Viessmann AirflowPLUS AH2A-213, AirflowPLUS AH2A-354, AirflowPLUS AH2A-385 Installation, Service And Operating Instruction
Page 1
Installation, Service and
Operating Instructions
for use by heating contractor
Viessmann AirflowPLUS AH2A series
Hydronic forced air handler
Viessmann Airfl owPLUS
5680 011 - 10 06/2016
Product may not be exactly as shown
IMPORTANT
Read and save these instructions
for future reference.
Please file in Service Binder
Page 2
Safety
Safety, Installation and Warranty Requirements
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).
Viessmann AirflowPLUS AH2A Installation, Operating and Service
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.
WARNING
Follow the Viessmann maintenance schedule of the boiler
contained in this manual.
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.
Fiberglass wool materials
WARNING
Inhaling of fiberglass wool materials is a possible cancer
hazard. These materials can also cause respiratory, skin
and eye irritation.
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.
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.
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.
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.
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
Table of Contents
Page
Safety
General Information
Product Description
Installation
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
Before Set-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 WB1B Wiring using DHW Connection.....23
HO1B Wiring............................................................24
Control Function.......................................................25
Supply Water Temperature (T1).................................25
Freeze Protection Temperature (T3)............................25
A/C Discharge Air Temperature (T4)...........................25
Remote Return Air Sensor (T5)..................................26
Ambient Sensor (T6).................................................26
Sensor Locations......................................................26
Override Settings.....................................................27
System Select Dip Switch Settings............................27
Door Safety Switch..................................................28
Electrical.................................................................29
Thermostat.........................................................29
Power Supply...........................................................30
Control Inputs.........................................................31
Setting Fan Speed....................................................32
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Table of Contents
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Page
Startup
Operation
Service
Quick Check.............................................................35
Pre-start Checklist.....................................................35
Startup Procedure....................................................36
Air handlers LED Indications for Temperature...............36
Closing the Air Handling Unit.....................................37
Indicators................................................................38
Flashing LED............................................................38
Normal Operation......................................................38
Heating mode.....................................................38
Cooling mode......................................................38
Summary............................................................38
External Heat Demand via Switching Contact -
Boilers equipped with HO1B User Interface..................39
Heating System Operation - Vitodens 100 WB1B..........39
DHW Contact for Air Handler - Vitodens 100 WB1B......40
Illuminated Alarm Indicator.........................................41
Home freeze protect............................................41
Heat exchanger freezing protection control.............41
Cooling lockout...................................................41
Temperature sensor failure....................................41
Audible Alarm Indicator.............................................41
Alarm Relay and LED Fault Codes..............................42
Control LED flash codes.......................................42
Alarm.................................................................42
Checking ECM (DC) Fan Motor Connections.................43
Troubleshooting.......................................................44
Service and Maintenance...........................................48
Checking temperature sensor................................48
Installed sensors..................................................48
Failed sensors......................................................48
Air filter..............................................................48
Circulator...........................................................48
Coils..................................................................48
Additional Information
4
System Layout 1......................................................49
System Layout 2......................................................50
System Layout 3......................................................51
System Layout 4......................................................52
System Layout 5......................................................53
System Layout 6......................................................54
System Layout 7......................................................55
System Layout 8......................................................56
Technical Data.........................................................57
Electrical Connectors.................................................58
Parts List.................................................................60
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
About these Installation Instructions
Take note of all symbols and notations intended to draw attention to potential hazards or important
product information.
WARNING
Warnings draw your attention to the presence of potential
hazards or important product information.
CAUTION
Cautions 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.
General Information
Necessary Tools
Testing/analysis equipment
(Use only calibrated equipment)
H Multimeter to measure 0 - 230V, 0 - 12A AC and
0-100 mA DC
H Manometer to measure air pressure 0 to 11 "w.c.
(accurately) (or a non-electric Magnehelic® manometer
may also be utilized)
This symbol indicates to note additional information
This symbol indicates that other instructions must be
referenced.
Cleaning supplies
H Plastic hand brush
H Rags
Special items
H Pipe joint sealant
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General Information
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Important Regulatory and Installation Requirements
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.
6
5680 011 -10
Page 7
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.
Product Description
Legend
A Standard adaptors (at the rear)
B Heating coil and pump slide out for easy service
C Integrate pump with check valve
D Fibreglass insulation with reinforced foil face and
gasket seals
E Fan and controls slide out on rails
F Integrated filter rack
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.
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Page 8
Product Description
Features
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Condenser freeze protection
If the evaporator coil outlet air temperature is too low or
operating outside of normal conditions, the control will
shut off the outdoor condenser for 5 minutes. Evaporator
coil freezing can cause slugging at the compressor. Dirty
air filters, oversizing of A/C equipment, improper A/C
installation and commissioning and/or poor duct design
may also contribute to evaporator coil freezing.
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 41.
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 an audible alarm
and/or 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 27, 32, 33 and 34.
8
5680 011 -10
Page 9
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.
Compatibility Charts
Air handler model AH2A-213
Boiler supply water temperature 120°F (28 MBH) 140°F (46 MBH) 160°F (62 MBH) 180°F (72 MBH)
Vitodens 100 WB1B-26
Vitodens 100 WB1B-35
Product Description
--
--
Vitodens 222 B2TB-19
Vitodens 222 B2TB-35
Vitodens 200 B2HB-19
Vitodens 200 B2HB-26
Vitodens 200 B2HB-35
Vitodens 200 B2HB-45
Vitodens 200 B2HB-57
Vitodens 200 B2HA-45
Vitodens 200 B2HA-60
Vitodens 200 B2HA-80
Vitodens 200 B2HA-88
Vitodens 200 B2HA-100
Vitodens 200 B2HA-112
Vitodens 200 B2HA-150
Vitocrossal 300 CU3A-26
Vitocrossal 300 CU3A-35
Vitocrossal 300 CU3A-45
Vitocrossal 300 CU3A-57
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.
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Page 10
Product Description
Compatibility Charts (continued)
Air handler model AH2A-354
Boiler supply water temperature 120°F (44 MBH) 140°F (61 MBH) 160°F (83 MBH) 180°F (98 MBH)
Vitodens 100 WB1B-26
Vitodens 100 WB1B-35
Viessmann AirflowPLUS AH2A Installation, Operating and Service
--
--
Vitodens 222 B2TB-19
Vitodens 222 B2TB-35
Vitodens 200 B2HB-19
Vitodens 200 B2HB-26
Vitodens 200 B2HB-35
Vitodens 200 B2HB-45
Vitodens 200 B2HB-57
Vitodens 200 B2HA-45
Vitodens 200 B2HA-60
Vitodens 200 B2HA-80
Vitodens 200 B2HA-88
Vitodens 200 B2HA-100
Vitodens 200 B2HA-112
Vitodens 200 B2HA-150
Vitocrossal 300 CU3A-26
Vitocrossal 300 CU3A-35
Vitocrossal 300 CU3A-45
Vitocrossal 300 CU3A-57
Air handler model AH2A-385
Boiler supply water temperature 120°F (51 MBH) 140°F (74 MBH) 160°F (90 MBH) 180°F (115 MBH)
Vitodens 100 WB1B-26
Vitodens 100 WB1B-35
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Vitodens 222 B2TB-19
Vitodens 222 B2TB-35
Vitodens 200 B2HB-19
Vitodens 200 B2HB-26
Vitodens 200 B2HB-35
Vitodens 200 B2HB-45
Vitodens 200 B2HB-57
Vitodens 200 B2HA-45
Vitodens 200 B2HA-60
Vitodens 200 B2HA-80
Vitodens 200 B2HA-88
Vitodens 200 B2HA-100
Vitodens 200 B2HA-112
Vitodens 200 B2HA-150
Vitocrossal 300 CU3A-26
Vitocrossal 300 CU3A-35
Vitocrossal 300 CU3A-45
Vitocrossal 300 CU3A-57
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.
10
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Viessmann AirflowPLUS AH2A Installation, Operating and Service
Before Set-up
Before placing Viessmann AirflowPLUS in its installation
location, ensure all necessary accessories are installed.
The air handler must be installed in such a way that
electrical components are protected from water (spraying,
splashing, etc.) during operation and service.
Minimum Clearances
Installation
CAUTION
Horizontal Installation
Recommended minimum service clearances
For typical Viessmann AirflowPLUS installation, it
is recommended to install the air handler with the
clearances shown in the illustration.
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.
Vertical Installation
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Page 12
Installation
Dimensions
Viessmann AirflowPLUS AH2A Installation, Operating and Service
IMPORTANT
The maximum ambient temperature must not exceed
104ºF (40ºC).
Top view
Legend
A Heating water supply connection
B Heating water return connection
AH2A-213 AH2A-354 AH2A-385
a in.
(mm)
b in.
(mm)18(457 mm)22(559 mm)22(559 mm)
c* in.
(mm)
d* in.
(mm)
e* in.
(mm)
f in.
(mm)2(51 mm)
g in.
(mm)3(76 mm)
h in.
(mm)
* Using the adjustable levelling feet can add up to 1b”
(38 mm) to the height of the air handler.
22c
(578 mm)
32b
(826 mm)
22a
(572 mm)
23b
(597 mm)
24c
(629 mm)
23
(584 mm)28(711 mm)
34b
(876 mm)
24e
(620 mm)
25b
(650 mm)
1c
(44 mm)
3f
(92 mm)
25
(635 mm)30(762 mm)
34b
(876 mm)
24e
(620 mm)
25b
(650 mm)
1c
(44 mm)
3f
(92 mm)
Front view
Side view
12
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Page 13
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Heating Circuit Pumps
Pump Model Grundfos UPS15-58RU
Rated voltage VAC 115
Rated current Amp 0.74
Capacitor
Power consumption Watts 87
Legend
A Speed 1 Pump curve
B Speed 2 Pump curve
C Speed 3 Pump curve
F
Installation
10
Note: All Viessmann AirflowPLUS air handlers come with
pump speed factory set to speed 3.
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.
The return air can ONLY be installed in the bottom of the
cabinet in horizontal installations. DO NOT install
the return air in the bottom of the cabinet in vertical
installations. To do so will not permit the installation of
the required drain pan and drain.
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.
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Page 14
Installation
Installation Examples
Horizontal installation
Viessmann AirflowPLUS AH2A Installation, Operating and Service
IMPORTANT
A field fabricated auxiliary drain pan with drain pipe is
recommended in all configurations.
Discharge air
Note: Return air openings are provided in both the bottom
and side panels.
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.
Suspension material
(field supplied)
Secure the suspension
material to the corners
of the air handler housing.
Cold air return
CAUTION
Return air openings shall not be installed in back panel.
IMPORTANT
You cannot install the air handler on it’s back or
suspended with front cover facing down.
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 26 for
information.
For horizontal 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.
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Page 15
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Installation Examples
(continued)
Installation
Vertical installation
The A/C coil is installed in the downstream air flow of the
Viessmann AirflowPLUS air handler.
Discharge air
Discharge 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.
Drill 3/8” dia. hole in return air duct a minimum of 15”
(381 mm) downstream of plenum.
Snap round bushing into hole and insert sensor lead
approximately 2” (51 mm) and secure to duct using
nylon strap included.
Discharge sensor lead and low voltage lead wires shall
be isolated from high voltage leads and routed through
knockouts provided.
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.
A/C coil
Cold air return
Air Filter
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 41 for additional
information regarding the remote return air temperature
sensor.
Discharge air
Discharge sensor lead and
low voltage lead wires shall
be isolated from high voltage
leads and routed through
knockouts provided.
Cold air return
For remote return air
temperature sensor drill 3/8”
dia. hole in return air duct a
minimum of 15” upstream
of plenum. Snap round
bushing into hole and insert
sensor lead approximately
2” (51 mm) and secure
to duct using nylon strap
included.
Air Filter
A/C Coil
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Page 16
Installation
Proper Piping Practice
Viessmann AirflowPLUS AH2A Installation, Operating and Service
2 imperfect threads
Leave 2 threads bare
Connecting to the Heating System
Support piping by proper suspension method.
Piping must not rest on or be supported by the air handler.
Use moderate amount of dope.
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.
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 49.
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.
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.
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Page 17
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Removing the Blower Shipping Bracket
1. Remove the bracket retaining thumb screws and
discard.
2. Remove the bracket and discard.
Opening the Air Handler Unit
1. Remove the lower front panel retaining screws and set
aside.
Installation
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.
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Page 18
Installation
Panels
Vertical opening
(left side)
Viessmann AirflowPLUS AH2A Installation, Operating and Service
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 opening
(bottom)
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.
18
5680 011 -10
Page 19
Viessmann AirflowPLUS AH2A Installation, Operating and Service
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.
Installation
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.
5680 011 -10
19
Page 20
Installation
Panels
(continued)
Viessmann AirflowPLUS AH2A Installation, Operating and Service
5. Install the side panel (removed from step 2) by placing
the panel into the air handler and pushing down with
the handle.
6. Reinstall the retaining screws.
Note: To install the filter tray, see page 19.
7. Install the side panel (removed from step 4) by placing
the panel into the air handler and pushing down with
the handle.
8. Reinstall the retaining screws.
20
5680 011 -10
Page 21
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Panels (continued)
Filter tray for vertical installation
Note: If an A/C condenser is installed upstream, a field
supplied filter tray maybe placed elsewhere in the
ducting, see page 15.
1. Remove the retaining screws from the side panel.
2. Install the filter tray into the side panel opening.
3. Drill into the filter tray and secure the filter tray to the
side panel using the retaining screws.
4. Remove the 3 plastic retaining screws, open the tray
and remove the supplied filter.
5. Remove the side panel of the filter tray and insert the
filter.
6. Connect the field supplied ducting to the filter tray as
required.
Accessing the Connection Board
Installation
Accessing the connection board with hinged cover
1. Remove the blower assembly retaining screws and
set aside.
2. Slide the blower assembly forward.
IMPORTANT
Careful not to slide the blower assembly out too far,
it could put excessive strain on the cables.
3. Remove the 2 retaining screws from the connection
board cover.
4. Swing the cover up to open.
OR
Accessing the connection board with removable cover
1. Remove the blower assembly retaining screw and
set aside.
2. Slide the blower assembly forward.
IMPORTANT
Careful not to slide the blower assembly out too far,
it could put excessive strain on the cables.
5680 011 -10
3. Remove the retaining screw from the connection
board cover.
4. Remove cover.
21
Page 22
Installation
Vitodens 100 WB1B Wiring
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Viessmann AirflowPLUS
Connection Board
Thermostat
Power Pump Module (PPM)
For more details, refer to the Vitodens 100-W
Installation Instructions.
Connect call for heat (K2) relay of the air handler to the
RT connection (X4 terminals 3 and 4) of the Vitodens
100 WB1B power pump module.
22
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Page 23
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Vitodens 100 WB1B Wiring using DHW Connection
Viessmann AirflowPLUS
Connection Board
Installation
Thermostat
A
A Heating circuit control connection.
Power Pump Module (PPM)
IMPORTANT
This cannot be used in conjunction with DHW or
CombiPLUS equipped boilers.
5680 011 -10
Connect call for heat (K2) relay of the air handler to the
DHW connection (X4 terminals 1 and 2) of the Vitodens
100 WB1B power pump module.
In a system where the DHW contact is not used, the DHW
contact may be used as a second set point (this set point
is not affected by outdoor reset). Refer to page 40 for
additional information.
23
Page 24
Installation
HO1B Wiring
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Viessmann AirflowPLUS
Connection Board
Thermostat
HO1B Connections
(Vitodens 200-W B2HA and B2HB
Vitodens 222-F B2TA and B2TB
Vitocrossal 300 CU3A)
Refer to the appropriate boiler Installation
Instructions.
Connect call for heat (K2) relay of the air handler to
terminals DE1 of the integrated EA1 module. For coding
and programming requirements refer to page 39.
24
5680 011 -10
Page 25
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Control Function
Installation
Temperature sensors
The Viessmann AirflowPLUS integrated Control includes
five temperature sensors. Temperature sensors are 2-wire
devices that are connected to the control board with a
two pin connector allowing field replacement of individual
sensors. In the event of a sensor failure for longer than
2 minutes, the alarm beeper will sound 2 beeps every 8
min. after 24 hr. of continuous power on.
Circulator
The circulator connection will support up to 5A 115VAC
pump motors, activated by control logic on call for heat.
Air conditioning relay (24VAC)
The Air Conditioning relay is on when the A/C cooling
function should be active. It is a 24VAC signal that will
energize the A/C power contactor.
Fan relay (24VAC 5A Max dry contact)
The fan relay is on at any time the fan is running. The
relay presents a contact closure that may be used to
activate external air cleaners, humidifiers, etc that should
be active while the fan is running.
Heat relay (24VAC 5A Max dry contact)
The heat relay is on when the thermostat calls for heat.
Alarm relay (24VAC 5A Max dry contact)
The alarm relay provides a dry contact closure that is
used to indicate an alarm condition. The contacts are
closed during an alarm condition.
The alarm relay contacts may be used to activate an
external device to alert the user that an alarm condition
exists.
Alarm conditions include:
• Heat exchanger freeze protection limit exceeded
• Return air temperature is too low
• Exhaust air temperature is too cold
Cooling lockout
If a freeze protect cycle is initiated 3 times within a single
cooling cycle, the system goes into cooling lockout mode.
The cooling cycle is stopped and new cooling cycles are
blocked. The alarm relay is turned on and the LED will
blink an error code.
Freeze protection mode
During cooling the Viessmann AirflowPLUS monitors for
freeze protection.
The A/C delta T rule is used when the return air
temperature is below 60°F (16°C). The difference
between the return air temperature (and the discharge
air temperature) is monitored as an indication of possible
core freezing (A/C delta T). While the A/C delta T exceeds
the threshold the normal modulation control is bypassed.
When the A/C delta T is greater than 24°F (13°C) the
A/C relay is turned off for 5 minutes.
Supply Water Temperature (T1)
Freeze Protection Temperature (T3)
A/C Discharge Air Temperature (T4)
The sensor is mounted at the supply end of the water
heating coil.
The sensor will be mounted above the water heat
exchanger to detect freezing temperatures from the
A/C heat exchanger that could damage the water heat
exchanger. The exhaust air is also monitored during the
cooling mode.
The sensor is installed in the discharge air path of the
Air Handler, downstream of the air handler and/or air
conditioning assembly. Refer to pages 14 and 15.
5680 011 -10
25
Page 26
Installation
Remote Return Air Sensor (T5)
Ambient Sensor (T6)
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Remote sensor installation
Note: If the A/C coil is installed in the return air plenum.
• The remote return air sensor must be installed.
This sensor is then inserted into the return air duct at
a location approximately 15” (380 mm) upstream of
the A/C coil. (Pages 14 and 15)
• Set dip switches as per the system preference.
The remote return air sensor is preinstalled within the
Viessmann AirflowPLUS cabinet complete with a 10 ft.
(3 m) cable lead for remote sensor locations. Remove
the strap from the sensor lead and install in the required
location.
It should be noted that this is a precautionary measure
and is not designed to prevent water line freezing in
situations where the ambient temperatures may get too
low.
The ambient sensor provides air handler operation when
ambient temperatures outside of the air handler cabinet
are less than 40°F (4°C).
The sensor connector is plugged onto the control board
and routed through the cabinet fan tray openings up to
the top panel.
Sensor Locations
Legend
A Supply water temperature
B Ambient temperature
C Return air temperature
D Discharge air temperature
E Remote air temperature (not shown)
26
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Page 27
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Override Settings
Dip switch settings
The dip switch will allow the selection of custom setup
options. Refer to Variable Table for system options.
Maximum heating override
The return air temperature will be monitored for
unreasonably high values. When the upper limit is reached
the unit will override the thermostat and maintain the
temperature at the set value.
Minimum cooling override
The return air temperature will be monitored for
unreasonably low values. When the lower limit is reached
the unit will override the thermostat and maintain the
temperature at the set value.
IMPORTANT
Start-up: Do not power the unit until the water supply
has been connected and the system purged of air. The
circulating pump may come on at anytime. Dry operation
of the pump will damage the pump and void warranty.
Installation
S1 S2 Maximum heating override S3 S4 Minimum cooling override
Off Off 90°F (32°C) Off Off 65°F (15.5°C)
On Off 85°F (29.5°C) On Off 68°F (20°C)
Off On 80°F (26.5°C) Off On 70°F (21°C)
On On 75°F (24°C) On On 72°F (22°C)
The adjustments are made on dip switch interface S1 (refer to the wiring diagram on page 58).
System Select Dip Switch Settings
Four system settings are available. Two for use when the
evaporator is in the supply air stream, two for use when
the evaporator is in the discharge air stream. In each
configuration, the hot water threshold of 85°F or 110°F
(29°C or 43°C) may be selected, this ensures that only
warm air is available during heating operations.
S5 S6 S7 S8 System
OFF ON ON ON Evaporator in Supply Air / 110°F (43°C)
ON OFF OFF OFF Evaporator in Return Air / 110°F (43°C)
ON OFF OFF ON Evaporator in Supply Air / 85°F (29°C)
ON OFF ON OFF Evaporator in Return Air / 85°F (29°C)
The adjustments are made on dip switch interface S1 (refer to the wiring diagram on page 58).
5680 011 -10
27
Page 28
Installation
Door Safety Switch
Viessmann AirflowPLUS AH2A Installation, Operating and Service
The door safety switch is located on the internal center
support panel. Once the lower front panel is removed,
the switch will disconnect power to the control board
and fan motor.
28
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Page 29
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Electrical
Thermostat
Most standard heat/cool, setback, or electronic thermostats
are compatible with the Viessmann AirflowPLUS AH2A
series air handlers.
Thermostat wire from the thermostat is connected to the
screw terminals located on the control board inside the
air handler. They should be connected as follows:
RH, RC – power (24VAC)
W – heating
Y – cooling (if present)
G – continuous run fan (if present on thermostat)
Note: During continuous fan operation, the fan speed will
operate at 40% of the set cooling speed.
IMPORTANT
A/C condenser must be connected to position “AC relay
-Y-C” only. Improper connections will result in loss of
protection functions.
Viessmann AirflowPLUS
Connection Board
Installation
Stage 2 Cool
Stage 1 Heat
5680 011 -10
Stage 1 Cool
Single stage thermostat
field supplied (typical)
24VAC
Fan Speed
Note: Before making the connection to the thermostat for
a two stage cooling function, remove the jumper
across terminals Y1 and Y2 on the Viessmann
AirflowPLUS connection board.
24VAC COM
29
Page 30
Installation
Power Supply
Viessmann AirflowPLUS AH2A Installation, Operating and Service
WARNING
If system components are not grounded, serious injury
from electric current can result if an electrical fault
occurs.
Connect the appliance and pipework to the
equipotential bonding of the building in question.
WARNING
Incorrectly executed electrical installations can lead to
injuries from electrical current and result in appliance
damage.
WARNING
Power connections L and N are not interchangeable.
Main power supply
120VAC, 1Ph, 60Hz, 12A
Main
Disconnect
Switch
External Connections
Internal Connections
>
Power Connection
Terminal
Viessmann AirflowPLUS
Connection Board
Door Safety
Switch
AC Line
PMP
XFO
XFI
ECM
Power
ECM
Control
30
5680 011 -10
Page 31
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Control Inputs
Heating control
A 24VAC input is provided to control the heating
function. When the thermostat calls for heat 24VAC
is applied to the W contact and a heating cycle will be
initiated.
Note: the heating cycle control will be ignored while a
cooling cycle is in progress.
If the heating control is turned off during the initial heat
exchanger warm up or during the fan cycle up to speed
the heat mode will be terminated with a short run period
for the fan prior to shutting down.
When thermostat changes off to on:
Initially pump speed is active, Fan is off. Provide time for
heating coil to warm up. After 15 sec. the fan will active at
normal operating speed as set up by the selected dip switch
settings. See setting fan speed pages 32, 33 and 34.
Cooling control
A 24VAC input is provided to control the cooling function.
When the thermostat calls for cooling 24VAC is applied
to the Y contact and a cooling cycle will be initiated.
Note: the heating cycle control will be ignored while a
cooling cycle is in progress.
If the cooling control is turned off during the fan cycle up
to speed period the cool mode will be terminated without
an end of cycle fan period.
Installation
Thermostat fan on/auto control
The 24VAC Thermostat Fan On/Auto input will select the
fan operation. When the thermostat is in the Auto state
the fan will be off while not heating/cooling. In the fan ON
position, 24V is applied to the G contact and the fan will
run at the lowest speed while not heating/cooling. During
a heating cycle the fan is always off during the initial heat
exchanger warm up period.
5680 011 -10
31
Page 32
Installation
Setting Fan Speed
Heat Fan Speed Switches 1 & 2
OFF OFF 1050
ON OFF 825
OFF ON 675
ON ON 550
Adjust Fan Speed Switches 3 & 4
OFF/OFF ON/OFF OFF/ON OFF/OFF ON/OFF OFF/ON
Heating CFM 1050 1155 924 825 910 726
Cooling CFM 1175 1290 1034 925 1010 814
Heating CFM 675 740 594 550 605 484
Cooling CFM 750 825 660 600 660 528
Viessmann AirflowPLUS AH2A Installation, Operating and Service
AH2A-213 Viessmann AirflowPLUS Air Handler
1/3 hp ECM - air flow selectable options
Set at dip switch S2.
Cool Fan Speed Switches 5 & 6
OFF OFF 1175
ON OFF 925
OFF ON 750
ON ON 600
Cool Fan Speed Profiles Switches 7 & 8
Pre-Run
Time Min.
OFF OFF 5 82 2 88 2 75
ON OFF 382288275
OFF ON 2 82 - - 4 75
ONON----475
Note: Power to the Viessmann AirflowPLUS air handler must be turned off before changing switch settings.
The above values are approximations only, actual results may vary.
Note: Factory switch set positions are shown in bold.
Motor % Short Run
Time Min.
Motor % Motor OFF
Time Min.
Motor %
32
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Page 33
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Setting Fan Speed
Heat Fan Speed Switches 1 & 2
OFF OFF 1300
ON OFF 980
OFF ON 675
ON ON 760
OFF/OFF ON/OFF OFF/ON OFF/OFF ON/OFF OFF/ON
Heating CFM 1300 1430 1140 980 1050 860
Cooling CFM 1640 1804 1440 1270 1400 1100
Heating CFM 760 830 660 760 830 660
Cooling CFM 980 1050 860 740 800 650
(continued)
AH2A-354 Viessmann AirflowPLUS Air Handler
1/2 hp ECM - Air Flow Selectable Options
Set at dip switch S2.
Adjust Fan Speed Switches 3 & 4
Installation
Cool Fan Speed Switches 5 & 6
OFF OFF 1640
ON OFF 1270
OFF ON 980
ON ON 740
Cool Fan Speed Profiles Switches 7 & 8
Pre Run
Time Min.
OFF OFF 5 82 2 88 2 75
ON OFF 382288275
OFF ON 2 82 - - 4 75
ONON----475
Note: Power to the Viessmann AirflowPLUS air handler must be turned off before changing switch settings.
The above values are approximations only, actual results may vary.
Note: Factory switch set positions are shown in bold.
Motor % Short Run
Time Min.
Motor % Motor OFF
Time Min.
Motor %
5680 011 -10
33
Page 34
Installation
Setting Fan Speed
Heat Fan Speed Switches 1 & 2
OFF OFF 1650
ON OFF 1590
OFF ON 1470
ON ON 1320
OFF/OFF ON/OFF OFF/ON OFF/OFF ON/OFF OFF/ON
Heating CFM 1650 1800 1480 1590 1750 1430
Cooling CFM 1875 2060 1680 1730 1900 1560
Heating CFM 1470 1620 1320 1320 1450 1180
Cooling CFM 1620 1780 1450 1500 1650 1350
(continued)
Adjust Fan Speed Switches 3 & 4
Viessmann AirflowPLUS AH2A Installation, Operating and Service
AH2A-385 Viessmann AirflowPLUS Air Handler
3/4 hp ECM - Air Flow Selectable Options
Set at dip switch S2.
Cool Fan Speed Switches 5 & 6
OFF OFF 1875
ON OFF 1730
OFF ON 1620
ON ON 1500
Cool Fan Speed Profiles Switches 7 & 8
Pre-Run
Time Min.
OFF OFF 5 82 2 88 2 75
ON OFF 3 82 2 88 2 75
OFF ON 2 82 - - 4 75
ON ON - - - - 4 75
Note: Power to the Viessmann AirflowPLUS air handler must be turned off before changing switch settings.
The above values are approximations only, actual results may vary.
Note: Factory switch set positions are shown in bold.
Motor % Short Run
Time Min.
Motor % Motor OFF
Time Min.
Motor %
34
5680 011 -10
Page 35
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Quick Check
Startup
WARNING
This appliance is not intended for installation in a
non conditioned space where the potential may exist
for the water and or drain lines to freeze.
1. Is the purge valve installed on the return line from the
air handler upstream from the isolation valve?
2. Is the air handler hung and isolated to avoid
transmitting vibration through framing and duct work?
3. Full port isolation valves MUST be provided.
Restrictive valves will limit performance.
4. Is outdoor cooling unit contactor wired to
screw terminals on controller to provide hard-start
protection?
5. Are thermostat connections correct, including cooling
and continuous run connections?
6. Have the packing materials been removed from the
blower and the pump?
Pre-start Checklist
7. Is there an installation manual for the home owner?
8. Is the unit accessible? Are there clearances for service
and component replacement?
9. Is the discharge air stream sensor mounted
downstream of the cooling coil?
10. Is the remote return sensor installed upstream of the
A/C coil if the A/C coil is in the return air duct?
Refer to page 16.
11. Are the supply plenum and return duct/drop
acoustically lined? [at least 6 ft. (1.8 m)] of the return
duct/drop must be lined in addition to the supply
plenum).
12. Is the filter cover in place? Is a clean filter in place?
Is the supplied filter rack installed?
13. If this appliance is installed with air conditioning, the
A/C refrigerant charge and system operation must be
verified by a certified/ licensed mechanic prior to
commissioning.
1) REMOVE PACKING MATERIALS FROM LEFT SIDE OF BLOWER
2) ONLY IN HORIZONTAL CONFIGURATIONS REMOVE THE PACKING IN THE WATER LINE.
3) BLEED ALL AIR FROM WATER LINES
4) BLEED AIR FROM END OF CIRCULATOR AT SLOTTED BLEED SCREW GENTLY OPEN BLEED SCREW ABOUT
1/2 TURN UNTIL AIR BLEEDS OUT ENSURE WATER DOES NOT LEAK ONTO CONTROL BOARD IN FAN
COMPARTMENT
5) DISCHARGE AIR SENSOR INSTALLED DOWNSTREAM OF A/C COIL WHEN A/C COIL INSTALLED IN SUPPLY
DUCT DOWNSTREAM OF AIR HANDLER. REFER TO INSTALLATION INSTRUCTIONS.
OR
REMOTE RETURN AIR SENSOR INSTALLED UPSTREAM OF A/C COIL
IF COIL IS INSTALLED IN RETURN AIR DUCT, UPSTREAM OF AIR HANDLER.
OR
IF A/C COIL IS INSTALLED IN RETURN AIR DUCT UPSTREAM OF AIR HANDLER,
AIR FILTER IS INSTALLED UPSTREAM OF A/C COIL
6) INITIATE CALL FOR HEAT,
PUMP TURNS ON
FAN TURNS ON
7) DISCONNECT POWER TO OUTDOOR CONDENSER. INITIATE CALL FOR COOLING, ONCE FAN IS
RUNNING, CONFIRM 24 VOLT OUTPUT AT Y AND C AT COM RELAY ON MAIN CONTROL.
RECONNECT POWER IF TEST SUCCESSFUL
8) CANCEL CALL FOR COOLING APPROXIMATELY 1 MINUTE LATER, FAN TURNS OFF
5680 011 -10
35
Page 36
Startup
Startup Procedure
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Do not start the air handler or BOILER until ALL Air has
been purged from water lines and air handler pump!
1. Fill the boiler loop with water, but do not start it.
2. Purge all air from the heating boiler.
3. Purge all air from the space-heating loop by closing the
isolation valve on the return leg of the loop and open
the drain to purge air. Open the return leg isolation
valve and then close the drain valve.
4. When there is no bleed screw, we recommend running
on high speed #3 for approximately b to 1 minute.
If this does not work and you can still hear a
‘swooshing/swirling’ at the pump, then attempt to
pulse the air out of the pump by going back and forth
between high speed and low speed, 10 seconds on
each speed for about 1 minute and that should
eliminate the air within the pump.
Air Handler LED Indications for Temperature
Temperature for 5 sensors
The Air Handler allows the attachment of up to five
sensors.
The LED sequence for displaying five sensors uses a
bicolor LED to indicate the sensor number followed by the
sensor temperature reading. The sequence starts with a
one red blink to indicate sensor T1, this is followed by
the temperature indication using green blinks as described
above. This is followed by a 2-blink red LED indication
for system select. This is followed by a 3 blink red LED
indication for sensor T3. This is followed by the T3
temperature reading using green blinks. This continues up
to 6 red blinks indicating the reading for sensor T6. After
a short delay sequence begins again with 1 red blink.
For example, if sensor T1 is reading 59°F (15°C) and
sensor T3 is reading 75°F (24°C) the sequence will start
with 1 red blink (sensor T1), 1 green blink, 5 green blinks,
2 red blinks (sensor T3), 2 green blinks, 4 green blinks.
The sequence will continue to indicate the temperature, or
status, of sensor T4 through T6.
5. Start the boiler according to the instructions provided
with the boiler. Set the design water temperature and
wait for the system to shut off.
6. Turn on the power to the air handler and set the room
thermostat for heat to energize the fan and pump.
If a gurgling sound is present, it should subside within
one minute. If noise is still present after one minute,
repeat step 3 to purge air as necessary.
7. Check supply and return pipes for temperature
differences to make sure there is flow. There should
be a noticeable difference in temperature between
supply and return lines.
Normal temperature indication
The LED will blink to indicate temperatures between
32°F and 176°F (0°C and 80°C). When the temperature
is below 32°F (0°C) it will indicate 0°C. When the
temperature is above 176°F (80°C) it will indicate 80°C.
Refer to page 38 for fahrenheit conversion.
The temperature is indicated by blinking the most
significant digit followed by the least significant digit. If
the temperature is 79°F (26°C) the led will blink 2 times,
short delay, then 6 times.
When the least significant digit of the temperature is
32°F (0°C), the blink indication will substitute 1. If the
temperature is 86°F (30°C) the LED will blink 3-1, if it is
122°F (50°C) it will blink 5-1.
If the temperature is between 32°F and 48°F (0°C and
9°C), the LED will blink only the least significant digit,
that is, if the temperature is 43°F (6°C) the LED will only
blink 6 times. If the temperature is 32°F (0°C), a 1 will
be substituted, and the LED will blink 1 time.
36
5680 011 -10
Page 37
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Installing Connection Board
Installing connection board with hinged cover
1. Close connection board cover.
2. Secure cover with the retaining screws.
3. Slide in blower assembly.
4. Reinstall retaining screw.
OR
Installing connection board with removable cover
1. Install the connection board cover.
2. Secure cover with retaining screw.
3. Slide in blower assembly.
4. Reinstall retaining screw.
Startup
Installing the Access Panels
1. Set the top of the upper front cover in place and
slide up.
2. Reinstall retaining screws.
3. Set the bottom of the lower front panel in place and
slide up.
4. Reinstall retaining screws.
5680 011 -10
37
Page 38
Operation
Indicators
Flashing LED
Viessmann AirflowPLUS AH2A Installation, Operating and Service
A bicolour LED is used as a system status indicator to
indicate alarm, test mode, normal operation, etc.
The indicator will display the temperature sensor values
during normal operation. When abnormal behavior is
noted the LED will display an indication to indicate the
condition.
°F = °C x 1.8 + 32
e.g. 24 x 1.8 + 32 = 75.2°F
During normal operating mode the LED will blink to
indicate the temperature reading of the five sensors.
The LED will blink RED to indicate the sensor number.
It will then blink the temperature in GREEN.
All temperature readings are in Celsius. Example, while
sensor T3 is reading 75°F (24°C) the LED will blink
RED 3X then GREEN 2X then GREEN 4X then RED 4X
followed by the reading for the next sensor.
LED flash code will indicate the sensor location in RED
and temperature in GREEN.
e.g. 3RED then 2GREEN, pause, 4GREEN = Sensor T3 is
75°F (24°C)
• An 8RED then 8RED flash indicates a bad reading or
defective sensor, this may repeat several cycles.
Note: If a defective sensor is present, the audible alarm
will sound. For corrective action refer to
troubleshooting.
Sensor 1 should see GREEN flashes of 4GREEN – 3GREEN
110°F (43°C) to 8GREEN –2GREEN 180°F (82°C)
depending on the temperature of the hot water source.
With 120°F (49°C) to 180°F (82°C) entering water
the reading would be 3GREEN – 6GREEN 97°F (36°C)
to 7GREEN – 1GREEN 160°F (71°C), after the correct
number of red flashes to indicate the sensor #.
Refer to page 25 and 26 for sensor numbers and
description.
Anytime a fault condition exist, the specific fault
condition will be displayed represented by a specific LED
flash code (refer to page 42) approximately 2 seconds
after the display of temperature reading for temperature
sensor T6.
Normal Operation
Heating mode
On a call for heat from the thermostat, the circulating
pump will turn on. Giving the pump 15 sec. to heat the
coil, the fan will activate heating the home until the
thermostat is satisfied.
Once the thermostat is satisfied, the circulating pump
will shut down and fan will continue to run for 2 min.
During the heating cycle the hot water temperature is
monitored. If the hot water temperature drops below
a threshold the fan will be turned off. The hot water
temperature continues to be monitored after the fan
is shut off. When the temperature rises to 10°F (6°C)
above the selected threshold the fan will be restarted.
The threshold may be set according to the system select
switch. The threshold may be set at 110°F or 85°F
(43°C or 29°C)
38
Cooling mode
On a call for cooling from the thermostat, if the fan is on,
it will turn off and the A/C relay will be energized. The
outdoor condenser will turn on and flood the evaporator
coil with refrigerant. The fan will turn on and deliver cool
air to the system. After approximately 5 min. (this gives
the condenser and coil time to normalize pressures), the
microprocessor control will cause multiple fan speed
adjustments in order to target the latent load first
(humidity) before speeding up to capture the sensible
load. Sensor feedback allows this enhanced blower
fan feature to protect the outdoor unit from refrigerant
slugging caused by lower fan speeds, dirty filters, poor
duct design or poor installations.
Summary
In heating mode, most error codes and/or improper
unit operation are caused by too low of supply water
temperature or sensors not installed correctly. Cooling
mode errors are caused by too low or too high of
refrigerant charge or gross over sizing of equipment.
5680 011 -10
Page 39
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Operation
External Heat Demand via Switching Contact - Boilers equipped with HO1B User Interface
Contact closed:
Set address 3A to 3A:2, for external demand upon
closure of DE1.
• The burner is switched ON subject to load. The boiler
heats to the set boiler water temperature selected in
coding “9b” in the “General” group.
Limiting the boiler water temperature by means of the
set boiler water temperature and the electronic
maximum limit of the boiler water temperature
(coding “06” in the “Combustion Controller” group)
Heating System Operation - Vitodens 100 WB1B
Note: When using the RT connection, refer to the wiring
Factory
default
diagram on page 22.
Room dependent control:
Outdoor temperature sensor not connected
With no outdoor sensor installed, the “tr” dial will
provide a constant temperature set-point for the boiler
based on the dial position selected.
Setting the dial between 1 and 6 will provide a set-point
value of 81°F to 178°F (27°C to 81°C) respectively. The
dot between 4 and 5 represents the factory default setpoint value of 140°F (60°C).
Boiler water or supply temperature
Outside temperature
Legend
A Selector dial “tr” setting: 1
B Selector dial “tr” setting: 2
C Selector dial “tr” setting: 3
D Selector dial “tr” setting: 4
E Factory default
F Selector dial “tr” setting: 5
G Selector dial “tr” setting: 6
5680 011 -10
Weather dependent control
Outdoor temperature sensor connected
With the outdoor sensor connected, the boiler will
automatically recognize the sensor and switch the setpoint dial operation from constant temperature calculated
to outdoor reset calculated.
Adjusting the “tr” dial will select the heating curve
corresponding with the heating curve chart. The setpoint will be calculated from the design boiler water
temperature associated with the heating curve selected,
and reset from the actual outdoor air temperature. Setting
the dial between 1 and 6 will select the corresponding
curve from the chart. The dot between 4 and 5 is the
factory default curve.
The display “tr” indicates when a heat request has
been made.
Note: When using the weather compensated operation,
ensure that the minimum temperature of the
selected heating curve exceeds minimum entering
water temperature set on page 27 ‘System Select
Dip switch Settings’.
39
Page 40
Operation
DHW Contact for Air Handler - Vitodens 100 WB1B
Note: This is not applicable for Vitodens 100 WB1B
boilers equipped with CombiPLUS or DHW storage tank.
Viessmann AirflowPLUS AH2A Installation, Operating and Service
If the Viessmann AirflowPLUS air handler is installed
with a Vitodens 100 WB1B boiler in a multi zone system.
Without DHW, the DHW contact of the boiler can be
used as a second temperature setpoint for the air handler.
When the air handler call for heat closes, the boiler supply
temperature will automatically adjust to 172°F (78°C).
There is no adjustment available for this temperature set
point.
When using the domestic hot water contact, the display
shows “ ”, during a call for heat from the Viessmann
AirflowPLUS.
Dial setting
0-6 boiler supply water temperature automatically
adjusted to 172°F (78°C) regardless of dial setting.
40
5680 011 -10
Page 41
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Illuminated Alarm Indicator
• All Viessmann AirflowPLUS AH2A series air handlers
are equipped with a housing mounted Illuminated alarm
indicator. This indicator light illuminates any time the
control mounted alarm relay is activated.
• The control mounted alarm relay is turned on under
the following circumstances.
1) Home freeze protect
Automatic Home Freeze Protection is initiated when the
ambient air temperature reads lower than 40°F (4°C).
During this time the alarm relay and heat cycle are turned
on until the ambient temperature rises above 54°F (12°C).
2) Heat exchanger freezing protection control.
The system is protected from damage that may occur due
to freezing during an A/C cycle. The system will enter a
freeze protect cycle under the conditions described below.
During the freeze protect cycle the fan and pump will run
at high speed and the A/C relay will turn off. The system
will run in this state for five minutes and then return to
normal operation. While the unit is in freezing protection
mode, the alarm relay will be activated.
If the freeze protection sensor is below limit freeze
protection is initiated. The limit is 57°F (14°C) for
systems with the evaporator in the supply air stream,
and 43°F (6°C) for systems with the evaporator in the
return air stream. Freeze protect is also initiated when
the discharge air temperature is less than 41°F (5°C) ,
the unit will go into freeze protection mode.
3) Cooling lockout
If the A/C coil Freeze Protect Cycle (2 above) is
initiated three times within the same cooling cycle,
the system goes into Cooling Lockout Mode. During
this time the cooling cycle is disabled and new cooling
cycles are blocked. The cooling cycle can only be
reintroduced by cycling the power to the air handler,
off and on. During this lockout mode the air handler
Legend
A Ambient air temperature sensor
B Indicator light
control audible alarm will also sound.
4) Temperature sensor failure
If a sensor has a bad read, or is malfunctioning, the LED
will blink RED 8X-8X rather than the green temperature
reading. This 8X blink may repeat. Be sure to cycle
through all sensors at least three times to determine is
a sensor is faulty.
Service
Audible Alarm Indicator
Enabled Sound Error
Immediately 4 beeps A/C locked out after three successive freeze protect cycles
After 24 h 2 beeps One or more bad temperature sensors
After 10 min 1 beep low ambient temperature
5680 011 -10
Certain error conditions enable a beep code output. The
beep code repeats every 8 min. after it is enabled. Some
conditions have the beep enabled immediately, others are
not enabled until the unit has been on for at least 24 hours.
This allows the beeping to be cancelled by cycling power.
For service, note the beep condition before cycling power.
41
Page 42
Service
Alarm Relay and LED Fault Codes
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Control LED flash codes
A visual display is provided by the housing mounted LED.
This display advises of the current status of the air handler
behavior and its environment should unusual conditions
exist. Refer to the chart below. When multiple flash codes
are being displayed, they will be displayed in the following
order:
Flash Code Explanation Cause
RRR Cooling Lockout Page 41
RRG Freeze protect cycle in process Page 41
GRR A/C Delta exceeded 3 times Page 41
RGR High A/C coil delta Page 25
RGG Low ambient temperature Page 41
R = Red
G = Green
Alarm
Alarm Relay is on when an unusual condition is detected.
The connector is a two terminal connector that provides
a contact closure when the Alarm Relay is on. The alarm
beeper may be silenced for 24 hr. (if sounding due to a
defective sensor) by turning power to the unit off and
then on. If the condition still exists after 24 hr. the alarm
will be activated again.
It can be silenced again by turning power to the unit off
and on. An alarm condition does not mean the unit is
not working, it just means the information the control is
receiving does not meet specifications. These conditions
could be cool supply water, discharge air temperature too
cold, room air too cold, etc.
The alarm will shut off when the condition is corrected.
Note: There must be 1 sensor on all inputs in the proper
locations. If A/C coil is in the return air plenum then
the return MUST be installed on the board at the
RETURN AIR receptacle with the sensor lead
end located 15” (381 mm) upstream of the A/C
coil in the return air duct.
The discharge air sensor (supplied) shall be
installed downstream of the heating coil in
the supply air ductwork and attached to the
DISCHARGE AIR receptacle location on the
control.
Refer to pages 25 and 26 for detailed sensor information.
Alarm Buzzer
Sounding
YES 3 flashes
YES 4 flashes
YES 1, 3, 4, 5 or 6
YES 1, 3, 4, 5 or 6
RED LED Sensor
Indication
(Freeze Sensor)
(Discharge Air Sensor)
flashes
flashes
Followed
by:
LED
Flash Code
7 green flashes,
then 7 green flashes
7 green flashes,
then 7 green flashes
8 red flashes,
then 8 red flashes
8 red flashes,
then 8 red flashes
Temperature Sensor RED LED Flash Code Identification
1 Flashes Water In Temperature Sensor
3 Flashes Water Coil Freeze Temperature Sensor
4 Flashes Discharge Air Temperature Sensor
5 Flashes Return Air Sensor
6 Flashes Ambient Temperature Sensor
Reason
Water coil Freeze Sensor temperature or
Discharge Air Sensor limit exceeded –
inadequate air flow, A/C locked on.
Water coil Freeze Sensor temperature or
Discharge Air Sensor limit exceeded –
inadequate air flow, A/C locked on.
Temperature Sensor misread,
wait for next indication.
Failed Temperature Sensor.
Replace.
42
5680 011 -10
Page 43
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Checking ECM (DC) Fan Motor Connections
Service
ECM Motor Control
Connector
(female)
Control
(male)
Pin number
1 Common C1
2 W/W1
3 Common C2
4 Delay tap select
5 Cool tap select
6 Y1
7 Adjust tap select
8 Output 9 Return (reversing) valve (heat pump only)
10 Humidistat (BK)
11 Heat tap select
12 24VAC (R)
13 2nd stage heat (EM/W2)
14 2nd stage cool (Y/Y2)
15 Fan (G)
16 Output +
Note: The fan motor operates independent of the
controller temperature control logic. Externally
installed temperature sensors operate as system
safeties only.
5680 011 -10
43
Page 44
Service
Troubleshooting
Power is on at the air handler.
Air handler ambient air sensor
is activated by a temperature,
less than 40°F (4°C).
The red light is illuminated
on the housing.
The internal pump and
circulation fan is running.
Yes
Yes
Yes
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Pump does not run
Often, closing the isolation valve on the return leg and
opening the drain port so that water flows through the
pump can free the pump. For the integrated Grundfos
pumps, remove the screw-on cover from the face of
the pump, and rotate the shaft one turn with a slotted
screwdriver.
If either method fails to free the pump, removal for cleaning
or replacement is necessary. The pump exercise function
will help prevent pump seizing.
Pump is noisy at start-up
Air is present in heating loop. If sound has not diminished
within 1 minute, purge air in accordance with the Start-Up
procedures.
Insufficient or no heat
- Plugged air filter or coil. Refer to Maintenance section
for filter care and coil cleaning.
- Air in heating loop; purge system.
- Inlet and outlet connections to air handler backwards;
reverse connections.
- Supply water temperature set too low or not calibrated
properly; check water temperature.
- Restriction in heating loop; remove restrictions, check
valves stick, valves too restrictive, left partially closed
after purging or closed valve.
Yes
The air handler is in home freeze
protect mode. Once return air
exceeds 45°F (7°C), pump, fan
and red light will turn off.
Fan runs for cooling but not for heating
Room thermostat may be connected improperly.
Heating during standby mode
Probable cause is thermal Siphoning. See check valve
description for details; repair or replace check valve.
Home freeze protection
This sequence is initiated by extreme low air temperatures
[less than 40°F (4°C)] and are detected by the ambient
air temperature sensor.
44
5680 011 -10
Page 45
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Troubleshooting (continued)
Service
The air handler internal water coil
freeze sensor T3 is activated
by low air temperature.
Yes
Housing mounted LED
is illuminated.
Yes
Internal pump and circulation
fan running at high speed for
5 minutes, A/C compressor
is disabled for 5 minutes.
Yes
Cooling cycle restarts after
5 minute delay
Yes
Water coil freeze protection
This sequence is initiated by extreme low air temperatures
crossing over the freeze protection sensor located directly
above the air handler water coil.
Yes
The air handler internal water coil
freeze sensor T3 is activated
by low air temperature.
Continue
Check for poor air flow,
restrictions, plugged filters,
low refrigerant charge
Continue
3 protect cycles occur in a single
cooling cycle, cooling cycle is
inhibited, sensor T3 indicates 7
green-7 green, alarm buzzer ON
Yes
Refer to cooling lockout chart.
.
5680 011 -10
45
Page 46
Service
Troubleshooting
Viessmann AirflowPLUS AH2A Installation, Operating and Service
(continued)
Power is on at the air handler.
Yes
The air handler internal water
coil freeze sensor is activated by
three extreme low temperature
cycles. Alarm buzzer sounds
continuously.
Yes
The red light is illuminated
on the housing.
Yes
Observe each sensor code and
record related flash codes as
shown on the housing mounted
LED. Refer to page 42.
Cooling lockout
This feature is initiated if three freeze protect cycles occur
within a single cooling cycle or, if three freeze cycles
occur when a cooling cycle is not in progress.
A freeze protect cycle is when the air handler integral
A/C coil freeze sensor is triggered by unacceptably low
discharge air temperatures.
Yes
Sensor T3 flash code indicates
7 green then 7 green.
Buzzer is also ON.
Yes
The alarm buzzer can be silenced
by cycling the power to the
air handler OFF then ON.
Continue
Cooling lockout active, cooling
can only be reactivated by cycling
the power OFF and then ON.
Continue
Inadequate air flow, plugged filter,
extreme ESP, low refrigerant.
No
Outdoor ambient or
thermostat set too low.
46
5680 011 -10
Page 47
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Troubleshooting
(continued)
Service
Power is on at the air handler
for more than 24 hours.
Yes
The alarm buzzer is on.
Yes
The red housing mounted
LED is illuminated after
5 minutes of power on.
Yes
The housing mounted LED will
flash an error code. Record
colors and number of flashes
(5 cycles/min). Refer to chart
on page 42 for identification.
No
Temperature sensor failure identification
Temperature sensor failure is identified by viewing the
housing mounted LED.
Continue
If 8 red flashes followed by
8 red flashes repeats after
a specific sensor, then
replace that sensor.
Continue
Note: the alarm buzzer can be
silenced for 24 hours by
cycling the power to the
air handler OFF then ON.
5680 011 -10
47
Page 48
Service
Service and Maintenance
Resistance in k Ohms
Temperature sensors
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Checking temperature sensor
1. Remove cables from temperature sensor.
2. Check the sensor resistance and compare the actual
values with the curve in the chart.
3. Replace sensor in case of severe deviation.
Uninstalled sensors
Systems may elect to not use one, or more, of the five
sensors. In this case, the absent sensor temperature is
replaced by one long green blink following the red sensor
number blinks.
Coils
The heating coil should not require cleaning if the filter
maintenance schedule is adhered to. If a filter is damaged
or collapses from plugging, dust may foul the coils. If this
happens, remove the front covers, replace the filter and
carefully vacuum the bottom of the heating coil. During
this process, avoid dust from falling into the fan below.
Failed Sensors
When a sensor is incorrectly installed or defective,
the LED indication will substitute red 8-8 for a normal
temperature reading. The alarm beeper will also beep
periodically to indicate a problem. The alarm beeper will
sound for 1 minute after power on and then stop.
In normal operation, after installation, the alarm beeper
will sound to indicate a failed temperature sensor. The
alarm may be silenced for 24 hours by cycling the power
on the unit. Note that the beeper will sound for the first
minute after cycling power and then remain silent for 24
hours.
Air filter
The Viessmann AirflowPLUS AH2A series of air handlers
are provided with a disposable filter media. This filter
should be inspected monthly and removed and replaced
as required.
Circulator
The circulator is water lubricated and should require no
regular maintenance. The system control has a pump
exercise function during prolonged periods of no heat
to avoid seizing from long idle periods.
48
5680 011 -10
Page 49
Viessmann AirflowPLUS AH2A Installation, Operating and Service
System Layout 1
Additional Information
Legend
A Vitocrossal 300 CU3A high mass boiler
B System fill with expansion tank
C Viessmann AirflowPLUS air handler
D Thermostat (field supplied)
E Indirect fired DHW storage tank
Refer to page 24 for the Viessmann AirflowPLUS
connection to external heat demand of the boiler.
IMPORTANT
Please note location of expansion tank.
Sizing of field-supplied pumps are critical for proper
boiler operation in this system layout. An undersized
pump may cause short-cycling and/or improper operation
of the boiler.
5680 011 -10
49
Page 50
Additional Information
System Layout 2
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Legend
A Vitocrossal 300 CU3A high mass boiler
B System fill with expansion tank
C High temperature heating loop
D Viessmann AirflowPLUS air handler
E Thermostat (field supplied)
F Low temperature heating loop with mixing valve
G Indirect fired DHW storage tank
H Low loss header (or closely spaced tees)
Refer to page 24 for the Viessmann AirflowPLUS
connection to external heat demand of the boiler.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter) is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
System separation is required of underfloor heating
systems employing non-oxygen diffusion barrier tubing.
All components on the secondary side of the heat
exchanger must be made of corrosion-resistant materials.
The 3-way mixing valve, built-in to achieve the low
temperature level of the under floor heating circuit, is
controlled by an accessory kit for a heating circuit with
mixing valve.
50
5680 011 -10
Page 51
Viessmann AirflowPLUS AH2A Installation, Operating and Service
System Layout 3
Additional Information
Legend
A Vitodens 222-F B2TA/B boilers
B System fill with expansion tank
C High temperature heating loop
D Viessmann AirflowPLUS air handler
E Thermostat (field supplied)
F Low temperature heating loop with mixing valve
G Low loss header (or closely spaced tees)
Refer to page 24 for the Viessmann AirflowPLUS
connection to external heat demand of the boiler.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter) is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler, or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
System separation is required of underfloor heating
systems employing non-oxygen diffusion barrier tubing.
All components on the secondary side of the heat
exchanger must be made of corrosion-resistant materials.
The 3-way mixing valve, built-in to achieve the low
temperature level of the under floor heating circuit, is
controlled by an accessory kit for a heating circuit with
mixing valve.
5680 011 -10
51
Page 52
Additional Information
System Layout 4
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Legend
A Vitodens 200 B2HA/B boilers
B System fill with expansion tank
C High temperature heating loop
D Viessmann AirflowPLUS air handle
E Thermostat (field supplied)
F Low temperature heating loop with mixing valve
G Indirect fired DHW storage tank
H Low loss header (or closely spaced tees)
Refer to page 24 for the Viessmann AirflowPLUS
connection to external heat demand of the boiler.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter) is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler, or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
System separation is required of underfloor heating
systems employing non-oxygen diffusion barrier tubing.
All components on the secondary side of the heat
exchanger must be made of corrosion-resistant materials.
The 3-way mixing valve, built-in to achieve the low
temperature level of the under floor heating circuit, is
controlled by an accessory kit for a heating circuit with
mixing valve.
52
5680 011 -10
Page 53
Viessmann AirflowPLUS AH2A Installation, Operating and Service
System Layout 5
Additional Information
Legend
A Vitodens 100 WB1B boiler
B System fill with expansion tank
C Viessmann AirflowPLUS air handler
D Thermostat (field supplied)
E Switching relay heating and DHW control (field supplied)
F Indirect fired DHW storage tank
G Closely spaced tees (optional LLH accessory)
Refer to page 22 for the Viessmann AirflowPLUS
connected in parallel with heating circuit demand to
‘RT’ connection.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter) is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler, or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
If the heating system does not include a DHW storage
tank connected to the boiler the DHW demand contacts
of the boiler may be connected to the Viessmann
AirflowPLUS heat demand, use the DHW temperature
set point to set the desired supply temperature to the air
handler.
5680 011 -10
53
Page 54
Additional Information
System Layout 6
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Legend
A Vitodens 100 WB1B boiler with CombiPLUS
B System fill with expansion tank
C High temperature heating loop
D Viessmann AirflowPLUS air handler
E Thermostat (field supplied)
F Switching relay heating circuit control (field supplied)
G Low loss header (or closely spaced tees)
Refer to page 22 for the Viessmann AirflowPLUS
connected in parallel with heating circuit demand to
‘RT’ connection.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter) is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler, or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
54
5680 011 -10
Page 55
Viessmann AirflowPLUS AH2A Installation, Operating and Service
System Layout 7
Additional Information
Legend
A Vitocrossal 300 CU3A high mass boiler / Vitodens
200 B2HA/B boilers (shown)
B System fill with expansion tank
C High temperature heating loop
D Viessmann AirflowPLUS air handler
E Thermostat (field supplied)
F Low temperature heating loop with mixing valve
G Indirect fired DHW storage tank
H Low loss header (or closely spaced tees)
Note: For installations with multiple air handler units,
the call for heat from each air handler must be
connected in parallel to the boiler demand.
Note: The low loss header is optional with the Vitocrossal
300 CU3A boiler.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler, or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
System separation is required of underfloor heating
systems employing non-oxygen diffusion barrier tubing.
All components on the secondary side of the heat
exchanger must be made of corrosion-resistant materials.
The 3-way mixing valve, built-in to achieve the low
temperature level of the under floor heating circuit, is
controlled by an accessory kit for a heating circuit with
mixing valve.
5680 011 -10
55
Page 56
Additional Information
System Layout 8
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Legend
A Vitodens 200 B2HA/B boilers
B System fill with expansion tank
C Thermostat (field supplied)
D Viessmann AirflowPLUS air handler
E Low loss header (or closely spaced tees)
Refer to page 24 for the Viessmann AirflowPLUS
connection to external heat demand of the boiler.
IMPORTANT
The use of a low-loss header (or closely spaced tees
with a maximum spacing of 4X pipe diameter) is strongly
recommended if the maximum water flow rate in the
application concerned exceeds the maximum or minimum
flow rates of the boiler, or if the system flow rates are
unknown.
The low-loss header is available as accessory part.
Please note location of expansion tank.
Sizing of field-supplied pumps are critical for proper boiler
operation in this system layout. An undersized pump may
cause short-cycling and/or improper operation of the boiler.
56
5680 011 -10
Page 57
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Technical Data
Description AH2A-213 AH2A-354 AH2A-385
Motor (ECM) hp
Electrical VOLTS/PH/HZ 120/1/60 120/1/60 120/1/60
Heating BTUH
(kW)
Flow USG/min
Nominal (CFM) Heating .5” e.s.p.
Cooling capacity (tons) 1.5 - 3.0 2.50 - 4.0 3.5 - 5.0
Cabinet D x W x H* in.
Supply air opening in.
Return air opening in.
Weight lb.
Circulating pump
Type Grundfos 15/58RU
Volts AC 115 115 115
Motor horsepower hp 1/25 1/25 1/25
Capacitor MFD/VOLTS 10/180 10/180 10/180
Motor rated amps - loaded AMPS 0.74 0.74 0.74
- locked rotor AMPS 4.44 4.44 4.44
Maximum working pressure PSI 145 145 145
Min./max. fluid temperature ºF
Hydronic heating coil
Construction Copper tubing, aluminum fins, galvanized steel support frame
Rows...fins/in. 3...12 3...12 3...12
Total face area sq. ft. (m
Piping connections
Supply in.
Return in.
Pressure drop through the coil feet of head
* Using the adjustable levelling feet can add up to 1b” (38 mm) to the height of the air handler.
120°F (49°C) 28,000
140°F (60°C) 46,000
160°F (71°C) 62,000
180°F (82°C) 72,000
(L/H)
Cooling .5” e.s.p.
Heating .2” e.s.p.
Cooling .2” e.s.p.
22c x 18 x 32b
(mm)
(578 x 457 x 825)
(mm)
(mm)
kg
(ºC)
2
) 1.3 (0.12) 2.8 (0.26) 2.8 (0.26)
[@ 160°F (71°C)
supply water
temperature]
gbc
(8)
(13)
(18)
(21)
3
(681)
600
700
1,100
1,200
23 x 22 x 34b
(584 x 559 x 876)
16 x 20
(406 x 508)
14 x 18
(356 x 457)
85
(39)
120/200
(49/93)
b FIP c FIP c FIP
b FIP c FIP c FIP
12 2 2
(508 x 508)
(457 x 457)
Additional Information
44,000
(13)
61,000
(18)
83,000
(24)
98,000
(29)
5
(1135)
1,200
1,400
1,300
1,600
20 x 20
18 x 18
100
(45)
120/200
(49/93)
115,000
28 x 22 x 34b
(711 x 559 x 876)
20 x 25
(508 x 635)
18 x 23
(457 x 584)
120/200
51,000
(15)
74,000
(22)
90,000
(26)
(33)
5
(1135)
1,600
1,800
1,900
2,100
110
(50)
(49/93)
5680 011 -10
57
Page 58
Additional Information
Electrical Connections
WARNING
DISCONNECT POWER BEFORE
SERVICING BOILER.
Viessmann AirflowPLUS AH2A Installation, Operating and Service
Main power supply
120VAC, 1Ph, 60Hz, 12A
Main
Disconnect
Switch
If any of the original wires as
supplied with the appliance must be
replaced, it must be replaced with
the exact equivalent.
CAUTION
Label all wires prior to disconnection
when servicing controls. Wiring errors
can cause improper and dangerous
operation. Verify proper operation
after servicing.
Viessmann AirflowPLUS
Connection Board
External Connections
Internal Connections
Power Connection
Terminal
AC Line
PMP
XFO
XFI
>
Door Safety
Switch
58
24VAC
Fan Speed
Stage 2 Cool
Stage 1 Cool
Stage 1 Heat
Thermostat - field supplied
(optional two stage
cooling shown)
ECM
Power
ECM
Control
24VAC COM
A/C Relay Heat Fan Alarm
Dry Contacts
5680 011 -10
Page 59
Viessmann AirflowPLUS AH2A Installation, Operating and Service
9
8
7
5
4
3
2
1
Electrical Connections (continued)
Legend
1 Diagnostic LED
2 Ambient temperature sensor
3 Return air temperature sensor
4 Discharge air temperature sensor
5 Freeze protection temperature sensor
7 Supply water temperature sensor
8 A/C power
9 Pump motor
10 24VAC transformer secondary
11 24VAC transformer primary
12 ECM power
13 ECM control
Legend
AC Line
1 115VAC line
2 115VAC neutral
Pump (PMP)
1 115VAC neutral (switched)
2 115VAC line
XFO
1 24VAC
2 N/C
3 24VAC-COM (GND)
XFI
1 115VAC line
2 115VAC neutral
ECM Power
1 N/C
2 N/C
3 N/C
4 115VAC neutral
5 115VAC line
ECM Control
1 Common C1
2 W/W1
3 Common C2
4 Delay tap select
5 Cool tap select
6 Y1
7 Adjust tap select
8 Output
9 Return valve (heat pump only)
qP Humidistat (BK)
qQ Heat tap select
qW 24VAC (R)
qE 2nd stage heat (EM/W2)
qR 2nd stage cool (Y/Y2)
qT Fan (G)
qZ Output +
Additional Information
5680 011 -10
59
Page 60
Additional Information
Parts List
Model No. Serial No.
AH2A 213 7561230
AH2A 354 7561231
AH2A 385 7561232
Ordering Parts:
Please provide Model and Serial Number A when
ordering replacement parts. Order replacement
components from your Viessmann distributor.
Parts
0001 Side panel with return air opening
0002 Side panel
0003 Front panel, top
0004 Front panel, bottom
0005 Bracket for air filter
0006 Panel, return air
0007 Fan motor
0008 Circuit board
0009 Leveling feet (set of 4)
0010 Bracket for fan motor
0011 Blower housing
0012 Blower wheel
0013 Hot water coil
0014 Circulation pump head, GF UPS15-58RU
0015 Sensor for return air (T5)
0016 Sensor for AC discharge air (T4) *1
0017 Sensor for freeze protect (T3)
0018 Sensor for supply water (T1)
0019 Pump support block
0020 Sensor, ambient (T6)
0021 Diagnostic LED
0023 Door safety switch
0024 Terminal block (main power supply)
0025 Transformer, 120VAC / 24VDC
0026 Filter frame *2
0027 Air filter *3
0028 Power factor correction choke *4
0029 Circuit board enclosure
Viessmann AirflowPLUS AH2A Installation, Operating and Service
(recycled and recyclable) paper.
Other Parts (not illustrated)
0022 Sensor clamp
0050 Technical Data Manual
0051 Installation and Operating Instructions
0052 Parts List
*1 Sensor installed in downstream plenum.
*2 For floor-standing installations only.
*3 Please purchase quality replacement air
filters from a local hardware store:
AH2A 213 16 x 20”
AH2A 354 20 x 20”
AH2A 385 20 x 25”
*4 Only for Model AH2A 385.
Technical information subject to change without notice. Printed on environmentally friendly
5680 011 -10
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