Gasmaster GMI 2M User manual

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Gasmaster Industries
7480 MacDonald Road
Delta, British Columbia
Canada V4G 1N2
GMI 8M
8,000,000 Btu/hr Input
Gas-Fired Stainless Steel Boilers
INSTALLATION, OPERATION AND
MAINTENANCE MANUAL
Serial Number: XXX.xx
Generic

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List of Contents
Title Page
GMI 8M SPECIFICATIONS AND DIMENSIONS 3
SECTION 1: INTRODUCTIONS
1.1 Boiler Description
1.2 Control System
1.3 Safety Features
1.4 Gas Line
1.5 Gas Manifold and Control Assembly
1.6 Code Compliance
1.7 Freeze Protection
1.8 Water Treatment
5
6
6
7
8
8
9
9
SECTON 2: INSTALLATION
2.1 Boiler Package
2.2 Location
2.3 Relief Valve
2.4 Water Connection
2.5 Condensate Line
2.6 Gas Line Connection
2.7 Vent Connection
2.8 General Instruction
11
12
13
13
13
14
14
17
SECTION 3: OPERATION
3.1 Sequence of Operation
3.1.1 Safety Loop
A: Components
B: Sequence of Events
3.1.2 Pre-Purge
3.1.3 Pilot Flame
3.1.4 Main Flame
3.1.5 Operation
3.2 Pre Commissioning
3.3 Commissioning
3.4 General Instruction
20
20
20
21
21
21
22
22
23
25
26
SECTION 4: MAINTENANCE
4.1 Service Hint
Troubleshooting
29
30
ATTACHMENTS:
1- Wiring diagram
2- Start-up report
33
33

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GMI 8M SPECIFICATIONS AND DIMENSIONS
Input
Output
Boiler Efficiency @ full load
Btu/h
Btu/hr
%
8,000,000
7,600,000
95.0
Fuel Natural Gas
Electrical Rating V/PH/Hz/
A
208-230/460/575/3/60, less than 12 amps
Heating surface Ft21039.0
Boiler Shell Dimensions
-Width
-Depth
-Height
Overall Dimensions
-Width
-Depth
-Height
Inches
Inches
Inches
Inches
Inches
Inches
68.125 ±¼
56 ±¼
68.5 ±¼
68.125 ±¼
102 ½ ±¼
89.5 ±¼
Shipping Weight1Lbs 5200
Supply/Return
Connections
Water content
Inches
USG
4 - Stainless Steel Flange, ANSI 150 lbs
165.0
Gas connection Inches 2.5 NPTF
Gas inlet pressure Inches WC 28 to 56
Flue connection Inches 24 O.D.
Flue duct material Stainless Steel (air tight, corrosion resistant)
Air supply connection Inches N/A
Maximum working pressure psig 160
Maximum working temperature Degrees F 210
Minimum inlet water temperature Any temperature above (32ºF)
Recommended flow rate2USG/min 152 ( For ∆T= 100F)
Minimum service clearance Inches Top 24, Front 363, Back 24, Floor 0
Minimum clearances to combustibles Inches Top 40, Front 40, Back 24, Left Side 24,
Right Side 24, Floor non-combustible
1. Dry weight of unit
2. Above flow rate is for typical boiler condition. For each case, please consult engineering.
3. Clearance from front of the burner.

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SECTION 1:
INTRODUCTION

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1.1 Boiler Description
The Gasmaster GMI 8M series is a gas-fired water-tube boiler with nominal input rating of
8,000,000 Btu/hr. The heat exchanger has 24 vertical coils that are held parallel by clamps. The
clamps are connected by three sets of SS spacers/ready rods and adjustment nuts. The coils are
constructed of ASME SA-249 Grade 316/316L stainless steel tubes of 0.065” wall thickness.
There are two horizontal flanged inlets on the front side of the boiler. The outlet is vertical, on top
and at the rear of the boiler. The inlets of the coils are welded to the stainless steel inlet manifold
pipes. The outlets of the coils are welded to the tube sheet assembly. The outlet manifold assembly
is bolted onto the tube sheet assembly. The manifold connections are all 4” Stainless Steel flanges.
The standard safety devices, such as pressure relief valve and LWCO are all on the outlet
manifold.
The space in the central part of the coils defines the combustion chamber of the boiler where
natural gas is ignited with air to form hot gas. The volume outside the coils and within the boiler
liner is the boiler chamber. The chamber is sufficiently big to establish a stable flu gas condition
outside the heat exchanger. The inner liner and the outer casing are typically all corrosion resistant
stainless steel sheets. In between the liners there is a two-inch thick mineral insulation, to provide
optimal thermal and sound insulation. A catch tray is secured to the base of the housing for
collection of the condensate. The condensate exits the housing through an outlet at the bottom
right of the boiler.
The heat exchanger operates in a simple fashion. Gas burner ignites natural gas and air in the
central part of the heat exchanger. The hot gasses cool as they pass through the gaps of the coils.
Combustion products exit the housing through a 24” diameter exhaust outlet on the top panel.
Meanwhile, the water flows through the inlet manifolds and is divided into each coil. Water enters
each coil from the perimeter of the heat exchanger and exits at the center (near the burner). The
water from the coils is then collected and mixed in a dish end cap to achieve a uniform water
temperature before it exits out of the boiler. The water flows in the opposite direction of the
combustion, thus allowing for a gradual pick up of heat as it circulates through the coil. Finally,
heat is transferred through a “counter flow” process. This design reduces the chances and impact
of thermal shock and increases the life of the heat exchanger.
The exact mechanism of heat exchange is a complicated engineering phenomenon, involving
combination of flow, temperature, fouling factors, and two-phase conditions. The boiler is
designed for flue gas condensation for the high energy extraction. Flue condensation will occur if
the temperature of the inlet water is below dew point, usually 120 degrees Fahrenheit. Because the
flue condensate is corrosive, the internal structure of the boiler is constructed out of stainless steel
304/316L or better to offer the highest service life. Corrosion related failures are the typical
problems which can be managed through a scheduled progressive inspection and maintenance
program. Lastly the condensate and the flue venting should be safely processed to the environment
according to local jurisdiction and building codes.

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1.2 Control System
The boiler control module consists of an “Individual Boiler Control Module”, or the “BMS”
(Boiler Management System) signal input module as an option.
With the “Individual Boiler Control Module”, the unit’s operation is governed by the desired
outlet (hot water) temperature. Using a digital, high precision temperature controller, the owner
will identify the required hot water temperature. A temperature sensor installed on the boiler
outlet manifold continuously measures the outlet water temperature.
A servomotor controlling the gas butterfly valve and the air damper (by means of a variable profile
cam mechanism) allows for throttling of the air/gas mixture flowing into the burner. For as long as
the set temperature is above that of the outlet water, the boiler operates at maximum output
capacity. An output signal from the temperature controller, throttles the flow of gas and
combustion air in the gas butterfly valve and the air damper. Therefore, the appropriate volume of
air/gas mixture flows into the burner, allowing for almost perfect air/gas mass, and volume ratios.
As the outlet temperature approaches the set temperature, the air/gas mixture flow is gradually
reduced by the servomotor (connected to the gas butterfly valve and the air damper). This results
in the corresponding gradual decrease in the unit’s capacity. Thus the throttle system allows for
optimum continuous operation of the boiler, significantly reducing on/off cycles. The said system
offers the user almost infinite modulating capacity within the boiler operating range.
1.3 Safety Features
Each Gasmaster GMI 8M boiler is equipped with a number of safety features.
I: Low Water Cut Off Switch: One “McDonnell & Miller” low water cut off switch
is installed on the outlet manifold. When the water reaches the LWCO position, the
burner should fire.
II: Flame Sensor: A flame probe is used as a flame proving sensor. This is connected
to the burner controller, and is installed inside the burner head. At any time after
the main gas valve is opened, if flame is not detected for a period longer than 4
seconds, the burner controller will be deactivated and the main gas valve will
immediately close.
III: High Temperature Limit: Each unit is equipped with a “Honeywell” high
temperature limit switch. If outlet water temperature exceeds the temperature set
on this switch, the burner controller will be deactivated and the gas valve will
immediately close.
IV: Air Pressure Switches: One low air pressure switch is installed on the side of the
burner/blower and measures air pressure entering the burner (for exact location of
the switch please see item #15 on the drawing presented on page 4 of the Riello
catalogue). If the combustion air pressure drops by more than 20% below the
nominal air pressure (minimum pressure of 0.4” wc), the burner controller will be
deactivated and the main gas valve will immediately close.

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V: Relief Valve: A “Conbraco” safety relief valve with prescribed nominal pipe size
of 1 1/2”valve inlet/outlet, and discharge capacity of 11,871,000 Btu/hr and 150
psig relief pressure, is installed on the water outlet manifold and supplied as
standard equipment. When the boiler is used in heating applications having working
pressures in the range 40–160 psig, an appropriate pressure relief valve should be
installed.
VI: Gas Pressure Switches: One manual reset low gas pressure switch is installed on
the gas train in between the gas pressure regulator and the first safety shut off valve
(please see the schematic diagram “Typical UL Schematic Gas Piping” on page 9 of
the Riello catalogue). If the line pressure drops below 0.5”wc, the switch will open
and the unit will immediately shut down. One high gas pressure switch is also
installed on the side of the Riello burner (for exact location please see item #4 on
the drawing presented on page 4 of the Riello catalogue). If the gas manifold
pressure increases above 20” wc, the switch will open and the unit will immediately
shut down.
1.4 Gas Lines
1.4.1 Pilot Gas Line
Referring to the “Typical UL Schematic Gas Piping” diagram on page 9 of the Riello catalogue,
gas from the main supply line flows at the pressure range of 1- 5 psi through the manual valve into
the pilot line and main line. The gas in pilot line will flow through the regulator and the safety shut
off valve into the burner. The pressure regulator is adjusted such that gas flows within 2”–5” wc
pressure into the safety shut off valve. If pilot flame is not established within 5 seconds of the
ignition time, the flame safeguard will shut off the pilot safety gas valves and burner locks out
(Riello catalogue, page 16).
The pilot flame will ignite the air/gas mixture flowing through the burner within 5 seconds of the
mixture flowing into the burner otherwise it locks out (Riello catalogue, page 16).
1.4.2 Main Gas Line
Referring to the same drawing, main supply line gas flows (at a pressure of 1-5 psig) through the
manual gas valve into the main gas line. The gas flowing into the main gas line flows through the
two safety shut off valves and the pressure regulator. Finally gas flows through the gas adjustment
butterfly valve into the burner where it is ignited by the pilot flame. The pressure regulator is
adjusted such that the manifold gas pressure remains within 1.6”–12” wc. This pressure is tested
at the manifold gas pressure test point located on the top of the Riello burner (for exact location of
the test point please see item #17 on the drawing presented on page 4 of Riello catalogue). Signals
from the temperature controller are sent to the servomotor, which controls the opening of the
butterfly valve and the air damper. Subsequently, the valve and damper are proportionately closed
or opened in order to decrease or increase the air/gas mixture flow into the burner. Hence,
maintaining the outlet water at constant temperature, during changes in the load/demand (i.e.
throttle or load tracking function).

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1.5 Gas Manifold and Control Assembly Tests
Safe operation and all performance criteria of all Gasmaster products, incorporating the installed
gas manifold and control assembly, are proven before delivery when the products are factory
tested in accordance with the latest revision of CSA CAN 1-3.1-77 and UL 795 standards.
1.6 Code Compliance
In Canada, boiler installation must conform to the requirements identified in the CSA B149.1 for
gas burning appliances, CSA Codes B51 for boiler, pressure vessel, and pressure piping, and/or all
applicable local codes. All electrical connections are to be made in accordance with the
requirements of CSA C22.2, No. 3 electrical features of fuel burning equipment and No.0 general
requirements- Canadian Electrical Code, Part 1 and /or all applicable local codes.
In the United States of America, the installation must conform to the requirements of the authority
having jurisdiction or, in the absence of such requirements, to the National Fuel Gas Code, ANSI
Z223.1-latest edition. All electrical wiring must be carried out in accordance with the National
Electrical Code ANSI/NFPA No.70-latest edition and The Canadian Electrical Code, and any
WARNING
Exceeding the maximum allowable gas manifold pressure could result in
over-firing of the unit and may cause permanent damage to the unit.
NOTES
¾Air and gas flow rates are factory adjusted for optimum combustion
quality. Note that these settings may vary slightly at different site
conditions (calorific value of gas, duct length, etc.).
¾After installation is completed, using a gas analyzer, the CO and O2
contents of the exhaust gases should be re-checked to ensure their
compliance with those achieved at the factory and reflected in the test
report provided to your local Gasmaster representative.
¾IF adjustments to the factory settings of air and gas flows are made,
ensure that the manifold gas pressure does not exceed the 12” wc
specified on boiler label.

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additional state or local code requirements. If an external power source is used, the unit must be
electrically grounded in accordance with the requirements of the authority having jurisdiction. In
the absence of such authority, the boiler must be electrically grounded in accordance with the
National Electrical Code ANSI/NFPA No. 70-latest edition and The Canadian Electrical Code.
The plumbing and condensate disposal must be carried out in accordance with the local plumbing
codes.
1.7 Freeze Protection
¾When used in an open or closed loop configuration, whenever necessary, the boiler
must be isolated before draining. Due to the radial geometry of the unit, it must be
drained by forced air only.
¾When used in a closed loop configuration, if absolutely necessary, system
antifreeze can be utilized, in which case the boiler or does not need to be drained.
The antifreeze must be compatible with hydronic heating systems.
1.8 Water Treatment
All heat exchanger coils are constructed from high grade stainless steel. Therefore, high oxygen
content in the feed water should not result in any corrosion inside the coils. Since water flow
through coils is in turbulent mode, and they are continuously expanding and contracting; the
operation of the unit is to a large extent self cleaning. Therefore, other potential minerals that may
exist in water should not have any adverse effect (on the tubes). However, if it is wished to supply
soft water to the boiler or, then a sodium-based ion-exchanger may be used. Note that generally
“soft water” is defined as one having less than 1.2°British, or 17°US hardness level. Consult a
local water treatment consultant to determine if boiler water treatment is required. Water
treatment is highly recommended because it will increase the life of the boiler.
NOTES
¾Boiler can be used in both closed loop and open loop (one pass)
operations.
¾In the commonwealth of Massachusetts the installation shall be
carried out by a licensed gas fitter/plumber and comply with
48CMR

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SECTION 2:
INSTALLATION

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2.1 Boiler Package
Each unit is supplied with:
1. Riello burner/blower.
2. Inlet and outlet manifolds.
3. All safety features as described in Section 1.3
4. Fully assembled gas train.
5. One temperature sensor installed on the outlet manifold.
6. Flame sensor (inside burner)
7. Condensate drain connection. (On boiler)
8. Flue gas connection. (On boiler)
9. Pressure gauge. (On outlet manifold)
10. One vent valve installed on the outlet manifold.
Please contact Gasmaster Industries if items listed above are missing. Please be familiar with
major parts of the boiler before operating. Always exercise caution when transporting.
Instructions provided are only general guides, and are not substitute for common sense and sound
safe practices.

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2.2 Location
I: This boiler is for indoor installation only.
II: For service access to the Riello control box, condensate drain “U” trap, and gas
train, refer to the clearances indicated on the boiler rating plate. Note that some
jurisdictions may have their own clearance requirements. In such cases refer to all
applicable local codes.
III: The boiler can be placed in a basement or utility room. It should not be placed in
an unconditioned area where the unit and condensation could be subject to freezing
temperatures.
IV: For reduced installation cost, locate the boiler as close to an outside wall as
possible.
V: Flue gases must be vented in accordance with the local codes and in absence of
local codes with the CSA B149.1 or ANSI Z223.1.
VI: Keep boiler area clear and free from combustible materials, gasoline, flammable
vapors and liquids.
VII: Ensure that inlet to the blower is kept clear of any obstruction so that combustion
air can flow freely through to the air intake blower.
VIII: A resilient pad to separate the boiler from floor IS NOT REQUIRED.
IX: Refer to burner manufacturer manual for Air requirement into the burner. Provide
2000 CFM or the air recommended by burner manufacturer whichever is greater.
The boiler installer must provide the proper size or dimensions of minimum air
opening into room based on the location of installation, altitude and in accordance
with the local codes and in absence of local codes with the CSA B149.1 or ANSI
Z223.1.
XI: Transportation
Lift only from the bottom welded frame. Never lift from the manifold
Avoid lifting from bottom, condensate drain and the gas line.
Burner should be supported during moving.
Center of the mass of the boiler is about 28” from the front edge of the panel.
Lift the boiler straight up and install moving pads. Do not tilt the boiler more than 5
degree.

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2.3 Relief Valve
A pressure relief valve is supplied as standard equipment. The relief valve is a mandatory
protection against damage that could be caused by excessive water pressure. Mal-functioning of
the boiler controls can build up heat and excessive pressure to destroy the boiler.
The pressure relief valve should be connected to a suitable water drain. The drain pipe MUST
pitch down from the valve and its internal diameter should not be less than that of the relief valve.
The end of the drain line should not cause any restriction to the water flow, and should be
protected from freezing. There should not be any valve installed between the pressure relief valve
and the end of the drain line. Similarly, there should not be any instrument installed anywhere
along the length of the drain valve, between the relief valve and the end of the drain line. The relief
valve is installed in vertical position and should remain in that position at all times.
2.4 Water Connection
All pre-installation work has been completed at the factory. Three water manifolds (two inlet and
one outlet headers) are provided with the unit. One low water cut off switch is installed on the
outlet manifold. One high temperature limit switch and one pressure relief valve are installed on
the outlet manifold. A temperature sensor installed on the outlet manifold is connected to the
appropriate terminals in the electrical control panel.
Cold-water inlets and hot water outlet connections are clearly marked on the respective manifolds
of the boiler. The cold water supply line (in one pass applications), or return water (in closed loop
applications) should be connected to the cold water inlet of the unit. The hot water supply line
should be connected to the hot water outlet of the boiler. Both manifolds have 4” stainless steel
flange, ANSI B16.5#150 lbs inlet/outlet connections. Use minimum Grade 5 bolts (5/8-unc),
carbon steel and applicable lock washer and nuts. Torque the bolts and check the torque rating.
Ensure a water tight gasket, if used, is not destroyed by the applied torque.
Insulate the outlet manifold with applicable insulation to reduce heat loss is highly recommended.
For further information on methods of connecting supply and return water piping to boilers consult
available installation and piping guides developed according to local plumbing codes.
2.5 Condensate Line
Connect 3/4” ABS tubing from the condensate drain “U” trap, directly to the floor drain. Notice
that the line MUST be pitched downward towards the floor drain to avoid traps. DO NOT install
any valve of any type, or any other instrument between the condensate drain “U” trap and the end
of the condensate line. If the condensate is properly drain or is trapped inside the boiler, the boiler
will not operate properly.

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2.6 Gas Line Connections
The gas train comprises of a low gas pressure switch, solenoid valves, pressure regulator, and the
main gas valve. Gas pressure at the inlet to the gas line should be 1-2 psi. If higher pressures are
present, consult the local gas company or gas installation codes for installing the appropriate gas
pressure regulator. Gas line from the meter to the boiler should be of adequate size to prevent
undue pressure drop. A manual shut off valve should be installed in the gas line upstream of the
solenoid valves and pressure regulator, so that the control instruments (solenoid valves, regulator,
and low gas pressure switch) can be easily isolated and removed, whenever necessary. The valve
should be clearly marked, located outside the unit’s housing, readily visible and accessible for
turning on and off. The valves need to be certified for gas application.
2.7 Vent Connection
Connect a 24” OD vent to the exhaust gas outlet on the boiler top panel. Venting installation
should be in compliance with the requirements of the authority having jurisdiction. In the absence
of an authority the venting must comply with CSA B149.1 or ANSI Z223.1.
NOTE
¾Inlet gas pressure upstream of the unit(Gas train ) must be1-2 psi
NOTE
¾To ensure proper flow of condensate, it is recommended to install a
“drain vent” of approximately 1 foot height at 0.5-1 foot downstream of
the U trap.
NOTE
¾Install a trap at the inlet of the gas connection of the unit.

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Equivalent Lengths
90 deg. Elbow 3’
45 deg. Elbow 2’
Condensate Tee 2’
Vent Cap 3’
2.7.1
Periodically inspect the vent duct for pin holes or cracks. Maintaining gas tight seal is very
necessary and important. Please apply appropriate condensate sealant (Mill-Pac) on these
openings.
When an existing boiler is removed from a common venting system, the common venting
system is likely to be too large for proper venting of the appliances remaining connected to it.
Therefore:
At the time of removal of an existing boiler , the following steps should be followed with each
appliance remaining connected to the common venting system placed in operation, while the
other appliances remaining connected to the common venting system are not in operation
NOTES
¾The exhaust venting system must meet the requirements of boilers with
corrosion resistant, water and air-tight venting system.
¾The exhaust duct outlet to the atmosphere MUST be wind protected by
an approved wind cap.
NOTES
¾This product must be vented in accordance with the local codes and in
absence of local codes with the CSA B149.1 or ANSI Z223.1

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I: Seal any unused openings in the common venting system.
II: Visually inspect the venting system for proper size and horizontal pitch and
determine there are no blockages, restrictions, leakage, corrosion or other
deficiencies, which could cause an unsafe connection.
III: Any improper operation of the common venting system should be corrected, so the
installation conforms to the National Fuel Gas Code, ANSI Z223.1 or the CSA
B149.1. When resizing any portion of the common venting system, the common
venting system should be resized to approach the minimum size as determined
using the appropriate tables in Appendix G in the National Fuel Gas Code, ANSI
Z223.1 or the CSA B149.1.
IV: To insulate the single wall duct against condensate corrosion, add about 1” mineral
wool insulation or equivalent all around. The insulation will also assist exhaust gas
draft.
2.7.2
For connection to gas vents or chimneys, vent installations should be in accordance with Part
7, Venting of Equipment, of the National Fuel Gas Code, ANSI Z223.1 or the CSA B149.1, or
applicable provisions of the local building codes.
Vent connectors serving appliances vented by natural draft should not be connected into any
portion of mechanical draft systems operating under positive pressure.
The horizontal portions of the venting system should be supported to prevent sagging. The
methods of and intervals for support should be in accordance with the local code standards.
Furthermore, the following installation requirements should also be satisfied:
I: Horizontal runs should slope upwards not less than 1/4” per foot (21 mm/m) from
the boiler to the vent terminal.
II: The vent system should be installed to prevent accumulation of condensate.
III: Where necessary, the vent system must provide the means for drainage of
condensate.
2.7.3
Vent termination should be in accordance with all applicable local codes. In addition, the
following conditions must be satisfied:
I: Distances from adjacent public walkways, buildings, windows and building
openings, should be consistent with the National Fuel Gas Code, ANSI Z223.1 or
the CSA B149.1.

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II: Minimum clearance of 4 feet (1.22 m) horizontally and in no case above or below,
unless a 4-foot (1.22 m) horizontal distance is maintained from electric meters, gas
meters, regulators and relief equipment.
2.7.4
It is recommended to install prefabricated factory-made vent parts each designed to be
assembled with the other without requiring field fabrication.
MANUFACTURER VENT PART MODEL MATERIAL
Heat-Fab Inc. Saf-T Vent system Stainless Steel
2.8 General Instructions
2.8.1
The boiler and its individual shutoff valve must be disconnected from the gas supply piping
system during any pressure testing of that system, at test pressures in excess of 5 psig. The
unit must be isolated from the gas supply piping system by closing its individual manual
shutoff valve, during any pressure testing of the gas supply piping system at test pressures
equal or less that 5 psig.
2.8.2
The boiler should be installed such that the gas ignition system components are protected from
water (dripping, spraying, rain, etc.) during appliance operation or service.
2.8.3
The boiler and its gas connection must be leak tested, before placing the boiler in operation.
2.8.4
The boiler when installed must be electrically grounded and bonded in accordance with the
local codes or in the absence of such codes, in accordance with the National Electrical Code,
ANSI/NFPA 70 and the Canadian Electrical code.

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2.8.5
The boiler should be located in an area where leakage of the tank, or connections, will not
result in damage to the area adjacent to the appliance or to the structure. When such locations
cannot be avoided, it is recommended that a suitable drain pan, that drains adequately be
installed under the boiler. The pan must not restrict air- flow.
2.8.6
The boiler is a fairly complex and expensive equipment. The instructions provided require a
lot of common sense but require a great deal of care. The people handling the unit should be
experienced with proper training. Please understand the complete unit and its parts before
operating.

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SECTION 3:
OPERATION

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3.1 Sequence of Operation
3.1.1 Safety Loop
A: Components
Referring to Control System Schematic, the safety loop includes the following components:
I: High temperature cut off switch: This is a manually reset switch and is normally
closed. It is installed on the outlet manifold. The desired high limit temperature is
set by the owner and is usually 10 °F above the maximum operating temperature.
In no event should this switch be set at above 210 °F (it is fixed in the factory). If
the outlet temperature increases above the set temperature, this switch will open and
the unit will go into the “lock-out” mode. The unit will remain in this mode until
the operator manually resets the switch.
II: Operating temperature switch: This switch normally closes when the actual value
is less then the set point and is embedded in the temperature controller unit. The
desired outlet temperature (desired set point) is set by the owner on the same
temperature controller.
III: Low water cut off switch: This switch is installed at the end of the manifold. The
switch is normally open, and as soon as water level in the system reaches the point
where the switch is installed, it will close.
IV: Remote Enable/Disable Terminals: There are “Remote Enable/Disable” terminals
in the control panel. These terminals can be used for the BMS connections, if
required.
V: High and Low gas pressure switches: A manual reset low gas pressure switch is
installed on the gas train before the first safety shut off valve (please see item #4 on
the schematic diagram “Typical UL Schematic Gas Piping” on page 9 of the Riello
catalogue). If the line pressure drops below 0.5 psi, the switch will open and the
unit will immediately shut down. One high gas pressure switch is also installed on
the side of the Riello burner (for exact location please see item #4 on the drawing
presented on page 4 of the Riello catalogue). If the gas manifold pressure increases
above 20” wc, the switch will open and the unit will immediately shut down.
VI: Air Pressure Switches: One low air pressure switch is installed on the side of the
blower (on Riello burner) and measures air pressure entering the burner (for exact
location of the switch please see item #15 on the drawing presented on page 4 of the
Riello catalogue). If the combustion air pressure drops by more than 20% below
the nominal air pressure, the burner controller will be deactivated and the main gas
valve will immediately close.