Greenheck PVF, PVG User Manual
Document 474645
Model PVF and PVG
®
Indirect Gas-Fired Heat Modules
Installation, Operation and Maintenance Manual
Please read and save these instructions for future reference. Read carefully before attempting to assemble, install,
operate or maintain the product described. Protect yourself and others by observing all safety information. Failure
to comply with instructions could result in personal injury and/or property damage!
Recognized Component
Model PVF
Model PVG
General Safety Information
These indirect gas-fired furnaces are commonly used
in many different manufacturer’s ventilating products.
For unit-specific information, refer to the Installation,
Operation and Maintenance manual (IOM) for the unit in
which this furnace is installed.
• Both the furnace units are listed for installation in the
United States and in Canada.
• Installation of gas-fired duct furnaces must conform
with local building codes. In the absence of local
building codes, installation must conform to the
National Fuel Gas code, ANSI Z223.1 or in Canada,
CAN/CGA-B149 Installation codes.
• All electrical wiring must be in accordance with the
regulations of the National Electric Code, ANSI/
NFPA-70.
• Unit is approved for installation downstream from
refrigeration units. In these conditions, condensate
could form in the duct furnace and provision must be
made to dispose of the condensate.
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. Do not touch electrical switches.
3. Extinguish any open flame.
4. Immediately call your gas supplier.
FOR YOUR SAFETY
The use and storage of gasoline or other
flammable vapors and liquids in open
containers in the vicinity of this appliance is
hazardous.
WARNING
Improper installation, adjustment, alteration,
service or maintenance can cause injury or
death. Read the installation, operating and
maintenance instructions thoroughly before
installing or servicing this equipment.
®
Indirect Gas-Fired Heat Modules 1
NOTE
This unit is an indirect gas-fired heat module that will
be referred to in this manual as a furnace.
Receiving
Since this furnace is already installed in a ventilation
unit, follow the Receiving Instructions for the unit which
are provided in the unit-specific Installation, Operating
and Maintenance manual (IOM).
Unpacking
If unit is to be installed, tested and operated right
away, locate and remove all packing materials from the
furnace, including any protective coverings that may
be on the combustion air intake and on the furnace
exhaust. Follow Unpacking Instructions as found in the
unit-specific IOM.
Storage
If unit must be stored after it is received, follow the unitspecific storage instructions found in the unit IOM. Also
plug all piping.
Unit Identification
It is necessary to know the unit model number, the
burner control turndown and the serial number. This
information is needed when ordering replacement parts
and is available on labels located on the unit.
Burner Control Turndown
Burner turndown ratio is used in many places and must
be calculated. On the data label, locate the INPUT
BTU/HR (the largest number on the label) and also
the MINIMUM INPUT BTU/HR. Calculate the burner
turndown ratio and record it.
INPUT BTU/HR
MINIMUM BTU/HR
Example:
150,000
75,000
Burner Control
=
Turndown Ratio
=2
The turndown ratio is 2:1 in this example.
Burner Turndown: _______________
Furnace Serial Number
The furnaces are assigned the same serial number
as the main ventilating unit. On the main unit control
access door is a stamped metal plate identifying the
unit serial number. Record that information here.
Furnace/Unit Serial Number: _____________________
Furnace Model Number
On the furnace access door or immediately next to the
door is a Mylar data label. See image below. Locate the
furnace model number at the top of the label and record
it here:
Furnace Model Number: _____________________
Model
Number
Minimum Input
BTU/HR
Input
BTU/HR
Typical Furnace Data Label
Typical Unit ID Plate
ETL Listing
Model PVF and PVG furnaces have been ETL tested
as gas-fired heat modules intended for installation as a
component within heating equipment in duct or cabinet
mounted applications. They are ETL Recognized
Components.
Product Overview
Burner
Assembly
Heat
Exchangers
Combustion
Blower
Indirect Gas-Fired Heat Modules2
Collector
Box
®
Table of Contents
General Safety Information . . . . . . . . . . . . . . 1
Receiving, Unpacking, Storage . . . . . . . . . . . . 2
Unit Identification . . . . . . . . . . . . . . . . . . . 2
Furnace Model Number . . . . . . . . . . . . . . . . 2
Burner Control Turndown . . . . . . . . . . . . . . . 2
Furnace Serial Number . . . . . . . . . . . . . . . . 2
ETL Listing . . . . . . . . . . . . . . . . . . . . . . . 2
Product Overview . . . . . . . . . . . . . . . . . . . 2
Furnace Control Center
Furnace Control Center Components. . . . . . . . 4
Typical Furnace Control Logic. . . . . . . . . . . . 4
Typical Furnace, Electrical and
Control Components . . . . . . . . . . . . . . . . 5
Gas-Fired Burner Turndown . . . . . . . . . . . . 6
Electronic Modulation . . . . . . . . . . . . . . . . 6
Two Stage Valve . . . . . . . . . . . . . . . . . . . 6
Combinations . . . . . . . . . . . . . . . . . . . . 6
Available Turndown Control Options . . . . . . . 6
Installation of Venting for Outdoor Units. . . . .7
Installation of Venting for Indoor Units. . . . . .7
Venting Methods . . . . . . . . . . . . . . . . . . 8
Installation of Standard Indoor Venting
Horizontal . . . . . . . . . . . . . . . . . . . . . . 8
Vertical. . . . . . . . . . . . . . . . . . . . . . . . 8
Installation of Concentric Venting
Horizontal . . . . . . . . . . . . . . . . . . . . 9-10
Vertical. . . . . . . . . . . . . . . . . . . . . 10-11
Two-Pipe Venting - Horizontal. . . . . . . . . 11-12
Two-Pipe Venting - Vertical . . . . . . . . . . . . 12
Installation of Control Wiring . . . . . . . . . . 13
Installation of Discharge Air Sensor . . . . . . 13
Installation of Gas Piping. . . . . . . . . . . 13-14
Gas Supply Requirements . . . . . . . . . . . . 14
Connect the Supply Gas Line . . . . . . . . . . . 14
Installation Addition Regulator . . . . . . . . . . 14
Testing the System for Leaks . . . . . . . . . . . 14
Gas Pressure Test Ports. . . . . . . . . . . . . . 14
Sequence of Operation . . . . . . . . . . . . . . 15
Start-Up / Standby . . . . . . . . . . . . . . . . 15
Heat Mode. . . . . . . . . . . . . . . . . . . . . 15
Recovery from Lockout . . . . . . . . . . . . . . 15
Performance Data . . . . . . . . . . . . . . . . . 15
Gas Valves . . . . . . . . . . . . . . . . . . . . . 16
Start-Up - Furnaces (all units) . . . . . . . . . . 17
4:1 Turndown Electronic Modulation . . . . . . . 18
Adjust High Fire and Low Fire Settings . . . . . 18
Modulating Valve High Fire Setting . . . . . . . 18
Modulating Valve Low Fire Setting . . . . . . . 18
8 Stage Combustion . . . . . . . . . . . . . . . 19
Single Stage . . . . . . . . . . . . . . . . . . . . 19
2 Stage Combustion . . . . . . . . . . . . . . . 20
Combination Turndown Configurations . . . . . . 20
Troubleshooting
Ignition Controller . . . . . . . . . . . . . . . . . 21
4:1 Electronic Modulation . . . . . . . . . . . 22-23
2:1 Electronic Modulation . . . . . . . . . . . . . 24
8 Stage . . . . . . . . . . . . . . . . . . . . 25-26
Single and Two Stage . . . . . . . . . . . . . . . 27
Reference: FX Controller . . . . . . . . . . . . . 28
Stand-Alone Furnace Control . . . . . . . . . . . 28
Program Mode . . . . . . . . . . . . . . . . . 28
Inlet Air Sensor (optional) . . . . . . . . . . . . 28
Discharge Air Temperature . . . . . . . . . . . 28
Outside Air Temperature . . . . . . . . . . . . 29
Go to High Fire Mode . . . . . . . . . . . . . . 29
Return to Normal Operation. . . . . . . . . . . 29
Access to Set Points Menu . . . . . . . . . . . 29
Access the Discharge Air Temperature . . . . . 29
Access the Inlet Air Sensor (optional) . . . . . . 29
Access the Room Override Setting . . . . . . . 29
Furnace Control with Microprocessor. . . . . 29-30
Maintenance
Combustion Blower Motor . . . . . . . . . . . . 30
Burners and Orifices . . . . . . . . . . . . . . . 30
Heat Exchanger . . . . . . . . . . . . . . . . . . 30
Flue Collector Box. . . . . . . . . . . . . . . . . 30
Electrical Wiring . . . . . . . . . . . . . . . . . . 30
Gas Train . . . . . . . . . . . . . . . . . . . . . 30
Replacement Parts . . . . . . . . . . . . . . . . 30
Maintenance Log . . . . . . . . . . . . . . . . . 31
Our Commitment . . . . . . . . . . . . . Backcover
®
Indirect Gas-Fired Heat Modules 3
Furnace Control Center
Each ventilating unit containing a furnace or a pair of
furnaces will have a furnace control center located on
the furnace vest plate. The control center receives high
voltage AC from the main unit control center and in
most cases, also receives low voltage control signals
(call for heat) from the main unit control center. In all
cases, see the unit-specific wiring schematic located
inside the main control center door.
Furnace Control Center Components
(Components and their locations will vary.)
Components shown are for a typical 4:1 turndown
electronic modulation configuration.
13
10
5
4
6
6a
7
3
2
8
1
9
14
Typical Furnace Control Logic
In all cases, refer to the unit-specific wiring diagram
located on the unit control center door.
This illustration is only for a typical 4:1 turndown
electronic modulation configuration
Temperature Sensor
If there is no DDC, the sensor
is connected to the FX
DDC
Located in
unit main
control center
Input Converter
FX Controller
Activates
Ignition Controller
Call for heat
JOHNSON
CONTROLS
(optional)
(optional)
Activates and modulates
Modulating Valve
Controls Speed
of Combustion
Blower
.
12
11
High Voltage Side
1. Power Distribution Block
2. Inducer Relay (controls combustion fan)
3. Combustion Blower
Low Voltage Side
4. Input Converter
5. FX Controller (modulates heat and switches entire
unit on/off
6. Spark Generator (also has high voltage present)
6a. Spark Igniter
7. 24 volt Terminal Strip
Control Sensors
8. High Temperature Sensor (auto reset)
9. Airflow Switches
10. Flame Sensor
Gas Train
11. Combination Valve
12. Modulating Valve
13. Burner Manifold
14. Collector Box
Ignition
Controller
Activates
Combustion Blower
Activates
Combination Valve
Spark to Igniter
1. Microprocessor (if present) senses low temperature
on temperature sensor, sends 10 VDC signal to
signal input converter.
2. Input converter changes analog signal to a form that
can be read by the FX controller and sends the signal
to the FX controller (call for heat).
3. FX controller receives call for heat, activates
modulating valve and the ignition controller.
4. Ignition controller receives call for heat from FX
controller, sends spark to igniter and activates the
combination valve. It looks for verification that the
combustion blower is running.
5. Flame sensor detects flame and ignition controller
shuts off igniter.
Indirect Gas-Fired Heat Modules4
®
Typical Furnace, Electrical and Control Components
Microprocessor
The microprocessor provides the call for heat to the
ignition controller and also
monitors the discharge air
temperature. It is found only
in the unit main control center.
On units with electronic
modulation, it also determines
the required burner firing rate.
Discharge Air Temp Sensor
This sensor is shipped with all
units and must be field-installed in
the discharge air duct. This may
be located in the main unit control
center or the furnace control center
depending on the control type.
Input Converter
The input converter takes an analog signal from a
microprocessor or a BMS
and converts it to a control
signal that can be used
by the FX programmable
controller. It is found in the
furnace control center.
Airflow Switch
Airflow switches are used on both
furnaces and are found on the furnace
vest plate. If the combustion blower
is multi-speed, there will be two of
them and each will switch in response
to a different pressure. The switch is
connected to the combustion blower
by means of a vacuum tube and is used to sense
operation of the combustion blower. The internal switch
is Normally Open (NO). If the blower fails to operate, the
open circuit will cause the ignition controller to disable
the furnace.
Flame Igniter
The igniter receives a high voltage
input from the ignition controller to
produce a spark between the two
electrodes. It operates only during
the ignition phase. On split burner
manifolds, there will be two igniters.
Flame Sensor
The flame sensor is identical to the flame igniter. It is
located on the opposite end of the burner manifold from
the igniter.
FX Programmable Controller
Used on all 4:1 electronic
modulating controls and
8:1 staged turndown.
The FX controller turns on and
electronically modulates gas
valves. It will also enable the
ignition module. The FX controller has a digital readout
and four push buttons, one for Function, one for Enter
and two for scrolling up or down. It is pre-programmed
at the factory for each specific furnace configuration
and it may be used to control two furnaces at the same
time.
Ignition Controller
This controller is found only in the furnace control
center. It has an LED indicator
light on the top right of the
controller that will flash GREEN
for normal operation or RED
for an error. Some furnace
configurations have two of
these controllers.
Burner Manifold
Auto Reset High Temperature
Limit Switch
This limit switch is installed through the
vest plate into the supply air plenum.
A350 and S350 Control System
Used on two stage and
single stage controls. Used
in conjunction with a fieldinstalled remote temperature
sensor. Has an LED indicator
light to show when the
output relay is energized.
When used with multiple
stages, the S350 controller is
used for the extra stages.
A350
Controller
S350
Controller
Single Section
Burner Manifold
®
Split Burner
Manifold
Indirect Gas-Fired Heat Modules 5
Gas-Fired Burner Turndown
Furnaces are available in single stage, multi-stage or
electronically modulated configurations. In single stage,
the entire furnace is either on or off. In multi-stage
furnaces, combustion occurs in stages and is expressed
as the number of different stages (example: 8 stage).
Electronically modulated furnaces have continuously
variable firing rates. In both staged and electronically
modulated furnaces, the result is burner turndown.
Turndown is the capability of the furnace to operate
at less than full capacity, accomplished by reducing
the amount of gas flow when the unit is operating. The
advantage in being able to turn down firing rate is that
when the demand for heat is low, the furnace will not
cycle as often. Turndown is expressed as a ratio and
is found by dividing the maximum BTU input by the
minimum BTU input.
Electronic Modulation
Turndown is specified by the customer. Most common
is the use of an electronically-controlled gas valve which
provides a 4:1 turndown. The entire furnace is sized
appropriately for the maximum heat
output ordered by the customer,
but it can operate as low as 25%
of its maximum capacity. The
electronically-controlled gas valve
will modulate the combustion rate
continuously, dependent on the
output from an FX controller. With
this method, all the burners fire
at the same time but at a varying
capacity. The Modulating Valve is used in conjunction
with an FX electronic controller and a combination valve
which provides an ON/OFF function.
Combinations
Various combinations of the methods outlined may be
used to accomplish the turndown requested by the
customer.
Available turndown control options include:
Electronic Modulation
4:1 uses modulating valve and FX
Single Furnace
Unit
Two Furnace
Unit
Single Furnace
Unit
Two Furnace
Unit
programmable controller
2:1 uses modulating valve and
1092 control system
8:1 uses one 4:1 modulating furnace with
FX controller and one 2 stage furnace
4:1 uses two 4:1 modulating furnaces
running in parallel
Staged
8 stage
2 stage
1 stage
16 stage uses one 8 stage furnace and
one single-stage furnace
4 stage uses two 2 stage furnaces
2 stage uses two single-stage furnaces
Two Stage Valve
The two-stage valve is switched electrically from closed
to full output to half output, producing a 2:1 turndown.
In some cases, multiple furnaces may be used in a
ventilating unit. When this is
done with two single-stage
furnaces, it is possible to run
just one furnace at a time,
resulting in a 2:1 turndown.
If each furnace is already
configured for a 2:1 turndown,
the overall result can then be a
4:1 turndown.
Indirect Gas-Fired Heat Modules6
®
Installation of Venting for
Outdoor Units
Installation of Venting for
Indoor Units
Follow Guidelines
All of the following guidelines must be followed when
installing the unit.
WARNING
Do not install units in locations where flue products
can be drawn into adjacent building openings such
as windows, fresh air intakes, etc. Distance from
vent terminal to adjacent public walkways, adjacent
buildings, operable windows and building openings
shall conform with the local codes. In the absence
of local codes, installation shall conform with the
National Fuel Gas Code, ANSI Z223.1 or the Canadian
CAN/CGA B-149 Installation Codes.
WARNING
The following guidelines must be followed for all
outdoor units:
1. Building materials that will be affected by flue
gases should be protected.
2. Maintain minimum horizontal clearance of 4
feet from electric meters, gas meters, regulators
and relief equipment. In Canada, the minimum
clearance is 6 feet.
3. The combustion blower discharge on outdoor
units must be located a minimum of 42 inches
from any combustible materials.
4. Do not modify or obstruct the combustion air inlet
cover or the combustion blower weatherhood.
5. Do not add vents other than those supplied by the
manufacturer.
6. During the winter, keep the unit clear of snow to
prevent any blockage of the combustion venting.
Install Stack (optional)
Clearance may require an exhaust stack. Install an
exhaust stack as needed to the exhaust connection on
the unit. Install a vent terminator on the exhaust pipe.
Exhaust transition and vent termination must be
purchased from the factory for proper operation.
Exhaust pipe is by others.
WARNING
The following guidelines must be followed for all indoor
units:
1. Installation of venting must conform with local
building codes. In the absence of local codes,
installation must conform with the National Fuel
Gas Code, ANSI Z223.1 or in Canada, CAN/
CGA-B149 installations codes.
2. For the exhaust pipe, use pipe approved for a
Category III appliance or single wall, 26 gauge or
heavier galvanized vent pipe. The piping is required
to be gas-tight by ANSI.
3. For the combustion air pipe on separated
combustion units, sealed single-wall galvanized air
pipe is recommended.
4. The joints must be sealed with a metallic tape or
Silastic™ suitable for temperatures up to 350°F.
5. A minimum of 12 inches of straight vent pipe is
recommended after the exhaust connection and
before any elbows.
6. Vertical combustion air pipes should be fitted with
a tee, drip leg and clean-out cap to prevent any
moisture in the combustion air pipe from entering
the unit.
7. To reduce condensation, insulate any vent runs
greater than 5 feet.
8. All vent pipe connections should be made with at
least three corrosion-resistant sheet metal screws.
9. Refer to the National Fuel Gas Code for additional
piping guidelines.
NOTE
Vent piping is supplied by others and not supplied by
manufacturer.
NOTE
The drip leg should be cleaned out periodically during
the heating season.
NOTE
Clearances from combustible material for indoor units
are determined by the National Fuel Gas Code and/or
other local codes.
®
Indirect Gas-Fired Heat Modules 7
Venting Methods
There are three venting methods for indoor mounted
units. For each method, the units can be vented
horizontally through an exterior wall or vertically
through the roof. Specific venting instructions are
provided for each method and shown in the following
pages. Construct the vent system as shown in these
instructions. Refer to your unit specific submittal to
determine the applicable venting option.
The venting method options are:
Standard Indoor Venting
• uses building air for combustion
• vents exhaust to outdoors
• one exterior roof or wall penetration
Separated Combustion Concentric Venting
• uses outside air for combustion
• vents exhaust to outdoors
• one exterior roof or wall penetration
Separated Combustion 2-Pipe Venting
• uses outside air for combustion
• vents exhaust to outdoors
• two exterior roof or wall penetrations
NOTE
For each method, the units can be vented horizontally
through an exterior wall or vertically through the roof.
Refer to the specific venting instructions for your
unit. Construct the vent system as shown in these
instructions.
A = 12 inch minimum
Pitch vent pipe
downward
from furnace
¼ inch per foot
EXHAUST
Air Inlet
Standard Indoor Venting - Horizontal
A = 12 inch minimum
B = 12 inch minimum,
but should size
according to expected
snow depth
B
Roof Line
A A
EXHAUST
Exhaust Vent
Terminal
Exterior
Wall
A
Exhaust
Vent
Terminal
Installation of Standard Indoor
Venting
Standard indoor venting uses one penetration through
an exterior wall or roof for venting the flue exhaust.
The combustion air is supplied from the air inside the
building. Units must not be installed in a potentially
explosive, flammable, or corrosive atmosphere. To
prevent premature heat exchanger failure, do not locate
unit where chlorinated, halogenated or acid vapors are
present.
When units are installed in tightly sealed buildings,
provisions should be made to supply an adequate
amount of infiltration air from the outside. The rule of
thumb is that an opening of one square inch should be
provided for every 1000 BTUs per hour of input rating.
Vent terminals must be used. Construct the vent
system as shown in the drawings. Reference the Vent
Pipe Diameter table and Exhaust Vent Pipe table for
additional details.
Air Inlet
Standard Indoor Venting - Vertical
Vent Pipe Diameter
Select the vent pipe
diameter. Use only the
specified pipe diameter.
Furnace Size
(MBH)
75-175 4
200-400 6
Exhaust Pipe
Diameter (inches)
Installing Exhaust Vent Pipe
Install the vent pipe with a minimum downward slope
(from the unit) of 1/4-inch per foot (horizontal venting
only). Securely suspend the pipe from overhead
structures at points no greater than 3 feet apart.
The minimum vent length
is 5 feet for horizontal
and 10feet for vertical.
The maximum vent
length is 70 feet. The
total equivalent vent length must include elbows. The
equivalent length of a 4 inch elbow is 6feet and the
equivalent length of a 6inch elbow is 10 feet.
Attach the vent terminal to the end of the exhaust pipe.
Vent
Length
Horizontal 5 70
Vertical 10 70
Minimum
(feet)
Maximum
(feet)
Indirect Gas-Fired Heat Modules8
®
Installation of Concentric Venting
Concentric venting allows the exhaust pipe and
combustion air pipe to pass through a single hole in the
roof or wall of the building. A concentric venting adapter
(CVA) is required for concentric venting.
The concentric venting adapter is designed for indoor
installations and should never be installed on the
exterior of the building.
The exhaust pipe must terminate with the vent terminal.
For horizontal venting, the combustion air pipe must
terminate with the combustion air guard. For vertical
venting, the combustion air pipe must terminate with
the inlet terminal. Depending on what was ordered, one
of these vent terminals will be provided in the optional
venting kit along with the concentric venting adapter
(CVA).
If venting vertically through the roof, refer to the vertical
concentric venting instructions. If venting horizontally
through the wall, refer to the horizontal concentric
venting instructions.
NOTE
Vent piping is supplied by others and not supplied by
manufacturer.
Concentric Venting – Horizontal
Refer to the diagram below for venting on horizontal
concentric systems. Maintain at least 12 inches from
the combustion air inlet guard to the exhaust vent
terminal (Dim. B). To prevent water from running into the
combustion air pipe and to allow for easy installation
of the combustion air inlet guard, the combustion air
pipe must terminate at least 2 inches from the exterior
surface of the outside wall (Dim. A).
A = 2 inch minimum
B = 12 inch minimum
Pitch vent pipe
downward
from furnace
1/4 inch per foot
Mounting
Bracket
EXHAUST
COMBUSTION AIR
Mounting
Bracket
Exterior
Wall
B A
Exhaust
Vent
Terminal
Combustion
Air Inlet Guard
Vent Connection Diameter
Vent terminals must be used (one vent terminal included
with each furnace). Construct the vent system as shown
in the drawings and refer to the table for the correct vent
connection diameters.
CVA-4
4-inch Concentric
Venting Adapter
Combustion Air Connection
Concentric Side
Combustion Air Connection
Non-Concentric Side
CVA
Top View
CVA-6
6-inch Concentric
Venting Adapter
Exhaust Connection
Concentric Side
Exhaust Connection
Non-Concentric Side
Non-Concentric Vent
Connection Diameter
Furnace Size
(MBH)
75-175 4446
200-400 6668
Exhaust
(inches)
Combustion Air
(inches)
Concentric Vent
Connection Diameter
Exhaust
(inches)
Combustion Air
(inches)
Vent Length
Refer to table for minimum and maximum vent lengths.
The total equivalent vent length must include elbows.
The equivalent length of a
4 inch elbow is 6feet and
the equivalent length of a
6inch elbow is 10feet.
Vent
Length
Horizontal 5 70
Minimum
(feet)
Maximum
(feet)
Determine Venting Location
Determine the location of the concentric venting adapter
(CVA) based on any clearances that must be maintained
(follow all codes applicable).
Attach Mounting Brackets
Attach field-supplied, corrosion-resistant, mounting
brackets to the CVA using corrosion-resistant sheet
metal screws.
®
Indirect Gas-Fired Heat Modules 9
Install Exhaust Pipe
Slide the exhaust pipe through the CVA. Provide enough
exhaust piping to pass through the wall (or floor) and
provide the minimum clearance of 12inches between
the exhaust pipe termination and the combustion air
intake. With all required clearances satisfied, attach the
exhaust pipe to the CVA.
Install Combustion Air Pipe
Attach a field-supplied combustion air pipe to the
concentric side of the CVA.
Be sure to provide enough combustion air piping
to pass through the wall and provide the minimum
clearance of 2 inches between the combustion air intake
and the exterior surface of the outside wall.
Be sure to maintain the minimum clearance of
12inches between the exhaust pipe termination and the
combustion air intake.
Install CVA Assembly
Place the CVA assembly through the wall and verify
that all minimum clearance requirements as specified
in these instructions are met. Secure the CVA assembly
to the wall with corrosion-resistant sheet metal screws
through the mounting brackets.
Attach CVA Assembly to Unit
Attach the exhaust pipe to the unit’s combustion
exhaust. Using an additional combustion air pipe,
connect the unit’s combustion air supply intake to the
combustion air connection on the CVA.
Concentric Venting – Vertical
Refer to the diagram below for venting on vertical
concentric systems. Maintain at least 12 inches
between the top of the combustion air inlet terminals
and the bottom of the exhaust terminal. (Dim. B).
The bottom of the combustion air intake pipe must
terminate above the snow line or at least 12 inches
above the roof, whichever is greater.
A tee with clean-out must be provided on the
combustion air and exhaust pipe to prevent debris from
entering the heat exchanger.
A = 12 inch minimum, but
should size according to
expected snow depth
B = 12 inch minimum
C = 12 inch minimum
Roof Line
A
Mounting
Bracket
B
C
C
EXHAUST
Exhaust Vent
Terminal
Combustion Air
Inlet Terminal
Mounting
Bracket
COMBUSTION AIR
Tee with
drip leg and
clean-out cap
Install Combustion Air Inlet Guard and
Exhaust Vent Terminal
Slide the combustion air inlet guard over the exhaust
pipe and fasten it to the combustion air pipe. Attach
the exhaust vent terminal to the discharge end of the
exhaust piping on the outside of the building.
Seal Opening
Seal the opening between the wall and the air intake
pipe using an appropriate method.
Vent Connection Diameter
Vent terminals must be used. Construct the vent system
as shown in the drawings and refer to the table for the
correct vent connection diameters.
Non-Concentric Vent
Connection Diameter
Furnace Size
(MBH)
75-175 4446
200-400 6668
Exhaust
(inches)
Combustion Air
(inches)
Concentric Vent
Connection Diameter
Exhaust
(inches)
Combustion Air
(inches)
Vent Length
Refer to table. The total equivalent vent length must
include elbows. The
equivalent length of a
4inch elbow is 6feet and
the equivalent length of a
Vent
Length
Vertical 10 70
Minimum
(feet)
Maximum
(feet)
6inch elbow is 10feet.
Determine Venting Location
Determine the location of the concentric venting adapter
(CVA) based on any clearances that must be maintained
(follow all codes referenced in these instructions).
Attach Mounting Brackets
Attach field-supplied corrosion-resistant mounting
brackets to the CVA using corrosion resistant sheet
metal screws.
Indirect Gas-Fired Heat Modules10
®
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