SIAL MIRAGE 37 H, MIRAGE 55 H, MIRAGE 85 H, TORNADO 67, TORNADO 115 Servicing Manual

Date Revision Nr

09.06.2004 00

Item Nr

Servicing Manual

MOBILE (OIL- OR KEROSENE-FIRED) EMERGENCY AIR HEATERS

MIRAGE - TORNADO

SIAL S.p.A

C.so Inghilterra, 15 - 12084 MONDOVI’ (CN)
Tel. [phone] fax. [phone]

Website www.sialspa.it
e-mail: [e-mail]

Copyright

No section of this document can be reproduced in any form or processed by means of electronic systems, copied or distributed
without written permission by SIAL S.p.A. The translation into other languages is also allowed only under written permission
by SIAL S.p.A. The use of this document is restricted to SIAL servicing centers and to distributors of SIAL products. This
manual is not intended for end users.

Technical changes

IAL S.p.A. has the right to modify any instruction, description and specification contained in this document without prior

S
notice.

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Servicing Manual

FOREWORD

Thank you for choosing the SIAL MIRAGE-TORNADO heaters. We would like to remind you that, as
for any machine, you can get good operation and performance only if the heaters are correctly used and
always kept in perfect efficiency. If required, the SIAL Technical Service can give you suggestions and
assistance.

The SIAL MIRAGE-TORNADO heaters are especially intended for the professional heating of civil,
industrial and agricultural premises.

Read and follow carefully the instructions contained in this manual before starting any

servicing or maintenance operation.

SIAL S.p.A. will not accept any responsibility for damages to persons, goods, properties or to the
machine itself that may result from non-compliance with the instructions contained in this manual and
with the Laws and safety rules in force in the Country of destination.

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Servicing Manual

INDEX OF CONTENTS

1 Operational diagrams and sequences

1.1 Indirect-fired heaters with flue

1.2 Direct-fired heaters without flue

1.3 Heaters with and without flue: operational sequence

1.4 Safety options in case of abnormal operation

2 Functional description of components

2.1 Casing/Frame

2.2 Motor/fan assembly

2.3 Fuel circuit

2.4 Burner head/Combustion chamber

2.5 Electrical board

3 Troubleshooting guide - Operating flow-chart

3.1 Checking the supply voltage

3.2 Checking/replacing the power cord

3.3 Checking/replacing the motor

3.4 Checking/replacing the fan

3.5 Exhaust gas analysis. Combustion air adjustment

3.6 Cleaning the fuel tank

3.7 Checking/cleaning/replacing the fuel filter

3.8 Checking/cleaning/replacing the fuel nozzle

3.9 Checking/cleaning/replacing the burner head and the whirl disc..

3.10 Cleaning the combustion chamber

3.11 Replacing the motor/pump joint

3.12 Checking/adjusting/replacing the fuel pump

3.13 Checking and replacing the fuel solenoid valve

3.14 Checking/cleaning/replacing the ignition electrodes

3.15 Checking/replacing the high voltage cables

3.16 Checking/replacing the ignition transformer

3.17 Replacing the fuse

3.18 Checking/cleaning/replacing the flame sensor

3.19 Checking/replacing the overheat thermostat

3.20 Checking operation of flame control unit

4.1 Setting chart - Indirect-fired heaters with flue
Setting chart - Direct-fired heaters without flue
Technical data sheets for indirect-fired heaters with flue
Technical data sheets for direct-fired heaters without flue

4.2 Wiring diagrams - Basic version and versions with filter and nozzle fuel pre-heater

4.3 Special tools for servicing

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Servicing Manual

1. OPERATIONAL DIAGRAMS AND SEQUENCES

1.1 INDIRECT-FIRED HEATERS WITH FLUE

Flue

Burner head

Fuel pump

Combustion chamber
(closed)

Fuel tank

4

Motor

Fan

Servicing Manual

1.2 DIRECT-FIRED HEATERS WITHOUT FLUE

Burner head

Fuel pump

Combustion chamber
(open)

Fuel tank

5

Motor

Fan

Servicing Manual

1.3 HEATERS WITH AND WITHOUT FLUE: OPERATIONAL SEQUENCE

T1
T2
T3
T4
T5

SW

M

T
SV
PH

F

Prepurge time
Ignition time
Operation time
Safety time at flame failure
Aftercooling time

Switch
Motor
Ignition transformer
Fuel solenoid valve
Flame sensor
Flame

Prepurge sequence

During the prepurge time (about 10 s) the fan blows air into the combustion chamber to expell any
residual exhaust gases. The ignition transformer T produces a spark so that any small fuel residuals
coming from the solenoid valve through the nozzle are completely burnt. At the same time the flame
control unit checks for presence of flame or spurious light inside the combustion chamber: should this
occur, the ignition sequence is interrupted and the heater locks out, that is all the electrical components
are immediately unpowered.

Ignition sequence

During the ignition time, after the prepurge time, the fuel solenoid valve EV opens and the spark
produced by the electrode ignites the fuel mist sprayed by the nozzle. The flame sensor (photoresistor)
PH must feel the presence of flame within 1 s (safety time), otherwise the flame control unit locks out and
the motor is stopped. If the flame sensor only feels a small flash and not a continuous flame, the whole
prepurge and ignition sequence is repeated and then, if ignition is still unsuccessful, the unit goes to lock­out and stops.

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Servicing Manual

Operational sequence
15 s after a regular flame ignition, the flame control unit de-energizes the ignition transformer and the
electrodes stop sparking. The heater goes on operating with self-sustained combustion. The flame control
unit monitors the regular presence of flame by means of the flame sensor. Any abnormal condition, such
as lack of fuel, blockage of air inlet/outlet, dirty or clogged nozzle, that impairs regular combustion has
the effect to close the fuel solenoid valve SV and to interrupt the fuel flow to the burner within the safety
time. The flame control unit will then start a new complete prepurge/ignition sequence, and, should the
problem repeat, the unit will lock out and the aftercooling sequence will start.

Restart sequence

If the flame shuts down for any reason, the flame control unit repeats the whole start sequence, consisting
of the prepurge and the ignition sequences. If there is no flame signal within the safety time T4, the
control unit goes to lock-out and the red lamp on the control panel lights up. If, on the contrary, a small
flame signal is detected within the safety time, the control unit repeats the start sequence. The whole
sequence will be repeated 3 times maximum and then the unit will definitely lock out. A maximum
number of 3 ignition tries has been fixed to avoid that excessive smoke is produced during the repeated
starting sequences. This effect could occur when the fuel tank is almost empty and the suction hose
contains fuel and air mixed, or when the nozzle is partially blocked or damaged, and therefore the
pressurized fuel is incorrectly sprayed.

Aftercooling sequence
During this time the heater is subjected to a cooling cycle to avoid excessive overheating of materials
and components that could occur if the motor/fan suddenly stopped. This sequence is also very important
from the point of view of efficiency, as all the residual heat that accumulates in the combustion chamber
can be recovered and sent in the space to be heated.
For safety reasons, it has been established that the high voltage ignition transformer must be energized
during the aftercooling time. By doing this, any small fuel residuals coming from the solenoid valve SV
will burn completely and will not accumulate inside the combustion chamber. Any explosion risk or
abnormal heat release during future ignition sequences is therefore prevented.
The aftercooling time is factory set and independent of the action of a limit control or similar devices on
the combustion chamber. The aftercooling time lasts about 1 minute and 45 seconds.

Lock-out sequence

In the event of flame shut down due to lack of fuel or to another reason (see also the par. “SAFETY
OPTIONS IN CASE OF ABNORMAL OPERATION”) the flame control unit will put the heater in a
safety condition starting the lock-out sequence. During this sequence the fuel solenoid valve SV is
immediately closed within the safety time T4 (< 1s) and then an aftercooling cycle will start to cool the
surfaces of the combustion chamber. The ignition transformer is powered, and therefore a spark is
produced by the electrodes, during the aftercooling cycle as described above.

eset sequence

R

The unit can be reset by pushing the red reset pushbutton with integral warning lamp on the control panel.
For safety reasons, reset will only be possible after about 30 s from lock-out. Also in the event of
electrical supply failure/restoration, reset will only be possible after 30 s approximately.

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Servicing Manual

1.4. SAFETY OPTIONS IN CASE OF ABNORMAL OPERATION

• Spurious (external) light or anticipated ignition

During the prepurge time no flame signal must come to the flame control unit. A flame signal with no
flame could be due to external lights, short-circuit in the flame sensor or in the flame sensor leads, fault in
the flame signal amplifier, fire on board of the unit, or, should the solenoid valve SV not properly
interrupt the fuel flow to the nozzle, to anticipated ignition of the fuel/air mist during the prepurge time.
In this case after the prepurge time and the safety time, the unit goes to lock-out.
Special attention is required in the event that the heater is directly exposed to sunlight (e.g. when used
outdoors). It may happen that sunrays come into the combustion chamber and give a false flame signal,
especially when the heater is new and the inner surfaces are bright and reflect light.

• Flame failure at ignition

If there is no flame signal at the end of the safety time T4, the flame control unit goes to lock-out
condition.

• Flame failure during operation
If the flame signal fails during operation, the flame control unit closes the fuel solenoid valve, the fuel
flow to the nozzle is interrupted and a new prepurge/ignition cycle is started. In case of lock-out, the unit
can be manually reset after 30 s approx.

• Overheat thermostat activation
In the event of combustion chamber overheating, the overhat thermostat interrupts the electrical supply to
the flame control unit and to all components. The heater is immediately stopped.
The possible causes of overheating are described in par. 3 “TROUBLESHOOTING GUIDE”

2. FUNCTIONAL DESCRIPTION OF COMPONENTS

ASING/FRAME

2.1 C

Description

The heater casing consists of :

a tank made of galvanized steel which also acts as a support for the whole machine.
a support fixed on the tank to which the lower half-shell of the heater is connected. This support

also contains the electrical board.

a lower half-shell which, together with the upper half-shell, forms the air duct where heat is

transferred to the flowing air. All main components are directly fixed onto the lower shell.

an upper half-shell that completes the air duct and can be disassembled by unscrewing 6 screws

for servicing and maintenance. On the indirect-fired heaters with flue the upper shell includes a
circular hole for the flue collar.

on the upper shell you can also find an inspection door that allows operators to reach the

components inside the heater and to carry out most of the repair and maintenance operations.

on the rear, a protection guard is fitted on the air inlet to prevent any contact with the rotating

parts of fan/motor.

on the front, a half cylindrical protection shield if fitted between the combustion chamber and the

lower shell, to limit the temperature of such part, that is directly accessible and can be touched by
the operators.

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Servicing Manual

On the front a diffuser outlet cone allows the warm air (on indirect-fired heaters) or the mixture of

warm air and exhaust gases (on direct fired heaters) to be released into the heated room. The axle
with wheels and the support foot are connected below the tank.

2.2 FAN/MOTOR ASSEMBLY

Description

An electrical motor drives both the fan and the oil pump. A helicoidal fan provides a constant air flow in
the axial direction, a part of which is used for the combustion ; the remaining part flows along the
surfaces of the combustion chamber and of the heat exchanger, and it is consequently heated. The fan is
connected to the motor shaft by means of a threaded pin.
The oil pump has the function to suck fuel from the tank and to drive it to the nozzle at the rated
pressure : the pump is connected to the motor shaft by a resin joint and fixed to the motor casing by
means of 3 threaded pins. Single-phase, 2- or 4-poles motors with rotational speeds of 2800 rpm or 1400
rpm are used according to the heater model. See technical data sheet for detailed motor specifications.

ILL. 1: particolare gruppo motore MIRAGE 85H – TORNADO 115

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Servicing Manual

2.3 FUEL CIRCUIT

Description

The fuel circuit is basically composed of :

tank
suction and return hoses
fuel filter,
fuel pump,
fuel solenoid valve,
high pressure microhose
combustion head
nozzle

The gear pump, driven by the motor, sucks fuel from the tank and increases its pressure to the rated value.
At the pump outlet a fuel cut-out solenoid valve SV is fitted. The pump is controlled by the flame control
unit. During normal operation the valve is open and the pressurized fuel flows to the nozzle, where it is
atomized, mixed with primary combustion air and ignited by the electrode spark. The flow of primary air
to the burner is adjusted by an air lock on the combustion head.
Under abnormal operating conditions (see also flow-chart) the flame control unit closes the solenoid
valve SV, fuel does not come to the nozzle but goes back to the tank through the return hose. An
adjustment screw is fitted on the front of the pump ; it allows to adjust the pressure and consequently the
fuel flow.

ILL. 2: particolare gruppo filtro gasolio

2.4 BURNER HEAD/COMBUSTION CHAMBER

ILL. 3: particolare pompa gasolio

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Description

Servicing Manual

A certain amount of air coming from the fan flows around the combustion head, and, depending on the
air lock setting, a part of it - the so-called primary air - flows inside the burner head. The primary air is
distributed and mixed with the atomized fuel jet exiting the nozzle by means of a baffle disc. To get good
combustion and therefore high efficiency, the adjustment of the primary air/fuel ratio must be very
accurate. For this purpose, please carefully follow the setting specifications and instructions contained in
this manual.

The burner head includes :

nozzle holder
air lock
baffle disc (whirl disc)
fuel nozzle
ignition electrode
flame sensor (photoresistor)

The fuel coming out of the nozzle is atomized and mixed with primary air. Additional circumferential
openings on the burner head allow another amount of air, called secondary air, to flow into the chamber.
That is an additional air delivery that completes combustion.
During the whole ignition sequence the electrodes are powered by the high voltage transformer and
produce a spark that ignites the fuel-air mixture.
The function of the whirl disc is to induce a rotational component in the primary air flow and therefore to
decelerate it : this way the mixing of fuel and air is increased and the combustion improved.

The combustion chamber is made of stainless steel. It includes :

a rear end on which the combustion head is fitted
a front end with hole on direct heaters, without hole on indirect heaters
a front flame shield on direct heaters
the heat exchanger with gas passageways
the exhaust gas flue collar
the protection shield around the chamber
a manually resettable overheat thermostat

2.5 ELECTRICAL BOARD

ILL. 4: particolare testa di combustione

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Description

Servicing Manual

ILL. 5: particolare cruscotto

The electrical board has the function to broadcast the electrical supply coming from the electrical system
through the power cord to all components, by means of a control/command electronic device, called
burner (flame) control unit. This part has also the task to monitor flame and to ensure safe operation of
the heater during all its operational sequences.

The electrical board consists of the following parts :

Control panel
Protecting cover (against water/dust)
Power cable with strain relief and plug
ON/OFF switch
Remote room thermostat socket with plastic cover and inner electrical bridge (closing circuit for

operation without thermostat)

Reset pushbutton with built-in warning lamp
high voltage ignition transformer
fuse with fuseholder
electronic burner (flame) control unit

3. TROUBLESHOOTING

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Servicing Manual

SWITCH

ON

Check for correct voltage

rating ( see data plate)

Check that the green warning

lamp on the control panel is

alight

• Check all electrical connections

• Check the warning lamp

THE HEATER STARTS

yes

no

Check fuse (burn-outs,

damages, etc.)

Check the burner control unit

Check that the red lock-out

warning light is not alight

Check that the overheat

thermostat has not been

activated

• Replace with a new one with
identical ratings

• See chapter 3...

• Replace the burner control unit

• Wait 30 seconds and push to

reset

• Open the inspection cover and
push to reset

Check that the remote
thermostat is properly

connected and adjusted

For operation without remote

thermostat, check that the
thermostat socket cover is

correctly inserted

in the socket

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• Check connections

• Set a temperature value higher

than room temperature

• Check the metal bridge inside
the cover

• Reinsert and lock