FloAire F-D User Manual

FOR YOUR SAFETY

Standard and Modular

Direct Fired

Re-Circulating

Heater

s

Installation, Operation, and Maintenance Manual

Save these instructions

RECEIVING AND INSPECTION

WARNING!!

FOR YOUR SAFETY

WARNING

Modular Direct Fired Re-Circulating Heater

1. Open windows.

2. Don’t touch electrical switches.

3. Extinguish any open flames.

4. Immediately call your gas supplier.

The use and storage of gasoline or other flammable vapors and liquids in open containers in the
vicinity of this appliance is hazardous.

If you smell gas:

On heaters that recirculate room air, outside
ventilation air must be provided in accordance
with the information shown on the heater name
plate.

Upon receiving unit, check for any interior and exterior damage, and if found, report it
immediately to the carrier. Also check that all accessory items are accounted for and are
damage free. Turn the blower wheel by hand to verify free rotation and check the damper (if
supplied) for free operation.

Improper installation, adjustment, alteration, service or maintenance can cause property
damage, injury or death. Read the installation, operating and maintenance instructions
thoroughly before installing or servicing this equipment. ALWAYS disconnect power and gas
prior to working on heater.

. This document is the property of the owner of this equipment and is
required for future maintenance. Leave this document with the owner when installation or
service is complete.

August 2013 Rev. 1

A0020936

TABLE OF CONTENTS

WARRANTY ...................................................................................................................................................................................... 4

INSTALLATION ................................................................................................................................................................................. 5

Mechanical ................................................................................................................................................................................... 5

Site Preparation ...................................................................................................................................................................... 5

Assembly ................................................................................................................................................................................ 6

Curb and Ductwork ................................................................................................................................................................. 6

Indoor (INLINE) Installation ..................................................................................................................................................... 7

Roof Mount Installation ........................................................................................................................................................... 7

Gas .............................................................................................................................................................................................. 8

Gas Connection Sizes ............................................................................................................................................................ 8

Gas Pressure Table ................................................................................................................................................................ 8

Gas Connection Diagram ........................................................................................................................................................ 8

Electrical ...................................................................................................................................................................................... 9

Copper Wire Ampacity ............................................................................................................................................................ 9

PSC (Permanent Split Capacitor) Motor Speed Control ........................................................................................................ 10

ECM (Electronically Controlled Motor) Speed Control ........................................................................................................... 10

Motorized Intake Damper ...................................................................................................................................................... 10

Electric Cabinet Heater ......................................................................................................................................................... 10

Remote Control Panel ........................................................................................................................................................... 11

Fan to Building Wiring Connection ........................................................................................................................................ 11

Start Up ...................................................................................................................................................................................... 12

Special Tools Required ......................................................................................................................................................... 12

Start Up Procedure ............................................................................................................................................................... 12

Pilot Adjustment .................................................................................................................................................................... 12

Pilot Assembly ...................................................................................................................................................................... 12

Main Burner Adjustment ........................................................................................................................................................ 13

Maxitrol M511 and M611 Low Fire Bypass Screw ................................................................................................................. 13

Heater Start Up Summary ..................................................................................................................................................... 14

Final Start Up Procedure ....................................................................................................................................................... 15

Pulley Adjustment ................................................................................................................................................................. 15

Pulley Alignment ................................................................................................................................................................... 15

Proper Belt Tension .............................................................................................................................................................. 15

Pulley Setscrew Torque ........................................................................................................................................................ 15

Pulley Combination Chart ..................................................................................................................................................... 16

Sequence of Operation ............................................................................................................................................................... 17

Flame Safety Control ............................................................................................................................................................ 17

Air Flow Switch ..................................................................................................................................................................... 17

DC Flame Signal ................................................................................................................................................................... 17

Modulating Gas System ........................................................................................................................................................ 18

High Temperature Limit......................................................................................................................................................... 18

Operation Summary .............................................................................................................................................................. 18

Optional Remote Panel Circuit .............................................................................................................................................. 19

Re-Circulating Control Options ........................................................................................................................................................ 20

Manual Positioning Control (Potentiometer) .......................................................................................................................... 20

Two Position Control ............................................................................................................................................................. 20

Static Pressure Control (Photohelic) ..................................................................................................................................... 21

A306 Outdoor Sensor ........................................................................................................................................................... 22

Building Signal Damper Control ............................................................................................................................................ 22

Components .................................................................................................................................................................................... 23

Remote Panel Option ............................................................................................................................................................ 24

Troubleshooting ............................................................................................................................................................................... 25

Airflow Troubleshooting Chart ............................................................................................................................................... 25

Burner Troubleshooting Chart ............................................................................................................................................... 26

Remote Panel Troubleshooting Chart ................................................................................................................................... 27

Troubleshooting Flowcharts .................................................................................................................................................. 28

MAINTENANCE .............................................................................................................................................................................. 29

General Maintenance ................................................................................................................................................................. 29

2 weeks after startup .................................................................................................................................................................. 30

Every 3 months .......................................................................................................................................................................... 30

Filter Quantity Chart .............................................................................................................................................................. 30

Yearly ......................................................................................................................................................................................... 31

Burner Orifice Drill Size ........................................................................................................................................................ 31

Start-Up and Maintenance Documentation ................................................................................................................................. 32

Job Information ..................................................................................................................................................................... 32

Heater Information ................................................................................................................................................................ 32

Maintenance Record ............................................................................................................................................................. 32

Factory Service Department.................................................................................................................................................. 32

3

WARRANTY

This equipment is warranted to be free from defects in materials and workmanship, under normal use and
service, for a period of 12 months from date of shipment. This warranty shall not apply if:

1. The equipment is not installed by a qualified installer per the MANUFACTURER’S installation
instructions shipped with the product,

2. The equipment is not installed in accordance with federal, state and local codes and regulations,

3. The equipment is misused or neglected,

4. The equipment is not operated within its published capacity,

5. The invoice is not paid within the terms of the sales agreement.

The MANUFACTURER shall not be liable for incidental and consequential losses and damages
potentially attributable to malfunctioning equipment. Should any part of the equipment prove to be
defective in material or workmanship within the 12-month warranty period, upon examination by the
MANUFACTURER, such part will be repaired or replaced by MANUFACTURER at no charge. The
BUYER shall pay all labor costs incurred in connection with such repair or replacement. Equipment shall
not be returned without MANUFACTURER’S prior authorization and all returned equipment shall be
shipped by the BUYER, freight prepaid to a destination determined by the MANUFACTURER.

4

INSTALLATION

CLEARANCES

It is imperative that this unit is installed and operated with the designed airflow, gas, and electrical supply
in accordance with this manual. If there are any questions about any items, please call the service
department at 1-866-784-6900 for warranty and technical support issues.

Mechanical

WARNING: DO NOT RAISE VENTILATOR BY THE INTAKE HOOD, BLOWER OR
MOTOR SHAFT, OR BEARINGS – USE LIFTING LUGS PROVIDED OR A SLING

Site Preparation

1) Provide clearance around installation site to safely rig and
lift equipment into its final position. Supports must
adequately support equipment. Refer to manufacturer’s
estimated weights.

2) Consider general service and installation space when
locating unit.

3) Locate unit close to the space it will serve to reduce long,
twisted duct runs.

4) Do not allow air intake to face prevailing winds. Support
unit above ground or at roof level high enough to prevent
precipitation from being drawn into its inlet. The inlet must
also be located at least 10 feet away from any exhaust
vents. The heater inlet shall be located in accordance with the applicable building code
provisions for ventilation air. If in doubt regarding the application, consult the manufacturer. All
ventilation air to the heater shall be ducted directly from the outdoors.

5) Recirculation of room air may be hazardous in the presence of:
a) Flammable solids, liquids and gases
b) Explosive materials (e.g., grain dust, coal dust, gunpowder, etc.)
c) Substances which may become toxic when exposed to heat (e.g., refrigerants, aerosols, etc.)

6) Recirculation is not recommended in uninsulated buildings where outside temperatures fall below
32°F (0°C).

7) Excessive recirculation or insufficient ventilation air, which results in inadequate dilution of the
combustion products generated by the heater, may create hazardous concentrations of carbon
dioxide, carbon monoxide, nitrogen dioxide, and other combustion products in the heated space.

8) If gas fork trucks or other fossil fuel powered equipment are utilized in the conditioned area,
additional ventilation requirements for the facility must be addressed separately.

9) If the heater utilizes room sensors for limiting room CO2 concentration:
a) The CO2 control set-point shall be no greater than the maximum allowable room

concentration of 5000 ppm less the sensor’s published accuracy tolerance. The control shall

prevent the CO2 concentration in room air from exceeding 5000 ppm.
b) A minimum of one sensor shall be installed per room served by the heater.
c) When a room area, served by a single heater, does not exceed 10,000 ft2 (929 m2) and height

does not exceed 20 ft (6 m), a duct sensor may be installed in the return air opening of the

heater.
d) Sensors shall be calibrated per the sensor manufacturer’s recommended procedure and

frequency or annually, whichever is more frequent.
e) Sensors shall not be place near sources of CO2.
f) Each heater shall require its own CO2 sensor(s).

The top, back, and front
surfaces of this heater may not
be installed less than 6” from
combustible materials. The
heater base may be installed
on combustible surfaces.
Allow 24” minimum service
clearance on both sides of this
heater.

5

Assembly

Mixing Box Size

Duct Size

1

19 x 15

2

25 x 24

331 x 2

9

5

44 x 44

Intakes and curbs are shipped unassembled. Upon unit arrival, follow the following procedure to
assemble the intake to the heater:

1. Apply silicone or weather-proof gasket on the back
side of the flanges of the intake hood or v-bank
intake.

2. Screw the flanges of the intake hood or v-bank to
the unit with the supplied sheet metal screws.
Place caulk on the outside of the screws to prevent
water leaks. If the unit is a modular unit with a v­bank or evaporative cooler section, the v-bank or
evaporative cooler will bolt to the heater with the bolts provided.

Curb and Ductwork

This fan was specified for a specific CFM and static pressure. The ductwork attached to this unit will
significantly affect the airflow performance. Flexible ductwork and square elbows should not be used.
Also, transitions and turns in ductwork near the fan outlet will cause system effect and will drastically
increase the static pressure and reduce airflow. The chart below shows the minimum fan outlet duct
sizes and straight lengths recommended for optimal fan performance. Follow SMACNA guides and
recommendations for the remaining duct run. Fans designed for rooftop installation should be
installed on a prefabricated or factory built roof curb.
Follow curb manufacturer’s instructions for proper
curb installation. The unit should be installed on a
curb and/or rail elevated not less than 20” above
any surface. Be sure duct connection and fan outlet
are properly aligned and sealed. Secure fan to curb
through vertical portion of the ventilator base
assembly flange using a minimum of eight (8) lug
screws, anchor bolts, or other suitable fasteners (not
furnished). Shims may be required depending upon
curb installation and roofing material. Check all
fasteners for tightness. The diagrams below show
different mechanical installation configurations.

Adequate building relief shall be provided so as to not
over pressurize the building when the heating system
is operating at its rated capacity. This can be
accomplished by taking into account, through standard
engineering methods, the structure’s designed
infiltration rate; by providing properly sized relief
openings; or by interlocking a powered exhaust
system; or by a combination of these methods.

Heaters installed with intake ductwork must be purged to replace at least four air changes of the volume
of the intake duct.

If the failure or malfunction of this heater creates a hazard to other fuel burning equipment in the building
(e.g. when the heater is providing make up air to a boiler room), the unit is to be interlocked to open inlet
air dampers or other such devices.

Units being installed in airplane hangars should be installed in accordance with the Standard for Aircraft
Hangars, ANSI/NFPA 409. Units being installed in public garages should be installed in accordance

Recommended Supply Ductwork Sizes

Blower Size Duct Size Straight Duct Length

10 14 x 14 48 in.
12 16 x 16 54 in.
15 20 x 20 72 in.
18 24 x 24 86 in.
20 26 x 26 108 in.
25 32 x 32 168 in.

Recommended Return Ductwork Sizes

4 37 x 34

6

with the Standard for Parking Structures, ANSI/NFPA 88A, or the Standard for Repair Garages,
ANSI/NFPA 88B, and with CAN/CGA B149 Installation Codes.

Indoor (INLINE) Installation

Roof Mount Installation

7

NOTICE

Gas

Installation of gas piping must conform with local building codes, or in the absence of local codes, with the
National Fuel Gas Code, ANSI Z223.1 (NFPA 54) – latest edition. In Canada, installation must be in
accordance with CAN/CGA-B149.1 for natural gas units and CAN/CGA-B149.2 for propane units.

WARNING: INLET GAS PRESSURE MUST NOT EXCEED PRESSURE INDICATED
ON NAMEPLATE. SEE UNIT NAMEPLATE FOR PROPER GAS SUPPLY
PRESSURE AND GAS TYPE.

1. Always disconnect power before working on or near a heater. Lock and tag the disconnect
switch or breaker to prevent accidental power up.

2. Piping to the unit should conform with local and national requirements for type and volume of gas
handled, and pressure drop allowed in the line. Refer to the Gas Engineer’s Handbook for gas
line capacities.

3. The incoming pipe near the heater should be sized to
match the connection on the outside of the unit. Unit inlet
sizes are shown in the table to the right. Avoid multiple
taps in the gas supply so the unit has a steady supply of
gas at all times.

4. Install a ground joint union with brass seat and a manual
shut-off valve external to the unit casing, as shown below,
adjacent to the unit for emergency shut-off and easy
servicing of controls.

5. Provide a sediment trap, as shown below, before each
unit and where low spots in the pipe line cannot be avoided.

6. Blow out the gas line to remove debris before making connections. Purge line to remove air
before attempting to start unit. Purging of air from gas lines should be performed as described in
ANSI Z223.1-latest edition “National Fuel Gas Code”, or in Canada in CAN/CGA-B149.

7. All field gas piping must be pressure/leak tested prior to unit operation. Use a non-corrosive
bubble forming solution or equivalent
for leak testing. The heater and its
individual shut-off valve must be
disconnected from the gas supply
piping system during any pressure
testing of that system at test
pressures in excess of ½ psi. The
heater must be isolated from the gas
supply piping system by closing its
individual manual shutoff valve
during any pressure testing of the gas supply piping system at test pressures equal to or less
than ½ psi.

8. This unit requires a constant 7 in. w.c. minimum
natural gas supply, when the unit is operating at
maximum gas flow. If the gas supply exceeds 14 in.
w.c. (5 psi. for sizes 4-5 housings) it will damage the
internal valve components, and if it is below 7 in.
w.c., the heater may not perform to specifications.

Max. Manifold Pressure - Natural Gas 5 in. w.c. maximum

Max. Manifold Pressure - Propane 2.5 in. w.c. maximum

Gas Pressure Type Gas Pressure
Size 1-3 Inlet Pressure 7 in. w.c. – 14 in. w.c.
Size 4-5 Inlet Pressure 7 in. w.c. – 5 psi.

Gas Connection Sizes

Unit Size Gas Pipe Size (NPT)

Size 1 ¾”
Size 2 1”
Size 3 1”
Size 4 1-1/4”
Size 5 1-1/2”

Gas Pressure Table

Gas Connection Diagram

Refer to the heater rating
plate for determining the
minimum gas supply
pressure for obtaining the
maximum gas capacity for
which this heater is specified.

8

WARNING!!

Electrical

Before connecting power to the heater, read and understand this
entire section of this document. As-built wiring diagrams are
furnished with each fan by the factory, and are attached to the
door of the unit.

Electrical wiring and connections should be done in accordance
with local ordnances and the National Electric Code,
ANSI/NFPA70. Be sure the voltage and phase of the power
supply and the wire amperage capacity is in accordance with the
motor nameplate. For additional safety information refer to AMCA publication 410-96, Recommended

Safety Practices for Users and Installers of Industrial and Commercial Fans.

Disconnect power before
installing or servicing fan. High
voltage electrical input is
needed for this equipment. This
work should be performed by a
qualified electrician.

1. Always disconnect power before working on or near a
heater. Lock and tag the disconnect switch or breaker to
prevent accidental power up.

2. An electrical drop containing the motor power wiring is
shipped with every fan. The electrical drop should be
brought through one of the conduit openings located in
the base of the unit, run through the curb, and connected
to a junction box inside the building.

3. A dedicated branch circuit should supply the motor circuit
with short circuit protection according to the National
Electric Code. This dedicated branch should be run to the junction box mentioned above and
connected as shown in a following
illustration labeled “Fan to Building
Wiring Connection”.

4. Make certain that the power source
is compatible with the
requirements of your equipment.
The heater nameplate identifies
the proper phase and voltage of
the motor.

5. Units shipped with an optional
remote panel have two electrical
circuit drops. It is important to run
the motor wires in a separate conduit from the remote control wiring. The DC wires from the unit
temperature controller, located in the control drop, should either be shielded cable or be run in a
separate conduit.

6. Before connecting heater to the building power source, verify power line wiring is de-energized.

7. Secure the power cables to prevent contact with sharp objects.

8. Do not kink power cable and never allow the cable to come in contact with oil, grease, hot
surfaces or chemicals.

9. Before powering up the heater, check fan wheel for free rotation and make sure that the interior of
the heater is free of loose debris or shipping materials.

10. If any of the original wire supplied with the heater must be replaced, it must be replaced with type
THHN wire or equivalent.

Copper Wire Ampacity

Wire Size AWG Maximum Amps

14 15
12 20
10 30

8 50
6 65
4 85

9

10

PSC (Permanent Split Capacitor) Motor Speed Control

Some single phase direct drive fans contain speed controls that regulate the amount
of voltage going to the motor. Specific PSC motors must be used in conjunction
with speed controls. The speed control has a knob with an off position, and high to
low range. At high speed, the speed control allows all of the line voltage to pass
right to the motor.

A minimum speed adjustment is provided to allow independent control of the
minimum speed setting. Minimum speed adjustment ensures motor runs with
sufficient torque to prevent stalling. To adjust this:

1) Motor must be in actual operating conditions to achieve proper speed
adjustment. Motor will not slow down unless proper load is applied.

2) Turn main control knob to lowest speed position.

3) Locate and adjust minimum speed setting and adjust with small screw driver. This can be found
under the speed control faceplate. (rotate clockwise to decrease minimum speed; counter­clockwise to increase minimum speed).

4) Motor will now operate from this preset minimum speed to full speed.

The lowest minimum voltage that may be applied to these motors is 65VAC. Running lower
voltages to the motor can cause premature failure and overheating problems.

ECM (Electronically Controlled Motor) Speed Control

ECM motors and control allows accurate manual adjustment of fan speed.
The benefit of ECM motors is exceptional efficiency, performance, and
motor life.

The control used with ECM motors features a 4 digit LED numerical
display. The blue knob on the control allows the user to set the flow index
with a screwdriver. Twenty seconds later, the display shows the motor
RPM. Then, the display periodically alternates between the flow index and
motor RPM. The flow index has a range of 0 to 100% and is typically linear with motor RPM.

The ECM control requires a 24 VAC input and can locally turn the motor on and off. The motor can be
adjusted between 300 RPM and maximum speed with this control.

NOTE: To adjust the speed of 3 phase direct drive motors, a variable frequency
drive is required.

Motorized Intake Damper

On units shipped with the optional motorized intake damper, a power transformer is supplied with the unit
if the main incoming voltage is greater than 120V. The damper motor is automatically energized when
the main disconnect switch is in the ON position. No external wiring to the damper motor is required.

Electric Cabinet Heater

On units shipped with an optional electric cabinet heater, ensure that the heater is wired to a separate
120V, 15 amp input, the thermostat sensing bulb is mounted correctly in the control vestibule where the
heater is located, and the thermostat set to 0 Degrees Fahrenheit.

11

Remote Control Panel

On units shipped with the optional remote control panel, an electrical drop containing the panel wiring is
provided with the heater. There is a terminal strip inside the remote panel that matches the terminals in
the heater unit. The remote panel should be wired as shown below.

Fire System
Microswitch

NC

NOPRC

BK

OR

WH

GY

BR

RD

PK

YW

RD

BK

BK

OR

WH

GY

BR

RD

PK

YW

RD

BK

BK

1

E

BK

OR

WH

GY

BR

RD

PK

YW

RD

BK

BL

Fan to Building Wiring Connection

BK

OR

WH

GY

BR

RD

PK

YW

RD

BK

12

OPERATION

Prior to starting up or operating the heater, check all fasteners for tightness. In particular, check the set
screw in the wheel hub, bearings and the fan sheaves (pulleys). With power and gas to the heater OFF or
prior to connecting ventilator to power, turn the fan wheel by hand to be sure it is not striking the inlet or
any obstacles. Re-center if necessary.

Start Up

Special Tools Required

• AC Voltage Meter

• Tachometer

• Standard Hand Tools

Start Up Procedure

1. Check all electrical connections for tightness and continuity.

2. Check pulley alignment and belt tension as described below.

3. Inspect the condition of the intake damper and damper linkage, if provided.

4. Inspect the air-stream for obstructions and install intake filters if missing.

5. Compare the supplied motor voltage with the fan’s nameplate motor voltage. If this does not
match, correct the problem.

6. Start the fan up, by turning the external disconnect to the ON position, and shut it OFF
immediately to check rotation of the wheel with the directional arrow on the blower scroll.
Reversed rotation will result in poor air performance, motor overloading and possible burnout.
For units equipped with a single-phase motor check the motor wiring diagram to change rotation.
For 3-phase motors, any two power leads can be interchanged to reverse motor direction.

7. When the fan is started up, observe the operation and check for any unusual noises.

• Amperage Meter

• Manometer

• Differential Pressure Gauge

Pilot Adjustment

1. Restart the fan and check the gas supply pressure at the inlet
gas tap upstream of all electronic valves. The inlet pressure
should be 7 in. - 14 in. w.c. ( 7 in. w.c. – 5 psi on Size 4-5
heaters). If the inlet pressure is too high, install an additional
pressure regulator external to the unit.

2. Open the field installed manual gas shut-off valve and the
manual main gas valve on the combination gas control valve.

3. Call for heat with the intake air thermostat (turn set-point to
temperature above outside air) and allow the pilot to light. If the
pilot does not light, purge the pilot line. If air purging is
required, disconnect the pilot line at the outlet of the pilot valve.

4. Check the pilot flame voltage at the Flame Safety Control
interface test jacks. A weak pilot flame can be caused by low
gas pressure, or a dirty pilot orifice. To adjust the pilot flame,
remove the cap from the pilot adjustment screw on the
combination gas valve. Increase the pilot gas flow by turning
the screw counter-clockwise. Decrease the pilot gas flow by
turning the screw clockwise. The pilot DC voltage should read
12 VDC minimum and should typically be 15 VDC.

5. Once the pilot has been established, open the main manual gas
shut-off valve downstream of the electronic valves. Check to
make sure that the main gas valve opens, and gas flows to the
burner.

Pilot Assembly

13

Mod Valve Voltage Summary

Maxitrol MR212

Main Burner Adjustment

1. Once the pilot has been properly established, the
manifold gas pressure or temperature rise should be
adjusted to jobsite conditions. The gas pressure
regulator (integral to the combination gas control on size

Volts DC Firing Mode

0 to 5 VDC Low Fire

5 to 15 VDC Modulation

15 to 20 VDC High Fire

1-3 heaters and located in the modulating valve on size
4-5 heaters) is adjusted at the factory for average gas
conditions. It is important that the gas be supplied to the burner in accordance with the input
rating on the rating plate.

2. Create a high fire call for heat. This should be done with the blower on and all gas controls on.
High fire can be achieved by removing the wire at terminal #4 (remove wires #2 and #4 for
Maxitrol 44 systems) from the Maxitrol 14 amplifier.

3. The manifold pressure should be checked
at the pressure tap downstream of the

Av era ge M an ifold Pre ssu re vs. Fi rin g Rate /Ft . of B ur ner

6.00

modulating valve. The graph to the right
indicates the proper manifold pressure for
the desired amount of BTUs per foot of
burner. For natural gas systems, the high
fire manifold pressure should not exceed 5
in. w.c. For propane gas, the high fire
manifold pressure should not exceed 2.5
in. w.c. Another method of checking high
fire is to measure the temperature rise of
the unit. The temperature rise should be
set to design conditions and typically is
minimum 70°F.

4. Remove the cap from the combination gas
valve regulator adjustment (size 1-3) or

5.00

4.00

3.00

2.00

1.00

Mani fold Pre ssure (in. w .c.)

0.00

-1.00

0 100000 20000 0 300000 400000 500000 600000

Natural Gas Propane Gas

Firing Rat e (BT U/Hr /Ft. o f B urne r)

the cap from the MR212 valve (size 4-5).
Using the regulator pressure adjusting screw, adjust the high fire manifold pressure to 5 in. w.c.
maximum for natural gas and 2.5 in. w.c. maximum for propane gas. High fire should be set to
generate the desired temperature rise. If the high fire screw is at the end of its adjustment and
more pressure is needed, then adjust the main building gas pressure regulator spring (located
external to the unit) to achieve the proper manifold pressure. Turning the regulator screw
clockwise will increase pressure and counter-clockwise will decrease pressure. Remember -

The high fire DC voltage should read 12 VDC minimum and should typically be 15 VDC on
the Flame Safety Controller test jacks.

5. Reconnect the wire on the Maxitrol 14 amplifier at terminal #4 (wires #2 and #4 for
Maxitrol 44).

6. The low fire manifold pressure must now be set. Low fire can be achieved by

Low Fire

Bypass Screw

removing the wire at terminal #5 from the Maxitrol 14 amplifier (remove #8 for
Maxitrol 44). Check the low fire flame signal to ensure that the DC voltage is 12
VDC minimum on the Flame Safety Controller test jacks.

7. Using the bypass screw (located on the side of the M511 and M611 valves, and
under the cap of the MR212 valve), adjust low the low fire manifold pressure until
there is a very thin flame along the entire length of the burner. No dark spot should
be seen in the burner. The burner may be observed through the view-port located
on the external wall of the heater. Replace the cap to the Maxitrol valve and restore
all of the original wiring on the Maxitrol amplifier and gas components.

8. A final gas leak check shall be performed to verify the gas-tightness of the heater’s

Maxitrol M511 and

M611 Low Fire
Bypass Screw

components and piping under normal operating conditions. This can be done by
measuring the gas pressure at the ¼” gas plug just downstream of the modulating
valve.

14

Heater Start Up Summary

Is incoming gas pressure

7"-14"?

No

(7"-5 psi. for size 4-5 units)

Yes

Adjust

incoming gas

pressure.

Adjust pilot flame.

Lock unit into

high fire.

Does high fire produce

at least a 70°F temp

rise and produce the

correct manifold

pressure?

Yes

Lock unit into low fire.

Does thin flame fill

entire burner length?

Yes

Burner start up

complete.

No

Adjust high fire

No

Adjust low

fire.

Setting incoming pressure:

Presure must be measured at first "T" in
supply gas line before the first gas valve.

Adjusting the pilot:
The pilot DC signal should be 12 VDC
minimum.

Adjusting high fire:

High fire manifold pressure should be 5"
maximum for natural gas and 2.5"
maximum for propane. High fire should
produce at least a 70°F temperature rise.
Remove wire #4 from the Maxitrol 14
amplifier (#2 and #4 for Maxitrol 44). This
will drive the valve into its full open
position. Adjust high fire with the
regulator inside the unit. Turn clockwise
to increase temperature rise. Ensure that
DC flame signal is minimum 12 VDC.
Replace the wires on the Maxitrol
Amplifier.

Adjusting low fire:

Remove wire #5 from the Maxitrol 14
amplifier (#8 for Maxitrol 44). This will
drive the valve into its lowest position.
Adjust the low fire by turning the low fire
bypass screw on the side of the
modulating valve for M511 and M611
models. For MR212 valves, the low and
high fire are both under the valve cover.
Refer to the included Maxitrol literature for
more detailed information. Ensure that
DC flame signal is minimum 12 VDC and
that the enite length of burner is filled with
a thin flame.

15

Maximum RPM

and

HP Chart

Pulley Adjustment Illustration

Final Start Up Procedure

1. With the air and burner systems in full operation and all ducts attached, measure the system
airflow. Motor sheave (pulley) is variable pitch, and allows for an increase or decrease of the fan
RPM to adjust the airflow, as shown in the illustration below. For your convenience, a RPM chart
is included in the following pages.

2. Once the proper airflow is achieved, measure and record the fan speed with a reliable
tachometer. Caution - Excessive speed will result in motor overloading or bearing failure.
Do not set fan RPMs higher than specified in the maximum RPM chart. See the
troubleshooting guide for more information.

3. Measure and record the voltage and amperage to the motor and compare with the motor
nameplate to determine if the motor is operating under safe load condition.

4. Once the rpm of the ventilator has been properly set, disconnect power and recheck belt tension
and pulley alignment as described below.

Blower Size Maximum RPM Maximum HP

10” 1800 2
12” 1500 3
15” 1400 5
18” 1200 5
20” 1000 10
25” 900 20

Pulley Adjustment

The adjustable motor pulley is factory set for the RPM specified.
Speed can be increased by closing or decreased by opening the
adjustable motor sheave. Two groove variable pitch pulleys must
be adjusted an equal number of turns open or closed. Any
increase in speed represents a substantial increase in
horsepower required by the unit. Motor amperage should always
be checked to avoid serious damage to the motor when the
speed is varied. Always torque setscrews according to the
setscrew torque chart.

Pulley Alignment

Pulley Setscrew Torque

Thread Size Torque (IN/Lb)

No. 10 (bushing) 32

1/4” (bushing) 72

5/16” 130

Proper Belt Tension

Pulley Combination Chart

** 2HP Motors on 20 IN Blowers use 2VP42 Pulleys

Motor RPM 1725

1/3 to 1-1/2 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2

AX BELTS 1VL34 1.9 2.9 2 3

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

AK114 11 11.2 308 323 339 354 370 385 400 416 431 447 462

1/3 to 2 HP MOTOR PULLEY D d1 Dd2 Pd1 Pd2
AX BELTS 1VL40 2.4 3.4 2.6 3.6

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

AK114 11 11.2 400 416 431 447 462 477 493 508 524 539 554

AK94 9 9.2 488 506 525 544 563 581 600 619 638 656 675

AK79 7.5 7.7 582 605 627 650 672 694 717 739 762 784 806

AK66 6.2 6.4 701 728 755 782 809 836 863 889 916 943 970

AK54 5 5.2 863 896 929 962 995 1028 1062 1095 1128 1161 1194

AK46 4.2 4.4 1019 1059 1098 11 37 1176 1215 1255 1294 1333 1372 1411

AK39 3.5 3.7 1212 1259 1305 13 52 1399 1445 1492 1539 1585 1632 1678
AK32 3 3.2 1402 1455 1509 1563 1617 1671 1725 1779 1833 1887 1941

3 to 5 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2

BX BELTS 2VP42 2.9 3.9 3 4

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 6 5 1/2 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

2BK160H 15.4 15.7 330 339 348 357 366 375 385 394 403 412 421 430 439

2BK140H 13.4 13.7 378 388 399 409 420 430 441 451 462 472 483 493 504

2BK120H 11.4 11.7 442 455 467 479 491 504 516 528 541 553 565 577 590

2BK110H 10.4 10.7 484 497 511 524 537 551 564 578 591 605 618 631 645

2BK100H 9.4 9.7 534 548 563 57 8 593 608 622 637 652 667 682 697 711

2BK90H 8.4 8.7 595 611 628 644 661 677 694 710 727 744 760 777 793

2BK80H 7.4 7.7 672 691 709 728 747 765 784 803 821 840 859 877 896

2BK70H 6.4 6.7 772 794 815 837 858 880 901 923 944 965 987 1008 1030

10 - 20 IN. BLOWER**

2BK60H 5.4 5.7 908 933 958 984 1009 1034 1059 1084 1110 1135 1160 1185 1211

2BK55H 4.9 5.2 995 1023 1050 1078 1106 1133 1161 1189 1216 1244 1272 1299 1327

2BK50H 4.4 4.7 1101 1132 1162 11 93 1223 1254 1285 1315 1346 1376 1407 1438 1468

7-1/2 to 10 HP MOTOR PULLEY D d1 Dd2 Pd1 Pd2

BX BELTS 2VP60 4.3 5.5 4.7 5.9

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 6 5 1/2 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

2BK160H 15.4 15.7 516 527 538 549 560 571 582 593 604 615 626 637 648

2BK140H 13.4 13.7 592 604 617 630 642 655 667 680 693 705 718 730 743

2BK120H 11.4 11.7 693 708 722 737 752 767 781 796 811 826 840 855 870

2BK110H 10.4 10.7 758 774 790 806 822 838 854 871 887 903 919 935 951

2BK100H 9.4 9.7 836 854 871 88 9 907 925 943 960 978 996 1014 1031 1049

2BK90H 8.4 8.7 932 952 972 991 1011 1031 1051 1071 1091 1110 1130 1150 1170

2BK80H 7.4 7.7 1053 1075 1098 11 20 1143 1165 1187 1210 1232 1255 1277 1299 1322

3 to 5 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2
BX BELTS 2VP42 2.9 3.9 3 4

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 6 5 1/2 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

2B5V278 27.8 28.1 184 189 194 200 205 210 215 220 225 230 235 240 246

2B5V250 25 25.3 205 210 216 222 227 233 239 244 250 256 261 267 273

2B5V234 23.4 23.7 218 224 230 237 243 249 255 261 267 273 279 285 291

2B5V200 20 20.3 255 262 269 276 283 290 297 304 312 319 326 333 340

2B5V184 18.4 18.7 277 284 292 300 307 315 323 331 338 346 354 361 369

2B5V160 16 16.3 317 326 335 344 353 362 370 379 388 397 406 414 423

2B5V154 15.4 15.7 330 339 348 357 366 375 385 394 403 412 421 430 439

2B5V136 12.6 12.9 401 412 423 435 446 457 468 479 490 501 513 524 535

2B5V124 12.4 12.7 407 419 430 441 453 464 475 487 498 509 521 532 543

2B5V110 11 11.3 458 471 483 496 509 522 534 547 560 572 585 598 611

7-1/2 to 10 HP MOTOR PULLEY D d1 Dd2 Pd1 Pd2
BX BELTS 2VP60 4.3 5.5 4.7 5.9

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 6 5 1/2 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

2B5V278 27.8 28.1 289 295 301 307 313 319 325 331 338 344 350 356 362

2B5V250 25 25.3 320 327 334 341 348 355 361 368 375 382 389 395 402

2B5V234 23.4 23.7 342 349 357 364 371 378 386 393 400 408 415 422 429

2B5V200 20 20.3 399 408 416 425 433 442 450 459 467 476 484 493 501

2B5V184 18.4 18.7 434 443 452 461 470 480 489 498 507 517 526 535 544

2B5V160 16 16.3 497 508 519 529 540 550 561 571 582 593 603 614 624

2B5V154 15.4 15.7 516 527 538 549 560 571 582 593 604 615 626 637 648

25 IN. BLOWER

2B5V136 12.6 12.9 628 642 655 669 682 695 709 722 735 749 762 776 789

2B5V124 12.4 12.7 638 652 666 679 693 706 720 733 747 761 774 788 801

2B5V110 11 11.3 717 733 748 763 779 794 809 824 840 855 870 885 901

15 to 20 HP MOTOR PULLEY D d1 Dd2 Pd1 Pd2
BX BELTS 2VP75 5.8 7 6.2 7.4

BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 6 5 1/2 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0

2B5V278 27.8 28.1 381 387 393 399 405 411 417 424 430 436 442 448 454

2B5V250 25 25.3 423 430 436 443 450 457 464 470 477 484 491 498 505

2B5V234 23.4 23.7 451 459 466 473 480 488 495 502 509 517 524 531 539

2B5V200 20 20.3 527 535 544 552 561 569 578 586 595 603 612 620 629

2B5V184 18.4 18.7 572 581 590 600 609 618 627 636 646 655 664 673 683

2B5V160 16 16.3 656 667 677 688 698 709 720 730 741 751 762 773 783

2B5V154 15.4 15.7 681 692 703 714 725 736 747 758 769 780 791 802 813
2B5V136 12.6 12.9 829 842 856 869 883 896 909 923 936 949 963 976 990

Open Closed

Open Closed

Open Closed

Open Closed

Open Closed

Open Closed

Open Closed

TURNS ON MOTOR PULLEY

TURNS ON MOTOR PULLEY

TURNS ON MOTOR PULLEY

TURNS ON MOTOR PULLEY

TURNS ON MOTOR PULLEY

TURNS ON MOTOR PULLEY

TURNS ON MOTOR PULLEY

16

17

Flame Safety Controller

Air Flow Switch

Sequence of Operation

The direct-fired heater is most easily understood when broken down into smaller individual systems.
There are two main systems, a make-up air fan and a heater. The make-up air fan consists of a blower
and motor. The heater may be further broken down into two control systems, the Flame Safety Control
(FSC) and the Modulating Gas System (MGS). The burner mixes air with the gas (Natural or LP) which
heats the air.

Flame Safety Control

The first system to understand is the Flame Safety Control. The FSC
is there only to monitor the flame, NOT to control temperature. The
FSC uses a flame rectification sensor mounted on the pilot assembly
to detect the presence of flame in the burner. Flame strength and
presence can be measured at the FSC by reading the rectified flame
signal. This is done by using a DC voltage meter attached to the test
jacks on the top of the control. Flame is present when the DC voltage
reads between 6 and 18 VDC. Ideal flame intensity produces a signal
of 12 VDC or greater. The FSC is also wired into an airflow switch,
which tells it whether there is proper airflow through the unit (not just
any airflow, but proper airflow). Proper airflow occurs when there is a

.15 in. w.c. to .80 in. w.c. differential pressure drop across the
burner. When the airflow through the heater produces a pressure

drop in this range, the FSC indicates so by illuminating the AIRFLOW
LED. The FSC controls the opening of the redundant solenoid gas
valves and the operation of the spark igniter to initiate a pilot flame
upon start-up.

The OPR CTRL LED indicates that there is power to the FSC. Next,
the AIRFLOW LED will come on if there is proper airflow through the
unit. Third, the unit will pause to purge any gasses or combustible vapors before attempting flame
ignition. Then, there is a Pilot Trial For Ignition (PTFI) and the PTFI LED comes on. During PTFI, the FSC
opens the pilot gas valve and allows gas to flow to the pilot assembly. At the same moment, the spark
igniter is started, causing the spark to ignite the pilot gas. When the flamerod sensor detects the flame, it
turns on the FLAME LED, turns off the PTFI LED, and powers the modulating gas system. This is the
normal operating mode. The FSC continues to monitor the flame and airflow. Once this occurs, the unit is
in a main flame cycle and thus powers the main gas valve and the modulating gas system. This is the
normal operating mode. The FSC continues to monitor the flame and airflow. The last LED on the FSC is
the ALARM LED. This will turn on when the FSC determines an unsafe condition has occurred, and will
not allow the unit to recycle for heat until it has been properly reset. Anytime the FSC has gone into
“Alarm” mode, the problem must be diagnosed and corrected to avoid future lockouts after resetting. To
begin troubleshooting, or to reset the FSC, shut down power to the heater and restart the heater. This
will clear the alarm from the flame safety.

DC Flame Signal

DC Voltage Flame Status

0 to 5 VDC No Flame

6 to 11 VDC Weak Flame

12 to 18 VDC Strong Flame

Air Flow Switch

There are both high and low airflow switches contained within one housing
measuring the pressure drop across the burner. This is to insure that there is
proper airflow (.15 in. w.c. to .80 in. w.c.) across the burner and proper
combustion at all times. Both switches are wired in series and have single pole
double throw (one common contact, one normally open contact, and one normally
closed contact) switches that are ‘switched’ by air pressure. There are two airflow
tubes in the heater, located near the burner and profile plate assembly (profile
plates surround the burner and control air into the burner section). In the case of
clogged filters, blocked intake, excessive duct static pressure, or a broken belt, the
correct burner differential pressure may not be achieved, not allowing the low

18

Maxitrol 14

High Temperature L

imit

airflow switch to close. The high airflow switch protects against profile plate failures that cause excessive
airflow through the burner. In the event that the pressure drop across the burner is not in the range of the
airflow switch, gas flow to the burner is stopped by the Flame Safety Control.

The graphs below illustrate the approximate cfm going through the unit vs. the differential pressure
measured by the airflow switch. Simply measure the differential profile pressure drop at the airflow tubes
in the unit and match that value up to the matching unit curve below. This will show the cfms traveling
through the burner and will indicate proper airflow or airflow problems (too much or not enough). If the
pressure drop is outside of the .15” to .80” range, the blower rpm should be adjusted to fix airflow.

10000

CFM

9000

8000

7000

6000

5000

4000

3000

2000

1000

Size 1-3 Hea ter C FM vs. Bu rner Pr ofi le Pre ssu re

Size 1

Size 2

Size 3

0

0.15 0.2 0.25 0. 3 0.35 0. 4 0.45 0.5 0. 55 0.6 0.65

Burne r Differ ential Pr ofile Pre ssure (in . w.c.)

25000

23000

21000

19000

17000

15000

CFM

13000

11000

9000

7000

5000

3000

Size 4-5 Hea ter C FM vs. Bu rner Pr ofil e Pre ssu re

Size 4

Size 5

0.15 0.2 0. 25 0. 3 0. 35 0.4 0 .45 0.5 0. 55 0.6 0.65

Burne r Differe ntial Pro file Pre ssure (in. w.c.)

Modulating Gas System

The second system, the Maxitrol modulating gas system, consists of a
temperature selector dial, a discharge air sensor, an amplifier, and a
modulating gas valve. The two types of Maxitrol systems used are the Maxitrol
14 series or the Maxitrol 44 series. The Maxitrol 14 utilizes a discharge air
sensor and modulates the Maxitrol gas valve to provide discharge air to match
the selected temperature on the temperature selector. The Maxitrol 44 utilizes a
room temperature sensor to control room temperature as well as a discharge air
sensor in order to control the discharge air temperature. The modulating gas
valve controls the amount of gas flow to the burner based on the temperature
rise needed. When the modulating gas valve is all the way open and achieving
the maximum BTUs and temperature rise of the unit, it is called “high fire”.

High Temperature Limit

One of the back up safety device is the high temperature limit switch.
This switch is a mechanical thermostat that measures the temperature
inside the unit downstream of the burner. If the factory-set temperature
of 170°F is exceeded, it will signal the FSC to turn off the burner. This
requires a manual reset of the high temperature limit. This insures that
the discharge does not exceed 185°F.

Operation Summary

 With the blower already running and the airflow switch proven;

 The outside air temperature falls below the setting of intake air thermostat

or

 The optional remote panel is set to “Manual” and “Heat” mode

• The FSC in energized and the following occurs;

 FSC indicates that it has power by illuminating the OPR CTRL LED
 FSC verifies proper Airflow

Amplifier

19

 Begins Pilot Trial For Ignition and turns on PTFI LED
 The pilot gas solenoid valve is opened, the spark igniter begins sparking, and the flamerod

sensor watches for flame initiation

 When flame is established, the FLAME LED is illuminated and main valve opens and the

FSC powers the Maxitrol system and gas flow begins modulating

 The FSC monitors the flame while the Maxitrol system adjusts to the selected temperature

•

The Maxitrol system checks the discharge air temperature (and the room temperature for the Maxitrol

44) and regulates the gas going to the burner to satisfy the temperature setting. The Maxitrol system

will modulate the main burner gas from 100% down to 5% as needed.

Optional Remote Panel Circuit

Power

Supply From

Heater

"Auto"

Power is Sent to

Heater to Open

Damper (if

provided) and

Start Blower

"Blower On"

Light

On

"Power" LightOnOff

Panel is

Powered

Blower S witch

Off

No Power to

Panel

(3-Position Panels Only)

Damper is not

Open or Freeze­Stat has Detected
Low Temperature

Operation

"Off"

Position

"Manual"

Nothing Happens

No Power is Sent

to Heater

Power is Sent to

Heater to Open

Damper (if

provided) and

Start Blower

"Blower On"

Light

On

Off

Damper is not

Open or Freeze­Stat has Detected
Low Temperature

Operation

Nothing Happens

Intake Air is

Warmer Than

Thermostat

Set-Point

Intake Air is Cooler Than

Thermostat Set-Point

Heat Circuit is Energized

"Burner On" Light Illuminates with

"Flame Failure" Light illuminates
if proper flame is not established

Intake Air

Thermstat is

Powered

proper flame.

Blower Operates

Cooling Circuit is

Energized

"Cool"

Position

(if provided)

Temperature

Control Switch

Position

Heat Circuit is Energized

"Burner On" Light Illuminates with

proper flame.

"Flame Failure" Light illuminates
if proper flame is not established

Position

"Heat"

"Vent"

Blower Operates

Heat Does not

Operate

20

Re-Circulating Control Options

Minimum Outdoor

Minimum Indoor

Maximum Re

-

Maximum

The Re-Circulating system is for controlling the amount of make-up air being brought into a building. It
can be set from a minimum 20% fresh air/80% return air to a maximum of 100% fresh air/0% return air. In
order to comply with standards for recirculating direct fired heaters, different control schemes can be
chosen depending on maximum return air percentage preference, max discharge air temperature and
outside air temperature. They are shown below. If the outside air or return air falls below these minimums
the dampers will modulate to full fresh air until that respective temperature has risen above the threshold
again.

RCS

System

Air Temperature

(⁰F)

Air Temperature

(⁰F)

Circulating Percentage

(%)

Discharge

Temperature (⁰F)

RCS5 -30 7 60 90

RCS10 -30 25 50 120

RCS15 -25 58 80 90

RCS20 -25 54 60 120

RCS25 -20 55 50 140

RCS30 -15 47 60 120

RCS35 0 52 80 90

RCS40 0 35 50 140

The Re-Circulating damper motion can be controlled by four different options. With all of these options the
dampers will still modulate to full fresh air if the temperatures in the above table are not met.

Manual Positioning Control (Potentiometer)

The dampers can be controlled at a remote location by a manual potentiometer to any position from 20%
to 100% fresh air. This will allow manually setting the dampers to match the building ventilation
requirements. It will take an extra 3 control wires at the remote location. On a power failure, or if the unit is
turned off, the return air damper will close by spring return.

Two Position Control

The dampers can be controlled by a two position switch (a field supplied switching device) to open the
fresh air to 100%. On opening of the circuit, power failure, or if the unit is shutoff, the return air damper
will close by spring return.

21

Static Pressure Control (Photohelic)

The dampers can be controlled by a building static pressure control. This controller will sense the
difference between pressure inside the building, and pressure outside the building (sensed at the A306
outdoor sensor), and position the dampers to maintain the pressure setting on the controller. The
controller has two set points and an indicator. The two set points are a minimum desired static pressure
point, and a maximum static pressure point.

The actual building static pressure will be shown by a visual indicator between these two settings. The
controller will modulate the dampers to maintain a static pressure between these set points.

When building static pressure is below the minimum setting, the damper motor will proportionally open
the fresh air damper and close the return air damper until static increases above the minimum setting. At
this point, the damper motor will stop and hold this proportion.

If the building static continues to climb and goes above maximum setting, the damper motor will reverse
proportion, closing the fresh air damper and opening the return air damper until static drops below
maximum setting.

During the “OFF” or “Night” cycle of the unit, an internal switching circuit will close the return air damper.

See additional wiring and installation information on the static pressure controller and A306 outdoor
sensor.

Static Pressure Controller Installation Instructions

Avoid locating the front of the static pressure controller in sun light or other areas with high ambient light
or corrosive levels. Bright light shining on the photocells can cause false actuation of the load relays.

The static pressure controller should be zeroed out before attaching the low and high pressure hoses.
The zero adjustment is located between the minimum and maximum dials.

Using the supplied rubber tubing the high side of the static pressure controller should be plumbed to the
inside of the building. The low side of the static pressure controller should be plumbed to the A306
outdoor sensor. See the A306 installation instructions.

22

A306 Outdoor Sensor

Use the installation instructions shipped with the A306 outdoor sensor.

Building Signal Damper Control

When this option is ordered, the supply and return dampers will modulate based on a 0-10 VDC signal
from the Building automation system.

23

16

20

22

23

12

14

19

21

13

17

1

11

Components

The following image and list outlines the typical direct fired heater components and their functions

2

8

3

4

9

6

7

5

5

6

10

18

15

1. Gas Inlet – Main gas supply connection

2. Motor Starter – Contactor with overload protection to start and protect motor.

3. Freeze-Stat Thermostat (Optional) – De-energizes blower motor if the discharge air
temperature falls below the set point.

4. Cooling Interlock Relay (Optional) – Energizes power to cooling circuit on call for cooling.

5. Inlet Gas Pressure Tap – Inlet gas pressure should be measured here.

6. Combination Gas Valve - A combination of redundant solenoid valves, pilot valve and gas
regulator built into one unit.

7. Pilot Tubing – Pilot tube connection to combination gas valve.

8. Manual Reset High Temperature Limit – Safety device that prevents the heater from
overheating.

9. Maxitrol Modulating Amplifier - Regulates temperature by modulating gas valve

10. Power Transformer – Installed when motor voltage > 120V. Used to provide 120V service to
controls.

11. Circuit Breaker – Protects electrical components from high current spikes.

12. Terminal Strip – Central location to terminate control wiring. Should be used for troubleshooting.

13. Control Transformer – 120V primary; 24V secondary control transformer.

14. Low Pressure Airflow Probe – Measures profile pressure downstream of burner.

15. High Pressure Airflow Probe – Measures profile pressure upstream of burner.

16. Modulating Gas Valve – Modulates gas flow to burner to provide proper air temperature.

17. Manifold Gas Pressure Tap – Manifold gas pressure should be measured here.

18. Flame Safety Control – Initiates and monitors flame.

19. Airflow Switch – A safety device insuring proper air flow during burner operation.

20. Ignition Transformer – Produces high voltage spark to ignite flame.

21. Intake Air Thermostat – De-energize heating circuit when intake air exceeds set-point.

22. Damper Actuator – Motor containing end switch that opens intake damper.

23. Manual Gas Shut-Off Valve Allows gas flow to burner to be shut off to leak test gas train

24

1

2

3

4

FILTER

FAILURE

Remote Panel Option

The Remote Panel is a device used to control the operation of the heater from a remote location. This
unit is available in both a “2 Position” or “3 Position” configuration and with or without a cooling output. It
also will accommodate both the Maxitrol discharge temperature dial and the Maxitrol space sensing
Selectrastat. It is important to understand the following Remote Panel controls and uses:

FLAME

CLOGGED

1. Manual/Off/Auto Switch - Used to control blower operation and tempering mode of unit. The
AUTO position allows the unit to “decide”, through the use of the intake air thermostat, whether or

not heating is needed. The MANUAL position allows the user to control whether or not heat is
needed. The OFF position will turn the blower off when a “3 Position” remote panel is ordered.
The OFF position will disable all temperature controls when a “2 Position” remote panel is
ordered and fan power is then controlled by the pre-wire package only.

2. Heat/Vent Switch – This switch is powered when the Manual/Off/Auto switch is in the MANUAL
position. It is used to control the tempering mode of the unit. The VENT position will prevent the
burner from operating and the heater will deliver untempered air. The HEAT position will force
the burner on and the unit will heat the incoming air. This switch becomes a Heat/Vent/Cool
switch when the cooling interlock is ordered. This option provides a 120V cooling output from the
remote panel.

3. Lights- Displays the current status of unit features. The light definitions are as follows:

POWER - Illuminated when there is power to Remote Panel.
BLOWER ON - Illuminated when the blower motor is powered.
BURNER ON - Illuminates after pilot flame has established and main valve is powered.
FLAME FAILURE - Illuminated when the Flame Safety Control is in Alarm mode.
CLOGGED FILTER – (Optional) Illuminated when the Intake Filters are Dirty.

4. Temperature Control – Controls the discharge temperature of a standard unit. The temperature

dial is replaced with Maxitrol Selectrastat in Space Heating applications and is used to control the
space temperature.

25

Troubleshooting

The following tables list causes and corrective actions for possible problems with direct fired heater units.
Review these lists prior to consulting manufacturer.

Airflow Troubleshooting Chart

Problem

Fan Inoperative Blown fuse or open circuit breaker Replace fuse or reset circuit breaker

Motor Overload Fan rotating in the wrong direction Be sure fan is rotating in the direction

Insufficient Airflow Fan rotating in the wrong direction Be sure fan is rotating in the direction

Excessive Airflow Blower speed to high Reduce fan RPM

Excessive Vibration and Noise Misaligned pulleys Align pulleys

Potential Cause

Disconnect switch in “Off” position Turn to “On” position
Motor wired incorrectly Check motor wiring to wiring diagram

Broken fan belt Replace belt
Motor starter overloaded Reset starter and check amps
Remote panel set to “Off” Position Set Remote Panel to “Manual” or

Fan speed is too high Reduce fan RPM
Motor wired incorrectly Check motor wiring to wiring diagram

Overload in starter set too low Set overload to motor FLA value
Motor HP too low Determine if HP is sufficient for job
Duct static pressure lower than design Reduce fan RPM

Poor outlet conditions There should be a straight clear duct

Intake damper not fully open Inspect damper linkage and replace

Duct static pressure higher than
design
Blower speed too low Increase fan RPM. Do not overload

Supply grills or registers closed Open and adjust
Dirty or clogged filters Clean and/or replace
Belt slippage Adjust belt tension

Filters not installed Install filters
Duct static pressure lower than design Reduce fan RPM

Damaged or unbalanced wheel Replace wheel
Fan is operating in the unstable region
of the fan curve
Bearings need lubrication or
replacement
Fan speed is too high Reduce fan RPM
Belts too loose, worn or oily Inspect and replace if needed

Corrective Action

and check amps

located on fan motor

“Auto” Position

shown on rotation label

located on fan motor

shown on rotation label

at the outlet

damper motor if needed
Improve ductwork to eliminate or
reduce duct losses

motor

Refer to performance curve for fan

Lubricate or replace

26

Burner Troubleshooting Chart

Proper Spark

Gap

Problem

Pilot Does Not Light/Stay Lit Main gas if off Open main gas valve

Main Burner Does Not Light
(Pilot is Lit)

Not Enough Heat Main gas pressure too low Increase main gas pressure – do not

Too Much Heat Defective modulating gas valve Check/replace modulating valve

Potential Cause

Air in gas line Purge gas line
Dirt in pilot orifice Clean orifice with compressed air
Gas pressure out of range Adjust to proper gas pressure
Pilot valve is off Turn pilot valve on
Pilot orifice fitting leak Tighten pilot orifice
Excessive drafts Re-direct draft away from unit
Safety device has cut power Check limits and airflow switch
Dirty flame sensor Clean flame sensor
Remote panel in “Vent” mode Change to “Heat” mode
No spark at igniter Check wiring, sensor, and ignition

Defective valve Replace combination valve
Loose valve wiring Check wiring to valve
Defective pilot sensor Replace pilot sensor
Shut off valve closed Open shut off valve
Defective flame safety controller Replace flame safety controller
Pilot fails as main gas valves open
and main gas begins to flow

Too much airflow Decrease airflow if possible
Burner undersized Check design conditions
Gas controls not wired properly Check wiring
Thermostat setting too low Increase thermostat setting
Thermostat malfunction Check/replace thermostat
Unit locked into low fire Check wiring

Thermostat setting too high Decrease thermostat setting
Unit locked into high fire Check wiring
Thermostat wired incorrectly Check thermostat wiring

Corrective Action

controller. Check spark gap as shown
below.

Plug the first burner port next to the
pilot gas tube with burner cement

exceed 14 in. w.c. inlet pressure (5 psi.
on size 4-5 heater)

27

Remote Panel Troubleshooting Chart

Light Indication

No Lights Power not available to Remote Panel Bad voltage to unit

POWER Light Only Proper unit Off Operation No problem

POWER Light and
BLOWER ON Light

POWER Light and
BLOWER ON Light and
BURNER ON Light
CLOGGED FILTER Light On
(Optional)
FLAME FAILURE Light On Flame Safety Alarm Activated

Condition

No power to motor starter Manual/Off/Auto Switch in “Off” Position

Proper Ventilation Operation No Problem
No Power to Flame Safety Controller Manual/Off/Auto Switch in “Off” Position

Improper Airflow Insufficient Airflow

Proper Heating Operation No Problem

Filters Clogged Filters Dirty or Need Replacement

No Flame Detected during Pilot
Establishment Period

Possible Cause

Main disconnect in “OFF” Position
Circuit breaker tripped
Bad main transformer

(3 Position Remote Panels Only)
Improper damper function
Low Temperature Thermostat Timed
Out (Option)

(2 Position Remote Panels Only)
Heat/Vent Switch in “Vent” Position
Gas Pressure Switch Tripped (option)
High Temperature Limit Thermostat
Tripped
Manual/Off/Auto Switch in “Auto”
Position and Intake Air Thermostat not
Satisfied

Excessive Airflow
Bad airflow switch
Problem with air probes
Problem with airflow tubing
Broken Belt

Combination Valve in “Off” Position
(Unit Sizes 1-3)
Stuck Closed Gas Valve

No or Low Gas Pressure
Bad Spark Electrode
Bad Ignition Transformer
Flames Sensor Malfunction
Clogged Pilot Orifices

28

Nothing

Happens

Is Overload

tripped on

starter?

NO

Is Freeze-Stat

open?

NO

Is end switch on

Motorized

Damper closed?

Reset & measure FLA

YES

of motor. Is it high er

YES

NO

Troubleshooting Flowcharts

than rating?

Adjust or
Replace

Adjust or
Replace
actuator

YES

Adjust

or

change

Pulley

Blower runs

but there is

no heat

Is the air flow LED

on Flame Saftey

illumi nated?

Is outside air cooler tha n

intake air thermostat

YES

setting?

YES

Is High T emp.
Limit Tr ipped?

NO

Is there a

Remote Panel

Installe d?

YES

Is Remote set to

"Heat"

YES

Refer to Fl ame

Safety Guid e

NO

YES

NO

NO

Adjust pulley to
achieve proper

NO

Check wiri ng

"Manual" and
"Heat" mode.

airflow .

Proper

economizer

operation

Reset

Set Remote

Panel to

Burner lights but

heater stays in

Low Fire

Is there voltage on

Terminal #17

Yes

Are all valves

powered and open?

Yes

With wires 3 & 4

removed from the

Maxitrol Amplif ier, is

there 9.5K to 11K

Ohms between the

wires?

Yes

Remove Terminal #4

from the Maxitrol

Amplifier. Does t he

heater go into High F ire?

Yes

With wires 1 & 2

removed from the

Maxitrol Amplif ier, is

there 9.5K to 11K Ohms

between the wires ?

No

Replace

FSC

No

Check valve wiring

or open valves

No

No

Replace

Amplifier

No

Replace

Discharge Air

Sensor

Is there a short or open

circuit i n Modulating
Valve? Should be 45-55
Ohms (60-80 on MR212)

No

Replace the

Temperature

Selector

Yes

Replace

Modulating

Valve

Burner lights but heater

stays in High Fire

Is there a jumper between

terminals 2 & 3 on the

Maxitrol Amplifier?

Yes

Is there a short circuit in

the Remote Temperature

Selector or wiring?

No

Is there an open circuit in

the Discharge Air Sensor

or wiring?

No

Is Plunger in the

Modulating Valve jammed?

Inspect and clean. It

should operate freely in

the sleeve.

No

Foreign object holding

valve open. Remove
bottom plate and inspect
valve and seat. Clean or

replace valve.

No

Yes

Yes

Install

Jumper

Repair short or

replace

Temperature

Selector

Repair Circuit or

replace the

Discharge Air

Sensor

29

MAINTENANCE

To guarantee trouble free operation of this heater, the manufacturer suggests following these guidelines.
Most problems associated with fan failures are directly related to poor service and maintenance.

Please record any maintenance or service performed on this fan in the documentation section located at
the end of this manual.

WARNING: DO NOT ATTEMPT MAINTENANCE ON THE HEATER UNTIL THE
ELECTRICAL SUPPLY HAS BEEN COMPLETELY DISCONNECTED AND THE
MAIN GAS SUPPLY VALVE HAS BEEN TURNED OFF.

General Maintenance

1. Fan inlet and approaches to ventilator should be kept clean and free from any obstruction.

2. Motors are normally permanently lubricated. Check bearings periodically. If they have grease
fittings lubricate each season. Use caution when lubricating bearings, wipe the fittings clean, the
unit should be rotated by hand while lubricating. Caution: Use care when touching the exterior

of an operating motor. Motors normally run hot and may be hot enough to be painful or
cause injury.

3. All fasteners should be checked for tightness each time maintenance checks are preformed prior
to restarting unit.

4. Blowers require very little attention when moving clean air. Occasionally oil and dust may
accumulate causing imbalance. If the fan is installed in a corrosive or dirty atmosphere,
periodically inspect and clean the wheel, inlet and other moving parts to ensure smooth and safe
operation.

Re-Setting Of The Unit

If the flame safety control is locked out (alarm light on), reset the unit by:

1. Turn OFF Power to the unit.

2. Turn Power to the unit back ON.

Emergency shutdown of unit

To shut down the unit in the event of an emergency do the following:

1. Turn power OFF to the unit from main building disconnect.

2. Turn the external disconnect switch to the OFF position.

3. CLOSE the inlet gas valve located on the heater.

Prolonged shutdown of the unit

For prolonged shutdown the following steps should be done:

1. Turn the external disconnect switch to the OFF position.

2. CLOSE the inlet gas valve located on the heater.

To re-start the unit the following steps should be done:

1. Turn the external disconnect switch to the ON position.

2. OPEN the inlet gas valve located on the heater.

30

2 weeks after startup

Intake

16” x 20”

20” x 25”

1. Belt tension should be checked after the first 2 weeks of fan operation. Belts tend to stretch and
settle into pulleys after an initial start-up sequence. Do not tension belts by changing the
setting of the motor pulley, this will change the fan speed and may damage the motor. To re­tension belts, turn the power to the fan motor OFF. Loosen the fasteners that hold the blower
scroll plate to the blower. Rotate the motor to the left or right to adjust the belt tension. Belt
tension should be adjusted to allow 1/64” of deflection per inch of belt span. Exercise extreme
care when adjusting V-belts as not to misalign pulleys. Any misalignment will cause a sharp
reduction in belt life and produce squeaky noises. Over-tightening will cause excessive belt and
bearing wear as well as noise. Too little tension will cause slippage at startup and uneven wear.

Whenever belts are removed or installed, never force belts over pulleys without loosening
motor first to relieve belt tension. When replacing belts, use the same type as supplied by the

manufacturer. On units shipped with double groove pulleys, matched belts should always be
used.

2. All fasteners should be checked for tightness each time maintenance checks are preformed prior
to restarting unit.

Every 3 months

1. Belt tension should be checked quarterly. See instructions in the previous maintenance section.
Over-tightening will cause excessive bearing wear and noise. Too little tension will cause
slippage at startup and uneven wear.

2. Filters need to be cleaned and/or replaced quarterly, and more often in severe conditions.
Washable filters can be washed in warm soapy water. When re-installing filters, be sure to install
with the airflow in the correct direction as indicated on the filter.

Filter Quantity Chart

Size 1 Sloped 3
Size 2 Sloped 3
Size 3 Sloped 6
Size 4 Sloped 10
Size 5 Sloped 8
Size 1 V-Bank 3
Size 2 V-Bank 8
Size 3 V-Bank 8
Size 4 V-Bank 15
Size 5 V-Bank 12

31

4

2

4

4

9

1

1

2

2

3

Yearly

Optional Mixing Box Filters

Diagonal Filters

Unit Size Filter Quantity Filter Size

1

2

3

4

5

Vertical Filters

Unit Size Filter Quantity Filter Size

1

2

3

4

5

10 x 16

20 x 25

15 X 20

18 X 25

14.5 x 19

10 x 16

16 x 25

15 x 15

16 x 20

14.5 x 19

1. Inspect bearings for wear and deterioration. Replace if necessary.

2. Inspect belt wear and replace torn or worn belts.

3. Inspect bolts and set screws for tightness. Tighten as necessary.

4. Inspect motor for cleanliness. Clean exterior surfaces only. Remove dust and
grease from the motor housing to ensure proper motor cooling. Remove dirt
and grease from the wheel and housing to prevent imbalance and damage.

5. Check for gas leaks and repair if present.

6. Clean flame sensor by rubbing with steel wool to remove any rust build-up,

7. Clean burner with a wire brush and insure burner ports are free of debris.
Then wipe the burner with a clean rag.

Burner Orifice

Drill Size

Orifice Drill Size

Gas Port 31

Air Port 43

32

Start-Up and Maintenance Documentation

START-UP AND MEASUREMENTS SHOULD BE PERFORMED AFTER THE SYSTEM HAS BEEN
AIR BALANCED AND WITH THE HEAT ON (Warranty will be void without completion of this form)

Job Information

Job Name Service Company
Address Address
City City
State State
Zip Zip
Phone Number Phone Number
Fax Number Fax Number
Contact Contact
Purchase Date Start-Up Date

Heater Information

Refer to the start-up procedure in this manual to complete this section.
Name Plate and Unit Information
Model Number

Serial Number
Motor Volts
Motor Hertz
Motor Phase
Motor FLA
Motor HP
Blower Pulley
Motor Pulley
Belt Number
Gas Type
Min. Btu/Hr
Max. Btu/Hr

**

If measured amps exceed the FLA rating on the nameplate, fan RPM must be reduced.

Field Measured Information
Motor Voltage

Motor Amperage**
RPM
Burner Differential Pressure in. w.c.
Max Burner Pressure in. w.c.
Min Burner Pressure in. w.c.
Pilot Flame Signal VDC
Low Fire Flame Signal VDC
High Fire Flame Signal VDC
Gas Type
High Fire Inlet Gas Pressure in. w.c.
Low Fire Manifold Gas Pressure in. w.c.
High Fire Manifold Gas Pressure in. w.c.
Thermostat Set-Point
Temperature Control Discharge

Airflow Direction Correct

Space

Incorrect

Maintenance Record

Date Service Performed

Factory Service Department

Phone: [phone]

Fax: [phone]

August 2013 Rev. 1