Nagas DTH Series User manual

DTH –V9 - 2020
DTH Series
Installation • Outdoor
• Indoor
INSTALLATION AND OPERATION MANUAL
1385, Lionel-Boulet blvd, Varennes,
Quebec, Canada, J3X1P7

1
Installation and operation manual–DTH-V9-2020
This instruction manual should be kept with the unit and be readable.
Warning
FIRE OR EXPLOSION HAZARD
•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.
•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. 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.

2
Installation and operation manual–DTH-V9-2020
Table of contents
Code and regulation .................................................................................................. 3
Specifications............................................................................................................. 4
Gas supply.................................................................................................................. 4
Gas pressure adjustments ......................................................................................... 5
Unit Dimensions ........................................................................................................ 6,7,8
Installation guidelines................................................................................................ 9,10
Electrical control........................................................................................................ 11
Components .............................................................................................................. 11,12,13
Flue vent and combustion air.................................................................................... 14,15,16,17
Start-up instruction ................................................................................................... 18,19
Control sequence....................................................................................................... 20,21,22
Programmable logic controller features & I/O.......................................................... 23,24,25
Display (HMI) features............................................................................................... 26
Run window....................................................................................................... 27
Level 1: Air/Gas relation.................................................................................... 28
Level 1: Alarm history........................................................................................ 29
Level 2: Fan RPM auto tuning........................................................................... 30
Level 2: Signal supervision................................................................................. 31
Level 2: Step timer............................................................................................. 32
PLC alarms.................................................................................................................. 33
Flame safeguard alarms............................................................................................. 34
Flame safeguard troubleshooting ............................................................................. 35
Typical wiring diagram............................................................................................... 36,37
Start / stop recommendations .................................................................................. 38
Unit maintenance ...................................................................................................... 39
Warranty.................................................................................................................... 40
Start-up report........................................................................................................... 41,42
The features, illustrations and description in this document were, to our
knowledge, accurate at the time they were approved for printing. We reserve
the right to change or stop offering some feature as well as stop producing a
given model without prior notice and commitment on our part

3
Installation and operation manual–DTH-V9-2020
Important
This product is intended for installation on positive pressure side of the circulating air blower. This
heating unit is designed for industrial or commercial use only. The installation must comply with the
latest laws and regulation for heating units; CSA B149.1, ANSI Z223.1 / NFPA 54, to the electrical code
C22.1/ NFPA 70 and to local regulations. All inside and outside electrical installation must comply
with the unit’s electrical diagrams.
The electrical, gas and air flow ratings are described on the rating plate applied on the unit. Following
these rating is mandatory for a safe usage of the unit. To learn more, refer to the start-up instruction
and the operating sequence section of this manual.
Clearances to combustible material
A minimum clearance of 1 inch between the unit walls and any combustible material is required on
all side and top. A minimum clearance of 36 inches is required in front of the door to access controls
and 18 inches around the flue vent. Install the unit on a non-combustible floor.
Allocate enough space around the unit for maintenance and around the combustion air intake and
the inlet air hood to prevent harmful accumulation of snow.
Clearances to combustible materials
Position
Inch [mm]
Controls
36 [914]
Top
1 [25]
Back
1 [25]
Flue vent
18 [457]
Floor
Non-combustible
Caution
•Installation, alteration, setting or improper maintenance can cause property damage, injury or
death. Read carefully 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 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.
•When required to pipe to outdoor the regulator vent pipes must be terminated with a
downward elbow and a fine mesh screen in order to prevent blockage.
•The above instructions show the recommended installation and usage that we have tested
and get listed. If the installer decides to not follow these instructions, it will be his
responsibility to test safety, functionalities and make it listed by approval agency.
Code and regulation

4
Installation and operation manual–DTH-V9-2020
Electrical supply: 120VAC / 1ph/60Hz –(from 4 to 15 Amp. Refer to name plate for specific value)
Notes: 1. Intended for a 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 (2500 Btu/ft3for propane) at sea level. Reduce burner
capacity for altitude over 2000ft by 4% for each 1000ft above sea level.
Important
All gas piping must be performed by a qualified personel following the local codes and CSA B149
installation code for Canada or ANSI Z223.1/NFPA 54 for the United States.
*: With 10’’w.c. minimum inlet pressure.
**: With optional 2’’ NPT gas train for 7’’w.c. inlet pressure. The vent must be piped to outdoor.
***: To be used in ventilated space only. In other case the regulator vent must be piped to outdoor. Use ½’’ NPT tubing.
Note:
•This table should not be used to size the gas supply line.
•If supply gas pressure exceeds 14 inches w.c., a high pressure regulator must be installed at gas piping
inlet. The regulator must be suitable for modulation ratio of 40:1 to properly regulate gas pressure at
low fire.
•The regulator vent must be piped separately towards the outside of the building as stated by CSA B149.1
for Canada and ANSI Z223 for USA and local codes.
DTH
Model
Input capacity
Output capacity
Turndown
ratio
Air flow1
MBTU
kW
MBTU
kW
CFM
I/s
Min.
Max.
Min.
Max.
35
438
128
350
102
15:1
2701
6481
1275
3059
40
500
143
400
117
17:1
3086
7407
1457
3496
50
625
183
500
146
21:1
3858
9259
1821
4370
55
688
201
550
161
17:1
4247
10193
2004
4810
65
813
238
650
190
20:1
5019
12054
2368
5684
75
938
275
750
220
23:1
5790
13896
2733
6558
85
1063
311
850
249
27:1
6562
15748
3097
7432
100
1250
366
1000
293
31:1
7716
18519
3642
8740
125
1563
458
1250
366
26:1
9645
23148
4552
10925
150
1875
549
1500
439
31:1
11574
27778
5462
13110
Dim
Gas train connections (NPT)
Model
35
40
50
55
65
75
85
100
125
150*
150**
Ø Gas
1
1
1
1
1
1
1-1/2
1-1/2
1-1/2
1-1/2
2
Ø Regulator Vent***
N/A: Vent limiter factory installed***
1/2
Ø Vent valve
N/A: Valve proving system included with IRI gas train option.
Specifications
Gas supply

5
Installation and operation manual–DTH-V9-2020
DTH
Model
Natural Gas
Dynamic supply
pressure****
Nominal Manifold
pressure*
Pilot
pressure
Low fire inlet capacity
Minimum
In.w.c [kPa]
Maximum
In.w.c [kPa]
At maximum capacity
In.w.c [kPa]
In.w.c [kPa]
MBH
Kw
35
7”
[1.74]
10”
[2.5]
2.3” [0.57]
3.5” [0.87]
30
8.79
40
2.9” [0.72]
50
4.6” [1.15]
55
3.1” [0.77]
40
11.7
65
2.8” [0.69]
75
2.3” [0.57]
85
2.9” [0.72]
100
3.8” [0.95]
125
2.6” [0.65]
60
17.6
150**
3.9” [0.97]
150***
10”[2.5]
14”[3.5]
4.0” [0.99]
*: The pressure adjustment may vary slightly. See the unit name plate for the exact value.
**: With optional 2’’ NPT gas train.
***: With standard 1-1/2’’ NPT gas train.
****: At maximum capacity (dynamic pressure).
DTH
Model
Propane Gas
Dynamic supply
pressure****
Nominal Manifold
pressure*
Pilot
pressure
Low fire inlet capacity
Minimum
In.w.c [kPa]
Maximum
In.w.c [kPa]
At max. capacity
In.w.c [kPa]
In.w.c [kPa]
Minimum
In.w.c [kPa]
Maximum
In.w.c [kPa]
35
11”
[2.74]
14”
[3.5]
(Consult factory
or rating plate)
2.5” [0.62]
30
8.79
40
50
55
40
11.7
65
75
85
100
125
60
17.6
150
Gas pressure adjustments

6
Installation and operation manual–DTH-V9-2020
DTH - Horizontal discharge
• Left hand control (when facing air stream).
Unit dimensions
WARNING
Improper installation, adjustment, alteration can cause serious injury, death or
property damages.
Note: The controls shown are on the left-hand side of the unit (for a right-hand unit, the drawing is mirrored and
dimensions are identical).
A
AI
AIR
A
AI
AIR

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Installation and operation manual–DTH-V9-2020
DTH –Vertical discharge
• Left hand control (when facing air stream).
Note: The controls shown are on the left-hand side of the unit (for a right-hand unit, the drawing is mirrored and
dimensions are identical).
A
AIR
A
AIR
A
AIR

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Installation and operation manual–DTH-V9-2020
Dim
UNIT DIMENSIONS
35
40
50
55
65
75
85
100
125
150
Imperial [in]
A
47
47
47
521/2
521/2
56
58
61
673/4
673/4
B
43
43
43
48 1/4
48 1/4
48 1/4
48 1/4
48 1/4
55
55
C
64 ½
64 ½
64 ½
64 ½
70 ½
70 ½
76
76
78
95 ½
D
6 3/4
6 3/4
6 3/4
6 3/4
6 3/4
6 3/4
6 3/4
6 3/4
6 3/4
6 3/4
L
6
6
6
6
6
8
8
10
10
10
M
21 7/8
21 7/8
21 7/8
24 3/8
24 3/8
24 3/8
24 3/8
24 3/8
28 1/2
28 1/2
N
9
9
9
9
9
10
10
11
11
11
P
13 3/8
12 3/8
10 3/8
11 7/8
11 3/8
9 3/8
9 3/8
9 3/8
11
11
Q
17
19
23
25
26
30
30
30
35
35
R
48 1/2
48 1/2
48 1/2
48 1/2
54 1/2
54 1/2
60
60
60
75 1/2
T
21 1/2
21 1/2
21 1/2
21 1/2
21 1/2
21 1/2
21 1/2
21 1/2
26
26
U
10
11 1/2
14 1/2
16
17
19 1/2
20
23
29
28
V
16 7/8
16 1/8
14 5/8
16 3/8
15 7/8
14 5/8
14 3/8
12 7/8
14
14 1/2
W
29 5/8
29 5/8
29 5/8
35
35
36 3/4
37 3/4
39 1/4
46 1/4
46 1/4
AA
56 1/4
58 1/4
62 1/4
70
71
75
75
75
91 3/4
91 3/4
F
19
21
25
27
28
32
32
32
37
37
E
8 7/8
8 7/8
8 7/8
8 7/8
8 7/8
8 7/8
8 7/8
8 7/8
8 7/8
8 7/8
S
45
45
45
45
51
51
56 1/2
56 1/2
56 1/2
72
NN
18 1/4
20 1/4
24 1/4
26 1/2
27 1/2
29
27
25
35
35
Dim
Metric [mm]
A
1194
1194
1194
1334
1334
1422
1473
1549
1721
1721
B
1092
1092
1092
1226
1226
1226
1226
1226
1397
1397
C
1638
1638
1638
1638
1791
1791
1930
1930
1981
2426
D
171
171
171
171
171
171
171
171
171
171
L
152
152
152
152
152
203
203
254
254
254
M
556
556
556
619
619
619
619
619
724
724
N
229
229
229
229
229
254
254
279
279
279
P
340
314
264
302
289
238
238
238
279
279
Q
432
483
584
635
660
762
762
762
889
889
R
1232
1232
1232
1232
1384
1384
1524
1524
1524
1918
T
546
546
546
546
546
546
546
546
660
660
U
254
292
368
406
432
495
508
584
737
711
V
429
410
371
416
403
371
365
327
356
368
W
752
752
752
889
889
933
959
997
1175
1175
AA
1429
1480
1581
1778
1803
1905
1905
1905
2330
2330
F
483
533
635
686
711
813
813
813
940
940
E
225
225
225
225
225
225
225
225
225
225
S
1143
1143
1143
1143
1295
1295
1435
1435
1435
1829
NN
464
514
616
673
699
737
686
635
889
889

9
Installation and operation manual–DTH-V9-2020
•Install the unit on the positive side of the air-circulating blower (supply side).
•The air intake must be located in order to avoid snow, rain, flammable, toxic gases and other
harmful substances from entering the heater.
•In operation mode, the system design must provide enough air to the heat exchanger to ensure a
temperature rise between 50°F (28°C) and 120°F (67°C) and maintain an average supply
temperature of 130°F (54°C) maximum. Note that the temperature high limit protection is
factory set at 160°F (71°C).
•The inlet ducting must have the same cross-sectional area as the inlet connection. Both inlet and
outlet ducts must have a removable access panel. These panels shall be sized to permit
inspection of the heat exchanger at start-up on routine inspection.
•If fire dampers are used, they must be equipped with switches connected to the safety control
circuit in order to interrupt the heater if there is a fire or high temperature in the ventilation
duct. The electric actuators must be adjusted in order to close the safety loop on the flame
safeguard only when the dampers are fully open.
•Depending on the model, the flue vent connection diameter ranges from 6 to 10 inch. The DTH
models are designed to operate effectively and safely with a positive stack (category III) type
sealed single wall or double wall flue vent listed for this application, whether vertical or
horizontal arrangement or a combination of both. The minimum diameter of all sections must be
identical to the unit’s connection diameter. Refer to the exhaust system sections of this manual.
•If no control cabinet is supplied by Nagas with the unit, the installer must be made one for
component protection and must include aeration openings at least equal of two 2 inches holes.
See gas installations code for more requirements.
IMPORTANT NOTICE
•In order to minimize the risk of freezing pipes inside the building, the installer must equip
the system with a low temperature sensor that will interrupt operation, stop the fan and
close the dampers in the event that low temperature (lower than 40oF) are detected
downstream of the heater.
•In certain conditions these units can produce condensate. This corrosive liquid must be
treated and drain correctly with provision to prevent freezing.
•It is necessary to mechanically attach the unit to the roof base or other support structure
with screws or other suitable fasteners to prevent wind or earthquake damage.
Installation guidelines

10
Installation and operation manual–DTH-V9-2020
Positioning of the sensor controlling the supply temperature
WARNING
The positioning of the supply temperature sensor is essential for the proper operation of the
unit. Improper positioning of the supply temperature sensor could result in high temperatures in
the supply ducts, a thermal protection shutdown, the closing of the fire damper and may result
in damage to the unit and void the warranty. In addition, the control system (PID) must also be
calibrated to prevent temperature overruns.

11
Installation and operation manual–DTH-V9-2020
Warning
All electrical connections must be performed by a qualified electrician in accordance with the
electrical diagram provided with the unit following applicable local laws and regulations. Also refer to
Electrical codes CSA C22.1 for Canada and ANSI/NFPA #70 for the United States. The operating
sequence described by the wiring diagrams or in the PLC should never be changed without the
approval of the manufacturer.
Always use copper wire with the proper size suited for the application.
The unit is already pre-wired at factory. Refer to the wiring diagram for remaining wiring connections:
•Main 120V/60Hz/1ph ac power supply (see wiring diagram for current);
•On/Off contact for heating demand. This heating demand must be wired in series with at
least one of the following but not limited to; a motor contactor auxiliary switch, an air
proving switch or another air flow device.
•2-10 VDC modulation signal.
•Component minimum ambient temperature heating requirement
Warning
Every component requires a minimum ambient temperature during operation. If you don’t order
the Nagas heating and control cabinet solution you must build your own. Also, every component
must be protected from environmental elements and covered because of high voltage hazard.
Minimum operation temperature
Zone A
Zone B
Zone C
0oC (32oF)
-20oC (-4oF)
-40oC (-40oF)
Electrical control
Components

12
Installation and operation manual–DTH-V9-2020
•Component identification
Electrical box
1
HMI touch screen interface
2
Programmable logic controller (PLC)
3
Heating element
4
Input/output expansion module (I/O)
5
Ignition transformer
6
High limit protection (set at 160oF)
7
Flame safeguard module
8
Thermostat for heating element
9
Power supply transformer
10
Control relays
11
Safety pressure switches

13
Installation and operation manual–DTH-V9-2020
Gas train
1
Pilot solenoid valve and gas regulator
2
Pilot manual gas valve
3
Main manual valve (by other outside the unit)
4
Test port inlet pressure
5
Main gas regulator
6
Main gas safety shutoff valve 1
7
Valve proving system (with IRI option)
8
Main gas safety shutoff valve 2
9
Modulating gas valve actuator
10
Modulating gas valve
11
Low fire orifice bypass
12
Test firing gas valve
13
High gas pressure switch (FM and IRI option)
14
Test port manifold pressure
15
Main gas orifice (some models, various sizes)
16
Burner box
17
Air orifice plate (some models, various sizes)
18
Burner air blower
19
Low gas pressure switch (FM and IRI option)

14
Installation and operation manual–DTH-V9-2020
Depending on the model, the flue vent connector diameter ranges from 6 to 10 inches. The DTH
model series is designed to operate effectively and safely (against a positive pressure of 0.25 in.w.c)
with a positive stack (category III) type sealed single wall or double wall flue vent listed for this
application, whether vertical arrangement or horizontal or a combination of both. The minimum
diameter of all sections must be identical to the unit’s connection diameter or greater. Do not
intermix different listed vent system parts from different manufacturers in the same venting
system.
A listed vent cap or termination of the same diameter as the exhaust pipe must be used at the
extremity located at the exterior of the building (see drawings below). See pictures below for
recommended end cap and configurations. The exhaust pipe must end at the exterior of the building
while respecting (at least but not limited to) the following clearances:
Clearances for vent terminals **
Structure
Minimum Vent Terminal Clearances***
Motorised air intake less than 1.8m (6’)
0.9m (3’) above and 1.8m (6’) to the side
Combustion air intake from another device
1.8m (6’) above and 1.8m (6’) to the side
Door, openable window, revolving door or
all other openings
1.8m (6’) to the side
0.9m (3’) above
Electrical or gas meter, regulator and relief
equipment *
1.8m (6’) to the side (Canadian standards)
1.2m (4’) to the side (U.S.A. standards)
Vent outlet from another service
0.9m (3’)
Building or adjacent wall or parapet
1.8m (6’) (might have to be increased for horizontal
discharge)
Sidewalk or parking lot
2.1m (7’) above
Ground vent
0.3m (1’) above snow level
Wall of vent outlet
0.3m (1’) minimum
Roof of vent outlet
0.9m (3’) minimum and 0.6m (2’) above all obstacles
less than 3m (10’)
* Never install a flue vent outlet above a service regulator or a gas meter.
** Local codes always supersede the above provisions.
*** Take all necessary precautions to avoid the installation of vent outlets where snow accumulation
can occur naturally or due to roof snow slides or snow removal dumps. In the case of a
horizontal exhaust, a secure distance of 3m (10’) must be added to the distance found in the
table for horizontal direction, measured from the mechanical or gravity air intakes.
The flue vent must be built using a category III listed vent pipe system sealed corrosion resistant steel
pipe having a minimum thickness of 24 gauge or heavier, in the interior of the building. However, a
double-wall corrosion resistant pipe section is required to get through the external walls of the
building to the vent cap (consult vent pipe supplier instructions). Make sure to have provision for
combustion testing port close to the unit for verifications and adjustments.
Flue vent and combustion air

15
Installation and operation manual–DTH-V9-2020
The flue vent joints must be sealed in a manner that will not allow leakage of the combustion product
into the room. See flue vent manufacturer instructions for more details.
The horizontal conduit sections should be supported every six feet with non-combustible products
such as, chains or steel belts. Do not use the unit or the vertical conduit section as a support.
Flue vent dimensions must respect the unit diameters (minimum) and maximum equivalent lengths
of 100 feet calculated. The equivalent length is calculated by adding the lengths of straight sections
of the flue vent, to the equivalent length of all the elbow pipes used. A 90-degree elbow pipes has an
equivalent length of 3m (10’) and a 45-degree angle elbow pipes has an equivalent length of 1.5m
(5’).
To avoid accumulation of condensation in a horizontal exhaust pipe, a slope of at least 48:1 (1/4’’ per
foot) must be maintained on the entire length of the horizontal sections, headed towards the unit. If
a horizontal section is followed by a vertical section, a T section with drain can be added where the
condensation may accumulate.
To avoid condensation formation while the burner is functioning, it is suggested to isolate the flue
vent on its entire length, if the room temperature is maintained below 10 Celsius (50F). The flue vent
can be insulated using a 1/2 inch (minimum) thick fiberglass insulator, able to withstand
temperatures of 288 Celsius (550F).
In certain conditions these units can produce condensate. This corrosive liquid must be treated and
drain correctly with provision to prevent freezing.
It is very important not to orient the vent outlet towards a fresh air duct, another device’s
combustion air intake, or any other opening of a building. It is possible that the clearances indicated
in table above, from the vent cap, are not suitable because of the horizontal release of the
combustion products. Special attention must be taken to each application. In the case of a horizontal
exhaust, a secure distance of 3m (10’) must be added to the distance found in the table for horizontal
direction, measured from the mechanical or gravity air intakes.
If the combustion flue gas outlet is too close to a building’s opening or to where the direction of
gasses is undesirable, it is possible to add a vertical flue vent extension.
Warning
Two or several units installed in a common or independent ventilation system requires an installation
of a separate, independent exhaust system for each unit. The installation of two units onto one same
exhaust system is forbidden and dangerous. A repression of combustion gas of one of the devices
could migrate towards the second and cause combustion gas exhaust to drift into the room.
A secure and effective operation requires sufficient exhaust of combustion gas. An exhaust system
that is broken or that has a leak is dangerous and can be fatal. This can also prevent proper
functioning of the device and will result in the guarantee being void.

16
Installation and operation manual–DTH-V9-2020
•Recommended roof top Flue Vent Exhaust and/or Combustion Air Duct
•Recommended wall horizontal Flue Vent Exhaust and Combustion Air Duct –Concentric kit

17
Installation and operation manual–DTH-V9-2020
•Recommended wall vertical Flue Vent Exhaust
Important
The flue vent and combustion air duct can have a maximum equivalent length of 100 feet
calculated. The equivalent length is calculated by adding the lengths of straight sections of the flue
vent, to the equivalent length of all the elbow pipes used. A 90-degree elbow pipes has an equivalent
length of 3m (10’) and a 45-degree angle elbow pipes has an equivalent length of 1.5m (5’).
DTH
Model
Unit Flue vent
diameter
Ducting Flue vent
diameter
(minimum)
Combustion Air
intake diameter
(minimum)
Inches
mm
Inches
mm
Inches
mm
35
6
152.4
6
152.4
8
203.2
40
50
55
65
75
8
203.2
8
203.2
10
254
85
100
10
254
10
254
12
304.8
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18
Installation and operation manual–DTH-V9-2020
Important
Start-up can only be performed by a qualified technician qualified to install gas heating
system (with accreditation) with knowledge in electricity and ventilation.
Warning
•Do not smoke during start-up.
•Do not try to light the burner if the gas has accumulated in combustion chamber or in
the area, if the combustion chamber is filled with vapors or if it is very hot.
1.0 Preliminary
These instructions must be followed once the ventilation unit has been started, the fan is running,
and the supply air corresponds to design criteria. All gas piping must leak tested and regulator vents
must be piped (if necessary) adequately before start-up.
-Install a pressure gauge (0-20 in. w. c.) on the inlet pressure test port located upstream of the
low-pressure regulator. See component identification section for location.
-Ensure that the gas inlet pressure complies with the following value:
Standard inlet pressure
Natural Gas
Propane (LP)
Minimum
7in.w.c. (1.74 kPa)
11in.w.c. (2.74 kPa)
Maximum
10in.w.c. (2.49 kPa)
14in.w.c. (3.48 kPa)
*: See gas pressure adjustment section for more details.
-Before starting the burner and without any heating demand perform the Fan RPM auto tuning
in the Level 2 menu of the HMI touch screen.
2.0 Pilot adjustment
-Install a pressure gauge (0-10 in. w. c.) on the test port located on the pilot valve. See
component identification section for location.
-Close the test firing valve and open the pilot manual gas valve.
-Turn ON the main electrical disconnect and create a heat demand.
-Check for pilot lighting sequence then adjust the pilot pressure written in the Specification
section (3.5in.w.c. for natural gas, 2.5in.w.c. for propane).
-Take a reading of the flame signal (4-10VDC) directly on the flame safeguard relay to be sure
the flame signal is good and stable (above 6 VDC minimum).
Start-up instruction
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19
Installation and operation manual–DTH-V9-2020
3.0 Burner adjustment
-Install a pressure gauge (0-10 in. w. c.) on the manifold pressure test port located downstream
of the modulation gas valve. See component identification section for location.
-For the combustion test, it is recommended to use a (2-10VDC) manual potentiometer to
simulate the modulation signal to the burner.
-Start the burner at the minimum voltage of 2.5 VDC and verify the flame stability. Take a
combustion reading before increasing to high fire.
-Run the burner slowly to its maximum capacity (high fire) while looking to the combustion
tester to be sure to have good combustion and sufficient excess air.
-Compare the manifold pressure with the name plate indication. Adjust the gas regulator if
needed to obtain the right value.
-At high fire, you should have a combustion reading of 3-5% O2approx. and a CO reading close
to 0 ppm and never above 400 ppm of air-free CO.
-The targeted oxygen % over the modulation is ±3 to 5% O2at high fire and ±18% O2at low fire
with a progressive curve between the two operation points. Note that the combustion results
when increasing capacity and decreasing are different (less oxygen % when decreasing).
-If the readings are out of the range, use the Air/Gas relation window (level 1 menu) on the HMI
touch screen to adjust (see Air/Gas relation section on page 31).
Warning
Do not only adjust the flame visually. The use of an analyser and/or combustion instruments are the
only appropriate method to adjust the combustion burner.