Energy Tech Laboratories Modular Direct Fired Heaters User manual

A0011030
December 2011 Rev. 17
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.
Standard and Modular
Direct Fired
Heater
s
Installation, Operation, and Maintenance Manual
Modular
Direct
Fired
Heater
Standard Direct Fired Heater
Direct Fired Module
Save these instructions
. 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.
RECEIVING AND INSPECTION
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.
WARNING!!
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.
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. Don’t touch electrical switches.
3. Extinguish any open flames.
4. Immediately call your gas supplier.

3
TABLE OF CONTENTS
WARRANTY................................................................................................................................................................................................4
INSTALLATION...........................................................................................................................................................................................5
Mechanical.............................................................................................................................................................................................5
Site Preparation................................................................................................................................................................................5
Assembly..........................................................................................................................................................................................5
Curb and Ductwork ..........................................................................................................................................................................5
Roof Mount Installation....................................................................................................................................................................6
Installation with Exhaust Fan...........................................................................................................................................................6
Direct Fired Module Installation.......................................................................................................................................................7
Indoor (INLINE) Installation .............................................................................................................................................................7
Heat Module Add-On 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
Remote Control Panel....................................................................................................................................................................11
Fan to Building Wiring Connection................................................................................................................................................11
OPERATION .............................................................................................................................................................................................12
Start Up................................................................................................................................................................................................12
Special Tools Required..................................................................................................................................................................12
Start Up Procedure........................................................................................................................................................................12
Pilot Adjustment.............................................................................................................................................................................12
Pilot Assembly................................................................................................................................................................................12
Main Burner Adjustment................................................................................................................................................................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
Components.........................................................................................................................................................................................20
Remote Panel Option.....................................................................................................................................................................21
Troubleshooting...................................................................................................................................................................................22
Airflow Troubleshooting Chart.......................................................................................................................................................22
Burner Troubleshooting Chart.......................................................................................................................................................23
Remote Panel Troubleshooting Chart...........................................................................................................................................24
Troubleshooting Flowcharts...........................................................................................................................................................25
MAINTENANCE........................................................................................................................................................................................26
General Maintenance..........................................................................................................................................................................26
2 weeks after startup...........................................................................................................................................................................27
Every 3 months....................................................................................................................................................................................27
Filter Quantity Chart.......................................................................................................................................................................27
Yearly...................................................................................................................................................................................................27
Burner Orifice Drill Size.................................................................................................................................................................27
Start-Up and Maintenance Documentation ........................................................................................................................................28
Job Information...............................................................................................................................................................................28
Heater Information .........................................................................................................................................................................28
Maintenance Record......................................................................................................................................................................28
Factory Service Department..........................................................................................................................................................28

4
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.

5
INSTALLATION
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. All air to the heater must be ducted from the outdoors. Recirculation
of room air is not permitted. If in doubt regarding the application, consult the manufacturer.
Assembly
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 v-bank 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
CLEARANCES
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.

6
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.
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
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.
Roof Mount Installation
Installation with Exhaust Fan

7
Direct Fired Module Installation
Indoor (INLINE) Installation
Heat Module Add-On Installation
Modular heat units shipped to add heat onto existing blower only applications require field mechanical
and wiring installation.
1. Remove existing filter intake and lifting lugs from blower section intake side.
2. Attach heat module to blower intake using the provided sheet metal screws and bolts. Tighten
screws and bolts securely to compress the
gasket between the heat module and the
blower module.
3. Support and level the end of the heat module
(end opposite the blower) with the provided
equipment legs/rails.
4. Attach the filter hood to the intake side of the
heater module.
5. Drill a hole in the discharge of the blower large
enough to insert the mixing tube and discharge
sensor (if provided). Install the mixing tube in the proper airflow direction. The airflow direction is
labeled on the mixing tube.
6. Wire the sensor as indicated on the supplied wiring schematic. Run all wiring within metal
conduit. Supply 120V AC to terminals 1 and N in the direct fired module.
7. Follow the start up instructions located in this manual.

8
Gas Pressure Table
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.
Max. Manifold Pressure - Natural Gas 5 in. w.c. maximum
Max. Manifold Pressure - Propane 2.5 in. w.c. maximum
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 Connection Diagram
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.
NOTICE
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.

9
Copper Wire Ampacity
Wire Size AWG Maximum Amps
14 15
12 20
10 30
8 50
6 65
4 85
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.
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.
WARNING!!
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.

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; counter-
clockwise 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.

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.
BL
YW
RD
BK
PK
RD
WH
OR
BR
GY
BK
RD
YW
PK
RD
BK
WH
BK
OR
BR
GY
PK
RD
BK
YW
RD
OR
BR
GY
WH
BK 1
E
PK
YW
BK
RD
WH
GY
BR
OR
RD
NC
BK
Fire System
Microswitch
BK
NO
PR
C
Fan to Building Wiring Connection

12
Pilot Assembly
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
•Amperage Meter
•Manometer
•Differential Pressure Gauge
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.
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.

13
Maxitrol M511 and M611
Low Fire Bypass Screw
Mod Valve Voltage Summary
Volts DC Firing Mode
0 to 5 VDC Low Fire
5 to 15 VDC Modulation
15 to 20 VDC High Fire
Maxitrol MR212 Low
Fire Bypass Screw
Average Manifold Pressure vs. Firing Rate/Ft. of Burner
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0 100000 200000 300000 400000 500000 600000
Firing Rate (BTU/Hr/Ft. of Burner)
Manifold Pressure (in. w.c.)
Natural Gas Propane Gas
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
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 amplifier.
3. The manifold pressure should be checked
at the pressure tap downstream of the
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
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 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 removing the wire at terminal #5 from the 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 the low fire manifold pressure
until there is a very thin flame along the entire length of the burner. No dark
spots 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 valve and restore all of the original wiring on the amplifier and gas
components.
8. A final gas leak check shall be performed to verify the gas-tightness of the
heater’s 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
Adjust pilot flame.
Lock unit into
high fire.
Adjust
incoming gas
pressure.
Does high fire produce
at least a 70°F temp
rise and produce the
correct manifold
pressure?
Adjust high fire
No
Lock unit into lowfire.
Yes
Does thinflame fill
entire burner length? Adjust low fire.
Setting incoming pressure:
Presuremust be measured at first"T" in
supply gas linebefore the first gas valve.
Adjusting the pilot:
The pilot DC signal should be 12 VDC
minimum.
Adjusting high fire:
High firemanifold pressure should be5"
maximumfor natural gas and 2.5"
maximumfor propane. High fire should
produce at least a70°Ftemperaturerise.
Removewire #4 from the Maxitrol 14
amplifier (#2 and #4 for Maxitrol 44). This
will drive the valveinto 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 minimum12VDC.
Replace the wireson the Maxitrol
Amplifier.
Adjusting low fire:
Removewire #5 from the Maxitrol 14
amplifier (#8 for Maxitrol 44). Thiswill
drive the valve into itslowest position.
Adjust the low fire by turning the lowfire
bypassscrew on the sideof the
modulating valve for M511and M611
models. For MR212 valves, the lowand
high fireare both under the valve cover.
Refer tothe included Maxitrol literature for
more detailed information. Ensure that
DC flame signal is minimum12VDCand
that the enitelength of burner is filled with
a thin flame.
Yes
No
No
Burner start up
complete.
Yes
Is incoming gas pressure
7"-14"?
(7"-5 psi. for size 4-5 units)
Heater Start Up Summary

15
M
aximum RPM
and
HP Chart
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 Illustration
Pulley Setscrew Torque
Thread Size Torque (IN/Lb)
No. 10 (bushing) 32
1/4” (bushing) 72
5/16” 130
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.
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 Proper Belt Tension

16
Pulley Combination Chart
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
Open Closed
BLO ER 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 Dd1 Dd2 Pd1 Pd2
AX BELTS 1VL40 2.4 3.4 2.6 3.6
Open Closed
BLO ER 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 1137 1176 1215 1255 1294 1333 1372 1411
AK39 3.5 3.7 1212 1259 1305 1352 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
Open Closed
BLO ER 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 9.7 534 548 563 578 593 608 622 637 652 667 682 697 711
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
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 1193 1223 1254 1285 1315 1346 1376 1407 1438 1468
7-1/2 to 10 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2
BX BELTS 2VP60 4.3 5.5 4.7 5.9
Open Closed
BLO ER 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 9.7 836 854 871 889 907 925 943 960 978 996 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 1120 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
Open Closed
BLO ER 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 Dd1 Dd2 Pd1 Pd2
BX BELTS 2VP60 4.3 5.5 4.7 5.9
Open Closed
BLO ER 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
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 Dd1 Dd2 Pd1 Pd2
BX BELTS 2VP75 5.8 7 6.2 7.4
Open Closed
BLO ER 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
** 2HP Motors on 20 IN Blowers use 2VP42 Pulleys
TURNS ON MOTOR PULLEY
10 - 20 IN. BLO ER**
TURNS ON MOTOR PULLEY
TURNS ON MOTOR PULLEY
TURNS ON MOTOR PULLEY
TURNS ON MOTOR PULLEY
25 IN. BLO ER
TURNS ON MOTOR PULLEY
TURNS ON MOTOR PULLEY

17
Flame Safety Controller
Air Flow Switch
Airflow Switch
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
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.
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
Amplifier
High Temperature Limit
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.
Size 1-3 Heater CFM vs. Burner Profile Pressure
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65
Burner Differential Profile Pressure (in. w.c.)
CFM
Size 1
Size 2
Size 3
Size 4-5 Heater CFM vs. Burner Profile Pressure
3000
5000
7000
9000
11000
13000
15000
17000
19000
21000
23000
25000
0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65
Burner Differential Profile Pressure (in. w.c.)
CFM
Size 4
Size 5
Modulating Gas System
The second system, the modulating gas system, consists of a temperature
selector dial, a discharge air sensor, an amplifier, and a modulating gas valve.
The two types of modulating gas systems used are the Maxitrol 14 or RTC
Solutions controls and the Maxitrol 44 series. The Maxitrol 14/RTC 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 backup safety devices 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

19
FSC verifies proper Airflow
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 modulating gas system system and gas flow begins modulating
The FSC monitors the flame while the modulating system adjusts to the selected
temperature
• The modulating 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. This system
will modulate the main burner gas from 100% down to 5% as needed.
Optional Remote Panel Circuit
Power
SupplyFrom
Heater
"Power" Light
On
Off NoPower to
Panel
Panel is
Powered
Blower Switch
Nothing Happens
No Power is Sent
toHeater
Power is Sent to
Heater to Open
Damper (if
provided) and
Start Blower
"Off"
Position
(3-Position Panels Only)
"Manual"
"Blower On"
Light
Damper is not
Open or Freeze-
Stat has Detected
LowTemperature
Operation
On
Off
Temperature
Control Switch
Blower Operates
Heat Does not
Operate
"Vent"
Position
"Heat"
Position
Heat Circuit is Energized
"Burner On" Light Illuminates with
proper flame.
"FlameFailure" Light illuminates
if proper flame is not established
Blower Operates
Cooling Circuit is
Energized
"Cool"
Position
(if provided)
Power is Sent to
Heater toOpen
Damper (if
provided) and
Start Blower
"Blower On"
Light
Damper is not
Open or Freeze-
Stat has Detected
LowTemperature
Operation
On
Off
Intake Air
Thermstat is
Powered
Intake Air is Cooler Than
Thermostat Set-Point
Nothing Happens
IntakeAir is
Warmer Than
Thermostat
Set-Point
"Auto"
Heat Circuit is Energized
"Burner On" Light Illuminates with
proper flame.
"Flame Failure" Light illuminates
if proper flameis not established

20
Components
The following image and list outlines the typical direct fired heater components and their functions.
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. Modulating Amplifier - Regulates temperature by a 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
4
3
2 8 10
15
5
16
20
22
23
12
14
19
18
6
9
21
13
5
7
6
17
1
11