Reznor UESA User manual

1104UESAGBEN, page 1/31
WARNING
Please read this document carefully before commencing installation, commissioning and/or servicing.
Leave it with the user or attached to the appliance or gas service meter after installation.
Improper installation, adjustment, alteration, service or maintenance can cause property damage, injury or death.
All work must be carried out by appropriately qualified persons.
The manufacturer does not take any responsibility in the event of non-observance of the regulations concerning
the connection of the apparatus causing a harmful operation possibly resulting in damage to the apparatus and/or
environment in which the unit is installed.
Installation/Operation/Maintenance
Applies to: Model UESA
High-Efficiency, Separated-Combustion,
Low-Static Unit Heater
Reznor U.K. Limited - Park Farm Road - Folkestone - Kent - England
tel : [phone]
fax : [phone]
These appliances meet the following EC Directives:
DIR 2009/142/EC:GAD
DIR CE 89/336/EEG:EMC
DIR 73/23/EEG:LVD
DIR 89/392/EEG:MD
UESA

1104UESAGBEN, page 2/31
TABLE OF CONTENTS
1. General....................................................................................................................................................3
1.1 Warning
1.2 General information
1.3 Warranty
1.4 Installation codes
2. Unit heater location...............................................................................................................................4
3. Uncrating & preparation........................................................................................................................4
4. Clearances & dimensions.....................................................................................................................5
5. Hanging the heater................................................................................................................................7
6. Mechanical.............................................................................................................................................8
6.1 Gas piping & pressures
6.1.1 Gas supply
6.1.2 Gas connections
6.1.3 Burner gas pressure and adjustment
6.1.4 Gas conversion
6.2 Venting and combustion air
6.2.1 Flue requirements
6.2.2 Flue requirement for installations type B
6.2.3 Flue requirement for installations type C
7. Electrical connections.........................................................................................................................16
7.1 General
7.2 Wiring connection
8. Controls................................................................................................................................................18
9. Ignition system....................................................................................................................................20
10. Operation.............................................................................................................................................21
10.1 Installation check
10.2 Heater start-up
10.3 Operating instructions
10.4 Installation check after start-up
11. Maintenance and service....................................................................................................................22
11.1 Maintenance schedule
11.2 Maintenance procedure
11.3 Troubleshooting
12. Spare parts list.....................................................................................................................................30
Addendum : Technical data ......................................................................................................................31

1104UESAGBEN, page 3/31
1.1 Warnings FOR YOUR SAFETY
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.
• Evacuate all personnel.
Do not store or use petrol or other flammable vapours and liquids in the vicinity of this
or any other appliance.
WARNINGS
Improper installation, adjustment, alteration, service or maintenance can cause
property damage, injury or death. Read the installation, operation and maintenance
instructions thoroughly before installing or servicing this equipment.
Gas-fired appliances are not designed for use in hazardous atmospheres containing
flammable vapours, combustible dust, chlorinated or halogenated hydrocarbons or
in applications with airborne silicone substances.
Should overheating occur, or the gas supply fail to shut off, shut off the manual gas
valve to the appliance before shutting off the electrical supply.
Do not use this appliance if any part has been immersed in water. Immediately call a
qualified service technician to inspect the appliance and replace any gas control that
has been immersed in water.
This appliance is not intended for use by persons (including children) with reduced
sensory or mental capabilities or lack of experience and knowledge, unless they
have been given supervision or instruction concerning use of the appliance by a per-
son responsible for their safety. Children should be supervised to ensure that they
do not play with the appliance.
1. GENERAL
1.2 General
information
Models UESA 035 through 102 are design certified to the CE EN1020 standard for use
in industrial and commercial installations only. All models and sizes are available for use
with either natural, propane or butane gas with operating temperature between -15°C
and 40°C. The type of gas, input rate and the electrical supply requirements are shown
on the heater rating plate. Check the rating plate to determine if the heater is appropriate
for the intended installation.
The installation manual is shipped with the heater. Verify that the literature is correct for
the heater being installed. If the manual is incorrect for the heater, contact the supplier
before beginning installation.
The instructions in this manual apply only to the models listed.
Installation should be done by a suitably qualified installer in accordance with these in-
structions. The installer is responsible for the safe installation of the heater.
Model UESA heaters have a titanium stabilised primary heat exchanger with a Macro
ChannelTM secondary heat exchanger.
1.3 Warranty Warranty is void if :
a. Wiring is not in accordance with the diagram furnished with the heater.
b. The unit is installed without proper clearances.
c. A fan model is connected to a duct system or if the air delivery system is modified.
1.4 Installation
codes
These units must be installed in accordance with BS6230 or BS5440 as appropriate plus
any local building regulations.
CAUTION :
Model UESAheaters
should not be used
in an application
where the heated
space temperature
is below 10°C.

1104UESAGBEN, page 4/31
2. UNIT HEATER
LOCATION
Use the minimum clearances in section 4 and the throw data in the technical data
table addended when determining where to suspend the heater.
Recommended minimum height is 2.5mm.
WARNING
If touched, the vent pipe
and internal heater sur-
faces that are accessible
from outside the heater
will cause burns. Suspend
the heater such that these
components cannot be
touched.
REMARK
Flue requirements may
affect location. Consult
section 6 before making a
final determination.
For best results, the heater should be placed with certain rules in mind. Always
ensure that minimum clearances are maintained. Locating a unit heater above
the maximum recommended height can result in significant air stratification.
When possible, heaters should be arranged to blow toward or along exposed
wall surfaces.
Suspended heaters are most effective when located as close to the working zone
as possible, but care should be exercised to avoid directing the discharged air
directly on occupants.
Partitions, columns, counters, or other obstructions should be taken into consid-
eration when locating the unit heater so that a minimum quantity of airflow will be
deflected by such obstacles.
When units are located in the centre of the space to be heated, the air should
be discharged toward the exposed walls. In large areas, units should be located
to discharge air along exposed walls with extra units provided to discharge air
in toward the centre of the area. For optimum results heaters are best used in
conjunction with recirculating air fans suspended at high level.
At those points where infiltration of cold air is excessive, such as at entrance
doors and shipping doors, it is desirable to locate the unit so that it will dis-
charge directly toward the source of cold air, typically from a distance of 4.5 to
6.0 meters or install a downflow unit over the door opening.
CAUTION
Do not locate the heater
where it may be exposed
to water.
Hazards of Chlorine - applies to the location of the combustion air inlet
The presence of chlorine vapours in the combustion air of gas-fired heating
equipment presents a potential corrosion hazard. Chlorine, found usually in the
form of freon or degreaser compounds when exposed to a flame will precipitate
from the compound, and go into solution with any condensation that is present
in the heat exchanger or associated parts. The result is hydrochloric acid which
readily attacks all metals. Care should be taken to separate these vapours from
the combustion process. This may be done by wise location of the unit flue and
combustion air terminals with regard to exhausters or prevailing wind directions.
Chlorine is heavier than air. Keep this fact in mind when determining installation
location of the heater in relation to building extract systems.
3. UNCRATING &
PREPARATION
This unit was test operated and inspected at the factory prior to crating and was
in proper operating condition. If the heater has incurred damage in shipment,
document the damage with the transport company and contact your supplier.
Check the rating plate for the gas and electrical specifications of the heater to be
sure that they are compatible with the gas and electric supplies at the installation
site.
Read this booklet and become familiar with the installation requirements of your
heater. If you do not have knowledge of local requirements, check with the gas
supplier and any other local agencies who might have requirements concerning
this installation.
Before beginning, make preparations for necessary supplies, tools, and man-
power.
If the installation includes optional vertical louvres or downturn nozzle etc.,
install these options before the heater is suspended. Follow the instruc-
tions included in the option package.

1104UESAGBEN, page 5/31
4. CLEARANCES &
DIMENSIONS
Units must be installed so that the clearances in table below are provided for com-
bustion air space, inspection and service and for proper spacing from combustible
materials.
UESA
035,055, 083,102
Top Rear Bottom
(*)
Access
panel
Non-access
side
(mm) 100 450 100 700 100
Suspend the heater so that the bottom is a minimum of 2.5m above the floor.
Figure 1a:
Table 1a:
Clearances
(*) Heaters can be base mounted on suitable non combustible supports
Attention : The minimum
overall clearances to the
flue outlet system must be
150mm.
Dimensions UESA 035 & 055
Rear view Side view
Front view Top view
Legend
1. Combustion air inlet Ø 100
2. Flue connection Ø 100 with condensate drain tap 3/4” male
3. External gas connection
4. Electrical connections
5. Service panel
6. Condensate drain dia 32mm female

1104UESAGBEN, page 6/31
Figure 1b:
Dimensions UESA 083 & 102
Combustion air supply & flue system diameters
Diameter gas connection
Table 1b:
UESA 035 055 083 102
Flue outlet/Air inlet
diameter (mm) 100 100 130 130
Gas connection
diameter 3/4" 3/4" 3/4" 3/4"
Rear view Side view
Front view Top view
Legend
1. Combustion air inlet Ø 130
2. Flue connection Ø 130 with condensate drain tap 3/4”
3. External gas connection
4. Electrical connections
5. Service panel
6. Condensate drain dia 32mm female

1104UESAGBEN, page 7/31
The heater is supplied with four point suspension. All points must be used.
Threaded nut inserts are provided on each side of the top panel of the heater.
See figure below.
5. HANGING THE
HEATER
Before suspending the heater check the supporting structure to be used to
verify that it has sufficient load-carrying capacity to support the weight of the
unit. Suspend the heater only from the threaded nut inserts. Do not suspend
from the heater cabinet.
When the heater is lifted for suspension, leave the unit on the pallet. Before
hanging, verify that all screws originally used to fix the shipping supports, are
rescrewed into the cabinet.
WARNING
WARNING
Unit must be level for proper
Unit must be level for proper
operation. Do not place or
operation. Do not place or
add additional weight to the
add additional weight to the
suspended heater.
suspended heater.
UESA 035 055 083 102
kg 148 151 222 230
Table 2:
Weight (kg)
Figure 2:
Suspending the heater
with rods from the
threaded nut inserts
Be sure that the threaded hanger rods are locked to the heater as illustrated in
figure 2. Recommended maximum hanger rod length is 1.8m. Where longer
drops are required, ensure that restraints are fitted to prevent excess lateral
movement and supports are adequately sized.
Add a nut to lock the
M10x1.5 hanger rod to the
heater
Alternatively the unit can also be base mounted on a non-combustible sup-
port. In this case ensure that unit is securely fixed on the base.

1104UESAGBEN, page 8/31
6.1 Gas piping &
pressures
WARNING :
Do not over tighten and
do not rotate the gas valve
inside the heater control
compartment.
Table 3
Gas connections
6. MECHANICAL 6.1.1 Gas supply
WARNING : Pressure testing supply piping
Test pressures above 50mbar : Disconnect the heater and manual valve from the
gas supply line which is to be tested. Cap or plug the supply line.
Test pressures below 50mbar : Before testing, close the manual valve on the
heater.
All piping must be in accordance with requirements outlined in the National Gas
Codes (different for each country). Gas supply piping installation should also
conform with good practice and any local codes. Support gas piping with pipe
hangers, metal strapping, or other suitable material. Do not rely on the heater
to support the gas pipe.
All sealing products shall be resistant to the action of liquefied petroleum gas or
any other chemical constituents of the gas being supplied.
Install a ground joint union and manual shutoff the gas cock upstream of the
unit control system (see figure 3).
The unit is equipped with a nipple that extends outside the cabinet. The gas
connection is 3/4”,
Leak test all gas connections by brushing on a leak detecting solution.
6.1.2 Gas connections
WARNING
All components of a
gas supply system must
be leak tested prior to
placing equipment in
service. NEVER TEST
FOR LEAKS WITH AN
OPEN FLAME. Failure
to comply could result in
personal injury, property
damage or death.
Figure 3
Gas connection
WARNING
This appliance is
equipped for a maxi-
mum gas supply pres-
sure of 50 mbar.
UESA 035 055 083 102
Nat. Gas
3/4" 3/4" 3/4" 3/4"
Propane
6.1.3 Burner gas pressure and adjustment
The gas pressure is set for the required heat input before the appliance leaves the
factory. Provided that the gas supply to the air heater is in accordance with the sup-
ply pressure described on the appliance data plate, the operating pressure will not
require adjustment. To check the pressure use the following procedure:
* Ascertain from the heater data plate the correct operating gas pressure;
* Turn the room thermostat control to its lowest setting;
* Remove the screw from the burner pressure test point of the multi-functional
control valve. Connect a manometer to the supply pressure test point( see fig-
ure 4);
* Adjust the room thermostat to call for heat i.e. above room ambient tempera-
ture;
* Observe the burner gas pressure on the manometer and compare to the stated
pressure on the data plate;
* If necessary, adjust the burner gas pressure. Remove the cover screw. Turn
the regulator screw anti-clockwise to decrease pressure or clockwise to in-
crease pressure (see figure 4);
* Set room thermostat to lowest setting to turn OFF the burners. Replace the test
point screw/cap and with the main burner OFF, test for gas soundness using a
leak detector fluid.
Reset temperature control/room thermostat to comfort operating level.

1104UESAGBEN, page 9/31
Minimum inlet pressure natural gas : 17.0mbar
Minimum inlet pressure propane : 35.0 mbar
Table 4
Burner jets and
pressures
Figure 4
Honeywell gas
valve
1) Gas inlet
2) Gas outlet
3) Inlet pressure tap
4) Outlet pressure tap
5) 6.3mm AMP terminals and screws for wiring
6) 6.3mm AMP terminals
7) Earth terminal/screw (line voltage models only)
8) Pressure regulator adjustment screw
68 7 5
1
342
035 055 083 102
Nat. Gas
(G20)
Burner jet mm 5,30 6,80 7,60 8,90
Burner
pressure mbar 8,80 8,10 11,20 8,90 inlet pressure
20mbar
Prop. (G31)
Burner jet mm 2,90 3,65 4,50 5,00
Burner
pressure mbar 36,20 35,80 35,40 34,70 inlet pressure
37mbar
6.1.4 Gas conversion
Reznor UESA air heaters are designed to operate on natural, propane or butane gas
and will be supplied fitted for the gas type ordered. In the event a site conversion is
required it is necessary to change the burner jet and gas valve.
Affix new data plate and gas type label.
Upon completition of conversion re-commission the air heater in accordance with sec-
tion 9 of this document.
Changes to carry out :
Natural gas : set pressure regulator as per table in section 6.1.3
Propane/butane : set pressure regulator on maximum pressure and seal regulation
screw.
Additional information is supplied with the conversion kit.
6.2.1 Flue requirements
Model UESA heaters may be installed as Type-B or Type-C installations.
Flue must be in accordance with BS6230 or BS5440. Local requirements may apply in
addition to national requirements. The heaters are designed to operate safely and effi-
ciently with either a horizontal or vertical flue system when installed in accordance with
the manufactuerers instructions. If this heater is replacing an existing unit, ensure that
the flue is of the correct size and if suitable to use the existing flue is in good condition.
A correctly sized flue system is required for safe operation of the heater. An uncorrectly
sized flue system can cause unsafe conditions.
6.2 Flueing and
combustion air

1104UESAGBEN, page 10/31
The units may be installed as a balanced flue type C heater requiring both a com-
bustion air inlet pipe and a flue pipe or as a power vented heater type B where the
combustion air is taken from the space where heater is installed and which requires
only a flue pipe exhausting to outdoors.
All products of combustion must be flued to outdoor atmosphere.
Each heater installed as a type B appliance must be fitted with an individual flue pipe
and the combustion air inlet opening must be provided with a protection grill. Each
heater installed as a type C appliance must be fitted with an individual combustion
air/flue pipe system. Type C2 appliance, with single pipe system for supply of
combustion air and evacuation of flue gasses, are not allowed.
IMPORTANT :
A condense drain must be fitted to both the unit and the flue outlet to properly drain all
condensation (see figure 5).
The flue must be installed in accordance with national and local regulations. Failure
to provide proper flueing could result in death, serious injury and/or property damage.
The air heater must be installed with a flue to the outside of the building. Safe opera-
tion of any power vented gas apparatus requires a properly operating flue system,
correct provision for combustion air and regular maintenance and inspection.
The combustion products are loaded with moisture, some of which will condense out
within the flue. No condensate leakage is permitted. Horizontal flue runs must rise
by 1° (17mm per meter) from the appliance to ensure that the condense returns
to the flue drain.
Gasket sealed single wall seamless heavy gauge aluminium pipes are required for
use with condensing gas appliances. All joints must be sealed to prevent leakage of
flue gases or condensation into the building.
For testing, the flue pipe should include a sealable test point. Ideally the test point-
should be at least 450mm away from the air heater flue connection socket. However
if a concentric flue is attached directly to the connection sockets then the combustion
should be tested through the flue outlet collar via a drilled test point which must be se-
curely plugged on completion.
Follow the flue pipe manufacturers installation instructions for making joints, including
connections to the air heater, for passing through a building element and for support
requirements.
The installer must install a condensate drain system. A 3/4” male fitting connection is
furnished with the heater for the vent drain. All other material must be field supplied.
Table 5
Diameter & maximum flue
pipe lengths
UESA 035, 055 083, 102
Heater socket & pipe dia mm flue pipe 100 130
inlet pipe 100 130
Max. straight length (with wall/
roof terminal)
mflue pipe 9 9
inlet pipe 9 9
Equivalent length of 45° elbow m flue pipe 0.75 0.75
inlet pipe 0.75 0.75
Equivalent length of 90°
elbow
mflue pipe 1.5 1.5
inlet pipe 1.5 1.5
•Use only one dia of flue pipe on an installation
•Recommended minimum flue length is 1m

1104UESAGBEN, page 11/31
Figure 5:
Method to install conden-
sate drain
Condensate drain vent pipe
Condensate drain secondary
H.E.
Example connection of differ-
ent condensate drains
Connection for PVC tube dia
32mm
Table 6
Condense drain
rates of flow :
UESA 035 055 083 102
Natural gas l/h 2.3 3.1 6.6 7.5
Propane l/h 1.1 2.2 2.9 3.2
During operation, condensate is both produced in the heater and collected from the vent-
ing system. Therefore, the installaton requires a condensate drain from the secondary heat
exchanger and a condensate drain from the flue exhaust pipe. A short flue pipe with 3/4”
condensate drain point is supplied with the heater and a PVC collar for PVC tube of dia 32
is provided to drain the condensate from the secondary heat exchanger (see figure 5).
Important : each condensate drain must include a separate trap (no part of delivery).
3/4” male drain
tap
Remark : horizontal flue
must rise by 1° from the unit

1104UESAGBEN, page 12/31
Condensate drain traps :
Two condensate drain traps are required.
Figure 6 illustrates the trap in the drain attached to the heater and lists the minimum
required leg dimensions for that trap.
Figure 7 illustrates the flue exhaust pipe drain trap and shows the minimum dimen-
sions for the trap.
IMPORTANT : The most important part of fabricating and assembling the
traps is the length of the individual legs of the traps. If the pipes are not
installed as illustrated, it could prevent proper drainage of the condensate
and possibly permit flue gas to enter the building. The length difference is
also what provided a ‘water seal’ that prevents leakage of flue gas into the
sanitary drain.) The two traps may be drained into a common pipe that is
connected to the sanitary drain.
Downstream from the traps the condensate drains may be joined and both must be
connected to a sanitary drain within the building. Check codes to be certain that this
is permitted (condensate from the heater has about the acidity of soda pop and is
not harmful to a sanitary drain). UESA heaters will produce condensate depending
on size and gas type (see table 6).
A condensate disposal system that relies on gravity should be satisfactory for most
installations since unit heaters are normally installed several feet above the floor.
If a gravity system is not possible, a condensate pump must be installed. There
are a number of commercially available pumps made for this purpose. If using a
condensate pump, follow the pump manufacturer’s installation recommendations.
REMARK
Fill both drain taps with
clean water before com-
missioning the unit!
Figure 6
The orientation of the piping is not critical and may be arranged to suit the in-
stallation. Unions are recommended to permit maintenance of the drains and
to facilitate service of the heater. A union is shown in both of the traps and a
third union is recommended in the drain pipe.
During installation, fill the traps with water until they are completely filled.
Minimum dimensions
A = minimum 80mm
B = A + at least 50mm (min. 130mm)

1104UESAGBEN, page 13/31
Figure 7
6.2.2 Flues for power vented installations (type B appliances)
If the air heater is to be installed as a type B appliance, air for combustion will be taken
from within the space where the heater is installed. Ensure that an adequate air sup-
ply for combustion and ventilation is provided within the building in accordance with
BS6230/BS5440 plus other relevant regulations & rules in force.
Single wall flue pipe seamless aluminium pipes are required. All joints must be sealed
to prevent products of combustion from leaking into the building.
As condensation is unavoidable, provision must be made for the condensation to flow
freely to a point to which it can be released. Always use a slope of 1° (17mm/meter per
horizontal pipe) ensuring that the condensate flows to the flue drain.
Figure 8
Type B appliances :
combustion air and flue
pipe sockets
AIR INLET
FLUE OUTLET
Do not install vent piping near any source of heat (steam lines, radiant heaters, etc).
Minimum dimensions
D = minimum 130mm
C = D + at least 50mm (min 185mm)
Flue condensate drain tap

1104UESAGBEN, page 14/31
Figure 9
Approved appliances type
B.
For illustrative purposes
only. For actual pipe con-
nections see figure 8.
B22 - roof B22 - wall
It is important to ensure that there is an adequate air supply at all times for both
combustion and heating requirements. Modern buildings involve greater use of in-
sulation, improved vapour barriers, and weather proofing. These practices mean
that buildings are sealed much tighter than in the past.
Proper combustion air supply for a power vented Type B installation requires ven-
tilation of the heated space. Natural infiltration of air may not be adequate. Use
of exhaust fans aggravates this situation. It is important to ensure that there is
adequate combustion air supply at all times. Reliance on doors and windows is
not permitted.
Always ensure that adequate combustion air is provided to suit the total instal-
lation of all combustion equipment in accordance with BS6230 or BS5440 as
appropriate.
Ensure that the air combustion inlet opening at the rear side of the unit cannot be
obstructed (see. fig. 8).
Air supply
WARNING
When these air heaters
are installed as type B
appliances, they take
their air for combustion
from the space in which
they are installed. Do not
restrict the combustion air
intake.
6.2.3 Combustion air inlet pipe & flue pipe for balanced flue instal-
lation (type C appliances)
Balanced flue air heaters are designed to be fitted with a combustion air inlet pipe
that draws in outdoor air and a flue pipe that exhausts flue products to outdoors.
Both the flue and combustion air pipes must be sealed. Use gasket sealed seam-
less aluminium pipe or equivalent. C2 appliances must not be applied !

1104UESAGBEN, page 15/31
Figure 10
Approved appliances type
C.
For illustrative purposes
only. For actual pipe con-
nections see figure 11.
Figure 11
Type C appliances :
combustion air and flue
pipe sockets
C12
C52
C12b/C62
C32/C62

1104UESAGBEN, page 16/31
7. ELECTRICAL
SUPPLY AND
CONNECTIONS
DANGER :
THIS APPLIANCE
MUST BE EARTHED.
Electrical supply
The electrical installation must only be carried out in accordance with the IEE regu-
lations and by an appropriately qualified person. The electrical supply line to the
heater should include a main isolating switch. The minimum clearance distance
between the contacts must be more than 3 mm.
All electrical connections should be made in the heater control compartment (re-
fer figure ‘Wiring connections’). Screw type terminals are provided. Connections
should be in accordance with the terminal markings and the wiring diagram affixed
to the air heater.
Attention :
Permanent damage can occur to burner relay when faulty connection of thermo-
stat, reset switch or burner failure lamp.
Switching of wires for reset switch and flame failure (e.g. in a remote control box)
will destroy the burner relay.
The minimum external control required for the air heater is a room thermostat. It is
essential that the main input L and N terminals remain live at all times even when
the heater is switched off to ensure correct operation of the unit.
An external burner reset switch with red indicator light is fitted on the heater. To
add a remote reset button, make connections to the terminals in the electric box as
indicated on the wiring diagram.
IMPORTANT: If the reset button requires activating for any reason, the cause must
be determined. After determining and correcting the problem, restart the heater
and monitor long enough to ensure proper operation (approx. 5 minutes).
An external orange indicator light is fitted on the heater to signify when the burner
is on.
Ensure that all cables and installers wiring are appropriately fixed and that they do
not touch the flue combustion collector box.
Do not attempt to control more than 1 heater from a single thermostat or control
panel unless a properly wired relay is fitted. Follow the instructions supplied with
such panels.
The location of the room thermostat or sensor is very important. It should not be
positioned on a cold wall or cold surface. Avoid location in draughty areas or where
it may be influenced by heat sources e.g. the sun, process plant, etc. The thermostat
should be mounted on a vibration free surface and mounted about 1,5 metres above
floor level. Follow the thermostat manufacturers instructions.
Thermostat location
7.1 Electrical sup-
ply

1104UESAGBEN, page 17/31
7.2 Wiring
connection
co
nn
ec
ti
on
Smartcom

1104UESAGBEN, page 18/31
8. CONTROLS
8.1 Thermostats Use either an optional thermostat (1 stage room thermostat, 2 stage clock thermo-
stat, Smartcom control panel or wireless digital thermostat) available with the heater
or a field supplied 230V thermostat. Install them according to the manufacturer’s
instructions, paying full attention to the requirements regarding the thermostat loca-
tion (see section 7.2).
Important : never use a line voltage isolating switch as a means to operate the oper-
ate the heater.
8.2 Gas valve The main gas valve is powered through the thermostat and safety controls. The
gas valve provides regulated gas flow and is preset at the factory. The gas valve
requires no field maintenance except careful removal of external dirt accumulation
and checking of wiring connections. Instructions for testing pressure settings are
in section 6.
WARNING
The main gas valve is
the prime safety shutoff.
All gas supply lines must
be free of dirt or scale
before connecting to the
unit to ensure correct
sealing.
8.3 Safety controls 8.3.1 Combustion air pressure switch
The combustion air pressure switch ensures that proper combustion airflow is
available. The switch senses the differential pressure between the negative pres-
sure in the flue gas collector box and the pressure in the control section. (For
switch location, see figure 16a).
On startup when the heater is cold, the sensing pressure is at the most negative
level, and as the heater and flue system warm up, the sensing pressure becomes
less negative.
If a restriction or excessive flue pipe length causes the sensing pressure to be be-
low the allowable level, the pressure switch will shut off the main burner.
Figure 12
Combustion air
pressure switch
If it is determined that the
pressure switch needs
replacing, use only the
factory-authorised re-
placement part that is
designed for the model
and size of heater being
serviced.
Table 7
Set points OFF
UESA Set point Off (Pa)
035 238
055 388
083 300
102 450

1104UESAGBEN, page 19/31
Figure 13
LC1
Figure 14
LC3
Figure 15
Positioning LC1/LC3
8.3.3 Fan motor overload protection
The fan motor is equipped with an internal thermal overload protection of the auto-
matic reset type. In case the motor should fail to run it may be because of improper
voltage characteristics. Make certain that the correct voltage is available at the motor.
If a limit control needs
replacing, use only the
factory authorized re-
placement part for the
size of heater.
For limit locations, see
figure 16a.
8.3.2 Limit controls
WARNING
Never bypass the limit
controls, hazardous
conditions could result.
All units are equipped with temperature activated limit controls. The controls are fac-
tory set and non-adjustable. If either setpoint is reached, the corresponding limit con-
trol will interrupt the electric power to the gas valve. These safety devices provide
protection in the case of motor failure or lack of airflow due to restrictions. (For loca-
tions, see figure 17.)
LC1
LC3

1104UESAGBEN, page 20/31
This heater is equipped with a direct spark multi tray burner control relay. The con-
trol relay monitors the safety devices and controls the operation of the venter motor
and the gas valve between heat cycles.
The time line below illustrates a normal heat cycle.
Definitions
Start position: The system is not in lock-out position and can proceed with the start-up sequence upon a demand for
heat.
Pre-purge time: This is a period of 20 seconds during which the combustion fan (venter) operates prior to activation of the
ignition device.
Safety time: The safety time is the delay between the gas valve being energised and the flame sensor checking for the
presence of a flame. This is a period of 5 seconds.
Note: If no flame is sensed, the burner relay will attempt ignition 5 times before going into lock-out mode.
Post-purge time: This is the time of 10 seconds between burner shut-down and the moment the combustion fan (venter) is
de-energized.
Start pre-purge
Energisation of venter motor.
If the differential pressure switch
is in normally closed position
(start position).
Power to gas valve and ignitor
Sensor checks for the presence of a flame
End of heat demand.
De-energisation of gas valve.
De-energisation of venter motor
First heat demand signal.
Check on pressure switch.
Must be in closed or start position.
If not, there will be no power to
the venter motor.
The power to the burner relay is off
until the pressure switch goes to
normally closed - or start position.
Safety check on flame sensor.
If there is a flame, the relay will
go to lock-out. The light in the red reset
switch, mounted visibly on the heater
will glow.
Line output during ignition time to control
high fire start on two stage or modulation
applications.
If no flame, then repeat starting
at pre-purge for 5 attempts.
If no ionisation after 5 attempts, then
lock-out.
Pre-purge
time
Ignition
time=
Safety
time
Normal operation
of burner relay Post-purge time
20 sec 5 sec 10 sec
time
Start position
9. IGNITION SYSTEM