Super Hot MG series Manual

PN1480657
MG SERIES BOILERS
INSTALLATION AND SERVICE MANUAL
FOR MODELS MG-50-E TO MG-150-E
SEE REAR COVER FOR INDEX
Manufactured by
Allied Engineering Company
Division of E-Z-Rect Manufacturing Ltd.
Manufacturers of Gas and Electric Boilers, Stainless Steel Tanks, Heat Exchangers and Electric Boosters.
94 Riverside Drive, North Vancouver, B.C. V7H 2M6 Telephone [phone] www.alliedboilers.com
Branches: Calgary Edmonton Toronto Denver
Improper installation, adjustment, alteration, service or maintenance can cause property
damage, injury, or loss of life.Please carefully read this manual. For assistance or
additional information, consult a qualified installer, service agency or the gas supplier.
WARNING
H

2
DIMENSIONS AND SPECIFICATIONS
MG SERIES BOILERS
* For altitudes above 2,000 feet, refer to Section 3.6 to determine the appropriate Input de-rate or contact the factory.
** Based on piping and pickup allowance of 1.15
The Super Hot product improvement program may result in changes to the design and / or specifications being made without notice.
Standard Model Includes:
Natural Gas "N" or Propane "P"
Integrated Boiler Controller with
Electronic Ignition "E"
Zone Control Board with Transformer
Stainless Steel Burners
Combination Gas Valve
High-Limit Sensor
Temperature / Pressure Gauge
A.S.M.E. Pressure Relief Valve
Drain Valve
Draft Hood
Blocked Vent Safety Switch
Flame Roll-out Safety Switch
Automatic Vent Damper
“PS” Packaged Models Include
Standard Model Parts plus:
Circulating Pump
Custom Cast Iron Pump Adapter
Expansion Tank
Air Purger
Combination Fill / Regulator Valve
Automatic Air Vent
†Add 35lb. (16kg) to shipping weight
MODEL
NUMBER
INPUT*
HEATING
CAPACITY*
NET AHRI
RATING**
AFUE
DIM A
DIM B
DIM C
DIM D
DIM E
SHIPPING
WEIGHT†
MBH
MBH
MBH
%
In.
in.
in.
in.
in.
lb.
MG50
50
43
37
85.0
11.5
6.25
4.0
39.5
4.5
125
MG75
75
64
56
85.0
14.5
6.25
5.0
39.5
4.5
150
MG100
100
85
74
85.0
17.5
6.25
5.0
39.5
4.5
175
MG125
125
107
93
85.0
20.5
9.50
6.0
43.5
4.5
200
MG150
150
128
111
85.0
23.5
9.50
6.0
43.5
4.5
225
MODEL
NUMBER
INPUT*
HEATING
CAPACITY*
NET AHRI
RATING**
AFUE
DIM A
DIM B
DIM C
DIM D
DIM E
SHIPPING
WEIGHT†
kW
kW
kW
%
cm
cm
cm
cm
cm
kg
MG50
14.7
12.6
10.8
85.0
29.2
15.9
10.2
100.3
11.4
57
MG75
22.0
18.8
16.4
85.0
36.8
15.9
12.7
100.3
11.4
68
MG100
29.3
24.9
21.7
85.0
44.5
15.9
12.7
100.3
11.4
80
MG125
36.6
31.4
27.3
85.0
52.1
24.1
15.2
110.5
11.4
91
MG150
44.0
37.5
32.5
85.0
59.7
24.1
15.2
110.5
11.4
102
Allow 18” (457 mm) minimum in front for servicing.
Minimum clearances to combustible material: Top 24” (610 mm), Sides 2” (51 mm), Rear 2” (51 mm), Flue 6" (153 mm)
Approved for installation on combustible floors & closet installation

MG Series Boilers –Installation and Service Manual
3
Boiler Water Flow Data
NOTE: The boiler should be properly sized for its heating application and maintain an adequate water
flow rate during operation. Significantly oversizing the boiler or decreasing boiler water flow
rate will cause excessive stage cycling and may result in premature failure of components.
Water Flow versus Pressure Drop Across Boiler
Model
Number
20F Temperature Drop
30F Temperature Drop
Flowrate
(U.S. GPM)
Pressure Drop
(FT.)
Flowrate
(U.S. GPM)
Pressure Drop
(FT.)
MG-50
4.0
1.1
3.0
1.0
MG-75
6.0
2.2
4.0
1.1
MG-100
8.0
3.5
6.0
2.2
MG-125
10.0
5.2
7.0
2.8
MG-150
12.0
8.0
8.0
3.5

MG Series Boilers –Installation and Service Manual
4
ABOUT OUR MANUALS
Your Super Hot boiler has been provided with two manuals:
User's Information Manual - This manual is intended for the owner or user of the boiler and provides
information on routine operation and maintenance, and emergency shutdown.
Installation and Service Manual - This manual must only be used by a qualified heating installer,
service technician or gas supplier. Installation or service by anyone unqualified to do so may result
in severe personal injury, death or substantial property damage.
Both manuals should be kept in the envelope provided and affixed adjacent to the boiler so that they are
readily available for future reference.
Lighting Instructions Section 1
1.1 SAFETY INSTRUCTIONS
WARNING
If you do not follow these instructions exactly, a fire or explosion may result causing property
damage, personal injury or loss of life.
A. BEFORE LIGHTING smell all around the
boiler area for gas. Be sure to smell next to
the floor because some gas is heavier than
air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
Do not try to light any appliance.
Do not touch any electrical switch; do not
use any phone in your building.
Immediately call your gas supplier from a
neighbor's phone. Follow the gas
supplier's instructions.
If you cannot reach your gas supplier, call
the fire department.
B. Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will
not push in or turn by hand, don't try to repair
it, call a qualified service technician. Force or
attempted repair may result in a fire or
explosion.
C. Do not use this boiler if any part has been
under water. Immediately call a qualified
service technician to inspect the appliance and
to replace any part of the control system and
any gas control which has been under water.

MG Series Boilers –Installation and Service Manual
5
1.2 LIGHTING INSTRUCTIONS FOR INTERMITTENT ELECTRONIC WITH
COMBINATION GAS VALVE
1. This boiler is equipped with an ignition device
which automatically lights the pilot. Do not try
to light the pilot by hand. Ensure gas supply to
the boiler is turned on.
2. STOP! Read the safety instructions in
Section 1.1.
3. Set the room thermostat to lowest setting.
4. Turn off all electrical power to the appliance.
5. Remove control access panel if necessary.
6. Push in gas control knob slightly and turn
clockwise to "OFF".
NOTE: On some gas valves the knob cannot be
turned to "OFF" or “ON” position unless knob
is pushed in slightly. Do not force.
7. Wait five (5) minutes to clear out any gas.
Then smell for gas, including near the floor. If
you smell gas, STOP! Follow "A" in the safety
instructions in Section 1.1. If you don't smell
gas, go to the next step.
8. Turn gas control knob counterclockwise
to "ON".
9. Replace control access panel if necessary.
10. Turn on all electrical power to the Boiler.
11. Set room thermostat to desired setting.
12. If the appliance will not operate, follow the
instructions "To Turn Off Gas To Boiler" in
Section 1.5 and call your service technician or
gas supplier.
To turn off gas to boiler or emergency shut-off
Follow Section 1.3.
1.3 TO TURN OFF GAS TO THE BOILER OR EMERGENCY SHUT-OFF
WARNING
Should boiler overheat, or the gas supply fail to shut off, do not turn off or disconnect the
electrical supply to the circulating pump. Instead, shut off the gas supply at a location external
to the boiler.
1. Set the thermostat to the lowest setting.
2. Turn all electrical power to the boiler off.
3. Remove control access panel on the boiler if necessary.
4. Push in gas control knob slightly and turn clockwise to "OFF". Do not force it.
5. Replace control access panel if necessary.

MG Series Boilers –Installation and Service Manual
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Text
Description
Display
STA
Status (see status numbers)

BT
Boiler temperature

SP
Operating setpoint

HL
High limit setpoint

HDF
Differential set-point

FLA
Flame current

RUN
Run time hours

CYC
Boiler cycles

ERR
Error (see error numbers)

Table 1 Run Mode Parameters
1.4 CONTROLLER PROGRAMMING AND SERVICE CODES
2012 NRCan and DOE Compliance and Operation
Operation of this control may delay the burner operation while the residual heat is circulated out
of the boiler.
The integrated boiler control module provides ignition
sequence, flame monitoring and safety shutoff for intermittent
pilot spark ignition. It also provides limit rated water
temperature control for with two separate sensors in one
casing (3-wire).
The control is located on the front panel inside the boiler.
The control display, along with Up ▲, Down ▼, and “I” keys
may be used to view boiler operating status and program
parameters (Figure 1).
1.4.1 RUN MODE
In the RUN mode, status items and parameters are viewable.
To read settings, press and release the “I” key to find the parameter of interest. Each setting will
alternately flash between the relevant display code listed in the Table 1 and its corresponding value. For
example, press and release “I” key until “”setpoint is displayed, it will then flash a three-digit number,
i.e., 220, followed by ˚F (or ˚C). This indicates that the boiler water temperature of 220 ˚F is set. Other
operating parameters display the settings in a similar fashion.
Figure 1 Control Display

MG Series Boilers –Installation and Service Manual
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1.4.2 INSTALLER MODE
To enter the adjustment mode:
1. Press with Up ▲, Down ▼, and “I” keys (see Figure 1) simultaneously for three seconds.
2. Press and release the “I” key until the parameter (listed in the Table 2) requiring adjustment is
displayed.
3. Press with Up ▲ or Down ▼ key until the parameter has reached the desired value.
4. After 60 seconds without any key inputs, the control will automatically return to the RUN Mode.
3-Digit 7-Segment Display
Default
Range
Description
1st Screen
2nd Screen (setting value)
3rd Screen

<high limit>
˚F or ˚C
180 ˚F
130 to 220 ˚F
Adjust high limit setting

<high limit differential>
˚F or ˚C
15 ˚F
10 to 30 ˚F
Adjust high limit
differential

<pump overrun time>
Sec
60 sec
0 to 120 seconds
Pump post-purge time

<ODR maximal temp.>
˚F or ˚C
55 ˚F
40 to 70 ˚F
Maximal outdoor
temperature

<ODR minimal temp.>
˚F or ˚C
0 ˚F
-40 to 40 ˚F
Minimal outdoor
temperature

<minimal water temp.>
˚F or ˚C
140 ˚F
130 to 150 ˚F
Minimal boiler
temperature

<minimal boiler temp.>
˚F or ˚C
140 ˚F
OFF,
120 to 160 ˚F
Thermal purging
minimal temperature
(parameter is available
only if outdoor
temperature is invalid)

<maximal delay>
Min
2
1 to 10 minutes
Maximal thermal purge
time (parameter is
available only if outdoor
temperature is invalid)

On or OFF
N/A
N/A
Reset lockout

˚F or ˚C
˚F
˚F or ˚C
Select degrees ˚F or ˚C
mode
Table 2 Installer Mode Options

MG Series Boilers –Installation and Service Manual
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1.4.3 OPERATING CHECKOUT
After adjusting parameters, put the boiler into operation and observe operation through at least one
complete cycle to make sure that the controller operates properly. See controller troubleshooting section to
assist in determining boiler operation.
The sensor should fit snugly and should touch the bottom of the well for best temperature response. The
sensor is held inside the well using the well clip.
1.4.4 THERMAL PURGE
The intent of thermal purge is to ensure usable residual heat in the boiler is circulated until it is sufficiently
depleted from the system before the burner is allowed to fire. To that end, on a call for heat, the burner
remains off while the circulator runs until the boiler temperature drops to the thermal purge temperature
limit or the time delay is exceeded. Both of these parameters are adjustable. When the boiler temperature
falls below the thermal purge temperature limit or the time delay expires, the burner is allowed to fire.
In addition to the thermal purge temperature and thermal purge time delay parameters, two other
conditions release the integrated boiler controller from thermal purge and allow the burner to run in order to
maintain comfort in the space:
The boiler temperature has dropped 10 °F from the boiler water temperature measured at the beginning
of the call for heat.
Boiler temperature is cooling at a rate greater than 5 °F/minute while the circulator is running.
1.4.5 OPERATING STATE CODES AND TROUBLESHOOTING
When there is a problem during a call for heat or boiler operation, the controller provides specific
information to help resolve the issue quickly. If the controller is displaying “” by a number, use the state
code definitions in Table 3 to determine the problem and possible causes.

MG Series Boilers –Installation and Service Manual
9
Table 3 - State Codes
Display Code
State
Specific Description
Operation Sequence
↔
Idle/Standby
The boiler is in standby - no call for heat.
Run circulator
Heat request present but boiler water temperature sufficiently high to
run circulator pump only (no ignition sequence).
Thermostat Calls For Heat
↔
Self Test
Hardware self check, check of connected periphery, it is performed
at start up, in the beginning of the heat cycle and in the “Wait For
recovery” state.
Wait for recovery
There is an external error and the control is waiting to recover, no
lockout.
Circulator output energizes
↔
Wait for end switch to
open
The control is waiting for the end switch of the vent damper to open
at the beginning of a heat cycle. If the end switch doesn’t open in 60
seconds, the control goes to error code .
↔
Wait for end switch to
close
The control is waiting for the end switch of venting damper to close
at the beginning of a cycle. If the end switch doesn’t close within 60
seconds, the control goes to error code .
↔
Pump pre-purge/
thermal purge
System is purging before ignition trial-safety relay diagnostics
followed safety relay switch-on during last 2 seconds this state.
↔
Spark, ignition
activation
System is sparking permanently 13 seconds whilst pilot gas valve
relay is turned on.
↔ 
Prove flame
System is proving flame signal, typically 2 seconds.
↔ 
Running
System is in running mode, flame signal must be present.
Call For Heat Ends
↔ 
Pump post-purge
System is purging at the end of a call for heat.
Vent Damper Operation
↔ 
Wait for vent damper to
open
Damper actuator is energized and the system waits for damper to
close.
↔ 
Wait for vent damper to
close
Damper actuator is de-energized and the system waits for damper to
open.
↔ 
Wait for vent damper to
open - failed closed
Damper actuator is energized, system waits for damper to open, but
the damper is stuck in closed position (damper end switch is open).
↔ 
Wait for vent damper to
close - failed open
Damper actuator is de-energized, system waits for damper to close,
but the damper is stuck in open position (damper end switch is
closed).
Troubleshooting/Diagnostics
↔
Inter-purge
(retry/recycle delay)
If the control loses flame signal during state code 7 or 8, or flame is
not detected during stat code 6 to 8, it will recycle through the 30
seconds purge time and last 2 seconds part of pre-purge time.
↔
Wait for limit to close
There may be a call for heat from the thermostat, but the limit switch
is open.
↔
Flame out of sequence
–before trial
Flame signal sensed before trial for ignition.
Flame out of sequence
–after trial
Flame out of sequence during post-purge.
Wait for flame loss
Flame signal still present when not expected.

MG Series Boilers –Installation and Service Manual
10
If the controller is displaying “” followed by a number, use the error code definitions in the Table 4 to
determine the problem and possible causes.
Table 4 - Error Codes
Display
State
Solution
↔
End switch of venting
damper failed to open
The end switch of venting damper has not opened at the
beginning of the heat cycle. The end switch contacts are stuck
closed. The control is not in lockout. Check the venting damper
and replace it if necessary.
↔
Low flame current
Check pilot assembly and replace it if necessary.
↔
Flame sensed out of
normal sequence
Flame sensed out of normal sequence (before opening gas
valve or after closing gas valve).
↔
Gas valve relays
welded 5 consecutive
soft lockouts
A manual reset is required.
↔
Flame sensed during
pre-purge
Flame sensed during pre-purge (before gas valve signaled
opened).
↔
Flame sensed during
post-purge
Flame sensed during post-purge (before gas valve signaled
closed).
↔
End switch of venting
damper failed to close
The end switch contacts stuck open. Waiting time for pressure
switch to close expired. The control is not in lockout. Check the
venting damper and replace it if necessary.
↔
Sensor error
Temperature sensor or interface failure (open or short
connection, increased connection resistance, dual sensor
mismatch) or failure of A/D conversion (invalid offset or gain,
too many failures during A/D conversion).
↔
End switch error
Atmospheric Damper End Switch failed to close (end switch
contacts stuck open).
↔
End switch error
Atmospheric Damper End Switch failed to open (end switch
contacts stuck closed).
↔
Flame rod shorted to
burner ground
Check and adjust or replace if necessary. This may be caused
by excessive condensation from flue gas onto flame rod.
↔
AC line frequency error
AC signal is too noisy or frequency is incorrect.
↔
Line voltage error
AC voltage out of specification high or low.
↔
Thermostat input higher
than threshold
Check thermostat wiring and replace it if necessary.
↔
Line voltage unstable
Possibly too many heavy loads switching on and off cause
erratic supply voltage.
↔
Soft lockout
Maximum number of retries exceeded. System is shut down
and will re-start following an enforced delay.
↔
Soft lockout
Maximum number of recycles exceeded.
↔
Soft lockout
Internal failure (Electronics failure). Caused by general
electronics failure such as relay open or shorted contacts,
flame sensing circuit error, or A to D error.
↔
Over temperature error
Sensor measured temperature in excess of ECO limit (230 oF).
Purge all air from the system. Ensure there is adequate flow.

MG Series Boilers –Installation and Service Manual
11
Installation Instructions Section 2
2.1 RECEIVING
INSPECT SHIPMENT FOR POSSIBLE DAMAGE. All goods are carefully manufactured, inspected,
checked and packed by experienced workers. The manufacturer's responsibility ceases upon delivery of
goods to the carrier in good condition. Any claims for damage, shortage in shipment or non-delivery must
be filed immediately against the carrier by the consignee.
Use care when receiving and unpacking the boiler. Dropping the boiler may cause damage and prevent
safe and proper operation.
2.2 INSTALLATION CODES AND REQUIREMENTS
All applicable national, provincial/state, and local codes, laws, regulations, and ordinances must be
followed. They expand on and take precedence over any recommendations in this booklet. Authorities
having jurisdiction shall be consulted before installations are made.
In Canada, the installation must conform to the requirements of the authority having jurisdiction or, in the
absence of such requirements, to the CAN/CSA B149 Installation Codes (current edition). All electrical
wiring must be in accordance with the Canadian Electrical Code, CSA C22.1 Part 1 (current edition) and
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/NFPA 54
(current edition). All electrical wiring must be in accordance with the National Electrical Code, ANSI/NFPA
70 (current edition) and applicable local codes.
Where required by the authority having jurisdiction, follow the Standard for Controls and Safety Devices for
Automatically Fired Boilers, ANSI/ASME CSD-1 (current edition).
2.3 LOCATION
WARNING
Install the boiler so that if the boiler or any connections should leak, the water flow will not
cause damage to the area near the boiler or to the lower floors of the building. When such
locations cannot be avoided, install a floor drain or drain system with suitable drainage
capacity.
MG boilers are intended for indoor installation only. Observe the following minimum clearances from the
boiler to combustible materials:
Minimum Clearances to Combustible Materials
Model
Sides
Rear
Top
Front (service)
in.
mm
in.
mm
in.
mm
in.
mm
MG
2
51
2
51
24
610
18
457
Minimum clearance from the boiler front to combustible materials is 6 in (153 mm); however, a front
clearance of 18" (457 mm) is recommended for servicing.
Maintain a clearance of 6" (152 mm) from draft hood and the flue pipe in any direction.
Allow ample space for boiler inlet and outlet connections, and gas connection.
Boiler must be installed on a stable and level foundation.
MG Series boilers can be installed on a combustible floor but must not be installed directly on
carpeting.
A hot water boiler installed above radiation level or as required by Authority Having Jurisdiction
must be provided with a low water cutoff device at the time of boiler installation. The low water
cutoff device must be installed at a higher level than the boiler heat exchanger.
This boiler must be installed such that gas ignition system components are protected from water
(dripping, spraying, rain, etc.) during appliance operation and service.

MG Series Boilers –Installation and Service Manual
12
2.4 GAS SERVICE PIPING
The boiler and its gas connection must be leak tested before placing the boiler in operation. The gas
controls furnished are suitable for a maximum operating gas pressure of 1/2 psi (14 inches water column).
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 1/2 psig (14 inches water column).
The boiler must be isolated from the gas supply piping system by closing its individual manual shutoff valve
during any pressure testing at test pressures equal to or less than 1/2 psig (14 inches water column).
A manual main shut-off valve should be installed in the gas line outside the boiler jacket and as required in
Section 2.2. The valve should be readily accessible for turning on and off.
A drip pocket or sediment trap should be installed in the gas supply line upstream of the gas controls and
as close to the boiler as possible (example shown in Figure 3 in Section 5).
The pipe compound used should be resistant to the action of liquefied petroleum gases. Check for gas
leaks in piping before placing the boiler in operation by using a soap and water solution. DO NOT USE AN
OPEN FLAME.
INSTALLER MUST IDENTIFY EMERGENCY SHUT-OFF DEVICES.
All piping and fittings must be installed as per codes in Section 2.2.
2.5 AIR SUPPLY FOR COMBUSTION AND VENTILATION
A sufficient air supply MUST be provided to this boiler. Air openings to the boiler room provide the air for
combustion, flue gas dilution and ventilation and are always required, regardless whether the air is taken
from inside or outside. The air opening size and location (as well as other air supply and venting
considerations) must conform to Section 2.2.
The boiler room must never be under a negative pressure. Always provide air openings sized not only to
the dimensions required for the total input of all fuel-fired appliances in the boiler space, but also to handle
the air movement rate of any exhaust fans or air movers using air from the building or space.
The venting terminations must always be kept clear of obstructions (i.e. snow, ice, etc.). Louvers and
grilles used in the air supply and ventilation system should be kept clear of any dust, dirt, or debris which
will block proper air flow.
2.6 CORROSIVE ATMOSPHERES
If a gas boiler is to be installed near a corrosive or potentially corrosive air supply, the boiler should be
isolated from it and outside air should be supplied as recommended in Section 2.5.
Chemical vapors from products containing chlorine or fluorine must be avoided. Even though these
chemicals may be safe to breathe, corrosive substances can become liberated when passed through a gas
flame. Even at low concentrations, these chemicals can significantly contaminate the air supply and
shorten the life of any gas burning appliance. The following is a list of some of the products which should
be avoided:
bleaches and chlorinated cleaning products
paints and sprays
water softeners (calcium or sodium chloride)
leaking refrigeration equipment
freon from common aerosol dispensers
These chemicals are especially commons near swimming pools, beauty shops, dry cleaning
establishments, laundry areas, workshops, and garages. The warranty is void when failure is due to
corrosion.

MG Series Boilers –Installation and Service Manual
13
2.7 VENTING
The responsibility of providing a suitable vent of adequate draft capacity and in good usable condition is
that of the gas fitter/installer. Interference with the air supply for the boiler shall be prohibited.
Vent installation and type of gas vent or vent connector MUST follow all applicable national,
provincial/state, and local codes, laws, regulations, and ordinances as described in Section 2.2.
For boilers for connection to gas vents or chimneys, vent installations shall be in accordance with “Venting
of Equipment,”of the National Fuel Gas Code, ANSI Z223.1/NFPA 54, and/or “Venting Systems and Air
Supply for Appliances”of the Natural Gas and Propane Installation Code, CAN/CSA B149.1, or applicable
provisions of the local building codes.
Gas vents must be supported and supports spaced in accordance with the vent manufacturer’s installation
instructions and as required by any applicable codes. Laterals, offsets, and vertical components should be
securely supported with wall straps and at offsets so that the wall straps prevent the weight from stressing
the elbows. All portions of the venting shall be supported for the design and weight of the material
employed.
Horizontal runs shall slope upward not less than ¼ inch per foot (21 mm/m) from the boiler to the vent
terminal. Vent cannot go horizontally to vent terminal without a chimney.
This unit must be installed with the factory supplied draft hood in place. The draft hood is a safety device
designed to control chimney drafts that might affect combustion or blow out the pilot. The draft hood
supplied with the boiler must not be altered. The minimum skirt height, as indicated on the draft hood,
must be maintained.
Vent connectors serving the boiler must not be connected into any portion of mechanical draft systems
operating under positive pressure.
Vent Terminal Information
The minimum distance from the termination of a vent terminal to adjacent public walkways, adjacent
buildings, operable windows and building openings shall be not less than those values specified in the
National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CAN/CSA Installation Codes.
For proper operation, the vent terminal must be kept free of snow and other debris at all times.
To prevent discoloration and degradation of building materials by flue gases and flue gas condensation,
ensure that the vent terminal is installed clear of nearby obstacles. In all cases, installation shall be in
accordance with code.
Maintain a minimum clearance of 4 feet (1.22 m) horizontally, and in no case above or below, unless a 4
foot (1.22 m) clearance is maintained from electric meters, gas meters, regulators and relief equipment.
Removal of an Existing Boiler
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 connected to it.
At the time of removal of an existing boiler, the following steps shall 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.
a) Seal any unused openings in the common venting system.
b) Visually inspect the venting system for proper size and horizontal pitch and determine there is no
blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe
condition.
c) Insofar as is practical, close all building doors and windows and all doors between the space in which
the appliances remaining connected to the common venting system are located and other spaces of
the building. Turn on clothes dryers and any appliance not connected to the common venting system.
Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at
maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.

MG Series Boilers –Installation and Service Manual
14
d) Place in operation the boiler being inspected. Follow the lighting instructions. Adjust the thermostat so
the boiler will operate continuously.
e) Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the
flame of a match or candle, or smoke from a cigarette, cigar or pipe.
f) After it has been determined that each appliance remaining connected to the common venting system
properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers
and any other gas burning appliance to their previous conditions of use.
g) Any improper operation of the common venting system should be corrected so the installation
conforms with the National Fuel Gas Code, ANSI Z223.1/NPFA 54 and/or CAN/CSA Installation
Codes. When re-sizing 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 Part 11
of the National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CAN/CSA Installation Codes.
2.8 AUTOMATIC VENT DAMPER
This boiler is supplied with an automatic vent damper. The following instructions must be observed:
The automatic vent damper should be installed at the top of the factory supplied draft hood (Figure 1 -
Alternate 3). No modifications to the automatic vent damper are permitted.
The venting system must be arranged so that only the boiler is served by the automatic vent damper
with which it was supplied.
Connect the wiring harness from the boiler to the automatic vent damper as indicated on the supplied
wiring drawings.
The automatic vent damper position indicator should be clearly visible after installation.
A minimum clearance of not less than 6 inches (153 mm) must be maintained between the automatic
vent damper device and combustible construction. Provision must be made for service access to the
automatic vent damper.
The automatic vent damper must be in the open position when the boiler's main burner is operating.
For orientation other than vertical, refer to automatic vent damper installation instructions.
2.9 BLOCKED VENT AND FLAME ROLL-OUT SAFETY SWITCHES
All boilers with an input of 300,000 Btu/h and under are equipped with blocked vent and flame roll out safety
switches. The blocked vent safety switch is installed in the clip provided on the draft hood (Figure 2 -
Alternate 1) or is mounted with screws (Figure 2 - Alternate 2). The blocked vent safety switch is pre-wired
at the factory either directly to the boiler controls (Figure 2 - Alternate 1 & 2), or through a wiring harness for
a boiler with an automatic vent damper (Figure 2- Alternate 3). If the vent becomes blocked a boiler shut
down will occur. Ensure that the vent is free of obstructions.
The flame roll out safety switch will cause a boiler shutdown if the heat exchanger becomes blocked with
soot or corrosion.
WARNING
Shut down of the boiler by either the “Blocked Vent” or the “Flame Roll-out” safety switch is an
indication that carbon monoxide may be improperly venting into the premises and the boiler must
be serviced by a qualified person who is capable of determining the cause of the shut down and
can take corrective action. Carbon monoxide is a lethal, colorless and odorless gas.

MG Series Boilers –Installation and Service Manual
15
FIGURE 2 - MOUNTING LOCATION OF BLOCKED VENT SAFETY SWITCH AND WIRE ROUTING
2.10 BOILER PIPING SYSTEM
The boiler piping system of a hot water boiler connected to heating coils located in air handling units where
they may be exposed to refrigerated air circulation must be equipped with flow control valves or other
automatic means to prevent gravity circulation of the boiler water during the cooling cycle.
The boiler, when used in connection with a refrigeration system, must be installed so the chilled medium is
piped in parallel with the boiler with appropriate valves to prevent the chilled medium from entering the
boiler.
2.11 CORROSION PREVENTION (INTERNAL)
The use of oxygen barrier tubing is recommended to protect the system and its components (e.g. pump)
from corrosion. Should your system include "non-oxygen barrier” tubing, please contact the factory or a
heating professional for recommendations.
If freeze protection is required, use an inhibited propylene glycol solution which is specifically designed for
hydronic heating systems and always maintained at a neutral pH (e.g. Fernox Alphi-11 or equivalent).
Follow the supplier’s instructions for proper use and maintenance. Do not use automotive antifreeze.
Some types of chemical additives can cause problems such as accelerated corrosion and result in
premature failure of the boiler heat exchanger and/or system components, especially when not properly
used or maintained. Corrosion is a preventable condition and is not covered by the product warranty.
2.12 SYSTEM OPERATING REQUIREMENTS
WARNING
If you do not follow these instructions exactly, a fire or explosion may result causing property
damage, personal injury or loss of life.
Avoid unnecessary replenishment of system water. It can allow oxygen to enter the system and cause
serious corrosion problems. As well, minerals dissolved in the water supply will precipitate when heated;
minerals preferentially deposit in the heat exchanger. Do not draw water from the heating system for
cleaning, flushing, etc.
Super Hot MG series boilers are designed for use in closed loop systems and are not intended for open
systems, as in heating pool water or systems where water is constantly replenished. Operating the boiler in
an open system will result in premature failure of the heat exchanger. Super Hot boilers may be used to
heat water in open systems indirectly by installing a heat exchanger, such as the Super Hot C-Coil, to
separate open and closed systems.
Heating systems with low temperature return water may cause flue gas moisture to condense on the boiler
heat transfer surfaces, causing corrosion and restricting flue gas flow. Also, low temperature return water
may overcool the flue gases, resulting in reduced vent suction. These are natural phenomena and are
ALTERNATE 1 ALTERNATE 2 ALTERNATE 3

MG Series Boilers –Installation and Service Manual
16
independent of the boiler design. As a guide to avoiding such corrosion and draft problems, it is imperative
that the return water be not less than 135°F (57°C).
MG SERIES BOILERS MUST ALWAYS BE USED WITH FORCED SYSTEM CIRCULATION.
2.13 PRESSURE RELIEF VALVE
A pressure relief valve is supplied as standard equipment. The pressure relief valve is extra protection
against damage that could be caused by malfunctioning controls or excessive water pressure. If a
pressure relief valve is not used, the warranty is void.
The pressure relief valve should be installed on the boiler outlet with its spindle vertical. The connection
between the boiler and the relief valve must have at least the area of the valve inlet.
A discharge pipe should be used. The discharge pipe outlet should be positioned over a suitable drain and
so arranged that there will be no danger of being scalded. The discharge pipe must pitch down from the
valve and should be no smaller than the outlet of the valve. The end of the discharge pipe should not be
concealed or threaded and should be protected from freezing. Extensive runs, traps or bends could reduce
the capacity of the pressure relief valve.
No valve of any type should be installed between the pressure relief valve and unit or in the discharge pipe.
The pressure relief valve is a code requirement. Field installation of the relief valve must be consistent with
the ANSI/ASME Boiler and Pressure Vessel Code, Section IV.
Avoid contact with the hot water discharged to prevent personal injury.
WARNING
The pressure relief valve discharges pressurized hot water and/or steam. Steam exiting the
discharge outlet can explosively expand in any direction. Always maintain a safe distance from
the discharge pipe outlet in order to avoid potential contact with exiting hot water or steam.
2.14 ELECTRICAL WIRING
All electrical wiring must conform with the requirements in Section 2.2.
Run a separate circuit from the electrical service panel through a fused disconnect switch to the boiler. This
boiler must be electrically bonded to ground in accordance with the requirements of the authority having
jurisdiction or, in the absence of such requirements, with the National Electrical Code, ANSI/NFPA 70
(current edition) and and/or the Canadian Electrical Code, CSA C22.1 Part 1 (current edition). Field wiring
shall conform to Section 2.2 and to the temperature limitations of Type T [63F (35C) rise] or better.
Make connections as shown in the wiring diagrams provided. For details of electrical wiring for different
pilots and controls, refer to wiring diagrams included in this manual.

MG Series Boilers –Installation and Service Manual
17
Startup Instructions Section 3
3.1 PRE-STARTUP
a. Fill entire heating system with water and vent or purge air from system. Add water as needed to reach
boiler operating pressure. Water should be of suitable quality. Do not use water with high hardness.
b. Check for and repair any leaks in water piping.
c. Check burners to see that they are not dislodged.
d. Check for proper installation of pressure relief valve, draft hood, and venting.
e. Check that the electrical wiring matches the wiring diagram in this manual or on the boiler.
f. Check if the flame roll out safety switch and blocked vent safety switch are properly located and wired.
g. Use a soap solution to check for leaks in gas piping from meter to boiler pilot and manifold. Repair and
retest any leaks found.
h. Operate circulating pump and vent all radiation units and high points in system piping.
3.2 STARTUP
WARNING
The following instructions are intended as a guide for qualified persons. Before lighting the
boiler, the pre-startup instructions of Section 3.1 MUST be performed. If you do not follow these
instructions exactly, a fire or explosion may result causing property damage, personal injury or
loss of life.
WARNING
Should boiler overheat, or the gas supply fail to shut off, do not turn off or disconnect the
electrical supply to the circulating pump. Instead, shut off the gas supply at a location external
to the boiler.
This boiler does not have a continuous pilot flame. It is equipped with an ignition device which automatically
lights the pilot. Do not try to light the pilot by hand.
In the event of failure of any component, either the system will not operate or it will go into safety lockout.
1) Make sure the Gas Valve and all electrical power to the boiler are "OFF".
2) Set room thermostat to the lowest setting.
3) Connect a manometer at pressure tapping on downstream section of gas valve.
4) Wait five minutes to clear out any gas. If you smell gas, STOP! Follow the safety instructions
provided in Section 1.1 under WHAT TO DO IF YOU SMELL GAS. Remember that propane does
not vent upward naturally.
5) Program the controller following Section 1.4 and test as follows:
a) Set thermostat above room temperature to call for heat and turn power on for the boiler.
b) Watch for spark at pilot burner. All models will automatically lockout if no pilot flame is
detected within 15 seconds. Automatic retry will occur in 5 minutes.
6) Turn Gas Valve to ON. Pilot burner should ignite, followed by main burners. Check main and pilot
burners and adjust pilot, if necessary, as described in Section 3.3.
7) Assure that all other gas appliances are turned off, including their pilot flames.
8) Check manifold pressure reading on the manometer and make necessary adjustments. Check
that burner input matches rating plate input.
9) Return thermostat and controls to normal operation settings.

MG Series Boilers –Installation and Service Manual
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FIGURE 3 - PILOT FLAME
ADJUSTMENT
3.3 CHECK BURNER SYSTEM
To maintain safe and efficient operation, examine the burner system regularly through the inspection hole
near the pilot tube.
Check condition of burner system
It is possible for parts of the burners system to
become plugged, cracked, eroded and/or
dislodged resulting in unsafe operation.
Pilot Flame
Remove cap screw
cover on gas valve,
then adjust gas flow to
the point where the
sensor rod is
completely enveloped
by the flame (Figure 3),
but not necessarily
glowing red. Replace
and tighten cap.
Check for lifting
Flames should not lift excessively from the
burner ports. The flames may lift slightly during
ignition or when the burners are cold.
Check ignition and extinction
Ignition should flow quickly and smoothly across
all the burners. Popping noises or explosions
from the burners during ignition, extinction or
normal burner operation indicates the need for
service.
Check flame color
An extremely yellow flame, as seen on a burning
candle or match, is an indication of incomplete
combustion and is usually accompanied by the
formation of soot and carbon monoxide (carbon
monoxide is a lethal, colorless and odorless
gas). If soot is allowed to accumulate, it will
partially restrict free passage of products of
combustion to the flue. Under typically operating
conditions, the flame should have a distinct
bright blue inner cone and a blue/orange outer
cone.
If any of the above problems are observed or the burner system does not operate properly,
immediately take corrective measures.
3.4 AQUASTAT ADJUSTMENT
An optional aquastat may be installed to control the main burner firing by sensing outlet water
temperature. The optional aquastat should be set a minimum of 20°F (10°C) above the setting of the high
limit of the integrated boiler controller.
3.5 GAS MANIFOLD PRESSURE
The designated manifold pressures are as shown in the table below. A 1/8” NPT tapping is provided on
the manifold or gas valve for connecting a manometer to check this pressure. Both natural gas and
propane models are furnished with gas valves which have a built in gas pressure regulator. If necessary,
adjust to the proper value by removing cap and turning adjusting screw clockwise to increase manifold
pressure or counterclockwise to decrease manifold pressure.
Model
Natural Gas
Propane
MG
3.5” W.C.
11.0” W.C.

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3.6 CHECK INPUT & ORIFICES
For safety, the input shown on rating plate must not be exceeded. Check with the table below that
the orifice size and input rate shown on your boiler rating plate match your application, i.e. boiler model,
fuel type, and altitude. See MG Specifications to find a boiler model's input rate.
FOR CANADA
Model
Natural Gas
Propane
0 to 2,000 feet
2,000 to 4,500 feet
0 to 2,000 feet
2,000 to 4,500 feet
MG
#51 orifice
standard input
#51 orifice
standard input
#60 orifice
standard input
#61 orifice
10% de-rate input
NOTE: For elevations above 4,500 feet reduce high altitude input 4% for each additional 1000 feet.
Reference Natural Gas and Propane Installation Code B149.1, 3.22 High Altitude Installations
Example of High Altitude De-rate
Boiler: MG-150
Altitude: 5,500 feet
Standard Input (0 to 2,000 ft) = 150,000 Btu/h (from page 2)
High Altitude Input (2,000 to 4,500 ft) = De-rate Standard Input by 10% (see above table)
= 150,000 Btu/h x (1 - 0.10)
= 150,000 Btu/h x 0.90
= 135,000 Btu/h
% Reduction for additional 1000 ft = 4% x 1 = 4%
Input at 5,500 ft = De-rate High Altitude Input by 4%
= 135,000 Btu/h x (1 –0.04)
= 135,000 Btu/h x 0.96
= 129,600 Btu/h
FOR UNITED STATES
Model
Natural Gas
Propane
0 to 2,000 feet
Over 2,000 feet
0 to 2,000 feet
Over 2,000 feet
MG
#51 orifice
standard input
Input must be reduced
4% for each 1000 feet
above sea level. *
#60 orifice
standard input
Input must be reduced
4% for each 1000 feet
above sea level. *
*Reference National Fuel Gas Code ANSI Z223.1/NPPA 54, 8.1.2 High Altitude.
Example of High Altitude De-rate
Boiler: MG-100
Altitude: 5,000 feet
Standard Input (0 to 2,000 ft) = 100,000 Btu/h (from page 2)
% Reduction for 5,000 ft = 4% x 5 = 20%
Input at 5,000 ft = De-rate Standard Input by 20%
= 100,000 Btu/h x (1 - 0.20)
= 100,000 Btu/h x 0.80
= 80,000 Btu/h

MG Series Boilers –Installation and Service Manual
20
Small adjustments to the input rate can be made by varying the manifold pressure. Normally it should be
adjusted no more than 0.2 inch w.c. for natural gas or 0.5 inch w.c. for propane from the manifold
pressure specified on the rating plate.
WARNING
Exceeding the allowable input rate can produce dangerous concentrations of carbon monoxide,
and cause the boiler to overheat resulting in severe personal injury, death or substantial
property damage. Carbon monoxide is a lethal, colorless and odorless gas.
Input Rate Test
Consult gas company to determine the heating value of the gas supplied in Btu per cubic feet. Operate
boiler for 15 minutes starting with all parts at room temperature and check input by clocking gas meter
with all other gas appliances turned off, including their pilot flames. Use the following formula:
INPUT (Btu/h) =
SecondsinTimeClocked ft.)Cu.inGasof(Volumex)Btu/Cu.ft.inGasofValueHeating(High(3600)
To ensure accuracy for rating, clock enough cubic feet of gas so that there is at least one revolution of the
test dial and the clocked time is at least 60 seconds.
3.7 CHECK FOR DRAFT HOOD SPILLAGE
WARNING
Continuous spillage at the draft hood relief opening may result in severe personal injury, death
or substantial property damage.
After the main burners have operated for 5 minutes, check to see that combustion products are going up
the chimney or gas vent properly by passing a lighted match (or smoke from a cigar, cigarette, or pipe)
around the edge of the relief opening of the draft hood. If the chimney or gas vent is drawing properly, the
match flame or smoke will be drawn into the draft hood. If not, the combustion products will tend to
extinguish this flame. While performing this test, make sure all exhaust fans, air movers, and gas
appliances are operating and doors and windows are closed. If the combustion products are escaping
from the relief opening of the draft hood, IMMEDIATELY shutdown the boiler and make proper
adjustments or repairs.
3.8 CHECK OF CONTROLS
After the unit has been operated for awhile, lower the aquastat setting below the water temperature and
the burner should shut off. Set the aquastat higher than the water temperature and the main burner
should ignite. Return the aquastat to its original setpoint and make sure boiler cycles normally. Repeat
this type of check on the optional aquastat (when used), thermostat and other system controls to ensure
all are working satisfactorily. If any of the safety or controls do not function, necessary corrections should
be made immediately.
3.9 CHECK FOR GAS LEAKS
To identify gas leaks, smell for gas around boiler area and gas piping connections (See Section 1.1). To
check a specific area for leakage, spray a mixture of soap and water onto the suspected area –active
bubbling indicates a gas leak. DO NOT TEST FOR LEAKS WITH AN OPEN FLAME. Gas leaks must be
repaired immediately.