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

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.

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)

Activates and modulates

Modulating Valve

Controls Speed

of Combustion

Blower

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

Roof Line

A A

EXHAUST

Exhaust Vent

Terminal

Exterior

Wall

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 10feet 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 6feet and the equivalent length of a 6inch 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 6feet and the equivalent length of a 6inch elbow is 10feet.

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 12inches 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 12inches 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

Mounting

Bracket

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 4inch elbow is 6feet and the equivalent length of a

Vent

Length

Vertical 10 70

Minimum

(feet)

Maximum

(feet)

6inch elbow is 10feet.

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

Install Exhaust Pipe

Slide the exhaust pipe through the CVA. Provide enough exhaust piping to pass through the roof and provide the minimum clearance of 12inches 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 roof and provide the minimum clearance of 12 inches between the combustion air intake and the exterior surface of the roof. This clearance may need to be increased to allow for snow accumulation.

Be sure to maintain the minimum clearance of 12inches between the exhaust pipe termination and the combustion air intake.

Install CVA Assembly

Place the CVA assembly through the roof and verify that all minimum clearance requirements as speciﬁed in these instructions are met. Secure the CVA assembly to the ceiling 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.

Be sure to include the required tee’s with drip legs and clean-outs.

Install Combustion Air Inlet Guard and Exhaust Vent Terminal

Slide the combustion air terminal over the vent pipe and fasten it to the combustion air pipe. Attach the exhaust vent terminal to the discharge end of the exhaust piping.

Seal Opening

Seal the opening between the roofs and the air intake pipe using an appropriate method.

Installation of Two Pipe Venting – Horizontal

Refer to the diagram below for venting on horizontal concentric systems. Maintain at least 12 inches of clearance between the exhaust pipe termination and the exterior surface of the exterior wall (Dim. A).

The combustion air pipe must be a minimum of 12inches from the exhaust pipe and 24 inches from the exterior surface of the outside wall (Dim. B).

A minimum of 1 inch and a maximum of 48 inches of building wall thickness is required for separated combustion vent pipe.

A = 12 inch minimum B = 24 inch minimum

C = 12 inch minimum

EXHAUST

Pitch vent pipe downward from furnace ¼ inch per foot

COMBUSTION AIR

Two (2) ﬁeld-supplied support brackets

Vent Connection Diameter

Vent terminals must be used. The optional vent kit includes two terminals. Construct the vent system as shown in the drawings and refer to the table for the correct vent connection

Furnace Size

(MBH)

75-175 4 4

200-400 6 6

Exhaust

(inches)

diameters.

Vent Length

Refer to table for minimum and maximum vent lengths. The minimum vent length is 5 feet and the maximum vent length is 50 feet. The total equivalent vent length must include elbows. The equivalent length of a 4inch elbow is 6feet and the equivalent length of a 6inch elbow is 10feet.

Vent

Length

Horizontal 5 50

Minimum

(feet)

Exterior

Wall

Exhaust

Vent

Terminal

Combustion

Air Inlet Terminal

Combustion

(inches)

Maximum

(feet)

Install Exhaust Pipe

Run an exhaust pipe from the unit’s combustion exhaust through the exterior wall to the outdoors. The exhaust pipe must terminate at least 12 inches from the outside surface of the outside wall. Attach exhaust vent terminal to the end of the exhaust pipe. Using ﬁeld-supplied mounting brackets, support the exhaust pipe as needed.

Indirect Gas-Fired Heat Modules 11

Install Combustion Air Pipe

Run a combustion air pipe from the unit’s combustion air intake through the exterior wall to the outdoors. The combustion air pipe must terminate at least 12inches from the combustion vent pipe and 24inches from the exterior surface of the outside wall. Attach the combustion air inlet guard to the end of the combustion air pipe. Using ﬁeld-supplied mounting brackets, support the combustion air pipe as needed.

Vent Length

Refer to table for minimum and maximum vent lengths. The minimum vent length is 10 feet and the maximum vent length is 70 feet. The total equivalent vent length must include elbows. The equivalent length of a 4inch elbow is 6feet and the equivalent length of a 6inch elbow is 10feet.

Vent

Length

Vertical 10 70

Minimum

(feet)

Maximum

(feet)

Seal Wall Openings

Using an appropriate method, seal the wall openings around the piping.

Installation of Two Pipe Venting – Vertical

Refer to the diagram for venting vertical concentric systems. The combustion air pipe must terminate at least 12 inches above the roof. This clearance may need to be increased to accommodate for snow accumulation. The exhaust must terminate at least 12 inches above and 12 inches horizontally from the combustion air inlet.

Exhaust Vent

Terminal

Roof Line

Combustion

Air Inlet Terminal

Install Exhaust Pipe

Run an exhaust pipe from the unit’s combustion exhaust through the roof to the outdoors. The exhaust pipe must terminate at least 24 inches above the outside surface of the roof. This clearance may need to be increased to accommodate snow accumulation. Attach the exhaust vent terminal to the end of the exhaust pipe.

Install Combustion Air Pipe

Run a combustion air pipe from the unit’s combustion air intake through the roof to the outdoors. The combustion air pipe must terminate at least 12 inches horizontally and vertically from the combustion exhaust pipe and at least 24 inches from the exterior surface of the roof. These clearances may need to be increased to accommodate for expected snow accumulation. Attach the combustion air terminal to the end of the combustion air pipe.

Seal Roof Penetration

Using an appropriate method, seal the roof openings around the vent pipes.

EXHAUST

A = 12 inch minimum, but should size according to expected snow depth

B = 24 inch minimum

C = 12 inch minimum

D = 12 inch minimum

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.

Indirect Gas-Fired Heat Modules12

Furnace Size

(MBH)

75-175 4 4

200-400 6 6

Exhaust (inches)

COMBUSTION AIR

Tee with

drip leg and

clean-out cap

Combustion

(inches)

Installation of Control Wiring

Installation of Gas Piping

Disconnect power supply before making any wiring connections to prevent electrical shock and equipment damage.

All appliances must be wired strictly in accordance with the wiring diagram furnished with the unit. Any wiring different from the diagram could result in a hazard to persons and property.

Any original factory wiring that requires replacement must be replaced with wiring material having a temperature rating of at least 105° C.

1. Installation of wiring must conform with local building codes. In the absence of local building codes, installation must conform to the National Electrical Code and ANSI/NFPA 70 - Latest Edition. Unit must be electrically grounded in conformance with this code. In Canada, wiring must comply with CSA C22.1, Canadian Electrical Code.

2. All furnaces are provided with a wiring diagram located on the inside of the access panel or door to the unit’s main control center. Refer to this diagram for all wiring connections.

Installation of Discharge Air Sensor

Every furnace has a Discharge Air Sensor included. It is typically attached to the terminal strip on the furnace control center. If the ventilating unit has a microprocessor controller, it will be connected to the microprocessor controller. See the unit-speciﬁc wiring diagram. Install sensor in the supply air duct, as far downstream as possible for accurate temperature measurement. Additional wire may be added to the sensor as necessary.

IMPORTANT

All gas piping must be installed in accordance with the latest edition of the National Fuel Gas Code ANSI/Z223.1 and any local codes that may apply. In Canada, the equipment shall be installed in accordance with the Installation Code for Gas Burning Appliances and Equipment (CGA B149) and Provincial Regulations for the class. Authorities having jurisdiction should be consulted before installations are made.

IMPORTANT

All piping should be clean and free of any foreign material. Foreign material entering the gas train can cause damage.

WARNING

All components of this or any other gas fired heating unit must be leak-tested prior to placing the unit into operation. A soap and water solution should be used to perform this test. NEVER test for gas leaks with an open flame.

IMPORTANT

Do NOT connect the unit to gas types other than what is specified and do NOT connect the unit to gas pressures that are outside of the pressure range shown on the label.

WARNING

When leak testing pressures equal to or less than 14in. wg (3.5 kPa), first close the field-installed shutoff valve to isolate the unit from the gas supply line.

WARNING

When leak testing pressures above 14in. wg (3.5kPa), close the field-installed shutoff valve, disconnect the furnace and its gas train from the gas supply line and plug the supply line before testing.

NOTE

When connecting the gas supply, the length of the run must be considered in determining the pipe size to avoid excessive pressure drop. Refer to a Gas Engineer’s Handbook for gas pipe capacities.

NOTE

Each furnace has a single 3/4-inch connection.

Indirect Gas-Fired Heat Modules 13

Determine the Gas Supply Requirements

The data label located on the face of the furnace lists the requirements for the gas being supplied to the unit.

Type of

Gas

Minimum

Gas

Supply

Pressure

Typical Furnace Data Label

each unit will be different

Connect the Supply Gas Line

A manual shut off valve (gas cock), a 1/8 inch plugged test port and a drip leg must be installed between the gas supply pipe and the start of the gas train. The valve and test port must be accessible for the connection of a test gauge. Supply gas connections must be made by a qualiﬁed installer and are not furnished by manufacturer.

Install Additional Regulator (if required)

If the gas supply pressure exceeds 14 in. wg, an additional regulator must be installed to reduce the pressure. The additional regulator is to be provided and installed by others. The regulator must have a listed leak limiting device or it must be vented to the outdoors.

Test the System for Leaks

After installing the gas supply piping, perform a leak test in accordance with the instructions in Installation of Gas Piping in this manual. The leak test must be performed before placing the unit in service.

Gas Pressure Test Ports

Burner manifolds and gas valves used in the furnaces are supplied with test ports for temporary connection of a pressure gauge or a magnehelic gauge.

Test Ports

Gas Supply In

Typical Split Burner Manifold

From Gas Supply

Gas Cock

Bleeder Valve or 1/8 in Plugged Tap

Ground

Joint

Union

8 in. Trap

Gas to

Controls

Typical Gas Supply Piping Connection

IMPORTANT

Before applying gas to the valves, test the gas pressure to make sure it is less than 14 in. wg. Pressures greater than 14 in. wg will damage the gas valves.

Test Port

ON / OFF

Gas Control Knob

Test Port

Typical Single Stage Gas Valve

Indirect Gas-Fired Heat Modules14

Sequence of Operation

Start-Up / Standby

Prior to start-up, verify that all ﬁeld-installed sensors have been installed. This includes a room temperature sensor (optional) and a discharge air temperature sensor (typical).

Heat Mode

When the unit or furnace controller calls for heat:

1. The ignition control will check that the pressure switch for the combustion blower is open.

2. The combustion blower will energize and the 15second pre-purge begins.

3. The gas valve is energized and the igniter will spark for up to 10 seconds. If a ﬂame is not sensed during the trial for ignition, two additional tries will be attempted before going into lockout for one hour.

4. When a ﬂame is sensed, sparking stops immediately. The gas valve and combustion blower remain energized.

5. Ignition

4:1 Electronic Modulation - The burner will light at

100% ﬁre and remain there for up to 30 seconds. The main burner gas valve will then modulate from 100% down to a minimum of 25%, as needed. The combustion blower will change between high and low speed to maintain acceptable combustion airﬂow. If the high speed pressure switch does not pull in when required, the furnace will lock out.

8:1 Stage Control - The furnace controller will ignite

the necessary manifolds at 100% for 30 seconds, after which the unit or furnace controller will operate the manifolds at high and low ﬁre. Each time a manifold is initialized, the manifold will ignite at 100%.

Single Stage Control - The burner will light at

100% and remain at high ﬁre.

Two Stage Control - The burner will light at 100%

ﬁre and remain there for 10 seconds. The unit or furnace controller will operate the burners at either high or low ﬁre, depending on the demand for heat.

6. The ignition control constantly monitors the call for heat, the pressure switch and the burner ﬂame to assure proper operation.

7. When the unit or furnace controls are satisﬁed, the main gas valve is then de-energized and the combustion blower shuts off following a 30 second post-purge period.

Recovery from Lockout

If the furnace goes into lockout, the ignition control will automatically reset after one hour if the thermostat is still calling for heat. If needed, a manual reset can be accomplished by either shutting off the power or turning off the call for heat (turn off the thermostat) for a period of ﬁve seconds.

Performance Data

Supply Air Temperature Rise

20°F 30°F 40°F 50°F 60°F 70°F 80°F 90°F 100°F

Model

50 50,000 1852 1235 926 741 617 529 463 412 370

75 75,000 2778 1852 1389 1111 926 794 694 617 556

100 100,000 3704 2469 1852 1481 1235 1058 926 823 741

125 125,000 4630 3086 2315 1852 1543 1323 1157 1029 926

150 150,000 5556 3704 2778 2222 1852 1587 1389 1235 1111

175 175,000 6481 4321 3241 2593 2160 1852 1620 1440 1296

200 200,000 7407 4938 3704 2963 2469 2116 1852 1646 1481

225 225,000 8333 5556 4167 3333 2778 2381 2083 1852 1667

250 250,000 9259 6173 4630 3704 3086 2646 2315 2058 1852

275 275,000 10185 6790 5093 4074 3395 2910 2546 2263 2037

300 300,000 11111 7407 5556 4444 3704 3175 2778 2469 2222

325 325,000 12037 8025 6019 4815 4012 3439 3009 2675 2407

350 350,000 12963 8642 6481 5185 4321 3704 3241 2881 2593

400 400,000 14815 9877 7407 5926 4938 4233 3704 3292 2963

Input

(BTU/hr)

CFM

Indirect Gas-Fired Heat Modules 15

Gas Valves

Overview of typical Two Stage Valve. Used in eight stage and two stage furnaces.

Gas Control Knob

(ON / OFF)

Terminal Block

Close-up of Terminal Block

High fire terminal is the bottom of three terminals.

Low Fire

Adjusting Screw

Overview of typical Modulating Valve. Used in 4:1 Electronic Modulation

Low Fire and High Fire

adjustments are made

on printed circuit board

behind removable cover

High Fire

Indirect Gas-Fired Heat Modules16

Start-Up - Furnaces (all units)

IMPORTANT

For the unit to function properly, ALL gas valves must have their high fire and low fire settings adjusted for field conditions.

IMPORTANT

Confirm the discharge air sensor is installed at least three duct diameters downstream of the furnace.

IMPORTANT

Multi-furnace units may use a combination of the available turndown options. Each furnace must be set-up per the specific instructions for its control type. For additional information, see Gas-Fired Burner Turndown in this manual.

After the gas piping has been installed and leak tested, verify that all ﬁeld-installed components such as an air temperature sensor have been installed. Verify that ON/ OFF gas control knob on each stage-type gas valve is turned to the “ON” position (see image).

Verify the unit turndown ratio as shown on page2 of this manual. Consult the specific start-up instructions as shown on the following pages to accomplish the following steps:

Set Airﬂow

Airﬂow adjustment is done at the time of unit start-up. Refer to the unit-speciﬁc Installation, Operating and Maintenance manual (IOM) for instructions.

With 4:1 Turndown Electronic Modulation

Remote Temperature

Sensor

FX Controller

Ignition

Controller

EXA Valve

Single Section

Burner Manifold

Furnaces with electronically modulated 4:1 turndown use a combination valve for primary gas control. It controls the high ﬁre gas supply. In addition to the combination valve, there is a modulating valve located just after the combination valve. The modulating valve is the device that modulates or changes the gas volume that is being supplied to the furnace manifold. Both of

these valves require adjustment at the time of unit start-up.

The modulating gas valve has a built-in digital controller that will accept user settings for High Fire and Low Fire and will provide minimal hysteresis throughout the entire range of modulation. The modulating valve controls the amount of combustion gas that goes to the burners, while the combination valve acts as an on/off switching device. During normal use, the amount of combustion gas will vary constantly, depending on the settings put in by the owner. This allows the modulating valve to regulate the heat output from the furnace and maintain a constant space temperature with minimal variation, or hysteresis.

The modulating valve is controlled by a user interface known as the FX controller. The FX controller sends an analog signal to the modulating valve that causes the valve to send more or less gas to the furnace.

The combination valve is normally closed. It requires 24VAC to hold it open.

Single Stage

Valve

Indirect Gas-Fired Heat Modules 17

At start-up, remove the cover from the circuit board housing by loosening the two Phillips head retaining screws. Identify Button #1 and Button #2 and also locate the LED indicator light.

Send the furnace to High Fire by following the instructions below:

• Set the regulator screw on the combination valve as high as it goes — all the way in.

• Set the High Fire set point on the modulating valve to 3.5 in. wg for natural gas or 10.0in. wg for LP gas.

• Set the Low Fire set point on the modulating gas valve at 0.3 in. wg for natural gas or 1.0 in. wg for LP gas.

The modulating valve has four electrical connections on-board. Two are for the 24 VAC needed to power the valve and two are for the input signal from the FX controller. The location of the 24 VAC power source varies, see the unit-speciﬁc wiring diagram. The input signal that causes the modulating valve to change gas volume is always provided by the FX controller and varies from 2 - 10 VDC.

When a call for heat is provided to the FX controller, the controller will ﬁrst provide a 10 VDC signal to the modulating valve so that it will always start in a high ﬁre condition. After ignition, the controller will change its output signal, causing the volume of combustion gas to be reduced to as little as 25% of full ﬂow (4:1 turndown) based on demand.

Adjust High Fire and Low Fire Settings

NOTE

Before setting the modulating valve, make certain the combination valve is set to the maximum setting. Turn the regulator screw all the way in.

Terminals 1 & 2

(signal)

Button #1

Terminals 3 & 4

(power)

Button #2

LED Light

Modulating Valve High Fire Setting

1. Connect a manometer to the test port on the burner manifold.

2. Press and hold button #1 until the LED lights solid red. Release the button. Observe the gas pressure on the manometer.

3. Adjust the modulating valve by pushing

High Fire Settings

button #1 to increase the pressure or by pushing button #2 to decrease the

Natural Gas 3.5 in. wg

LP Gas 10.0 in. wg

pressure.

4. Save the High Fire setting by simultaneously

holding down buttons #1 and #2 until the LED turns off. If the new setting is not saved within ﬁve

minutes, the modulating valve will default back to its last saved setting.

NOTE

During the adjustment process, each push of either button will increase or decrease the pressure in steps. Holding down either button auto-steps and eliminates the need to repeatedly push the button. Use this feature to rapidly increase or decrease the gas flow.

Modulating Valve Low Fire Setting

1. With a manometer installed at the burner manifold test port, press and hold down button #2 until the LED blinks red. Release the button. Observe the gas pressure on the manometer.

2. Adjust the Low Fire setting by pushing

button #1 to increase the pressure or by pushing button #2 to decrease the pressure.

3. Save the Low Fire setting by simultaneously holding down buttons #1 and #2 until the LED turns off. If the new setting is not saved within ﬁve

minutes, the Modulating Valve will default back to its last saved setting.

Restore normal operation and shut off the furnace.

Reinstall the cover on the modulating valve, remove the manometer and reinstall the plug in the manifold test port.

Low Fire Settings

Natural Gas 0.3 in. wg

LP Gas 1.0 in. wg

EXA Modulating Gas Valve

(with cover removed)

Indirect Gas-Fired Heat Modules18

With 8 Stage Combustion

Remote Temperature

FX Controller

Ignition

Controller

Two Stage

Valve

Split Burner

Manifold

Two Stage

Valve

Sensor

8. Turn off furnace. Reconnect the wire to the high ﬁre terminal. Remove manometer and reinstall plug into manifold test port.

9. Connect manometer to the other manifold test port and repeat the high ﬁre / low ﬁre set up sequence on the other gas valve.

10. Turn off furnace. Reconnect the wire to the high ﬁre terminal. Remove manometer and reinstall plug into manifold test port.

11. Return to the normal operation.

With Single Stage

Remote Temperature

Sensor

A350

JOHNSON

CONTROLS

A350

Controller

Ignition

Controller

IMPORTANT

8 staged turndown furnaces use a split burner manifold and two 2-stage gas valves per furnace. The high fire and low fire manifold pressure must be checked and properly set on each manifold.

1. Connect a manometer to either test port on the burner manifold.

2. Send the unit to high ﬁre.

3. Check the gas pressure at the manifold test port. The recommended pressure is 3.5 in. wg for natural gas or 10.0 in. wg for LP gas.

4. Adjust the high ﬁre screw on the valve that is connected to the port being tested. Counterclockwise rotation will decrease the gas pressure and clockwise rotation will increase the pressure.

5. Send the furnace to low ﬁre by disconnecting and isolating the wire from the high ﬁre terminal on the valve.

6. Check the gas pressure at the manifold test port. The recommended low ﬁre manifold pressure is 7/8in.wg for natural gas or 2.5 in. wg for LP.

7. Adjust the low ﬁre screw on the valve being tested. Counterclockwise rotation will decrease the gas pressure and clockwise rotation will increase the gas pressure.

Single Stage

Valve

Single Section

Burner Manifold

1. Connect a manometer to the test port on the burner manifold.

2. Send the unit to high ﬁre.

3. Check the gas pressure at the manifold test port. The recommended pressure is 3.5 in. wg for natural gas or 10 in. wg for LP gas.

4. Adjust the high ﬁre screw on the valve. Counterclockwise rotation will decrease the gas pressure and clockwise rotation will increase the pressure.

5. Turn off furnace. Remove manometer and reinstall plug into manifold test port.

6. Return the unit to normal operation.

Indirect Gas-Fired Heat Modules 19

With 2 Stage Combustion With Combination Turndown

Conﬁgurations

JOHNSON

CONTROLS

A350

Controller

Single Section

Burner Manifold

A350

Remote Temperature

Sensor

Ignition

Controller

Two Stage

Valve

There are several different turndown options that may be used in the units that are simply combinations of basic conﬁgurations.

In all cases, all gas valves must be set for high fire and low fire as part of the Start-Up process.

Inspect the furnace(s) and verify the type of valve(s) and manifold used. Refer back to the previously described conﬁgurations and ﬁnd the one that most closely matches the valve and manifold types present in this unit. Adjust the high ﬁre and low ﬁre settings on all valves before placing the unit in service.

Remote Temperature

Sensor

A350

JOHNSON

CONTROLS

A350

Controller

Lead Furnace

S350

JOHNSON

CONTROLS

S350

Controller

IMPORTANT

Confirm that the discharge air sensor is installed in the duct at least three duct diameters downstream of the furnace.

1. Connect a manometer to the test port on the burner manifold.

2. Send the unit to high ﬁre.

3. Check the gas pressure at the manifold test port. The recommended pressure is 3.5 in. wg for natural gas or 10.0 in. wg for LP gas.

4. Adjust the high ﬁre screw on the valve. Counterclockwise rotation will decrease the gas pressure and clockwise rotation will increase the pressure.

5. Send the furnace to low ﬁre by disconnecting and isolating the wire from the high ﬁre terminal on the valve.

6. Check the gas pressure at the manifold test port. The recommended low ﬁre manifold pressure is 7/8in.wg for natural gas or 2.5 in. wg for LP.

7. Adjust the low ﬁre screw on the valve. Counterclockwise rotation will decrease the gas pressure and clockwise rotation will increase the gas pressure.

8. Turn off furnace. Reconnect the wire to the high ﬁre terminal. Remove manometer and reinstall plug into manifold test port.

9. Return the unit to normal operation.

Two Stage

Furnace

Provides 4 Stages

Two Stage

Furnace

Single Stage

Furnace

Provides 2 Stages

Single Stage

Furnace

A modulating furnace can also be combined with a single stage furnace. Both furnaces are then controlled by an FX controller.

FX Controller

Electronically

Modulated

4:1 Turndown

Furnace

Provides

8:1 Turndown

Single Stage

Furnace

Eight Stage

Furnace

Provides

16 Stages

Single Stage

Furnace

In some cases, two furnaces may be installed in parallel in one ventilating unit. In that case, the turndown is the same as just a single furnace.

Indirect Gas-Fired Heat Modules20

Troubleshooting - Ignition Controller

NOTE

The green LED light indicates NORMAL operation while the red LED light indicates an ERROR operation.

The ignition controller has a diagnostic LED light at the top right of the controller. The LED light will ﬂash GREEN for normal operation or RED for an error.

The following are the green LED codes of operation:

GREEN LED Indications - NORMAL OPERATION

Flash Code Flash Code Indication

Steady on Flame detected, main burner on

0.1 second on/off Controller is sparking

0.5 second on/off Purge or inter-purge time

0.5 second on/4.5 second off Retry or recycle time

The following are the red LED codes of error:

RED LED Indications - ERROR OPERATION

Flash Code Flash Code Indication

Blinks 1 time No flame in trial time error

Blinks 2 times Flame sense circuit error

Blinks 3 times Valve circuit error

Blinks 4 times Flame loss error

Blinks 6 times Airflow error

Blinks 7 times Ground or internal error

Steady on Line voltage/frequency error

Airﬂow Fault (6 red ﬂashes)

An airﬂow fault may occur for the following reasons:

• During the start-up sequence, the controller relay turned the combustion blower on but the blower did not prove airﬂow in 30 seconds.

• During the start-up sequence, the airﬂow was proven before the controller turned the combustion blower on. If this condition lasts for 30seconds, the control will error out.

To ﬁx fault, determine which error above is occurring, remove power from controller, ﬁx problem and re-power controller.

Flame Fault (2 red ﬂashes)

If the main gas valve fails to close completely and maintains a ﬂame, the full-time ﬂame sensor circuit will detect it and energize the combustion blower. Should the main valve later close completely and remove the ﬂame signal, the combustion will be de-energized.

Ignition lockout (1 red ﬂash for start-up, 4 red ﬂashes for during operation)

Possible Cause Solution

Manual gas valve not open

Air in the gas line Bleed gas line.

Supply gas pressure too high or too low

Loose wire connections

No Spark:

a. Spark electrode

b. Spark cable

shorted to ground

c. Ignition

controller not grounded

High Limit Control tripped

Faulty combination valve

Faulty ignition control

Open manual valve. If combination valves are used, verify that switch on top is in “ON” position.

Check that supply pressure is between 6 and 14 in. wg for natural gas and between 11 and 14in. wg for LP gas.

Check for tight wire connections.

Ensure spark gap is 1/8 inch and ceramic insulator is not cracked. Replace if necessary.

Replace spark cable.

Ground ignition controller.

Check unit airﬂow and manifold pressure.

Measure voltage between terminals MV and Common. If 24volts is present but valve remains closed, replace valve.

Check diagnostic LED on controller for “steady on”. If LED remains on constantly and there is NO voltage between V1 and V2, replace ignition controller.

Valve Circuit Error (3 red ﬂashes)

Check that the valve is a 24 volt AC valve. Check that the valve is wired correctly.

Internal Control Error (7 red ﬂashes)

Check all ground connections including the entire unit.

Line Frequency/Voltage Error (solid red)

Check that the controller power is 24 volt AC (+10%/-15%). Check for 60 Hz or 50 Hz.

If all checks have been made using the troubleshooting guide and you have conﬁrmed there are no other defective components, and the red LED error light is ﬂashing or on, then the ignition controller may need to be replaced.

Indirect Gas-Fired Heat Modules 21

Troubleshooting

4:1 Modulating Furnace Will Not Light

In all cases, verify correct terminals as shown on the unit-speciﬁc wiring diagram.

24 VAC across R and L?

Yes

24 VAC across W1 and L?

Yes

24 VAC across 22 and 21?

Yes

N.O. contact on

heat relay (RH) closed?

Yes

DT1 displayed

on furnace controller (SC1)?

Main disconnect (DS1) open or defective

Close, repair or replace

Main transformer (TR1) fault

Replace main transformer

Heat switch (S4) open or not wired

Close or replace heat switch (S4)

Heat transformer (TR2) fault

Replace heating transformer

Heat relay (RH) is not energized

Check for loose connections. Repair or replace heat relay (RH)

Yes

OT1 displayed

on furnace controller (SC1)?

Blank screen

on furnace controller (SC1)?

24 VAC across

terminals S and T?

Yes

Continues on next page...

Discharge air sensor (TS2) not wired or defective

Wire or replace discharge air sensor (TS2)

Yes

Outdoor air sensor (TS1) not wired or defective

Wire or replace outdoor temperature sensor (TS1)

Yes

Furnace controller (SC1) defective or not powered

Replace or wire furnace controller (SC1)

Discharge temperature was above high limit control (HLC1)

Wait for high limit to cool and reset

Inlet air sensor contact open

Adjust inlet air sensor setting (refer to 4:1 Modulation Start-Up section)

Furnace controller (SC1) defective

Replace furnace controller (SC1)

Indirect Gas-Fired Heat Modules22

Troubleshooting

4:1 Modulating Furnace Will Not Light

In all cases, verify correct terminals as shown on the unit-speciﬁc wiring diagram.

...continued from previous page

High limit switch (HLC#) open?

Ignition controller (IC#)

red LED blinks

7 times or is on

Ignition controller (IC#)

red LED

blinks 6 times

24 VAC between 24 VAC terminals

on mod valve

Yes

10 VDC between terminals

(+) and (-) on mod valve

Yes

Ignition controller (IC#)

red LED blinks

1 time, 2 times or 4 times

Everything is working properly,

consult factory.

Yes

Discharge temperature was above high limit setting

Let cool then reset high limit.

Ignition controller(s) (IC#) failed

Replace faulty ignition controller(s)

Pressure switch (PS2) failure

Repair or replace pressure switch (PS2)

Combustion blower (CM) not functioning

Replace fusing (FU7), combustion blower or relay (CM)

Secondary transformer (TR6) defective

Replace secondary transformer (TR6)

Furnace controller (SC1) defective

Replace furnace controller (SC1)

Improper manifold pressure

Set high and low manifold pressure

(refer to 4:1 Electronic Modulation Start-Up section)

Faulty spark rod or spark gap does not equal 1/8 inch

Replace spark rod or adjust gap to 1/8 inch

Indirect Gas-Fired Heat Modules 23

Troubleshooting

2:1 Modulating Furnace Will Not Light

In all cases, verify correct terminals as shown on the unit-speciﬁc wiring diagram.

24 VAC across R and C?

Yes

24 VAC across W1 and C?

Yes

24 VAC across S and X?

Yes

24 VAC across 29 and X?

Yes

24 VAC across A and X?

Main disconnect (DS1) open or defective

Close, repair or replace

Main transformer (TR1) fault

Replace main transformer

Heat switch (S4) open or not wired

Close or replace heat switch (S4)

Heat transformer (TR5) fault

Replace heating transformer

Discharge temperature was above high limit control (HLC1)

Wait for high limit to cool and reset.

Optional inlet air sensor contact (TS4 open)

Adjust inlet air sensor setting

(refer to Reference - FX Controller, Access the Inlet Air Sensor section)

Heat relay (RH) is not energized

Check for loose connections. Repair or replace heat relay (RH)

Yes

Ignition controller (IC#)

red LED blinks

7 times or is on

Ignition controller (IC#)

red LED

blinks 6 times

Ignition controller (IC#)

red LED blinks

1 time, 2 times or 4 times

Yes

Everything is working

properly, consult factory.

Yes

Discharge air selector (TS3) improperly set or faulty

Adjust setting (see staged start-up) or replace sensor

Ignition controller (IC1) failed

Replace ignition controller

Combustion blower (CM) not functioning

Replace combustion blower or relay (CM)

Air proving switch (PS2) defective

Replace air proving switch

Improper manifold pressure

Set high and low manifold pressure

(refer to the 2:1 Electronic Modulation Start-Up section)

Faulty spark rod or spark gap does not equal 1/8 inch

Replace spark rod or adjust gap to 1/8 inch

Indirect Gas-Fired Heat Modules24

Troubleshooting

8 Stage Furnace Will Not Light

In all cases, verify correct terminals as shown on the unit-speciﬁc wiring diagram.

24 VAC across R and C?

Yes

24 VAC across W1 and C?

Yes

24 VAC across 22 and 21?

Yes

N.O. contact on heat relay (RH)

closed?

Yes

DT1 displayed on furnace

controller (SC1)?

Main disconnect (DS1) open or defective

Close, repair or replace

Main transformer (TR1) fault

Replace main transformer

Heat switch (S4) open or not wired

Close or replace heat switch (S4)

Heat transformer (TR2) fault

Replace heating transformer

Heat relay (RH) is not energized

Check for loose connections. Repair of replace heat relay (RH)

Yes

OT1 displayed on furnace

controller (SC1)?

Blank screen on furnace

controller (SC1)?

24 VAC across terminals

S and T?

Yes

With the combustion blower

(CM) off, is the N.O.

airﬂow switch (PS2) closed?

Continues on next page...

Yes

Discharge air sensor (TS2) not wired or defective

Wire or replace discharge air sensor (TS2)

Outdoor air sensor (TS1) not wired or defective

Wire or replace outdoor temperature sensor (TS1)

Furnace controller (SC1) defective or not powered

Replace or wire furnace controller (SC1)

Discharge temperature was above high limit control (HLC1)

Wait for high limit to cool and reset

Inlet air sensor contact open

Adjust inlet air sensor setting

(refer to Reference - FX Controller, Access the Inlet Air Sensor section)

Furnace controller (SC1) defective

Replace furnace controller (SC1)

Airﬂow switch (PS2) defective

Replace defective airﬂow switch (PS2)

Indirect Gas-Fired Heat Modules 25

Troubleshooting

8 Stage Furnace Will Not Light

In all cases, verify correct terminals as shown on the unit-speciﬁc wiring diagram.

... continued from

previous page.

With the combustion blower

(CM) on for at least

30 seconds, is there

24 VAC across T and A or E?

Yes

Ignition controller (IC#)

red LED blinks

7 times or is on

Ignition controller (IC#)

red LED blinks

1 time, 2 times or 4 times

Cycle power to the unit

and wait 30 seconds

Does the combustion relay

(R9 or CR) close?

Yes

Does the combustion

blower (CM) run?

Yes

Does the combustion

blower stop after

30 seconds of operation?

Everything is working properly,

consult factory.

Yes

Furnace controller (SC1) defective

Replace furnace controller (SC1)

Ignition controller(s) (IC#) failed

Replace faulty ignition controller(s)

Improper manifold pressure

Set high and low manifold pressure (refer to 8 Staged Start-Up section)

Faulty spark rod or spark gap does not equal 1/8 inch

Replace spark rod or adjust gap to 1/8 inch

Internal high limit tripped (temperature above set point)

Let temperatures cool

Internal inlet air sensor open

Adjust inlet air sensor setting

(refer to Reference - FX Controller, Access the Inlet Air Sensor section)

Combustion relay (R9 or CR) defective

Replace defective combustion relay (R9 or CR)

Combustion blower fuse (FU9) blown

Replace combustion blower fuse (FU9)

Combustion blower (CM) defective

Replace defective combustion blower (CM)

Airﬂow switch (PS2) defective

Replace defective airﬂow switch (PS2)

Airﬂow relay (R9) defective

Replace defective airﬂow relay (R9)

Indirect Gas-Fired Heat Modules26

Troubleshooting

Single or 2:1 Stage Furnace Will Not Light

In all cases, verify correct terminals as shown on the unit-speciﬁc wiring diagram.

24 VAC across R and C?

Yes

24 VAC across W1 and C?

Yes

24 VAC across 22 and 21?

Yes

24 VAC across 24 VAC and

21 on SC1 controller?

Yes

24 VAC across A and 21?

Yes

High limit (HLC1) open?

Yes

Main disconnect (DS1) open or defective

Close, repair or replace

Main transformer (TR1) fault

Replace main transformer

Heat Switch (S4) open

Turn heat switch (S4) on

Heating Transformer (TR2) Fault

Replace heating transformer

Optional inlet air sensor (TS4) open

Adjust setting reference start up

Heat relay (RH) is not energized

Check for loose connections. Repair or replace heat relay (RH)

Discharge air selector (TS2) improperly set or faulty

Adjust inlet air sensor setting (refer to Reference - FX Controller/ Access

the Inlet Air Sensor section)

Furnace stage one contact (SC1) defective (stage only)

Replace furnace stage one contact

Ignition controller (IC#)

red LED blinks

7 times or is on

Ignition controller (IC#)

red LED

blinks 6 times

Ignition controller (IC#)

red LED blinks

1 time, 2 times or 4 times

Everything is working

properly, consult factory.

Yes

Discharge temperature was above high limit setting

Wait for high limit to cool and reset.

Ignition controller (IC1) failed

Replace ignition controller.

Combustion blower (CM) not functioning

Replace combustion blower or relay (CR)

Air proving switch (PS2) defective

Replace air proving switch

Improper manifold pressure

Set high and low manifold pressure (refer to Single Stage or

2:1 Staged Control Start-Up section)

Faulty spark rod or spark gap does not equal 1/8 inch

Replace spark rod or adjust gap to 1/8 inch

Indirect Gas-Fired Heat Modules 27

Reference - FX Controller

The FX controller is a programmable electronic controller that is used on the 4:1 electronically modulated furnace and the 8:1 staged furnace. It is preprogrammed at the factory and normally requires few or no changes to the settings. It has a digital readout consisting of three large digits and three smaller status indicator lights at the top. The status indicator lights show:

LED Status Indicators

If the FX controller detects a fault, it will go into alarm condition and a message code will appear on the screen. Message codes that may appear include:

Display Text Signiﬁcance

FXX

dtI

otI

HI F

AFF

Controller has returned to normal status

Discharge air temperature is invalid

Outdoor air sensor is invalid

High fire task

Air flow fault

Function

Enter Down

Controller Interface

Key Function Description

The controller has four buttons, one for “Function”, one for “Enter”, one for “Up” and one for “Down”. During normal operation, the screen will show the version number of the program that is installed in the FX controller. The version number typically consists of a letter followed by two digits. Press Up or Down arrows to scroll through main menu, press Enter for numeric reading.

Stand-Alone Furnace Control

Units without microprocessor controls will have a standalone furnace controller. In this case, all the logic for controlling the furnace is contained within the FX controller. On this type of controller, the LED status indicator lights show the following:

LED

Position

Left

Middle

Right

When the controller is ﬁrst turned on, or after 10 seconds of inactivity by the user, the display will show the main menu. The items in the main menu are:

Display Text Signiﬁcance

Status Signiﬁcance

Off No call for heat

On Call for heat

Blinking High fire task is on

Off Furnace is off

On Furnace is on

Blinking High fire task is on

Off High speed combustion fan is off

On High speed combustion fan is on

Blinking High fire task is on

FXX

oAt

Sot

rCt

Discharge air temperature setpoint by

Discharge air temperature by room

Default display

Discharge air temperature

Outdoor air temperature

Microprocessor input

command module

Program Mode

Program Mode allows the user to view the Program Menu and edit the factory default settings. To access Program Mode and view the Setpoints Menu, press and hold the Function button for three seconds. While viewing the Setpoints Menu, press the Up or Down buttons to scroll through the menu options. To view the setting of the selected menu option, press the Enter button. To edit the setting, press the Up or Down buttons while viewing the setting. To save the new setting and return to the Setpoints Menu, press the Enter button. To return to the Setpoints Menu without saving the change, wait 15 seconds. To exit Program Mode from the Setpoints Menu, wait for 15 seconds.

WARNING

Changing the default settings will significantly affect performance. Only change a setting after reading and understanding this entire manual. Before changing any settings, write down the factory-installed setting.

NOTE

The Enter button must be pressed to save any changes made to the settings. If the Enter button is not pressed, the unit will default back to the last saved setting.

Inlet Air Sensor (iAS) (optional)

The Inlet Air Sensor monitors the temperature of the inlet air. If the inlet air is above the setpoint, the inlet air sensor shuts off the furnace and continues to supply the warm outside air. The inlet air sensor is preset to the factory-recommended 65°F for 8stage furnaces and 60°F for 4:1 turndown modulated furnaces.

Discharge Air Temperature (dtS)

The Discharge Air Temperature setting is the temperature the unit will discharge. The Discharge Air Temperature setting is preset to the factoryrecommended 70°F. The actual discharge air temperature can be displayed by pressing the Up or Down button from the default screen.

Outside Air Temperature (OAt)

To temporarily display the outside air temperature, press the Up or Down buttons from the default screen to change the display until “OAt” is displayed, then press the Enter button.

Indirect Gas-Fired Heat Modules28

Field Adjustments

Field adjustments that can be made to the FX controller include:

• Go to high ﬁre and return

• Adjust discharge air temperature setting

• Adjust inlet air sensor setting

• Adjust room override setting

Go to High Fire Mode

Setting the controller to High Fire mode will cause it to activate the igniter circuitry and fully opens the modulating gas valves. With the gas valves fully open, the valves can be adjusted to permit the recommended maximum amount of gas to the burner manifold. To send the unit to High Fire, press the “Enter” button and the “Up” and “Down” buttons simultaneously for three seconds until the readout shows “HI F”. The unit will now remain in High Fire until the “Function” button is pressed.

Access the Discharge Air Temperature Setting

Go to the Setpoints Menu and then scroll up or down until the display reads “dtS”. Press the Enter button. To edit the settings, follow the instructions in Program Mode section.

Access the Inlet Air Sensor

Go to the Setpoints Menu and then scroll up or down until the display reads iAS. Press the Enter button. Once the display reads iAS, the display will change to the Inlet Air Sensor setting. To edit the setting, follow the instructions in Program Mode section.

UpFunction

Enter Down

NOTE

• If the unit is placed in High Fire, it will remain in High Fire until the “Function” button is pressed.

• Forcing the unit into High Fire in mild weather may cause the high limit switch to trip. If the high limit switch trips, it will reset automatically once the discharge air temperature is at a safe level.

Return to Normal Operation

Return the unit to Normal Operation by pressing the “Function” button. The readout will now show the software version number and the three blinking LEDs at the top of the screen will stop blinking.

NOTE

Always check low fire after adjusting high fire.

Access the Room Override Setting

Go to the Setpoints Menu and then scroll up or down until the display reads rot. Press the Enter button. The display will change to the room override setting. To edit the setting, follow the instructions in Program Mode section.

NOTE

The Room Override function requires a field-supplied thermostat to be installed in the heated space and to be wired between terminals 31 and 32 in the unit’s control center. Reference the unit-specific wiring diagram.

NOTE

The Room Override function temporarily changes the discharge air temperature to the room override setting if the room thermostat is not satisfied.

Access the Setpoints Menu

Press and hold the Function button for three seconds to access the Setpoints Menu. The display will read “SEt”. Press the Enter button. To edit the settings, follow the instructions in Program Mode section.

Indirect Gas-Fired Heat Modules 29

Furnace Control with Microprocessor Control

If the unit is equipped with a microprocessor control, the furnace controller acts as an interface between the microprocessor controller and the furnace. In this case, the FX controller has very little logic built into it since most of the logic is already contained in the microprocessor controller. On this type of controller, the LED status lights show the following:

LED

Position

Left

Middle

Right

Status Signiﬁcance

Off No call for heat

On Call for heat

Off Furnace is off

On Furnace is on

Off High speed combustion fan is off

On High speed combustion fan is on

Because of the limited logic in the FX controller in this case, the menu structure and programming options are much more basic. The items in the main menu are:

Display Text Signiﬁcance

HXX

IPt

Input signal from microprocessor

% Modulation

Program revision

If the FX controller detects a fault, it will go into alarm condition and a message code will appear on the screen. Message codes that may appear include:

Display Text Signiﬁcance

HXX

AFF

Controller has returned to normal status

Discharge air temperature is invalid

Maintenance

Combustion Blower Motor

Motor maintenance is generally limited to cleaning. Cleaning should be limited to exterior surfaces only. Removing dust and grease build-up on the motor housing assures proper motor cooling. Use caution and do not allow water or solvents to enter the motor or bearings. Under no circumstances should motors or bearings be sprayed with water, steam or solvents. The motor bearings are pre-lubricated and sealed, requiring no further lubrication.

WARNING

Turn off all gas and electrical power to the unit before performing any maintenance or service operations to this unit. Remember that if the unit is equipped with electric heat, there may be a second high voltage source that must also be disconnected.

Burners and Oriﬁces

Before each heating season, examine the burners and gas oriﬁces to make sure they are clear of any debris such as spider webs, etc. Clean burner as follows:

• Turn off both electrical and gas supplies to the unit.

• Disconnect the union between manifold and gas valve.

• Remove burner manifold and burner assembly.

• Inspect and clean oriﬁces and burners as necessary. Avoid using any hard or sharp instruments which could cause damage to the oriﬁces or burners.

a. Remove any soot deposits from the burner with a

wire brush.

b. Clean the ports with an aerosol degreaser or

compressed air.

c. Wipe the inside of the burner clean. Cleaning

the burner with a degreaser will slow the future buildup of dirt.

• Before reinstalling the burner assembly, look down the heat exchanger tubes to make sure they are clear of any debris.

• Reinstall manifold and burner assembly, reconnect wire leads and gas supply piping.

• Turn on the electrical power and gas supply.

• Follow the start-up procedure to light the burners and verify proper operation.

Heat Exchanger

The heat exchanger should be checked annually for cracks and discoloration of the tubes. If a crack is detected, the heat exchanger should be replaced before the unit is put back into operation. If the tubes are dark gray, airﬂow across the heat exchanger should be checked to make sure the blower is operating properly.

Flue Collector Box

The ﬂue passageway and ﬂue collector box should be inspected prior to each heating season and cleared of any debris.

Electrical Wiring

The electrical wiring should be inspected annually for loose connections or wiring deterioration.

Gas Train

The gas train connections, joints and valves should be checked annually for tightness.

Replacement Parts

When ordering replacement parts, include the complete unit model number and serial number as shown on the unit labels.

Indirect Gas-Fired Heat Modules30