Technical information

5
DESCRIPTION OF EQUIPMENT
Heat exchanger
• Stainless steel construction easily accessible for
inspection and cleaning and maintenance operations.
• Patented exchange elements made in stainless steel
modular sections with large surface area, trapezoidal in
section with swirl impressions for which give thermal yields
of over 90%. The exchange elements have no welded
joints or seams near to the burner flame so as to avoid
exposure of any weak points.
Flue outlet with integral flue venter to assist dispersal of
combustion gasses.
External casing
Encloses all controls giving a good aesthetic appearance and
streamlined look whilst allowing for easy inspection.
The casing consists of removable panels and also includes:
A burner compartment which is totally sealed off, with an
inspection door;
Radiant heat insulation on the surfaces closest to the heat
exchanger;
Outlet grille for directing the warm air.
Fan assembly
One or two centrifugal fans operated by a single electric
motor via pulleys and belts the motor pulley is adjustable to
give effective cooling of the combustion / heat exchanger.
The position of the fan(s) produce greater effective cooling of
the combustion chamber, optimising the heat exchange and
avoiding overheating.
An up rated fan is also available.
Control and protection equipment
This is electronic with ionisation flame detection and ignition
controls.
The equipment controls and monitors the operation of the
burner in the following sequence.
Checks the differential pressure switch operated by the flue
venter is in the closed position and the flue venter is working;
Checks the air temperature of the combustion chamber
(below 100ºC)
Opens the gas solenoid valve;
Starts burner ignition;
Detects flame signal from flame probe and allows normal
heater operation.
Failure in any of the above sequence will result in the control
box shutting the gas valve and stopping the heater.
The Heater will go to lockout and can be only be reset
manually by pressing the red light on the front of the
equipment.
Gas solenoid valve
The multifunctional 1 stage gas valve (Single Stage)
and 2 Stage gas valve (Two Stage ) consists of:
• Safety solenoid valve
• A regulatory solenoid valve
• A pressure regulator
• A gas filter
Atmospheric multigas burner assembly
Consisting of:
• Galvanised steel manifold
• Visual monitoring aperture for the electrodes and flame
observation
• 3 or 6 stainless steel burner bars
• Ignition and Detection electrodes
Note: the type 4-5-6 are equipped with two gas manifolds,
each manifold has an ignition electrode.
Control and safety thermostat
The heater is controlled by three thermostats pre set to the
following.
LM Limit thermostat (100°C)
Capillary type. Manual Reset
Act as a safety device and shuts down the burner if the
heater goes to overheat. The yellow light will flash when in
overheat. The LIMIT thermostat is reset by the removal of the
plastic cap situated on the control panel inside the heater, and
manually pressing the reset button, after first ensuring that the
fault has been rectified. (calibrated at100°C). Replace cap
after resetting thermostat.
TR Regulatory thermostat (0 – 90°C)
Capillary type. Automatic reset.
The thermostat monitors the temperature of the airflow and will
shut down the burner if the set level is exceeded (calibrated at
70°C). Once the fan has sufficiently cooled the heat
exchanger, the burner will automatically relight. The yellow
indication light will flash until the burner relights. If this fault
persists the cause should be investigated.
SND Control probe (0 – 40°C)
Connected in series with the thermostat TR. The probe will
start the fan when the temperature reaches 30°C
(approximately 30 seconds from burner ignition). When the
desired room temperature is reached and the burner shuts
down, the probe will allow the fan to run for approximately 3-
minutes until the heat exchanger has cooled sufficiently.
The probe also monitors the operation of the TR thermostat
and if a fault is detected will change the yellow flashing light to
a continous on light. In addition to this the SND probe monitors
the temper
ature of the return air and will switch off the fan prior
to the 3-4 minute run on time if the heat exchanger has cooled
sufficiently (this avoiding cold air flow from the heater).
Differential air pressure switch
This switch will shut the gas valve if the flue venter fails or
there is an obstruction in the flue, or in the air inlet preventing
the flue venter from operating.
Flue venter
This consists of a centrifugal fan which
Is run by an electric motor with self-cooling rotor the cooling air
is supplied through a duct pipe situated in the axial fan air flow.
Indication lights
These consist of three different coloured lights on the front of
the heater:
• Green light – indicates normal working. Illuminates when
the gas solenoid valve opens
• Yellow light – indicates the operation of the LM, TR and
SND thermostat.
• Red light - to indicate lockout of the heater by the control
circuit failure.
• Reset button to reset the lockout
Flue spigot
A flue spigot (100mm) is situated at the rear of the heater for
connection of flue pipes.
Combustion air spigot
A combustion air spigot (100/150mm) with a safety mesh of
less than 16 mm Ø on the rear of the heater allow for
connection of combustion air pipe