --
Vitocrossal 300 CU3A-125  
Vitocrossal 300 CU3A-160  
Vitocrossal 300 CU3A-199  
Air handler model AH2A-385
Note: Compatibility charts do not take into consideration systems using additional heat emitters, DHW load etc.
Ensure the boiler selected meets all of the system requirements for loads generated by additional components.
It is the responsibility of the system designer to ensure proper sizing and equipment selection.
Compatibility Charts (continued)
Product Description

Viessmann AirflowPLUS AH2A Installation, Operating and Service
5680 011 - 23
12
Installation
Before Set-up
Recommended minimum service clearances
For typical Viessmann AirflowPLUS installation, it
is recommended to install the air handler with the
clearances shown in the illustration.
Before placing Viessmann AirflowPLUS in its installation
location, ensure all necessary accessories are installed.
Minimum Clearances
CAUTION
The air handler must be installed in such a way that
electrical components are protected from water (spraying,
splashing, etc.) during operation and service.
Horizontal Installation
Vertical Installation
a - 24 in. (610 mm)
b - 12 in. (305 mm)
These dimensions reflect the recommended service
clearance for the air handler only, ensure adequate clearance
is left for the installation of ducting, piping and electrical
connections. Only the b clearance may be reduced providing
there is enough clearance for ductwork, plumbing and
electrical connections, with zero clearance between the air
handler unit and ducting being acceptable.

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5680 011 - 23
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Top view
Front view Side view
Installation
Dimensions
IMPORTANT
The maximum ambient temperature must not exceed
104ºF (40ºC).
AH2A-213 AH2A-354 AH2A-385
a in.
(mm)
22c
(578 mm)
23
(584 mm)
28
(711 mm)
b in.
(mm)
18
(457 mm)
22
(559 mm)
22
(559 mm)
c* in.
(mm)
32b
(826 mm)
34b
(876 mm)
34b
(876 mm)
d* in.
(mm)
22a
(572 mm)
24e
(620 mm)
24e
(620 mm)
e* in.
(mm)
23b
(597 mm)
25b
(650 mm)
25b
(650 mm)
f in.
(mm)
2
(51 mm)
1c
(44 mm)
1c
(44 mm)
g in.
(mm)
3
(76 mm)
3f
(92 mm)
3f
(92 mm)
h in.
(mm)
24c
(629 mm)
25
(635 mm)
30
(762 mm)
Legend
AHeating water supply connection
BHeating water return connection
* Using the adjustable levelling feet can add up to 1bin.
(38 mm) to the height of the air handler.

Viessmann AirflowPLUS AH2A Installation, Operating and Service
5680 011 - 23
14
The Viessmann AirflowPLUS AH2A can be suspended
by securing straps to the corners of the enclosure (field
supplied).
Install the air handler with the door screwed in place to
avoid distortion of the cabinet. The installing contractor
must ensure that suspension materials are sized and
installed to provide sufficient support to the air handler
and connected accessory fittings and materials.
Note: System layout examples are provided starting on
page 50 of these instructions.
Installation
The contractor shall adhere to all local, state and national
code requirements pertaining to the installation of this
equipment.
The Viessmann AirflowPLUS AH2A series air handler
can be mounted in most directions. Upflow, downflow,
horizontal left and horizontal right. You cannot install the
air handler on it’s back or suspended with front cover
facing down. An adequately sized drain pan and drain
connection must be installed under the appliance
if installed in or above a finished space.
If installed in an unfinished space, a drain pan is not
provided, necessary precautions must taken to ensure
proper drainage of water in the event of a water leak
(e.g. Floor drain, sump pump, moisture alarm...). This
appliance shall not be installed in a non conditioned space
where the potential may exist for the appliance and or
water lines and drain line to freeze.
Installation
Pump Model Grundfos UPS15-58RU
Rated voltage VAC 115
Rated current Amp 0.74
Capacitor F10
Power consumption Watts 87
Heating Circuit Pumps
Note: All Viessmann AirflowPLUS air handlers come with
pump speed factory set to speed 3.
Legend
ASpeed 1 Pump curve
BSpeed 2 Pump curve
CSpeed 3 Pump curve

15
5680 011 - 23
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Suspension material
(field supplied)
Secure the suspension
material to the corners
of the air handler housing.
Return air
Supply air
Installation Examples
Installation
IMPORTANT
A field fabricated auxiliary drain pan with drain pipe is
recommended in all configurations.
Horizontal installation
Note: Field selected suspension materials must be sized
by installing contractor so as to be of sufficient
strength to support air handler weight of 150 lbs.
(68 kg) and connected accessory fittings and
materials.
Note: Return air openings are provided in both the bottom
and side panels.
CAUTION
Return air openings shall not be installed in back panel.
For an installation over a finished space
A field fabricated auxiliary drain pan with drain pipe is
required to prevent damage by overflow due to blocked
condensate drain.
Temperature sensor and low voltage lead routing A/C
Coil installed upstream of Air Handler in return plenum.
Refer to “Remote Return Air Sensor T5” on page 27 for
information.
You cannot install the air handler on it’s back or
suspended with front cover facing down.
IMPORTANT

Viessmann AirflowPLUS AH2A Installation, Operating and Service
5680 011 - 23
16
Installation Examples (continued)
Installation
Vertical installation
The A/C coil is installed in the downstream air flow of the
Viessmann AirflowPLUS air handler.
IMPORTANT
A field fabricated auxiliary drain pan with drain pipe is
required in all configurations.
CAUTION
Return air openings shall not be installed in back panel.
Supply air temperature sensor lead shall be routed out of
air handler casing through knock-out provided in either
side of casing and secured to plenum using nylon clips
provided.
Snap round bushing into hole and insert sensor lead
approximately 2 in. (51 mm) and secure to duct using
nylon strap included.
Drill 3/8 in. dia. hole in return air duct a minimum of
15 in. (381 mm) downstream of plenum.
A
Supply air temperature sensor lead and low voltage
lead wires shall be isolated from high voltage leads
and routed through knockouts provided.
B
Return air
Supply air
A/C coil
Air Filter
A
B
For remote return air temperature
sensor drill 3/8 in. dia. hole in
return air duct a minimum of
15 in. upstream of plenum.
Snap round bushing into hole and
insert sensor lead approximately
2 in. (51 mm) and secure to duct
using nylon strap included.
Air Filter
A/C Coil
Supply air sensor lead and
low voltage lead wires shall
be isolated from high voltage
leads and routed through
knockouts provided.
Supply air
Return air
Vertical installation
The A/C coil is installed in the upstream air flow of the
Viessmann AirflowPLUS air handler. This will require the
use of the remote return air temperature sensor mounted
upstream of the A/C coil. See page 27 for additional
information regarding the remote return air temperature
sensor.

17
5680 011 - 23
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Support piping by proper suspension method.
Piping must not rest on or be supported by the air handler.
Use moderate amount of dope.
2 imperfect threads
Leave 2 threads bare
Proper Piping Practice
Connecting to the Heating System
Air handler piping
Depending on the boiler selected and system design it may
be required to use a primary, secondary piping arrangement
to de-couple the flow through the boiler from the flow
through the air handler. Refer to the system layout examples
starting on page 50.
Boiler
Follow the instructions provided with the boiler for
installation and start-up of the boiler. Make sure the
heating device is turned off during air handler installation
and service. Ensure system has been filled, and all air
is purged from the system before turning on the heating
boiler.
Installation
This section constitutes an overview only! Refer to
subsequent sections for detailed information on individual
piping connections.
Use an approved pipe sealant or teflon tape when
connecting the following installation fittings.
Duct work
All duct designs must be designed to conform with ARI
Manuals “J” and “D” or local codes and requirements.
To minimize fan noise in the living space, it is recommended
that the first six feet of supply and return air duct be lined
with acoustic insulation.
Return and supply air duct work should be the same size
as the air handler openings up to the first branch, fitting or
transition.
Installation Examples (continued)
Vertical installation
The A/C coil is installed in the downflow position of the
Viessmann AirflowPLUS air handler.
IMPORTANT
A field fabricated auxiliary drain pan with drain pipe is
required in all configurations.
CAUTION
Return air openings shall not be installed in back panel.
Supply air temperature sensor lead shall be routed out of
air handler casing through knock-out provided in either
side of casing and secured to plenum using nylon clips
provided.
Snap round bushing into hole and insert sensor lead
approximately 2 in. (51 mm) and secure to duct using
nylon strap included.
Drill 3/8 in. dia. hole in return air duct a minimum of
15 in. (381 mm) downstream of plenum.
A
Supply air temperature sensor lead and low voltage
lead wires shall be isolated from high voltage leads
and routed through knockouts provided.
B
Return air
Supply air
A/C coil
Air Filter
B
A

Viessmann AirflowPLUS AH2A Installation, Operating and Service
5680 011 - 23
18
Removing the Blower Shipping Bracket
1. Remove the lower front panel retaining screws and set
aside.
2. Tilt the lower front panel forward at the top and lift
out.
3. Remove the upper front panel retaining screws and
set aside.
4. Slide the upper front panel down and pull out.
Installation
Opening the Air Handler Unit
1. Remove the bracket retaining thumb screws and
discard.
2. Remove the bracket and discard.

19
5680 011 - 23
Viessmann AirflowPLUS AH2A Installation, Operating and Service Installation
Panels
Horizontal opening
(bottom)
Vertical opening
(left side)
There are 2 return air openings on the air handler. One
is located on the left side for vertical installations and
one is located at the bottom for horizontal installations.
For horizontal installations, remove the bottom panel and
install it to the left side panel opening.
Horizontal installation
1. Remove the bottom panel retaining screws and set
aside.
2. Remove the bottom panel and set aside.
Note: The fan tray is preinstalled into the bottom of
the air handler.
3. Install the bottom panel to the left side of the air
handler opening and secure with the retaining screws.
4. Connect the field supplied ducting to the bottom of
the air handler.
5. Connect the field supplied ducting as required.

Viessmann AirflowPLUS AH2A Installation, Operating and Service
5680 011 - 23
20
Installation
Panels (continued)
To change the duct connection side of the air handler
for vertical installation, the right and left side panel can
be interchanged. To interchange the panels refer to the
following instructions.
1. Remove the retaining screws and set aside.
2. Remove the side panel by pulling up on the handle
and then out.
3. Remove the retaining screws from the panel on
the opposite side and set aside.
4. Remove the side panel by pulling up on the handle
and then out.