Detroit Radiant Products HL2 Series User manual

WARNING
!
!
Improper installation, adjustment, alteration, service or maintenance can cause
property damage, injury or death. Read the installation, operation and maintenance
instructions thoroughly before installing or servicing this equipment.
This heater must be installed and serviced by trained gas installation and service
personnel only. Failure to comply could result in personal injury, asphyxiation, death,
fire or property damage.
In locations used for the storage of combustible materials, signs must be posted to
specify the maximum permissible stacking height to maintain the required clearances
from the heater to the combustibles. Signs must either be posted adjacent to the
heater thermostats or in the absence of such thermostats, in a conspicuous location.
Not for residential use! Do not use this heater in the home, sleeping quarters,
attached garages, etc. Installation of a commercial tube heater system in
residential indoor spaces may result in property damage, serious injury,
asphyxiation or death.
HL2 Series
Insert Manual
For complete installation instructions, see the Tube Heater General Manual
that accompanies this Series Insert Manual.
The HL2 Series Infrared Tube Heater is a positive pressure, two-stage radiant heater system. This insert
manual is a supplement to the Tube Heater General Manual and provides specific information related to
the HL2 Series model. All persons involved with the installation, operation and maintenance of the heater
system must read and understand the information in this insert manual and the accompanying Tube
Heater General Manual.
For Your Safety
If you smell gas:
• Do not try to light any appliance. • Immediately call your gas supplier from a neighbor’s phone.
• Do not touch any electrical switch. • Follow the gas supplier’s instructions.
• Do not use any phone in your building. • If you cannot reach your gas supplier, call the fire department.
LIOHL2a-Rev. 24414
Print: 2M-8/13_r7_10/19 (CDS)
Replaces: LIOHL2-2M-9/09(CDS)
INSTALLER: Present this manual to the end user.
Keep these instructions in a clean and dry place for future reference.
Model#: ___________________ Serial #: _________________________
(located on rating label)

2
Contents
1.0 Safety...................................................................3
Safety Labels and Their Locations .......................................3
Clearances to Combustibles ............................................4
2.0 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Gas Requirements ...................................................6
Electrical Requirements................................................6
Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Specifications ......................................................10
Tube Installation Sequence ............................................11
3.0 Operation ..............................................................12
Sequence of Operation ...............................................12
Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.0 Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.0 Parts ..................................................................18
Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Parts List ..........................................................18
Kit Contents Check List ...............................................20
Approvals..........................................................20
Limited Warranty ....................................................20
NOTE: See page 10 for a list of available models and specifications.
HL2 Series

1.0 Safety
DETROITRADIANT PRODUCTS COMPANY
21400 HOOVER ROAD - WARREN, MI
DETROIT RADIANT INFRA-RED RADIANTTUBE HEAT ER
FOROUTDOOR USE AND INDOOR (Non-Residential) INSTALLATION ONLY.
ClassIIIA Pe rmanentLabel
[phone] - www.drp-co.com
Volts AC:
AMPS - Starting:
AMPS - Running:
Combustion Chamber:
120V - 60Hz
4.8
1.1
4” BC Aluminized
DESIGN COMPLIES WITH:
ANSI Z83.20-2008-GAS FIRED LOW INTENSITY INFRA-RED HTR.
Manifold Pressure:
Maximum Inlet Pressure:
Minimum Inlet Pressure:
Serial No.: 0914XXXXXXXXXX0001
MODEL NO.
HL2 - 40 - 125N
Heater Type
Minimum Mounting Angle:
Maximum Mounting Angle:
C1
0
45
DEGREES
DEGREES
INPUT BTU/H
125,000 / 82,000
FOR USE WITH
Natural Gas
3.5 Inches
14 Inches
5.0 Inches
W.C.
W.C.
W.C.
ForStainless Steel Upgrades the Combustion
Table is upgraded to 409 Stainless Steel
DETROIT RADIANT PRODUCTS COMPANY
21400 HOOVER ROAD - WARREN, MI
DETROIT RADIANT INFRA-RED RADIANT TUBE HEATER
FOR OUTDOOR USE AND INDOOR (Non-Residential) INSTALLATION ONLY.
Class IIIA Permanent Label
[phone] - www.drp-co.com
Volts AC:
AMPS - Starting:
AMPS - Running:
Combustion Chamber:
120V - 60Hz
4.8
1.1
4” BC Aluminized
DESIGN COMPLIES WITH:
ANSI Z83.20-2008-GAS FIRED LOW INTENSITY INFRA-RED HTR.
Manifold Pressure:
Maximum Inlet Pressure:
Minimum Inlet Pressure:
Serial No.: 0914XXXXXXXXXX 0001
MODEL NO.
HL2 - 40 - 125N
Heater Type
Minimum Mounting Angle:
Maximum Mounting Angle:
C1
0
45
DEGREES
DEGREES
INPUT BTU/H
125,000 / 82,000
FOR USE WITH
Natural Gas
3.5 Inches
14 Inches
5.0 Inches
W.C.
W.C.
W.C.
For Stainless Steel Upgrades the Combustion
Table is upgraded to 409 Stainless Steel
HL2-40-125N
Data on this label is for the model shown on this label. If your heater has been converted,
this information is not accurate. Please contact the factory for assistance.
BURNER COMPONENTS:
For parts replacement information, contact factory at 586-756-0950 or visit www.drp-co.com/parts.
Serial No.: 0914XXXXXXXXXX 0001
Gas Valve:
Circuit Board:
Wire Harness:
N.O. Switch:
N.O. VL Orifice:
N.C. Switch:
N.C. VL Orifice:
Diff Switch:
Diff VL Orifice:
Igniter:
Burner:
16” Tube:
Ind. Lights:
Diag. Light:
Term. Block:
Transformer:
Fan:
Alt. Fan:
Alt. Fan Usage:
Relay:
Filter:
24 Volt In:
120 Volt In:
Gas In:
Extra VL Orifice:
Production Code:
Version:
Stock:
Add-On:
Internal Use Only:
HEATER
TYPE: Electric:
Tag:
Special 1:
Special 2:
Gas:
Air:
C1
C1 C2 C3
None
N/A
HL2-125
9.14
36E96-224-N
Micro60-24
3 PCS Harness
None
None
None
None
IS22010051F5169
Grey (+ / -)
Norton
Low-Mid
4” Gen.
Yellow - 120V
(Specify TP-#’s)
840
851
852
N/A
N/A
264E
50
3072
380
828
On Circuit Board
None
40 VA
Fasco Lg.
50Hz - 120V
When Specified
None
None
3 T-plug
2 x 4 Box
7/8” FC Flare
None
N/A
826
55A
55B
N/A
N/A
832
66
83
3
1 1/2”
TP-204#
TP-44#
3
1 5/8”
LLWT038
None
3
1 5/8”
Micro60
Plug-Wh.
Orifice Type:
SAMPLE
SAMPLE
WARNING
!
Improper installation, adjustment, alteration, service, or maintenance can cause
property damage, serious injury, or death. Read and understand the installation,
operating, and maintenance instruction thoroughly before installing or servicing this
equipment. Only trained, qualified gas installation and service personnel may install or
service this equipment.
3
Safety Labels and Their Locations
1.0 Safety • Safety Labels and Their Locations
Back Panel
Top Panel
Bottom Panel
HL2 Series
Rating Plate
F/N: LLTB018 (Natural Gas)
F/N: LLTB019 (Propane Gas)
F/N: LLTCL001 Clearances
to Combustibles Label
F/N: LLLOGO32
Burner Control Box
Component Label (located
under the top panel)
Product safety signs or labels should be replaced by the product user when they no longer are legible.
Contact either your local distributor or the product manufacturer for obtaining replacement signs or labels.
Air Metering Orifice
DO NOT REMOVETP-3014 3"
F/N: LLAC
Air Metering Orifice
SAMPLE

LED CODE FAULTSTAT US FAULTCODE DELAY
Initial flash on power up,
then steady off
Normal operation Immediate
Steady on Module failure / Internal faultImmediate
1 flashIgnition failure 30-32minutes
2 or 3 flashesAPS - Note: fan / intake / exhaust 10-12 minutes
4 flashes
Solenoid valve fault / Leaky valve /
Flame amplifier fault
Immediate
No flash on 117V start up Transformer faul
tI
mmediate
!
CAUTION
Provide 24
Volts Only
This heater has a 24 Volt
control system. Do not
connect 120 Volt power
supply, as it will damage
the controls.
LEDCODE FAULTSTATUS FAULTCODEDELAY
Initialflashonpowerup,
thensteadyoff
Normaloperation Immediate
SteadyonModulefailure/Internalfault Immediate
1flash Ignitionfailure 30-32minutes
2or3flashes APS-Note:fan/intake/exhaust 10-12minutes
4flashes
Solenoidvalvefault/Leakyvalve/
Flameamplifierfault
Immediate
Noflashon117VstartupTransformerfault Immediate
This heater is equipped with an
HLRB Relay(s) required for grouping
multiple heaters on the same
thermostat. This heater must be wired with a
field supplied transformer in accordance with
the installation, operation manual.
WARNING
!
Placement of explosive objects, flammable objects, liquids, and vapors
close to the heater may result in explosion, fire, property damage, serious
injury, or death. Do not store or use explosive objects, liquids, or vapors in
the vicinity the heater.
4
1.0 Safety • Safety Labels and Their Locations •Clearances to Combustibles
F/N: LLTB031
Clearances to combustibles is defined as the minimum distance that must exist between the tube
surface, or reflector, and any combustible items
(see Figure 1.1). It also pertains to the distance that must
be maintained from moving objects around the tube heater.
Clearances to Combustibles
HL2 Series
F/N: LLTB007(2)
F/N: LLDR003
(This label is located
on models with a relay
board installed only)
F/ N : LLV3EP2
Orange Crescent
(This label is on
models with a relay
board installed only).
F/ N : LLV3EP4
White Crescent
SERVICE ACCESS PANEL
IGNITER & FLAME SENSE COMPARTMENT
1. Turn off gas & electricity.
2. Remove cover by lifting top
cover upward and outward.
CAUTION: HOT SURFACE.
KEEP COVER IN PLACE. REMOVE FOR SERVICE ONLY.
SERVICE ACCESS PA NEL
IGNITER & FLAME SENSE COMPARTMENT
1. Turn off gas & electricity.
2. Remove cover by lifting top
cover upward and outward.
CAUTION: HOT SURFACE.
KEEP COVER IN PLACE. REMOVE FOR SERVICE ONLY.
F/N: LLTB026
Right Panel
(Valve Compartment)
Radiant Tube(s)Combustion Chamber
16” Burner Tube
Left Panel
(Fan Compartment)
AVOID EQUIPMENT FAILURE
THIS 10 FT. TUBE IS THE
COMBUSTION CHAMBER.
THIS TUBE MUST BE THE FIRST TUBE
FOLLOWING THE BURNER CONTROL BOX.
!
INSTALLER
The combustion chamber utilizes either 409
stainless, titanium alloy or aluminized steel -
depending on the model number of your heater.
Rotate the tube’s welded seam to bottom.
Consult the manual(s) for further details.
F/N: LLTB004 (orange)
F/N: LL001 - Clearance Safety Tag
(Affix adjacent to heater’s thermostat)
Clearances to combustibles must be maintained at
all times in order to prevent the ignition of
combustible materials. In locations used for the
storage of combustible materials, signs must be
posted to specify the maximum permissible stacking height to
maintain the required clearances from the heater to the
combustibles. Signs must either be posted adjacent to the
heater’s thermostats or, in the absence of such thermostats, in a
conspicuous location. Clearances are provided on the heater’s
safety label and in the heater’s Installation, Operation, and
Maintenance manual. Product installation and operation must
comply with applicable standards, codes, and regulations. Post
this tag adjacent to the heater’s thermostat or controls before
operating the heater.
- INSTALLER: READ AND POST THIS NOTICE -
LL001-XM-07/18 (CDS)
This product can
expose you to
chemicals including
lead and carbon
monoxide, which are known to the
State of California to cause birth
defects or other reproductive harm.
For more information go to
www.P65Warnings.ca.gov.
WARNING
!
Avoid Serious Injury, Death, or Property Damage.
Maintain Clearances to Combustible to Prevent the Risk of Fire.
California Proposition 65
F/N: LLV2EP9
24V LOW
24V OUT
HIGH
- 24V HEATER OUTPUT -

When installing the tube heater system, clearances to combustibles for the model tube heater and
configuration must be maintained. Refer to Chart 1.1 below to determine the required distances for your model.
5
Model Number
Mounting
Angle*
Sides
Front Behind Top Below
HL2 (20, 30, 40) - (65, 75) [N, P] 0° 99660
45° 39 810 60
with 1 side shield 0° 29 8 6 60
with 2 side shields 0° 99660
20 ft. from burner 0° 77630
HL2 (20, 30, 40) - (80, 96, 100) [N, P] 0° 14 14 666
45° 39 810 66
with 1 side shield 0° 29 8 6 66
with 2 side shields 0° 16 16 666
20 ft. from burner 0° 77630
HL2 (30, 40, 50) - 125 [N, P] 0° 20 20 676
45° 58 8 10 76
with 1 side shield 0° 42 8 6 76
with 2 side shields 0° 20 20 676
20 ft. from burner 0° 77630
HL2 (40, 50, 60) - 150 [N, P] 0° 24 24 681
45° 58 8 10 81
with 1 side shield 0° 42 8 6 81
with 2 side shields 0° 23 23 681
20 ft. from burner 0° 11 11 644
HL2 (40, 50, 60, 70) - 175 [N, P] 0° 34 34 692
45° 63 810 92
with 1 side shield 0° 50 8 6 92
with 2 side shields 0° 30 30 692
20 ft. from burner 0° 11 11 644
HL2 (50, 60, 70) - 200 [N, P] 0° 41 41 694
45° 63 810 94
with 1 side shield 0° 54 8 6 94
with 2 side shields 0° 30 30 694
20 ft. from burner 0° 11 11 644
1.0 Safety • Clearances to Combustibles
Chart 1.1 • Clearances to Combustibles in Inches (see Figure 1.1 for Mounting Angles)
HL2 Series
The stated clearances to combustibles represent a surface temperature of 90°F (50°C) above room
temperature. Building materials with a low heat tolerance (such as plastics, vinyl siding, canvas,
tri-ply, etc.) may be subject to degradation at lower temperatures. It is the installer’s responsibility to
assure that adjacent materials are protected from degradation.
Figure 1.1 •Mounting Angles
*
Heaters mounted on an angle between 0° and 45° must maintain clearances posted for 0° or 45°; whichever is greater.
45° Mounting Angle
0° Mounting Angle
with 1 Side Shield
(P/N: SSE)
0° Mounting Angle
with 2 Side Shields
(P/N: SSE)
Front Behind
Below
Top
Front Behind
Below
Top
Side Side
Below
Top
0° Mounting Angle
Side Side
Below
Top

6
2.0 Installation
2.0 Installation •Electrical Requirements HL2 Series
NOTICE
• 120 VAC - 60 Hz GRD, 3-wire
• 24 V thermostat connection
• Starting current 4.8 amps
• Running current 1.1 amps
Electrical Requirements
Connecting the thermostat with a voltage other than 24 V may damage the heater. The HL2 series
requires a 24 V connection to the thermostat. This is either supplied by the heater internally (standard)
or by an external transformer (with optional relay board, P/N: HLRB). See Figure 2.1.
Instructions for the following are detailed in the Tube Heater General Manual:
• Design considerations
• Hanger suspension and placement
• Tube layout and assembly
• Burner control box suspension
• Reflectors (and accessories)
• Venting and combustion air intake
• Gas requirements
• Baffle assembly
Note: Electronic versions of all manuals are available at www.detroitradiant.com
Gas Requirements
Type of Gas Required Manifold
Pressure
Minimum Inlet
Pressure
Maximum Inlet
Pressure
Natural 3.5 Inches W.C. 5.0 Inches W.C. 14.0 Inches W.C.
Propane 10.0 Inches W.C. 11.0 Inches W.C. 14.0 Inches W.C.
IMPORTANT: Consult the Tube Heater General Manual for gas connection requirements.
WARNING
!
Improper installation, adjustment, alteration, service, or maintenance can cause
property damage, serious injury, or death.
Read and understand the installation, operating, and maintenance instructions
thoroughly before installing or servicing this equipment.
Only trained, qualified gas installation and service personnel may install or service
this equipment.

WARNING
!
7
2.0 Installation •Wiring
Electric Shock
Field wiring to the tube heater must be connected and grounded in accordance with national,
state, provincial, and local codes, and to the guidelines in the Tube Heater General Manual
and Series Insert Manual. In the United States refer to the most current revisions to the
ANSI/NFPA 70 Standard and in Canada refer to the most current revisions to the CSA C22.1
Part I Standard.
Wiring
HL2 Series
THERMOSTAT
Ground Screw
on Control Box
BURNER BOX
(observe polarity)
120 Volt Power
L1 N
PANEL GROUND
Additional wire needed on thermostats
requiring constant power.
24VAC High
LowN
NOTE: If optional yellow
control cord is installed,
the following colors apply:
24VAC: Green
Low: White
High: Black
NOTE: If optional black
power cord is installed,
then L1 is brown or
black and Neutral is blue
or white.
1
24V
2
LO HI
1/4” spade
terminals required
(as supplied)
Figure 2.1 •Field Wiring Diagrams
A. Single Heater, Single Thermostat. No Relay Board (white label)
B. Multiple Heaters, Single Thermostat. With a Relay Board (HLRB orange label)
1
COM
2
LO HI
1
COM
2
LO HI
HL2 SERIES
BURNER CONTROL BOX
1
COM
2
LO HI
HL2 SERIES
BURNER CONTROL BOX
HL2 SERIES
BURNER CONTROL BOX
L1
N
PANEL GROUND
120 VAC
(Observe polarity)
PANEL GROUND
PANEL GROUND
NOTE: If optional yellow control cord is
installed, then the following wire colors apply:
Neutral = Green
Low = White
High = Black
NOTE: If optional black power
cord is installed, then:
L1 is brown or black
Neutral is blue or white.
1/4” spade
terminals required
(as supplied)
A
dditional wire needed on thermostats
that require constant power.
EXTERNAL TRANSFORMER
(Field Supplied)
120VAC
24VAC
Orange
Label
Orange
Label
Orange
Label
24V High
LowN
THERMOSTAT
120 VAC
(Observe polarity)
120 VAC
(Observe polarity)

24V
117N
BK
120V
24V
BK
W
O
BL
TRANSFORMER
R
LIGHT
BK
BK
GND
G
117N
R
O
N
120VAC
L1
N
L1 120VAC
2-STAGE T'STAT
(FIELD SUPPLIED)
12
STAGE
T'STAT
TERMINAL
PROBE
GND
TH
GND
VALVE
APS2 APS1 APS1
APS2
HSI HSI
FAN
117L
PRESSURE SWITCH
PK
PR
PK
PR
Y
BLOWER
FLAME
ROD
BK
IGNITOR
W
BK
BK
W
BK
BK
MICRO 60U-24
IGNITION
MODULE
R
W
PR
PR
STATUS
LIGHT
APS1
W
BK
T'STAT
TERMINAL
24V 12
STAGE
2-STAGE T'STAT
(FIELD SUPPLIED)
G
(FIELD SUPPLIED)
(FIELD SUPPLIED)
G
+
G
BK
BK
W
BLOWER
BL
IGNITOR
FLAME
ROD
TRANSFORMER
PRESSURE SWITCH
STATUS
LIGHT
MICRO 60U-24
BK
BK
BK
W
W
PK
PK
APS1 (NO)
G
BL
YBK
RW
WBK
IGNITION MODULE
G
G
G
G
BK
BL
R
GY
GAS VALVE
G
GY BK
LIGHT
BK
BK BK
GAS VALVE
G
LIGHT
LIGHT
ON
OFF
C
M
C
HI
HI
LO
HI M
CC
8
2.0 Installation • Wiring HL2 Series
Before field wiring this appliance - Check existing wiring; replace if necessary.
Note: If any of the original wire supplied with the appliance must be replaced, it must be replaced with
wiring material having a rating of at least 600 V, 105° C.
Figure 2.2 •Internal Wiring Diagrams
A. Micro 60U-24 Ladder Diagram
B. Micro 60U-24 Block Diagram

N
Y
W
120VAC
24VAC
BK
ROD
BK
BLOWER
BK
BK
W
BK
W
G
BL
W
BK
HSI
FAN
117L
HSI
117N
APS1 APS2
117N
VALVE
APS2
GND
TH
24V
APS1
FLAME
IGNITOR
BL
O
BK
Y
R
O
L1 120VAC
RELAY BOARD
PR
PR
APS
PRESSURE
SWITCH
G
G
GY
PK
PK
R
BK
PROBE
GND GND
G
G
GAS VALVE
BK
BK
G
2-STAGE T'STAT
(FIELD SUPPLIED)
120VAC
24VAC
BK
(FIELD SUPPLIED)
BK
G
PR
PR
BK
BK
BK
BK
W
BK
BK
BK
W
Y
G
2
1
STAGE
24V
W
R
2-STAGE T'STAT
(FIELD SUPPLIED)
STATUS
LIGHT
L1
N
120VAC
T'STAT
TERMINAL
MICRO 60U-24
IGNITION MODULE
BLOWER
PRESSURE SWITCH
(FIELD SUPPLIED)
LIGHT
STATUS
W
R
+
GY
G
TRANSFORMER
WBK
IGNITOR
BK
GAS VALVE
R
BK
PK
PK
APS (N.O.)
O
Y
R
RELAY
BOARD
O
G
G
BL
BL
W
120/24VAC
TRANSFORMER
(FIELD SUPPLIED)
THERMOSTAT
TERMINAL
TRANSFORMER
MICRO 60U-24
IGNITION
MODULE
120/24VAC
TRANSFORMER
(FIELD SUPPLIED)
FLAME
ROD
INDICATOR
LIGHTS
LIGHT
12
STAGE
LIGHT
ON
OFF
C
M
C
HI
HI
LO
HI M
C C
9
2.0 Installation •Wiring
Figure 2.3 •Alternative Wiring Diagrams
A. Micro 60U-24 Ladder Diagram - With Relay Board
B. Micro 60U-24 Block Diagram - With Relay Board
HL2 Series

Model Number Gas Type (select one) BTU/H (High Fire) BTU/H (Low Fire) Straight Length U-Tube Length Standard Weight (lbs.) Stainless Steel Weight (lbs.) Recommended Mounting Height Combustion Chamber (Black Coated) Radiant Emitter Tube(s) (Black Coated) Radiant Surface Area (sq. ft.) 36” Baffle Sections
HL2-20-65 N or LP 65,000 50,000 21’-7” 13’-0” 120 N/A 9’ to 14’ Alum Alum 20.2 5
HL2-20-75 N or LP 75,000 50,000 21’-7” 13’-0” 120 145 10’ to 15’ Alum Alum 20.2 5
HL2-20-80 N or LP 80,000 52,000 21’-7” 13’-0” 120 N/A 10’ to 15’ Alum Alum 20.2 5
HL2-20-96 N or LP 96,000 65,000 21’-7” 13’-0” 120 N/A 11’ to 18’ Alum Alum 20.2 5
HL2-30-65 N or LP 65,000 50,000 31’-3” **17’-8” 160 N/A 10’ to 15’ Alum Alum 30.4 4
HL2-30-75 N or LP 75,000 50,000 31’-3” **17’-8” 160 195 11’ to 18’ Alum Alum 30.4 4
HL2-30-80 N or LP 80,000 52,000 31’-3” **17’-8” 160 195 11’ to 18’ Alum Alum 30.4 5
HL2-30-100 N or LP 100,000 65,000 31’-3” **17’-8” 160 195 12’ to 20’ Alum Alum 30.4 5
HL2-30-125 N or LP 125,000 82,000 31’-3” **17’-8” 160 N/A 13’ to 23’ Alum Alum 30.4 5
HL2-40-65 N or LP 65,000 50,000 40’-11” 22’-8” 190 N/A 11’ to 18’ Alum Alum 40.5 2
HL2-40-75 N or LP 75,000 50,000 40’-11” 22’-8” 190 235 11’ to 18’ Alum Alum 40.5 2
HL2-40-80 N or LP 80,000 52,000 40’-11” 22’-8” 190 235 11’ to 18’ Alum Alum 40.5 5
HL2-40-100 N or LP 100,000 65,000 40’-11” 22’-8” 190 235 12’ to 20’ Alum Alum 40.5 4
HL2-40-125 N or LP 125,000 82,000 40’-11” 22’-8” 190 235 13’ to 23’ Alum Alum 40.5 4
HL2-40-150 N or LP *150,000 100,000 40’-11” 22’-8” 190 235 14’ to 25’ Titan Alum 40.5 4
HL2-40-175 N or LP *175,000 125,000 40’-11” 22’-8” 190 N/A 15’ to 27’ Titan Alum 40.5 4
HL2-50-125 N or LP 125,000 82,000 50’-7” **27’-4” 235 290 15’ to 27’ Alum Alum 50.6 4
HL2-50-150 N or LP *150,000 100,000 50’-7” **27’-4” 235 290 15’ to 27’ Titan Alum 50.6 4
HL2-50-175 N or LP *175,000 125,000 50’-7” **27’-4” 235 N/A 16’ to 30’ Titan Alum 50.6 2
HL2-50-200 N or LP *200,000 145,000 50’-7” **27’-4” 235 N/A 17’ to 35’ Titan Alum 50.6 2
HL2-60-150 N or LP *150,000 100,000 60’-3” 32’-4” 265 330 16’ to 30’ Titan Alum 60.7 2
HL2-60-175 N orLP *175,000 125,000 60’-3” 32’-4” 265 N/A 16’ to 30’ Titan Alum 60.7 2
HL2-60-200 N or LP *200,000 145,000 60’-3” 32’-4” 265 N/A 17’ to 35’ Titan Alum 60.7 2
HL2-70-175 N or LP *175,000 125,000 6 9’-11” **37’-2” 300 N/A 19’ to 42’ Titan Alum 70.9 2
HL2-70-200 N or LP *200,000 145,000 69’-11” **37’-2” 300 N/A 19’ to 42’ Titan Alum 70.9 2
Specifications
10
2.0 Installation • Product Specifications
Chart 2.1 • Specifications
HL2 Series
* Model requires stainless steel tube clamp (P/N: TP-220) to be located at the seam between the primary combustion
chamber and the secondary combustion tube downstream of the burner control box.
** Model requires 5EA-SUB accessory package when installing in a ‘U’ configuration (P/N: TF1B).
Titan = Black coated titanium stabilized aluminized steel.
Alum = Black coated aluminized treated steel.

Key
Tube Installation Sequence
11
20 Foot
50 Foot
60 Foot
70 Foot
30 Foot
40 Foot
Stainless Steel Clamp on 150 - 200 MBH models (P/N: TP-220).
HL2 Series
Figure 2.4 •Tube Installation Sequence
Burner Control Box with
16” Burner Tube
Black Coated Combustion
Chamber Tube*
Black Coated Aluminized Combustion
Chamber/ Radiant Emitter Tube
Standard Tube Clamp
Stainless Steel Tube
Clamp (P/N: TP-220)
150-200 MBH models only - Located
between 1st and 2nd 10 ft. tube sections.
2.0 Installation •Tube Sequence •Heater Length
Stainless Steel Clamp on 150-175 MBH models (P/N: TP-220).
Stainless Steel Clamp on 150 - 200 MBH models (P/N: TP-220)
Stainless Steel Clamp on 175 - 200 MBH models (P/N: TP-220)
Important! The combustion chamber & radiant tube sections must be installed in the following order:
*Aluminized Steel (50,000 to 125,000 BTU/H models), Alumi-Ti (titanium treated) steel tubes (150,000 to 200,000).
NOTE: Reference the Tube Heater General Manual, Chart 3.6 (page 23) for secured reflector joints.
Baffle Location

12
3.0 HL2 Series Operation •Sequence of Operation •Thermostat • Diagnostics
3.0 Operation
Sequence of Operation
Standby: The circuit board continually checks for internal faults, circuit integrity, and relay contact
positioning.
Starting Circuit: Upon a call for heat, the control verifies that the differential switch is in the proper
position (open). The control energizes the fan. Once operational static pressure is achieved, the
differential switch will close initiating the ignition sequence. The glo-bar is powered and the gas
valve opens after 45 seconds. If the flame is not sensed, the heater will attempt to re-ignite for a total
of three (3) trials for ignition before proceeding to soft lockout.
Single Stage Running Circuit: After ignition, the flame rod monitors burner flame. If sense of flame is
lost, the control closes the gas valve within one second and a new trial sequence (identical to the
starting sequence) is initiated. If flame sense is not established within 8.5 seconds, the heater will
attempt two (2) additional ignition sequences before proceeding to soft lockout. The control can be
reset by briefly interrupting the power source.
Two Stage Running Circuit: The second stage on the gas valve is powered directly from the second
stage of the thermostat. In order for two stage to flow to a higher output, single stage must be
energized as well. The thermostat determines which stage to maintain for the desired comfort level.
Shut Down: When the thermostat is satisfied, the fan will enter a two (2) minute post-purge cycle. Refer
to page 13 for diagnostics; soft & hard lockout.
Thermostat
NOTE: Different thermostats operate according to their particular features. Refer to thermostat
specifications for details.
HL2 series heaters require a 24 V, two-stage thermostat to operate. The burner control box is equipped
with either a round terminal strip that accepts three (3) 1/4-inch insulated female spade terminals or a
36-inch yellow 24 VAC control wire. Do not supply 120 VAC to the 24 VAC connection.
The HL2 series is equipped with or without a relay board (P/N: HLRB).
Standard Configuration
Without relay board (white terminal label*):
• Single burner control box.
• Single thermostat.
Optional Configuration (must be factory installed)
With relay board (orange terminal label*):
• Required when a single thermostat controls two or more burner control boxes or when heaters are
common vented.
NOTE: Units with a relay board installed must have an external transformer (field supplied), see wiring
diagram. (Figure 2.1B) Stainless steel heaters with a relay board are indicated with the suffix ‘D’ on
the heater’s rating plate.
*A yellow control wire replaces the external terminal plug on stainless steel models or models with water
resistant upgrades.
HL2 Series

13
3.0 Operation •Diagnostics
Chart 3.1 • LED Fault Code Status
LED Code Fault Status Fault Code Delay*
Initial flash on power up, No fault, normal operation No Delay
then steady off
Steady ON Module failure / Internal fault No Delay
1 flash Ignition failure 30 – 32 minutes
2 or 3 flashes APS (Air Proving Switch) 10 – 12 minutes
Fan / Intake / Exhaust
4 flashes Solenoid valve fault No Delay
Leaky valve
Flame amplifier fault
No flash on 117 V startup Transformer fault No Delay
*Some LED codes have a time delay before the LED will flash.
HL2 Series
Diagnostics
Lockout:
The controls will automatically lockout the heater system when an external or system fault occurs. There
are two types of lockout:
Soft Lockout: The heater will attempt to light three times. In the event of a failed attempt to light, (gas
pressure, valve, no flame sense etc.), the heater will enter Soft Lockout mode for 30
minutes and then attempt to light three more times before entering Hard Lockout mode.
Hard Lockout: If proof of flame is not established, a component failure occurs or blockages are evident,
the heater will enter hard lockout. If lockout occurs, the control can be reset by briefly
interrupting the power source. Refer to Chart 3.1 below for a description of LED codes.
Figure 3.1 • LED Operation Indicator Lights
Note: Hard Lockout LED CODE will appear upon completion of the soft lockout sequence of operation.
Light 1(amber)
Indicates Low
Fire Mode
Light 2 (amber)
Indicates High
Fire Mode
Light 3 (red)
Indicates Diagnostic
Fault Code Status
(see Chart 3.1)
Operational Indicator Lights

Does the heater have a relay board?
(identified with orange crescent
next to the terminal plug).
.
14
4.0 Troubleshooting Guide
4.0 Troubleshooting Guide
Turn up thermostat.
Does the fan
blower turn on?
Is the power at the
heater 120 V?
Find the source of the electrical problem between panel and heater.
No
Find the source of the
electrical problem
between panel and
external transformer.
Is there 120 V on the
primary side of the
external transformer?
Is the power across
the left and middle
terminals of the
24 V plug 24 V?
External transformer
is faulty and must be
replaced.
The thermostat or wiring
is faulty and should be
replaced or repaired.
Find source of electrical problem between
the external transformer and thermostat.
24 Volts
Is there 24 V on the
secondary side of the
external transformer?
Is there
24 V to the
thermostat?
Yes
Yes
No Yes
No
No Yes Yes
No
Is the power across the
left terminal of the 24 V
plug and ground (screw
on the burner control
box) 24 Volts?
Is there 120 V on
the primary side
of the internal
transformer?
Is there 24 V on
the secondary
side of the
transformer?
Replace transformer.
Repair the wiring
between the trans-
former and the
24 V terminal plug.
Repair the wiring between power in and transformer.
Yes
No No
Yes No
No
Yes
Yes
Does the ignitor
warm up and
glow orange?
Is the ignitor
physically
damaged?
Replace ignitor.
Check voltage at ignitor
sequence (usually 5 to 15
seconds after power to
heater). Is it 120 V?
Is the resistance through the
ignitor 50-400 Ω?
Is the inlet or the outlet
of the unit plugged or
obstructed?
Remove obstruction.
No
Yes Yes
No No No
Yes Yes
No
Continued on page 16
No
Troubleshooting with Relay Board
HL2 Series
No
Yes

.
NOTICE
Bypassing any switch is intended for testing purposes only. Do not leave switch bypassed
during normal operation or the heater’s built-in safety mechanisms will be compromised.
* Refer to LED diagnostic Fault Code Chart. 15
4.0 Troubleshooting Guide
Is the power across
the 24 V wire on the
circuit board and
ground 24 V?
Is the
circuit board
sending 120 V
to the fan?
Is the fan
obstructed?
Remove
obstruction.
Is the pressure
switch stuck in the
closed position?
Replace
switch.
Yes
Yes
Is there 120 V on the
primary side of the
internal transformer?
The relay board is faulty
and must be replaced.
The circuit board is
faulty and must be
replaced.
Repair wiring between
power in and transformer. The fan is faulty and must be replaced
The internal
transformer is
faulty and must
be replaced.
Is the power across
the t-stat wire on the
circuit board and
ground 24 V?
Yes
No
No
Yes Yes
No
No
Yes
Is the power across
the middle (low)
terminal of 24 V plug
and ground (screw on
the Burner Control
Box) 24 V?
Repair thermostat or wiring
from thermostat to heater.
Is there 24 V
across the TH and
ground terminals
on the circuit
board?
Correct wiring.
Is the circuit
board sending
120 V to the
fan?
Is the fan
obstructed?
Remove
obstruction.
Is the pressure switch stuck
in the closed position?
Replace
pressure
switch.
Yes Yes
Yes
Yes
Yes
No No
No
Check for loose wiring or
restrictions in hose connec-
tions to pressure switch.
Are they OK?
Replace wiring or hose connections.
*A fter 10-12 minutes of non-
operation has passed, is
there a flash code for APS
failure (2 or 3 flashes)?
Replace the pressure switch after verifying:
• Baffle(s) are in the radiant tube furthest from
the burner.
• Heater, fan blowers ,squirrel cage, intake and
exhaust are clean and free from dirt and
obstructions.
• The 4” air intake pipe does not exceed 20 ft.
and/or 2 elbows.
• There is not a negative pressure experienced
at the area of air intake (e.g.; high winds, attic
space, tightly sealed building).
Replace circuit board.
No
Yes Yes
No
Key
Without Relay Board:
Start
Question
Process
Question
Corrective
Action
With Relay Board:
Process
Question
Corrective
Action
No
No
No
HL2 Series
No

16
4.0 Troubleshooting Guide
After ignitor is
warmed up, does
gas valve open?
Test for 24 V at valve opening period (usually 45 to 60 seconds
after power to heater). Is there 24 V to valve for 8 seconds?
Replace circuit board.
Does the burner
light?
Does the burner
stay on?
Is the ball valve/
shut-off valve
in the ON position?
Check to make sure gas pressure is within
minimum and maximum inputs, as indicated on
heater’s rating plate. Is gas pressure OK?
Does the burner stay on
for approx. 8 seconds
and then shut off?
Does the burner come
on and turn off
immediately
(1 or 2 seconds)?
Check to make sure gas pressure
is within minimum and maximum
inputs, as indicated on heater’s
rating plate. Is gas pressure OK?
Pressure
switch may
be faulty or
there is a
restriction in
the exhaust.
Does the heater
stay ON until a call
for heat ends?
Troubleshooting ends.
The heater can shut down due to:
• Improper grounding.
• High winds.
• Taking combustion air from the attic.
• Dirty environment.
• Improperly positioned baffles.
• Fluctuating gas pressure.
No
Yes
No
No Yes
Yes
No
Correct problem.
Yes
Yes
Yes
No
Yes
No
Yes
No
Yes
No
Turn on.
Continued from page 14
Yes
HL2 Series
Correct problem.
No

17
Check to make sure gas pressure is within minimum and
maximum inputs, as indicated on heater’s rating plate.
Is gas pressure OK?
Were the gas lines purged of air?
Is the heater properly
grounded? Is the heater’s
polarity correct?
With microampmeter, check DC
voltage at flame rod. Is it greater
than .05 microamps?
Check to make sure flame
sensor wire is OK and then
replace circuit.
Sensing rod is faulty or flame is weak.
Check to make sure heater is operating
at proper gas pressure as indicated on
heater’s rating plate and then, if
needed, replace sensing rod.
Replace gas valve.
Yes
Correct problem.
Correct problem.
No
No
Yes Yes
No
Yes
Purge gas line.
No
4.0 Troubleshooting Guide
HL2 Series
Is there 24 V across the GROUND and HIGH
(HIGH to COM on heaters with optional
HLRB relay) on the terminal strip located on
the outside of the control box?
Repair or replace faulty
wiring or thermostat. Replace relay.
No
If heater does not go into high fire mode:
Measure voltage across the red wire
on the VALVE and GROUND (red wire
on RELAY to GROUND on heaters with
HLRB relay). Is it 24 V?
Yes
No
Yes
Replace gas valve.
NOTE: To confirm that the heater is not in high fire mode, check manifold pressure. If manifold
pressure is 3.3 to 3.5 inches W.C. for natural gas or 9 to 10 inches W.C. for propane, the light is faulty
and should be replaced.
When the heater is in low fire mode, manifold pressure is approximately 2.0 to 2.5 inches for natural
gas or 5.0 to 6.5 inches for propane. If this is the case, the following troubleshooting steps should be
followed:

205
383A 221
222
11
50A
321
18
Chart 5.1 • Parts List
5.0 Parts • Heater Components and Parts List
5.0 Parts 1
NOPS
207
97
218
219
55A
802, 802A
851
852
832
70
828 825 826
827
67
66 114
31B
68A
33B
83, 83A
212
208A
TP-840A, 841A
223
204
201B or 3072
303
12
9
10
217
5202
15
14
16
21B
222A
214
Figure 5.1 •Burner Assembly
Components
804
76
* May be used with stainless steel upgrades.
** 6 feet total required to cover outer edges of the
burner control box.
31B
13
13
17
HL2 Series
301
Part No. Description Part No. Description
TP-1 Control Box Cover TP-26E 10 ft. 409 Stainless Steel Combustion Tube*
TP-5 Flange Gasket TP-31B Control Box Mounting Bracket
TP-9 Conduit Coupling TP-33B 1/2” Shut-Off Ball Valve / Inlet Tap
TP-10 Conduit 4” x 1/2” TP-50A Glo-Bar™ Ignitor
TP-11 Glo-Bar™ Ignitor Box TP-55A Fan Blower
TP-12 Glo-Bar™ Ignitor Box Cover TP-65I 36” Interlocking Turbulator Baffle
TP-13 8 x 1/2” Self-Drilling Screw TP-66 2” x 4” Outlet Box
TP-14 Sight Glass Gasket TP-67 2” x 4” Outlet Box Cover
TP-15 Sight Glass TP-68A Strain Relief Bushing
TP-16 Sight Glass Washer TP-70 Control Box Cover Gasket (per foot**)
TP-17 Sight Glass Kit TP-76 Rubber Grommet
TP-19B 4” Wire Hanger with Tension Spring TP-82 Reflector Center Support (RCS)
TP-20C 120” Aluminum Reflector TP-83 24” Stainless Steel Flexible Gas Connector
TP-20D 120” Stainless Steel Reflector* TP-83A 24” PVC Coated S.S. Flexible Gas Connector*
TP-21B 4” Standard Tube Clamp TP-84 1/2” Female/Male Flare Fitting
TP-26A 10 ft. Aluminized Radiant / Combustion Tube TP-97 1/4” x 1/4” Brass Int./Ext. Atmos. Barb Fitting
TP-26B 10 ft. Titanium Coated Combustion Tube TP-105 Aluminum Reflector End Cap
TP-26D 10 ft. 304 Stainless Steel Radiant Tube* TP-106 Reflector End Cap Clips (8 pcs.)
84
206

19B
106 105
26A, 26B, 26E
21B, 220
20C, 20D
82
26A, 26D
65I
113
19
Figure 5.2 •Tube and Reflector Components
5.0 Parts • Heater Components and Parts List
* May be used with stainless steel upgrades.
HL2 Series
Combustion Chamber Radiant Emitter Tube(s)
Part No. Description Part No. Description
TP-113 Reflector Tension Spring TP-321 Ignition Plate Gasket
TP-114 Plastic Air Orifice with Screen TP-383A Glo-Bar™ Ignitor Plate
TP-201B Burner (Tan) - consult factory TP-802 End Panel, Left (with relay board)
TP-202 16” HSI Burner Tube with Flange TP-802A End Panel, Left
TP-204 Gas Orifice (consult factory) TP-804 Burner Control Box Outer Shell
TP-205 Glo-Bar™ Holder TP-825 Optional HLRB Relay Board
TP-206 Glo-Bar™ Holder Spring Clip TP-826 40 VA Transformer
TP-207 Pressure Switch Mounting Bracket TP-827 Red LED Display Diagnostic Light
TP-208A Gas Valve Mounting Bracket TP-828 Yellow Operational Indicator Light
TP-212 1/2” x 3” Pipe Nipple TP-832 Thermostat Terminal Strip
TP-214 Glo-Bar™ Wiring Harness TP-840A 36G54-224 Gas Valve - Natural Gas Assembly
TP-217 Pressure Switch Barb TP-841A 36G54-226 Gas Valve - LP Gas Assembly
TP-218 Differential Switch Vinyl Sensing Tube (exhaust) TP-851 Micro-60-24 Diagnostic Circuit Board
TP-219 Differential Vinyl Sensing Tube (burner) TP-852 3-Piece Wire Harness Set for Micro 60 Board
TP-220 Stainless Steel Tube Clamp (150 & 200 MBH)* TP-NOPS Normally Open Pressure Switch (see below)
TP-221 Glo-Bar™ Holder Gasket TP-264B Differential Pressure Switch, 65 to 100 MBH
TP-222 Flame Rod TP-264E Differential Pressure Switch, 125 to 150 MBH
TP-222A Flame Rod Wire TP-264D Differential Pressure Switch, 175 MBH
TP-223 Gas Manifold TP-264F Differential Pressure Switch, 200 MBH
TP-301 Burner Control Box Center Panel TP-3072 Burner (Green) - consult factory
TP-303 End Panel, Right

20
5.0 Parts •Kit Contents Check List HL2 Series
Part No. Description 20 ft. 30 ft. 40 ft. 50 ft. 60 ft. 70 ft.
TP-19B 4” Hanger w/ Tension Spring 345678
TP-21B 4” Tube Clamp 2345* 6* 7*
TP-25 1/4” Female Spade Terminal** 333333
TP-33B 1/2” Shut-Off Valve & Inlet Tap 111111
TP-82 4” Reflector Center Support 234567
TP-83 24” S.S. Flexible Gas Connector 111111
TP-105 Reflector End Cap 222222
TP-106 Reflector End Cap Clips 888888
LIOGTa General Tube Heater Manual 111111
LIOHL2 HL2 Series Insert Manual 11111
Filled By:
Chart 5.2 • Kit Contents for HL2 Series - Reference the length column for your model.
TP-19B 4” Hanger with
Reflector Tension Spring
TP-105 Reflector End Cap
TP-21B* 4” Tube Clamp
TP-106
Reflector
End Cap Clips
TP-33B 1/2” Shut-Off Valve
(Ball Valve & Inlet Tap)
TP-83 24” Stainless Steel
Flexible Gas Connector
Kit Contents Check List
HL2 Series Kit Contents
TP-82 4” Reflector
Center Support (RCS)
* NOTE: One 4” stainless steel tube clamp (P/N: TP-220) is provided for each 150,000 - 200,000 BTU model.
Place as shown on page 11.
** Not included with models installed with yellow control cord.
^ Part number for models upgraded with stainless steel options.
Approvals
• CSA
• Indoor approval
• Outdoor approval with OD-Kit
• Commercial approval
Limited Warranty
• 3 years - Burner box components
• 5 years - Combustion and radiant tubes
• 10 years - Stainless steel burner
• See page 40 of the General Tube Heater Manual
for terms and conditions.
^TP-829^TP-19C
^TP-220 ^TP-105A
^TP-83A
TP-25** 1/4”
Female Spade
Terminal
HL2 Series
Insert Manual
Tube Heater
General Manual and
HL2 Series Insert Manual
F/N: LIOGTa & LIOHL2a
Tube Heater
General Manual
© 2019 Detroit Radiant Products Co.
21400 Hoover Road • Warren, MI 48089
Phone: [phone] Fax: [phone]
www.detroitradiant.com • [e-mail]
Printed in U. S. A.