Midco MPG 1.5G Service Manual

BURNER MODEL

BILL OF MAT'L
NUMBER

SERIAL NUMBER #

WIRING DIAGRAM

FOR SERVICE CONTACT:

Name

Address

Phone

Date of Installation

Installation and Service Instructions

909

8471 51

Unipower

MPG Series

Gas Burners

S A F E T Y I N F O R M A T I O N T E R M S : The following terms are used to identify hazards, safety precaution of special

notations and have standard meanings throughout this manual. They are printed in all capital letters using a bold type face
as shown below, and preceded by the exclamation mark symbol. When you see the safety alert symbol and one of the
safety information terms as shown below, be aware of the hazard potential.

DANGER: Identifies the most serious hazards which will result in severe personal injury or death.
WARNING: Signifies a hazard that could result in personal injury or death.
CAUTION: Identifies unsafe practices which would result in minor personal injury or product and property damage.

Midco International Inc.

4140 West Victoria St. - Chicago, Illinois 60646
tel [phone] fax [phone]

web www.midcointernational.com e-mail [e-mail]

Quality Designed for Proven Performance

WARNING: If the information in these instructions
is not followed exactly, a fire or explosion may result,
causing property damage, personal injury or death.

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:

 Do not try to light any appliance.


Do not touch any electrical switch; do not use any

phone in your building.

 Immediately phone your gas supplier from another

building. Follow the gas supplier’s instructions. If
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.

In the United States, installation must conform with local codes or in
the absence of local codes, with the National Fuel Gas Code, ANSI
Z223.1-latest edition available from American National Standard

Institute. Further reference should be made to the recommendation of
your fuel supplier.
In Canada, installation must conform with local codes or in the
absence of local codes, with Installation Codes for Gas Burning

Appliances and Equipment, CGA Standard CAN/CGA 1-B-149.1
or 2.

WARNING: Additions, changes, conversions and service
must be performed by an authorized Midco representative,
service agency or the fuel supplier. Use only MIDCO specified
and approved parts.

INSTALLER: Inform and demonstrate to the user the correct
operation and maintenance of the gas utilization equipment.
Inform the user of the hazards of storing flammable liquids and
vapors in the vicinity of this gas utilization equipment and
remove such hazards. Affix this manual and associated
literature to the burner.

CODE COMPLIANCE IS THE SOLE RESPONSIBILITY OF THE
INSTALLER.

USER: Retain this manual for future reference. If other than
routine service or maintenance as described in this manual and
associated literature is required, contact a qualified service
agency. DO NOT ATTEMPT REPAIRS. An inadvertent service
error could result in a dangerous condition.

Part 1 Installation

Specifications

1

___________________________

CAUTION: MPG-Series are not intended for outdoor installation and must be protected

from excessive moisture. Provide adequate clearance for service and proper operation.



 Open basements will generally allow sufficient air infiltration, so special provisions will seldom

be required. If the heating plant is located in a separate furnace room or in an unusually tight
basement, permanent means must be provided to supply an ample volume of fresh air for
combustion and boiler room ventilation. A direct opening to the outside air should be provided
sized on the basis of 1/2 square foot of free opening for each 1,000,000 BTU of burner rating
when the vent connector is equipped with a barometric draft control, 11/2 square feet when
equipped with a draft hood. If the ventilation opening is screened, it should be of 11/4" mesh.

Part 1

Installation

2

I Ventilation

The Midco power gas burner, MPG Series, is designed for firing natural gas or propane
gas in most applications. The burner is a self-contained unit including a blower housing
assembly, a burner gas manifold assembly, a burner cartridge, a flame safeguard, and a
main and pilot gas train. The burner is easy to install, it includes mounting the burner to the
gas utilization equipment, piping the main and pilot gas train and connecting the power
supply. Before shipment every burner is operationally fire tested at the factory, for
unassembled valve trains the pilot solenoid and ignition system is tested.

Burner Style Power Type Sensing
Pilot Type Intermittent; Flame Rod Sensing, Spark Ignition(Standard)

Intermittent; UV Sensing, Spark Ignition (Optional)
Interrupted; Flame Rod Sensing, UV Flame Scanner (Optional)

Pilot Safety Instantaneous Electronic Flame Safeguard

Voltage Standard

Controls 120/1/60
Motor 115/1/60

230/1/60

(Optional)

U.L. Listed -U.L.C. Listed
Non UL 220V / 50HZ - Contact Factory

MPG 1.5G **

MPG 2.5G **

1500

2500

325

540

4" W.C.

4

4" W.C.

4" W.C.

4

4" W.C.

Natural Propane

Maximum

Input

1

MBH/HR.*

Maximum

Air

SCFM

3

Models

Inlet Gas Pressure

Required

2

MPG 1.5G

MPG 2.5G

1

/2

3

/4

0.13 - 1.20" W.C.

0.09 - 0.80" W.C.

0.08 - 0.70" W.C.

0.06 - 0.50" W.C.

Natural

Propane

Motor HP

(3450 RPM)

See Table 3

See Table 3

Recommended

Combustion

Chamber

Size

Models

Burner Manifold Pressure

1

*1 MBH=1,000 BTU/HR
** High Turn Down Models available - contact factory

1. Values given based on 0" W.C. firebox pressure, altitudes to 2,000 feet. Derate burner
for altitudes over 2,000 feet by 4% for each 1,000 feet over sea level.

2. Maximum inlet pressure both gases: 14" W.C. Refer to Section VI Piping for high pressure.

3. SCFM=Standard Cubic Feet/Minute

4. Requires special valve train - contact factory

Table 1: Burner Specifications

*1 MBH=1,000 BTU/HR. See Table 6 for gas pressure and air shutter settings

Models

MPG 1.5G

MPG 2.5G

500

850

1500

2500

1500

2500

1400

2450

1.0

1.0

1200

2000

Maximum Capacity in MBH at

Combustion Chamber-

Back Pressure

0" W.C. .25" W.C. .50" W.C.

Minimum

Firing

Rate

MBH*

Maximum

Back
Pressure
in " W.C.

Maximum

MBH* at

Maximum

Back Pressure

Table 2: Maximum Capacity at Specified Back Pressures

500

850

Minimum

Input

1

MBH/HR.*

The opening should be located at least six feet above ground level to prevent accidental
obstruction. If a direct opening to the outside air is not available, an amply sized air duct can be
run to the nearest outside air source or if practical, open stairwells or building corridors
connecting to an outside wall having a ventilating opening can be used for this purpose, provided
that no possibility of accidental closure exists.



 While the spark ignition pilot system performs successfully under moderate or momentary

back draft conditions, it is not intended for operation under sustained reverse draft, for example,
in a building with large ventilating fans but with insufficient make-up air. Even if burner operation
is successful under these conditions, they must be corrected to prevent the hazard of drawing
flue gases into the building. Consult your local gas company when doubt exists concerning boiler
room ventilation.

___________________________



 The heating system, both the gas utilization equipment and the distribution system, should be

in good operating conditions and sufficient to properly heat the building. It should be determined if
any serious faults are present that would cause excessive fuel consumption, unsafe operation or
improper heating, and measures taken to correct them.



 Firing door catches should be filed off or otherwise arranged so that the door will open easily

to relieve pressure. No positive catches should be used. The use of a spring-type door holder is
recommended.

___________________________



 Mount the burner to the gas utilization equipment. A tight seal between the mounting flange

and the front plate should be accomplished using the supplied high temperature rope. When
installing the gas burner the distance from the flange to the blast tube edge should be the same
as the gas utilization equipment wall thickness plus the flange gasket or rope thickness. That
means the burner blast tube will be flush with the inner chamber wall after the burner has been
installed. If the blast tube is extended into the combustion chamber possible damage to the
burner may happen. See Figure 1 & 2 for reference.

3

Part 1 Installation

II Preparation of

the Gas Utilization

Equipment

III Combustion

Chamber

Figure 1: Dry Base Boiler with Combustion

Chamber Liner (Warm Air Furnace

Construction is Similar)

Figure 2: Wet Base Boiler with Unlined

Combustion Chamber

Figure 3: Scotch Marine Boiler

Figure 4: Warm Air Furnaces

I Ventilation

Continued



 The MPG gas burner is designed for "in-shot" firing. It can be fired into the ash pit of a boiler

designed for solid fuels, or it can be fired into the primary heat exchanger of a boiler designed for
liquid or gaseous fuels. The ash pit installation requires a refractory lining.



 The combustion chamber serves to contain and promote combustion and to protect non-heat

exchange surfaces from direct flame contact. Built-up combustion chambers should be made of
2600° insulating firebrick. As an alternative, a monolithic floor can be cast in place, using a high
temperature (2400°) light weight insulating refractory. Check with your supplier to determine the
thickness which will yield equivalent insulating qualities.



 The combustion chamber sizes given in Table 3 are based on the maximum rated burner

capacity. If the input is to be permanently set at a reduced rate the combustion chamber floor
area can be reduced proportionately to the proposed input, with the length as closely
proportioned to twice the width as possible.



 Where recommended size combustion chambers (225,000 BTU/sq. ft.) can be

accommodated, the type of construction shown in Figure 1 should be used. If lack of space
prohibits use of this construction, higher BTU values per square foot can be allowed for by using
the constructions shown in Figures 2 and 3.



 The back wall of the combustion chamber should be carried 2 or 3 courses higher and

overhung to deflect the flames from direct impingement on the rear heat exchanger surface. Hard
firebrick should be used to prevent erosion of the brick by high velocity gases.



 The burner is equipped with a mounting flange for direct attachment to the boiler front. The

burner nozzle must not extend into the combustion chamber. It should be sealed into the opening
as shown in Figures 1 - 4.



 The refractory lined combustion chamber can be omitted in "Scotch Marine" and "Steam

Generator" boilers or warm air furnaces that do not include ash pits. The burner is fired directly
into the heat exchanger, requiring no refractory unless the combustion chamber is so short that
flame would impinge excessively on the rear heat exchanger wall (this is particularly important in
a warm air furnace). Refractory protection is recommended if the length of the primary chamber
is less than 20% larger than the length given in Table 3. In any case, the burner entry wall must
be refractory lined if it is not a heat exchanger surface.

___________________________

WARNING: The chimney shall be inspected for unsafe conditions such as
deteriorated masonry and excessive soot or other blockage or potential blockage.
Installation must conform with local codes or in the absence of local codes with NFPA,
ANSI Z223.1-latest edition.

WARNING: No movable vent connector damper is permitted on any power gas burner
installation. The chimney should be inspected for unsafe conditions such as deteriorated
masonry and excessive soot or other blockage or potential blockage. Check your local
authorities for regulations covering barometric draft regulators on gas equipment.

WARNING: The vent connector shall not be connected to a chimney already venting
solid fuel burning equipment, an incinerator or an open fire place.



 The MPG burner does not depend on chimney draft. Combustion air is supplied by the forced

air blower, which is sufficient to supply adequate air for any normal application. This reduces the
function of the chimney to remove of flue products from the boiler. A chimney height of 15' above
the boiler flue outlet will generally prove ample if the recommended or larger vent connector and
chimney diameters are used. The chimney must of course, extend several feet over the roof of
the building, or adjacent buildings. Vent connector material should be 24 gauge or heavier steel,
galvanized to resist corrosion. The horizontal run of vent connector should be pitched upward
from the appliance flue outlet at least 1/4" to the foot. Avoid excess elbows or other constructional
features that would create excessive resistance to flow of flue products. Fasten joints with sheet
metal screws to prevent sagging. The vent connector should be maintained at least 6" from
combustible building materials; more if it is uninsulated. Where it passes through partitions
constructed of combustible materials a ventilated thimble should be used. Refer to your local
building codes. The vent connector should be firmly cemented into the chimney but must not

4

Part 1 Installation

IV Chimney, Vent

Connector and

Draft Control

Gas Input,

MBH/Hr Width/Height " Length "

500 12" 26"
1000 15" 34"
1500 18" 42"
2000 21" 50"
2500 24" 58"

Table 3: Recommended Combustion

Chamber Minimum Required Dimensions

Max Input, Flue Pipe
MBH/Hr Diameter "

700 9"

950 10"
1400 12"
1950 14"
2500 16"

Table 4: Recommended Size of Flue
Pipe and Chimney - Based on Maximum
Height of 15’ and Lateral Run of 15’

OTE: For actual
vent diameter
information refer to
the ational Fuel
Gas Code Handbook

- Latest Edition

III Combustion

Chamber

Continued

extend beyond the inner face.
Where two or more appliances
use the same chimney, be sure
not to enter the chimney with
both flue pipes at the same level.



 Do not arbitrarily reduce the

vent connector size, since a back
pressure can build up, leading to
possible leakage of flue products
into the room.



 Chimney construction can be

either of brick, preferably tile
lined, or of steel. Joints in the
chimney should be smooth and
leak free to prevent
uncontrollable air infiltration. They
should be made so that
condensation if any, will not
collect in the joints or leak to the
outside.



 If the vent connector must be

extra long, the area of the pipe
and chimney should be increased
or the chimney height must be
increased, or both. Never allow
the horizontal length of the vent
connector to exceed the height of the chimney.



 Two kinds of draft control are acceptable; an A.G.A. type draft hood as illustrated in Figure 5,

or a barometric damper as shown in Figure 6. Use of a draft hood is usually limited to burners
with lower range capacities, while a barometric draft control is suitable for all capacities.
Application should depend on the requirements of the installation.



 If a draft hood is used, it should be of the same size as the vent connector and is free

swinging without interference from surrounding objects so that the velocity pressure of the flue
gases does not interfere with its operation. See Figure 5 for proper installation.



 When any vent connector passes through a partition the draft control must be located in the

same room as the heating appliance. A device which will automatically shut off gas to the burner
in the event of sustained backdraft is recommended if such backdraft might adversely affect
burner operation or if flue gas spillage might introduce a hazard. If such a device is used, it shall

5

Part 1 Installation

Figure 5: Recommended Locations for Draft Hoods

Note:
Figures 3 and 4 :
Copyright by
American Gas
Association.
Used by
permission of the
copyright holder.

Figure 6: Location for Barometric Draft Regulators

Note: Figures 3 and 4 :

Copyright by American Gas Association.

Used by permission of the copyright holder.

IV Chimney, Vent

Connector and

Draft Control

Continued