Modine Manufacturing POR oil-fired unit Service Manual

Oil Fired Unit Heaters

4-112.3

September, 2008

DESIGN FEATURES

Maximum Performance, Comfort, and Efficiency

Modine model POR oil-fired unit heaters offer an efficient and
reliable means of heating, particularly in regions where supplies
of other fuels, such as natural gas, may be unavailable,
undependable, or interruptible. The units are direct driven
propeller fan type units designed for overhead suspension and
horizontal delivery of heated air. They are available in three
model sizes: 100,000, 145,000, and 185,000 Btu/hr outputs.

Time-tested and field-proven components are engineered
into the design of these compact units which produce comfort
heating at the lowest cost through their highly efficient
operation. Models are UL-listed and require fuel oil grade No. 1
or 2, as specified by ASTM (American Society for Testing and
Materials) D396-73 Standard Specifications for Fuel Oils or
Canadian Government Specification Board, 3-GP-28.

The following are standard features and benefits of the model
POR unit (refer to Figure 2.1):

Advanced Burner and Burner Controls

The POR oil fired unit heater is equipped with the latest in
burner and burner control technology making the POR an
industry leader in efficient fuel handling. Features include:

pressure-atomizing, gun-type burner with a stainless steel,

• A
die-stamped flame retention head that produces a highly
stable flame with 20-30% greater combustion efficiency over
non-flame retention type burners. The flame retention head
matches the flame to the shape of the heat exchanger for
maximum heat transfer while ensuring a long life.

two-stage fuel unit for maintaining maximum fuel pressure

• A
delivery, even in high lift applications.

• The fuel unit utilizes an energy efficient permanent split
capacitor (PSC) motor with ball bearings for reduced energy
consumption, excellent starting characteristics, and reduced
maintenance.

latest in oil burner controls with a solid state

• The
microprocessor based controller featuring:

> Interrupted-duty ignition that disables the spark ignition

once the flame has been proven. This feature extends the
life of the ignition system, reduces component noise, and
saves energy over traditional controls that maintain a power
consuming spark during the entire call for heat period.

> Limited

of unburned oil in the combustion area.

> Communications port to enable communication with service

instruments or data acquisition equipment.

> Diagnostic LED to provide service personnel an easy

indication of cad cell resistance and operational status
(lockout, recycle, etc.).

> 15 second valve-on delay provides a pre-purge mode that

allows for clean starts and reduced maintenance.

> A cad-cell safety system de-energizes the burner controls

if a flame is not produced in 30 seconds. Manual reset of
flame protection is required following this safety shut-down.

• Beckett electronic oil igniter module that provides superior
spark ignition (20kV peak) and a smaller and lighter package
than older spark transformer designs.

• Beckett CleanCut burner pump with the following advantages:

> Cleaner operation by use of a solenoid valve that cuts oil flow

almost instantly when power is cut to the motor, eliminating
coasting stops that can cause soot formation on shut-down.

> Pre-purge type controls work hand-in-hand with the

CleanCut pump to establish airflow and bring pump
pressure up to full operating levels before light-off to ensure
smooth and clean ignition.

> More

conventional pumps and fewer troublesome oil fittings to
cause problems.

2

recycle/limited reset feature to limit the accumulation

reliable with fewer moving parts, compared to

Durable Attractive Casing Design

The casing is treated for protection against corrosion and
painted with an attractive, Modine Gray-Green, baked polyester
powdercoat paint finish.

Quiet, Efficient, and Safe Air Mover

The propeller fan is statically balanced and the motor resiliently
mounted to the finger-proof fan guard to minimize vibration and
noise. Additionally, the draw-formed casing venturi at the air
inlet is designed to reduce fan noise and power consumption.

The motor is a totally enclosed, permanent split capacitor
(PSC) type that provides excellent starting capabilities with low
amp draw on operation.

A fan and limit-control safety device performs three functions:

1) delays start of fan until the heat exchanger has warmed up
and prevents fan from stopping until the heat exchanger has
cooled, 2) protects the unit from overheating, and, 3) provides a
manual switch for constant fan operation.

Effective Heat Throw

Heat throw and coverage are controlled by manual adjustment
of standard horizontal and/or optional vertical louver blades.
Depending on the model, the heat throw will vary from 39 to 51
feet, maximizing heated air distribution at floor level.

Figure 2.1 - Model POR Unit Features

Fan and Limit

Control

Heat Exchanger

Assembly

(See Figure 3.1)

Casing with

Durable Baked

Powdercoat Paint

4-112.3

Polyester

Horizontal

Louvers

Flue Connection

Propeller Fan

with Finger-Proof

Fan Guard

Efficient PSC

Fan Motor

Oil Burner with

Microprocessor

Control

Junction Box

DESIGN FEATURES AND PERFORMANCE DATA

Superior Heat Exchanger Life Expectancy

Long life is due in part to the roll-formed design of the heat
exchanger. Stresses caused by thermal expansion and
contraction typically concentrate in areas of sharp angular
bends or adjacent to welds, all of which are minimized with
roll-forming to distribute thermal expansion stresses uniformly.
Made of corrosion-resistant, 14 gauge aluminized steel, the
heat exchanger contains a preformed, ceramic fiber fire pot
that is thermally efficient, lightweight, resilient, and resists
both mechanical and thermal shocks. It reaches operating
temperature quickly, contributing to the efficiency of operation.

Figure 3.1
Model POR Heat Exchanger Features

Flue Connection

Flue Collector

Heat Exchanger

Internal Baffles

(not shown)

Inspection Port

Service Door

Clean-out Ports

Ceramic Fiber Fire Pot

(not shown)

Efficient Combustion

Combustion products heat flow through the heat exchanger can
be traced by the arrows in the cross-sectional view in Figure 3.2.
Flue products rise to the top of the drum, then pass into the two
radiators of the heat exchanger where internal baffles cause
them to flow to the bottom of the radiators; then back up to
the flue collector and out of the stack. During this passage the
original temperature at the fire pot of 2200-2300° F, is reduced
to a stack discharge temperature of 470 to 570° F. The units
are designed to operate at a stack draft of minus 0.02” W.C.

Easy Installation

All units are factory-assembled, wired, and fire tested prior
to shipment. Units are ready to connect to 115V/60Hz/1ph
supply voltage, a 24V thermostat, fuel lines, and vents. Units
are shipped for a single-unit two pipe oil supply system, but
can be simply modified for a single pipe oil supply system or a
multiple-unit installation supplied by a common fuel distribution
system. They can be suspended with four threaded rods (1/2”­13NC tap) or with 3/4” pipe by use of an optional pipe hanger
kit accessory.

Reduced Maintenance, Easy to Service

Under average conditions Modine unit heaters typically
require inspection only once a year, more often if the air is
contaminated with fumes, dust, or spray.

The heat exchanger is equipped with a convenient inspection
port and the service door opening is ample in size to facilitate
the removal of the fire pot should replacement become
necessary. Two clean-out ports are also readily accessible for
periodic cleaning. Refer to Figure 3.1.

The motor is totally enclosed with permanently lubricated
bearings to minimize maintenance. The fan and limit control,
motors, and burner are externally mounted on the unit for easy
service access.

Application Suggestions

For recommendations on specifying, applications, and locating
unit heaters, refer to Modine Literature 75-203 “How to Specify
the Right Unit Heater”.

Performance Data

Input Input Output CFM Delivery Temp. Max Heat
Model Btu/Hr GPH Btu/Hr @ 70°F FPM Rise °F Height* Throw

POR100 119,000 0.85 100,000 1890 460 49 12' 39'

POR145 175,000 1.25 145,000 2400 580 56 13.5' 50'
POR185 231,000 1.65 185,000 3200 740 54 12' 51'

*Deflector blades pitched 45° at the floor (heated air). Mounting height is measured from floor to bottom of unit.

Fan Motor Specifications

Fan
Motor
Model HP Voltage Hz Phase Amps* RPM Type Fan Dia.

POR100 1/5 115 60 1 2.1 1100 PSC 18"

POR145 1/3 115 60 1 5.4 1100 PSC 18"
POR185 1/3 115 60 1 5.4 1100 PSC 22"

*T otal AMPS equals fan motor AMPS plus burner motor and ignition transformer load of 2.2 AMPS.

Figure 3.2 - Combustion Products Heat Flow

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