Nagas DT Series User manual

1385 Lionel-Boulet blvd.
Varennes, Quebec
J3X 1P7, Canada
www.nagasinnovation.com
INDIRECT GAS-FIRED DUCT FURNACE
INSTALLATION, OPERATION AND MAINTENANCE MANUAL
FOR INDOOR OR OUTDOOR INSTALLATIONS
Gas Unit Heaters, Gas Packaged Heaters, Gas Utility Heaters, And Gas-Fired Duct Furnaces
CSA 2.6 and ANSI Z83.8
DT Series

2 DT Series - Installation manual (V4_2022)
•Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or
any other appliance.
•WHAT TO DO IF YOU SMELL GAS:
oDo not try to light any appliance;
oDo not touch any electrical switch;
oDo not use any phone in your building;
oLeave the building immediately;
oImmediately call your gas supplier from a phone remote from the building and
follow the gas supplier’s instructions;
oIf you cannot reach your gas supplier, call the fire department;
•Installation and service must be performed by a qualified installer, service agency or the
gas supplier.
THIS INSTRUCTION MANUAL MUST ALWAYS BE AVAILABLE AND KEPT WITH THE HEATER AT ALL
TIMES.
WARNING! FIRE OR EXPLOSION HAZARD
IMPORTANT SAFETY INFORMATION
•Failure to follow safety warnings exactly, could result in serious injury, death, or property
damage.
•Be sure to read and understand the installation, operation, and service instruction in this
manual.
•Improper installation, adjustment, alteration, service, or maintenance can cause serious
injury, death, or property damages.

DT Series - Installation manual (V4_2022) 3
Hazard risk identification is the first step in conducting a risk assessment, please read carefully:
DANGER!
Indicates an imminently risky situation which, if not avoided, will result in
death or serious injury.
WARNING!
Indicates a potentially risky situation which, if not avoided, could result in
death or serious injury.
CAUTION!
Indicates a potentially risky situation which, if not avoided, may result in
personal injury or property damage.
NOTICE
Indicates special instructions on installation, operation, or maintenance
that are important but not related to personal injury or property damage.
•Before starting the installation of the unit, read, understand, and follow all the
instructions given in this manual, including all safety precautions and warnings.
•This unit is connected to high voltages and contains moving parts that can start
unexpectedly.
•Never open access doors to the unit while it is running.
•Unit must be securely and adequately grounded.
•Electrical shock, severe injury or death could occur if instructions given in this manual
are not followed.
•Always disconnect and lock out power before servicing this equipment. All work should
be done by a qualified technician.
•DO NOT bypass any interlock or safety switches under any circumstances.

4 DT Series - Installation manual (V4_2022)
PROJECT: ___________________________________________________________
ADDRESS: ___________________________________________________________
MODEL: ___________________________________________________________
SERIAL NUMBER: ___________________________________________________________
INSTALLER: ___________________________________________________________
ADDRESS: ___________________________________________________________
PHONE: ___________________________________________________________
EMAIL: ___________________________________________________________
INSTALLATION DATE: ___________________________________________________________
MANUFACTURER: Nagas Innovation
ADDRESS: 1385 Lionel-Boulet Blvd., Varennes, Quebec, J3X 1P7, Canada
PHONE: [phone]
FAX: [phone]
EMAIL: [e-mail]
WEB SITE: www.nagasinnovation.com

DT Series - Installation manual (V4_2022) 5
TABLE OF CONTENTS
1. CODES AND REGULATION............................................................................................................7
2. GENERAL INFORMATION.............................................................................................................8
2.1. INTRODUCTION ...................................................................................................................8
2.2. LISTED PRODUCT .................................................................................................................8
2.3. RESPONSIBILITY ...................................................................................................................8
2.4. RECEPTION & STORAGE.......................................................................................................9
2.5. LIMITED WARRANTY............................................................................................................9
2.6. PARTS, REPAIRS, AND SERVICE..........................................................................................10
2.7. NORMAL USAGE................................................................................................................11
3. SPECIFICATIONS.........................................................................................................................12
4. INSTALLATION GUIDELINES.......................................................................................................13
4.1. GENERAL............................................................................................................................13
4.2. TYPICAL ARRANGEMENT ...................................................................................................14
4.3. INSTALLATION ...................................................................................................................15
4.4. LIFTING ..............................................................................................................................15
4.5. MOUNTING........................................................................................................................16
4.6. UNPACKAGING ..................................................................................................................17
4.7. ELECTRICAL OR CONTROL SERVICE CONNECTIONS...........................................................17
4.8. ELECTRICAL INSTALLATION................................................................................................17
5. GAS PIPING CONNECTION .........................................................................................................19
6. TYPICAL GAS TRAIN ...................................................................................................................20
8. INLET GAS PRESSURE.................................................................................................................21
9. HEATER SHUTDOWN .................................................................................................................21
9.1. EXTENDED SHUTDOWN.....................................................................................................21
9.2. EMERGENCY SHUTDOWN .................................................................................................22
9.3. HEATER ON AFTER A FLAME FAILURE ALARM...................................................................22
10. FLUE VENT & COMBUSTION AIR INTAKE...............................................................................22

6 DT Series - Installation manual (V4_2022)
11. START-UP INSTRUCTIONS......................................................................................................27
11.1. RECOMMENDED TOOLS ................................................................................................27
11.2. BURNER ADJUSTMENT ..................................................................................................28
11.3. PILOT ADJUSTMENT.......................................................................................................29
11.4. COMBUSTIONS ADJUSTMENT .......................................................................................29
12. CONTROL SEQUENCE.............................................................................................................32
13. TROUBLESHOOTING ..............................................................................................................32
13.1. FIREYE NORMAL OPERATING SEQUENCE......................................................................32
13.2. STATUS OF WARNING LIGHTS (FIREYE) .........................................................................33
13.3. HONEYWELL NORMAL OPERATING SEQUENCE ............................................................34
13.4. TROUBLESHOOTING CHECK LIST ...................................................................................35
14. HEATER MAINTENANCE.........................................................................................................37
15. START-UP REPORT .................................................................................................................38
NOTICE: The features, illustrations and description in this document were, to our knowledge,
accurate at the time they were approved for printing. Nagas Innovation has a policy of
continuous product improvement and reserves the right to change design and specifications,
stop offering some features or stop producing a given model size without prior notice. For
more information, please contact your local representative and authorized distributor.

DT Series - Installation manual (V4_2022) 7
1.CODES AND REGULATION
Indirect gas-fired air heater must be installed according to local installation code for gas
equipment, and any provincial or state regulation applying to this category of equipment (CSA
B149.1 / ANSI Z223.1 / NFPA-54). All electrical installations must comply with Canadian electrical
code or American code (C22.1 / NFPA-70), and other local electrical applicable codes.
Any electrical installation to be done internally or externally to the heater must comply with the
electrical wiring diagram supplied with the heater. For more information, refer to start-up
instructions, operating sequence, and adjustment instructions.
CAUTION!
CLEARANCES TO COMBUSTIBLE MATERIAL
A minimum clearance of 6 inches between the heater and any combustible material is
required on all sides and top, 42 inches in front of the access panel and 18 inches all around
the flue vent. No clearance is required under the heater.
Allow sufficient space on both sides of the heater for maintenance and allow sufficient space
on the air inlet hood side to prevent snow accumulation and do not block the combustion air
inlets.
Clearances to combustible materials
Position
Inch [mm]
Controls
42 [1067]
Top
6 [152]
Back
6 [152]
Flue vent
18 [457]
Floor
Non-combustible
Table 1: Clearances to combustibles
•Installation, alteration, setting or improper maintenance can cause property damage,
injury, or death. Carefully read the installation, start-up, and maintenance instruction
before installing or repairing the unit.
•Units installed within a building must have fresh air for combustion in sufficient quantity
to get a good combustion. Refer to CSA B149.1 installation code for Canada and ANSI
Z223.1 for USA for more information and minimum requirements.
•Gas units must be connected to a flue vent properly sized to ensure proper and safe
operation and flue evacuation to outdoor.
•When required to pipe to outdoor the regulator vent pipes or vent valve, it must be
terminated with a downward elbow and a fine mesh screen to prevent blockage.

8 DT Series - Installation manual (V4_2022)
2.GENERAL INFORMATION
2.1. INTRODUCTION
This manual has been made to simplify the installation, maintenance, and the operation of this
equipment. The strict application of these instructions will ensure the conformity of the
installation to Nagas Innovation’s recommendations.
The application of the instructions given in this manual is one of the conditions of the
warranty, however it does not guarantee at any time conformity with the applicable laws,
rules, codes, and regulations of the country of destination of the equipment installed.
This manual is protected under international copyright laws. No part of this manual may be
reproduced, distributed, translated, or transmitted in any form or by any means, electronic or
mechanical, including photocopying, recording, or storing in any information storage and
retrieval system, without the prior written permission of Nagas Innovation.
2.2. LISTED PRODUCT
This equipment has been declared to conform to applicable Canadian and American standards
(CSA 2.6 and ANSI Z83.8) and bear the cETLus marking.
This equipment is intended for industrial or commercial use only. The installation must comply
with the latest laws and regulation for gas heating units CSA B149.1 / ANSI Z223.1 / NFPA-54,
to the electrical code CSA22.1 / NFPA-70 and to local laws, rules, and regulations. All the
electrical installation located inside or outside of this equipment must comply with the unit’s
electrical diagrams.
The electrical and ratings described on the rating plate appear on the unit. Following these
ratings is mandatory for a safe use of the unit. To learn more, read this manual carefully.
2.3. RESPONSIBILITY
This equipment must be used expressly for the purpose for which Nagas Innovation has
designed and manufactured it. Any contractual liability of Nagas Innovation is therefore
excluded in case of injury to persons, animals or damage caused to goods, following errors in
installation, settings, maintenance, or inappropriate use.
Nagas Innovation is responsible for the conformity of the device to the codes and standards of
construction in force at the time of sale. Knowledge and respect for the legal provisions as well
as the standards inherent in the design, implantation, installation, commissioning, or
maintenance are exclusively the responsibility of the installer or integrator.
Be advised that this manual does not cover all possibilities, situations, or eventualities. Regular
service is necessary to ensure proper and safe operation of this equipment. If you have any
doubts about performing these tasks yourself, you should hire a qualified specialist.

DT Series - Installation manual (V4_2022) 9
Negligence in maintenance can cause failure of the equipment, property damage and/or harm
to the building occupants and will void the warranty of the equipment.
2.4. RECEPTION & STORAGE
Immediately upon receipt of the equipment, check the crating and contents for any damage
that may have occurred during the shipment. Inspect protective covers for perforations or
other signs that there may be damage. Remove protective covers and check for external
damage. Open all the access doors and check for internal damage. Close access doors when
the inspection is finished. Replace covers if the unit is not being assembled or installed at that
moment.
All the units that leave our factory are tested and carefully inspected immediately prior to
shipping to ensure that they are in good operating condition at that time. Check the packing
slip to make sure that all loose parts for field installation were received; they can be found
inside the unit. If damages are found or parts are missing, please contact your local authorized
distributor or call factory.
If the equipment is to be stored prior to installation, you must observe the following
precautions:
•Store in a well-drained and dry area that will not accumulate surface water to prevent
damage by moisture from wet ground, dew, or rain.
•Do not store where the equipment could be physically damaged.
•Make sure that all protective coverings that were provided for shipping are not
damaged and are properly installed over the equipment.
•The entire perimeter and any full height cross members of the unit must be supported
by a level surface and the supporting surface must be adequate for supporting the
entire weight of the unit.
•Do not stack split unit sections one over the other for storage purpose.
2.5. LIMITED WARRANTY
Subject to the terms and conditions hereof, during the first year after the original installation
of the product or eighteen (18) months from date of shipment by Nagas Innovation Inc.
whichever occurs first, we will supply free of charge any component part(s) of our product
found to be defective in material or workmanship (except for the heat exchanger section
which carries a 5-year warranty). Any replacement part(s) so supplied will be warranted for
the balance of our product's original warranty. The part(s) to be replaced must be available in
exchange for the replacement part(s). Any labor, material, transportation, freight or other
charges incurred in connection with the performance of this warranty will be the responsibility
of the owner at the hourly rates and prices then in force. This limited warranty is only
applicable to new and unused products purchased from us or from our authorized
distributors, provided that our user instructions contained in our user guide have been

10 DT Series - Installation manual (V4_2022)
adhered to. You recognize and understand that our obligation is limited to replacing the part
found to be defective and that you have no further recourse the manufacturer.
THIS WARRANTY DOES NOT COVER:
(a) damages caused by accident, abuse, negligence, misuse, riot, fire, flood or Acts of God (b)
damages caused by operating the product in a corrosive atmosphere (c) damages caused by
any unauthorized alteration or repair of the system affecting the product's reliability or
performance (d) damages caused by improper matching or applications of the product or the
product's components (e) damages caused by failing to provide routine and proper
maintenance or service to the product (f) expenses incurred for erecting, disconnecting or
dismantling the product (g) parts used in connection with normal maintenance, such as filters
or belts (h) products no longer at the site of the original installation (i) products installed or
operated other than in accordance with the printed instructions, with the local installation or
building codes or with good trade practices (j) products lost or stolen.
No one is authorized to change this WARRANTY or to create for us or on our behalf any other
obligation or liability in connection with our product(s). There is no other representation,
warranty or condition in any respect, expressed or implied, made by or binding upon us other
than the above, nor will we be liable in any way for incidental, consequential, or special
damages however caused such as but not limited to: loss of productivity, damages caused by
delays, loss of profits and management time.
In order to obtain replacement parts under this product's warranty, contact the dealer or
contractor who installed or services our products. Only dealers or contractors who are
registered with us are authorized to perform this warranty. Should the dealer or the
contractor need assistance, the authorized agent for Nagas Innovation is available for
support, and we, at Nagas Innovation, in turn, support our agent's efforts.
RETAIN THIS WARRANTY IN YOUR FILES FOR FUTURE REFERENCE
This warranty is expressly given and accepted in lieu of any and all other warranties, expressed
or implied, including without any limitation any warranty of merchantability or fitness for a
particular purpose. Some states/provinces do not allow for the disclaimers, limitations and
exclusions identified above; as a result, they may not apply to you.
2.6. PARTS, REPAIRS, AND SERVICE
Any replacement part must be the same as or an approved alternate to the original part
supplied. The replacement part must meet the original’s specification in terms of functionality
including certifications, timing, input and output range, accuracy and operation. Failure to
replace parts or components with equivalent parts can cause equipment failure, equipment
damage, injury or death, and can void the warranty of the equipment.
When contacting Nagas Innovation customer service (or an authorized distributor) for parts,
repairs or service please be ready to provide the Model Number, Serial Number, Date of

DT Series - Installation manual (V4_2022) 11
installation and/or Nature of failure along with the description of the parts required. Be
advised that some parts may not be stocked items, that these parts must be made or ordered;
variable delays can be expected depending on the nature of the equipment damage or
defective part.
DANGER!
Always disconnect power before working on or near this equipment. Lock and tag the
disconnect switch or breaker to prevent accidental power up. Turn off gas supply whenever
power is disconnected.
When servicing the unit, the internal components may be hot enough to cause pain or
injury. Allow time for cooling before servicing.
2.7. NORMAL USAGE
This indirect gas-fired heater is intended for indoor or outdoor installation, in air ducts, or in
air handling unit made by original equipment manufacturers (OEM) of listed heating
equipment in cabinet. It must be mounted on the positive side of the circulating air blower
and may be downstream of refrigeration system. This product is designed to serve as a heating
for make-up air or/and recirculated air. The unit must be installed on non-combustible
surfaces, duct, or wall, and located in a neutral pressure environment. It can operate with a
minimum thermal efficiency of 80 % and use natural or propane gas. The heating output
capacities available range from 550 to 5,000 MBH (160 to 1,471 kW) and from 4,244 to 92,593
SCFM (2,003 to 43,690 L/s) of air at temperature differential of 50°F to 120°F (28°C to 67°C).
The maximum discharge temperature is limited to 130°F (55°C) at 3.00 in.w.c. (747 Pa)
maximum external static pressure. The discharge temperature high limit protection is
factory set at 160°F (71°C).

12 DT Series - Installation manual (V4_2022)
3.SPECIFICATIONS
MODEL
INPUT CAPACITY
NET OUTPUT CAPACITY
TURNDOWN RATIO
AIRFLOW
CFM
L/S
MBTU
KW
MBTU
KW
MIN
MAX
MIN
MAX
55
688
200
550
160
10:1
4244
10185
2003
4808
65
813
237
650
189
10:1
5015
12037
2368
5682
75
938
273
750
219
10:1
5787
13889
2732
6556
85
1063
310
850
248
12:1
6559
15741
3096
7430
100
1250
364
1000
291
12:1
7716
18519
3642
8742
125
1563
455
1250
364
12:1
9645
23148
4553
10927
150
1875
546
1500
437
12:1
11574
27778
5464
13112
175
2188
638
1750
510
17:1
13503
32407
6374
15298
200
2500
729
2000
583
18:1
15432
37037
7285
17483
250
3125
911
2500
729
15:1
19290
46296
9106
21854
300
3750
1093
3000
874
15:1
23148
55556
10927
26225
350
4375
1275
3500
1020
18:1
27006
64815
12748
30596
400
5000
1457
4000
1166
20:1
30864
74074
14569
34966
500
6250
1821
5000
1457
20:1
38580
92593
18212
43708
Table 2: General specifications
NOTES:
•Net output capacities are based on 80% combustion efficiency for natural gas, some
models may have higher efficiency
•Airflow is intended for temperature rise of 50°F to 120°F (28°C to 67°C)
•1 MBTU: 1000 BTU/ Hr
•CFM: Cubic foot per minute
•Ratings are based on 1000 Btu/ft3for natural gas at sea level
•Reduce burner capacity for altitude over 2000ft by 4% for each 1000ft above sea level
•Consult factory for turndown ratio for propane gas

DT Series - Installation manual (V4_2022) 13
4.INSTALLATION GUIDELINES
4.1. GENERAL
•Install the unit on the positive side of the air-circulating blower (supply side). In other
words, the fan must be installed upstream of the duct heater.
•Duct furnace shall be installed with an inlet duct that will provide air distribution
equivalent to a straight run of duct having the same cross-sectional area as the inlet
connection and not less than 2 equivalent diameters in length.
•Centrifugal twin blower, plenum blower, and centrifugal single blower (with diffuser plate)
to provide the airflow required by the duct heater.
•The installation must be adjusted to obtain an air throughput within the range specified
on the appliance rating plate.
•Always use a bypass damper for applications where temperature rise is below 50°F
through the duct heater.
•The fan motor contact and/or flow proving switch must be wired to the burner safety
loop.
•The final air temperature should be controlled by a duct temperature sensor located
downstream of the duct heater. The sensor must be installed at a position where it will
measure the average duct temperature (field testing may be required to find the optimal
position).
•The installation must be adjusted to obtain a temperature rise within the range specified
on the unit heater rating plate.
•The appliance shall be adjusted to the manifold pressure specified on the manufacturer's
rating plate.
•The ducts connected to the duct furnace shall have removable access panels on both
upstream and downstream sides of the duct furnace. These openings shall be accessible
when the appliance is installed in service and shall be of such size that smoke or reflected
light may be observed inside the casing to indicate the presence of leaks in the heating
element. The cover for the opening shall be attached in such a manner as to prevent leaks.
•The air intake must be located and oriented to prevent infiltration of snow, rain, and
flammable toxic gas, as well as any other harmful material in the make-up air heater.
•For indoor installation make sure that the minimum airflow required for combustion is
sufficient in the room where the duct heater is installed (refer to local code in effect).
•Always make sure that the air used for combustion by the gas burner is clean and free of
dust and corrosive particles or it could greatly reduce the service life of the unit.

14 DT Series - Installation manual (V4_2022)
4.2. TYPICAL ARRANGEMENT
Figure 1: Horizontal (multiple air discharge configuration available)
Figure 2: Single or Twin DWDI blowers with diffuser plate and horizontal arrangement (Do not use SWSI blower)
•Single or multiple plenum blower can be used in any configurations. For application with
high air flow. Temperature rises below 60°F to reduce system pressure loss (x = fan wheel
diameter)
Figure 3: Single or multiple plenum blower with horizontal arrangement

DT Series - Installation manual (V4_2022) 15
4.3. INSTALLATION
•When the heater is hung over a work area, it must be installed at an adequate height. The
installation of a service platform might be required.
•When fire dampers are used in the ducts, they must be equipped with an electric switch
wired to the safety control circuit of the unit to shut down the air heater when fire is
detected in ducts. These electric switches must be wired to re-activate the safety circuit
only when the fire dampers are completely opened.
•To prevent any risk of freeze-up, the installer must install a low temperature switch if not
supplied with the unit from the factory.
•Depending on unit size, diameters of the flue gas connection vary between 6 and 14
inches. DT series combustion systems are designed to operate safely against a maximum
back pressure of 0.25" water column with positive stock category IV type sealed corrosion
resistant single wall or double wall flue vent, either in a vertical arrangement (through the
roof) or in a horizontal arrangement (through the wall), or a combination of both.
•The heater should be attached to the roof curb or supporting structure with screws, bolts,
or any other appropriate fastening means.
•In some conditions the heater could produce condensate which is a corrosive liquid that
must be treated and drain correctly with provision to prevent freezing, or the heater could
become flooded and/or cause water damage in the surrounding area.
4.4. LIFTING
The heater is built on a base frame equipped with lifting lugs specifically located to help
proper lifting of the unit. Employ the use of spreader bar to maintain a vertical position of the
slings and keep them away from the unit casing to prevent scratches, surface blemishes or
other structural damages. The lifting lugs are designed to be lifted straight up vertically; the
maximum angle from a vertical lift which is allowed is 30 degrees. All lifting lugs must be used
at to distribute load properly and the equipment must be lifted simultaneously by all the lifting
lugs.
NOTICE!
If using a lift truck, ONLY lift using the perimeter base frame. DO NOT allow forks to lift on
unit casing or unit floor, it can be easily damaged.

16 DT Series - Installation manual (V4_2022)
CAUTION!
DO NOT handle the unit by attaching hooks, jacks, slings, or chains to any component or
parts protruding outside of the unit casing or base frame (except lifting lugs for vertical
lifting only) otherwise it may result in equipment damage, incorrect system operation or
personal injury.
WARNING!
Injury or death can result from incorrect rigging and lifting, these maneuvers must be
performed by qualified crane operator with proper equipment using appropriate and
approved safety precautions.
4.5. MOUNTING
This equipment must be mounted level to the ground to prevent operational issues.
The heater is designed for two types of mounting:
1. Base mounting: The total perimeter base frame structure must be supported level by
high density concrete or adequate steel beam. Refer to the shop drawing for
mounting information.
2. Roof curb mounting: Roof curbs are fabricated of heavy gauge load bearing,
galvanized steel, and must be fully insulated after installation by the installing
contractor. Wood nailed strips are provided for easy attachment of roof flashing. A
gasket material must be field mounted on the curb to seal the joint between the curb
and the unit frame. The curb must be supported along its entire perimeter and any full
height cross members as shown on the shop drawing. Point loading of the roof curbs
is not acceptable.
NOTICE!
Only use the closed cell foam gasket provided for sealing the curb.
WARNING!
This equipment has not been designed for suspended mounting without special mounting
frame. If you intend to suspend this equipment you must provide your own custom base
mounting. DO NOT USE lifting lugs to attach hanger rods. This special installation must
comply with local codes and applicable OSHA standards/requirements.

DT Series - Installation manual (V4_2022) 17
4.6. UNPACKAGING
Prior to installation and before you start operating the equipment, you must remove
packaging and shipping materials; it may include but are not limited to:
•Protective covers over openings, inlets, outlets, etc.
•Tie-down bolts, corner covers, plastic film, tape, and straps.
Always dispose of shipping and packaging materials according to the respective local
regulations in such a way that it may not cause any harm and/or pollution.
Be sure that all shipped-separate accessories for the installation are available. Shipped-
separate accessories could include a roof curb, a supply gas regulator, heated drain line, or
condensate neutralization kit. Be sure that all necessary equipment, tools, and manpower are
available at the installation site.
4.7. ELECTRICAL OR CONTROL SERVICE CONNECTIONS
This equipment is built with unit casing and floors designed to prevent water from
penetrating the building through the installed equipment.
All penetrations through the unit walls must be caulked and sealed to prevent air
and/or water from entering the unit.
NOTICE!
DO NOT install anything that will interfere with equipment access or the rating labels.
THE FLOOR OF THE UNIT HAS BEEN MADE WATER-RESISTANT. DO NOT CUT OR DRILL HOLES
IN THE FLOOR OR USE PENETRATING FASTENERS.
Control voltage is as indicated on the rating label.
Follow the wiring diagram supplied with the equipment.
Field wiring to be done by a qualified electrician is denoted by dotted lines on the wiring
diagram, solid lines indicated factory wiring by the manufacturer.
CAUTION!
Screw terminals may become loose during equipment shipment; they should be retightened
prior to starting and operating unit.
4.8. ELECTRICAL INSTALLATION
The unit must be electrically grounded, and all wiring must be installed by a qualified
electrician in accordance with the National Electrical Code (ANSI/NFPA-70) and/or the

18 DT Series - Installation manual (V4_2022)
Canadian Electric Code (CSA 22.1) and to the approval of the authorities having
jurisdiction.
Field wiring diagrams and internal wiring diagrams are included in the control cabinet.
The power requirements are indicated on the rating label. See the field wiring diagram
for requirements for shielded or twisted pair wire for solid state devices.
NOTICE!
When connecting to a three phases power supply, check for the correct rotation of all motors
and fans. If the rotation is incorrect, reverse the rotation at the incoming power only.
All electrical conduit outlets in the control panel must be sealed to prevent moist building air
from migrating to the control panel.
All penetrations through the unit walls must be caulked and sealed to prevent air and/or water
from entering the unit.
WARNING!
No unspecified and unapproved external load shall be added to the control transformer
circuit(s) or to the main power circuit(s) without the written consent from Nagas Innovation or
the warranty will be void.

DT Series - Installation manual (V4_2022) 19
5.GAS PIPING CONNECTION
For units installed indoor, purge and vent connections must be piped individually towards the
outdoor as stated by CSA B149.1 or other local codes in effect.
GAS CONNECTIONS PIPE SIZES (NPT)
MODEL
GAS CONNECTION
1/2 PSIG (14 in.w.c.)
National pipe thread
55 to 75
1’’ NPT
85 to 175
1-1/2’’ NPT
200 to 350
2’’ NPT
400 to 500
3’’ NPT
Table 3: Gas connection pipe sizes
VENT SIZES (NPT)
MODEL
REGULATOR
PURGE VALVE
(OPTIONNAL)
National pipe thread
National pipe thread
55 to 75
N/A*
3/4’’ NPT
85 to 175
N/A*
3/4’’ NPT
200 to 350
1/2’’ NPT
1’’ NPT)
400 to 500
3/4’’ NPT
1-1/2’’ NPT
Table 4: Vent sizes
NOTES:
1. Table 3 should not be used to size the gas supply line.
2. If gas pressure exceeds 1/2 psig (14 inches w.c.), a high-pressure regulator must be
installed at gas piping inlet.
3. The regulator must be suitable for modulation in a ratio of 20:1, to properly regulate gas
pressure at low fire.
4. The regulator vents and purge (IRI option) must be piped separately towards the
outdoor as stated by CSA B149.1 for Canada and ANSI Z223 for USA and local codes.
5. *Vent limiter factory installed. To be used in ventilated space only. In other case the
regulator vent must be piped to outdoor. Use ½’’ NPT pipe tubing.

20 DT Series - Installation manual (V4_2022)
6.TYPICAL GAS TRAIN
ITEM #
DESCRIPTION
PILOT PIPING
1
Manual shut-off valve
2
Gas pressure regulator
3
Automatic shut-off valve
4
Manual ignition cock
MAIN BURNER PIPING
5
Pressure regulator
6
Automatic safety shut-off valve
7
Automatic safety shut-off valve
8
Manual ignition cock
9
1/8’’ NPT diameter test port
10
Piping union
11
Modulating valve
OPTIONS
12
Low gas pressure switch (required for FM, IRI and pressure more than 1/2 psig)
13
Normally open automatic vent valve (required for IRI)
14
High gas pressure switch (required for FM, IRI and pressure more than 1/2 psig)
7. Table 5: Typical gas train components