Page 1
Room Sealed Unit Heaters
Installation, Commissioning,
Service & User Instructions
Models
FRSA, FRSB,
FRSC & FRSD
75 - 210
August 2000
Part No. X224B
Page 2
Page 3
Page 1
ROOM SEALED UNIT HEATERS
These appliances have been tested and certified as complying with the essential
requirements of the Gas Appliance directive, The low voltage directive ,The
Electromagnetic Compatibility Directive and the Machinery Directive for use on natural
gas and L.P.G gas when installed , commissioned and maintained in accordance with
these instructions.
These instructions refer to appliances designed to operate in the following countries...
Ireland (IE), Spain (ES), Italy (IT) & United Kingdom (GB)
Appliances designed for other countries are available on request.
These appliances are Cat II
2 H 3+
appliances for use with natural gas (G20) or L.P.G.
(G31 / G30) as stated on the heater data plate, and are intended for indoor installation
only.
For GB and IE They are type C32 appliances for vertical flue terminals and
type C 12 for horizontal flue terminals.
For use in ES and IT they are Type C32 appliances for connecting to suitable
approved sealed combustion air and flue systems.
This Appliance must be installed in accordance with the rules in force and used only
in a sufficiently ventilated space, as specified in these instructions.
Before installation, check that the local distribution conditions, nature of gas and
pressure, and adjustment of the appliance are compatible.
Page 4
Page 2
ROOM SEALED UNIT HEATERS
Contents
The parts of this manual are numbered by section, clause and sub clause. Hence 1:2:3 refers to section I
clause 2 sub clause 3. Figure numbers also follow this notation. Hence Fig. 2:3 is section 2 Fig. 3.
Section
1. General Specification
2. Technical Data
3. Heater Installation
4. Commissioning of the Air Heater
5. Wiring Diagram
6. Servicing Instructions
7. Removal and Replacement of Parts
8. Fault Finding Charts
9. User Instructions
10. Conversion between Natural gas and L.P.G.
11. Parts List
12. Commissioning Data Sheet
THIS AIR HEATER IS FOR USE WITH NATURAL GAS OR L.P.G. AS STATED ON THE HEATER DATA
PLATE
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR NEAR THE HEATER
NOTE
: Every effort is made to ensure the information within this manual is accurate. However, Roberts-Gordon
reserves the right to alter specifications without prior notice.
Roberts-Gordon shall not be liable to rectify any defects or damage caused by any modifications made or
attempted to be made to the heating units by the customer, his servants, agents or employees.
WARRANTY The Heat Exchanger has a ten year Warranty (subject to terms and conditions).
Page 5
Page 3
ROOM SEALED UNIT HEATERS
Section 1. General Specification
1.1 Basic Information
COMBAT® FRSA, FRSB, FRSC & FRSD ranges of unit air heaters are type C32 appliances for vertical flue
terminals and C12 for horizontal flue terminals both of which have room sealed combustion and fan assisted
flues. They are designed to be suspended or shelf mounted, and are produced in an 8 size range from 27 kW
(92,124 Btu/hr) to 76 kW (259,312 Btu/hr) heat input (Gross CV).
Heaters must be installed in accordance with local regulations and the requirements of Section 3 of these
Instructions.
A permanent electrical supply of 230 volts 50 Hz, single phase is required for all models and all models must
be earthed.
ON/OFF, temperature and time control may be obtained by use of CC1/A control consoles (obtainable from
Roberts-Gordon.) or by the use of individual controls as per the circuit diagrams in Section 5.
The FRSA range of heaters are fitted with quiet running axial fans.
The FRSB range of heaters are fitted with Direct Drive centrifugal fan blowers to allow them to be fitted to
duct distribution systems ,when supplied with the factory fitted outlet spigot.
The FRSC range of heaters are the same specification as the FRSB range, but are fitted with an enclosure for
the main fans to allow inlet ducting to be fitted.
The FRSD range are sold without a fan unit to be installed onto the customers ducting and air moving system.
1.2 Heater Operation
COMBAT® FRSA, FRSB, FRSC & FRSD warm air heaters are supplied ready for installation on site. They
are fitted with an automatic ignition control which ignites the gas and monitors for the safe operation of the
burner each time the external controls call for the heater to operate.
When the external controls call for heat, the automatic control operates the flue fan and burner, to supply heat
to the heat exchanger. After approximately 2 or 3 minutes the air delivery fan will start to run, supplying warm
air to the building.
When the external controls are satisfied they will turn off the burner leaving the fan running to cool down the
heat exchanger. When cool enough the fan thermostat will turn off the fan.
Page 6
Page 4
ROOM SEALED UNIT HEATERS
Fig. 1.1 General Arrangement - FRSA Models
WARNING:
The main electrical isolator should only be used in an emergency and should not be used for
closing down the burner, as this switches off the main fan prematurely and may damage the
heat exchanger.
Such action may cause a fire hazard and invalidate the warranty .
Mounting Brackets
Flue Pipe (front) Air Intake Pipe (rear)
Gas Pipe Connection
Outlet Grille with
Adjustable Louvres
Main Fan
on Rear
Panel
Lock for
door
Electrical entry
and Second
Limit Stat on
Rear
Lockout Reset Button
Lighting Instructions
Warning Lights:
GREEN - Burner On
RED - Lockout
Data Plate
Dimension Data (see Figs.1.2 to 1.4 - Dimension Diagrams)
Model
'A' - Width
'B' - Width between hanging points
'C' - Flue/Air Intake Diameter
'D'
'E'
'F'
'G' - Inlet/Outlet Duct Spigot Width
Weight - FRSA
Weight - FRSB
Weight - FRSC
Weight - FRSD
95
775
296
100
140
192
117
508
113
118
136
105
105
775
296
100
140
192
117
508
115
129
147
115
120
915
436
100
140
192
117
648
128
140
159
128
135
915
436
130
225
168
132
648
138
152
171
138
150
1055
576
130
225
168
132
788
150
163
184
150
170
1055
576
130
225
168
132
788
154
178
199
154
210
1195
716
130
225
168
132
928
174
200
223
174
75
705
226
100
140
192
117
438
105
110
127
97
mm
mm
mm
mm
mm
mm
mm
kg
kg
kg
kg
Page 7
Page 5
ROOM SEALED UNIT HEATERS
Fig. 1.2 Front View Dimension
All FRS Models*
Fig.1.3 Plan View
All FRS Models (Shown without main fan)
Fig.1.4 Side View Dimensions
FRSC
* Note:
FRSD models are fitted with an air outlet spigot as standard. All inlet and outlet duct spigots are complete with 25mm mez. flange.
140
510 (Centres)
751
680
1431
674 x G (Width)
234
FRSD
495 x G
(Width)
234
495 x G
(Width)
234
751
1051
150 150
140
510 (Centres)
140
510 Centres
751
837
FRSA FRSB
140
510 Centres
751
1211
(except Models 150 & 170: 1177)
240 240B Centres
A
990
Gas Connection
C (Air Intake)
C (Flue)
52
55
103
Rear
E
D
F
Front
Hanging Points
Page 8
Page 6
ROOM SEALED UNIT HEATERS
Note:
for FRSD ducted units sold without fans, the air flow provided by the system must be able to produce at least the lower of the air flows of the FRSA or the FRSB heater
of the same model.
Technical Data - General Data for all FRS... Range
TABLE 2.1 GENERAL DATA
LEDOM5759501021531051071012
SEVLAVSAGNIAM
EPYT&REBMUN
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
avoN.T.I.S
711.228.0
FFO1
EZISNOITCENNOCSAG
4/3R4/3R4/3R4/3R4/3R4/3R4/3R4/3R
EPYTNAFEULF
NIROT
61467OUA
NIROT
61467OUA
NIROT
61467OUA
NIROT
61467OUA
NIROT
61467OUA
NIROT
52157OUA
NIROT
52157OUA
NIROT
52157OUA
.qsmmEZISECIFIROEULF
05.4305.0407.1405.4402.8400.649445
NAFLAIXA-SLIATEDNAF
)sttaW(DAOLLACIRTCLELATOT
352352092092605605644644
ROTOMNAFNIAM
v032w071v032w071v032W012v032W012v032W081v032W081v032w071x2v032w071x2
)spmA(TNERRUCGNINNURROTOM
07.007.068.068.08.18.145.145.1
TNERRUCTRATSROTOM
09.109.103.203.24.34.32.42.4
EPYTNAFNIAM
&
DETTIFREBMUN
GMPnafiS
101-14053
1
GMPnafiS
101-14053
1
GMPnafiS
101-14093
1
GMPnafiS
101-14093
1
GMPnafiS
101-14024
1
GMPnafiS
101-14024
1
GMPnafiS
101-14053
2
GMPnafiS
101-14053
2
FµEZISROTICAPAC
5.25.2 3355 5.2x25.2x2
rh/³mWOLFRIA
)nim/³tf(
0323
)1091(
0323
)1091(
0063
)9112(
0063
)9112(
0663
)4512(
0093
)5922(
0654
)4862(
0046
)7673(
)a(BdRNm3TAGNITARESION
060600.1600.16461600.5600.46
NAFLAGUFIRTNEC-SLIATEDNAF
sttaWDAOLLACIRTCELELATOT
24624624624624624629112911
ROTOMNAFNIAM
v032W055x1v032W055x1v032W055x1v032W055x1v032W055x1v032W055x2v032W055x2v032W055x2
TNERRUCGNINNURROTOM
9.32.52.51.51.55.74.93.01
TNERRUCTRATSROTOM
8.44.64.60.60.63.96.118.21
NAFNIAM
dettiFrebmuN
deepsteslamroN
072-072NIROT
1
woL
072-072NIROT
1
muideM
072-072NIROT
1
muideM
072-072NIROT
1
muideM
072-072NIROT
1
muideM
142-142NIROT
2
woL
142-142NIROT
2
woL
072-072NIROT
2
muideM
rh/³mWOLFRIA
)nim/³tf(
0062
)0351(
0013
)5281(
0023
)3881(
0523
)0191(
0623
)9191(
0844
)7362(
0075
)5533(
0026
)9463(
deepshgihtasmumixaM
spmAtnerruCnuR
spmAtnerruCtratS
1.6
8
9.6
6.8
9.6
6.8
1.5
7
1.5
7
4.11
6.31
4.11
6.31
pmA7.31
1.71
)a(BdRNm3TAGNITARESION
00.7500.3600.3600.7602.5600.8600.6600.07
Section 2. Technical Data
Page 9
Page 7
ROOM SEALED UNIT HEATERS
L.P.G. II2H 3+
II2 H 3+ G20 H GAS
TABLE 2.2 BURNER DATA
LEDOM5759501021531051071012
VCSSORGTUPNITAEH
Wk
rh/utB
72
42129
43
800611
5.83
263131
00.44
821051
05.94
498861
5.45
459581
5.16
838902
00.67
213952
VCTENTUPNITAEH
Wk
rh/utB
13.42
5.55928
26.03
5.264401
76.43
4.882811
26.93
7.681531
5.44
580251
80.94
744761
83.55
459881
4.86
405332
TUPTUOTAEH
Wk
rh/utB
47.12
06147
73.72
68339
99.03
647501
24.53
358021
58.93
069531
78.34
396941
15.94
029861
81.16
647802
)SAGLARUTANKU(02GETARSAG
h/3m
rh/3tf
75.2
68.09
42.3
14.411
76.3
65.921
91.4
60.841
27.4
75.661
91.5
4.381
68.5
59.602
42.7
57.552
)SAGLARUTANKU(02GERUSSERPRENRUB
rabm
GWsni
9.31
85.5
5.41
28.5
8.21
41.5
5.21
20.5
8.21
41.5
9.11
87.4
1.21
68.4
0.31
22.5
EZISSROTCEJNIRENRUBNIAM
FFOREBMUN
GNIKRAMDNA
49.0x5
4
495
49.0x5
5
495
49.0x5
6
495
49.0x5
7
495
49.0x5
8
495
49.0x5
9
495
49.0x5
01
495
49.0x5
21
495
HCTIWSGNIVORPEULFROFGNITTES
rabm01.101.101.101.101.107.107.107.1
LEDOM5759501021531051071012
VCSSORGTUPNITAEH
Wk
rh/utB
5.52
60078
00.13
277501
5.73
059721
00.44
821051
5.94
498861
5.45
459581
5.16
838902
67
213952
VCTENTUPNITAEH
Wk
rh/utB
64.32
74008
25.82
21379
5.43
7177111
84.04
121831
45.54
683551
41.05
280171
85.65
550391
29.96
275832
TUPTUOTAEH
Wk
rh/utB
66.02
57407
11.52
57658
83.03
046301
46.53
406121
1.04
408631
51.44
326051
28.94
969961
65.16
340012
ENAPORP13GETARSAG
h/3m
h/gk
h/lediuqil
69.0
87.1
5.3
71.1
61.2
2.4
14.1
16.2
1.5
66.1
70.3
0.6
68.1
54.3
8.6
50.2
8.3
4.7
13.2
92.4
4.8
68.2
3.5
4.01
ENAPORP13GERUSSERPRENRUB
srabm
GWsni
0.63
54.41
08.53
73.41
07.53
33.41
08.53
73.41
04.53
12.41
03.53
71.41
02.53
31.41
06.53
79.41
ENATUB03GETARSAG
h/3m
h/gk
h/lediuqil
37.0
87.1
1.3
98.0
61.2
8.3
70.1
26.2
6.4
62.1
70.3
4.5
24.1
54.3
0.6
65.1
8.3
6.6
67.1
92.4
5.7
71.2
3.5
2.9
ENATUB03GERUSSERPRENRUB
srabm
GWsni
00.82
42.11
01.82
82.11
9.72
02.11
09.72
2.11
08.72
61.11
05.72
40.11
04.72
0.11
02.82
23.11
EZISSROTCEJNIRENRUBNIAM
FFOREBMUN
GNIKRAMDNA
45.0x6
4
45
45.0x6
5
45
45.0x6
6
45
45.0x6
7
45
45.0x6
8
45
45.0x6
9
45
45.0x6
01
45
45.0x6
21
45
HCTIWSGNIVORPEULFROFGNITTES
srabm01.101.101.101.101.107.107.107.1
Appliance Category II
2H3+
Propane Gas Inlet pressure 37 mbar (25 - 45)
Natural gas inlet pressure 20 mbar (17 - 25) Butane gas Inlet pressure 29 mbar (20 - 35)
Page 10
Page 8
ROOM SEALED UNIT HEATERS
2.1 Gas Controls
The heaters will be fitted with S.I.T Nova gas control valves.
Main Gas Control Valve - Natural Gas
The multifunctional main gas valve contains two automatic shut off valves. When set up as defined in Section
4 the valves will have a step or slow opening operation on the main gas, to give smooth lighting. Settings of
the valves are given in Section 4 and tables in Section 2.
Main Gas Control Valve - L.P.G.
The Multifunctional main valve is tha same as used for natural gas (see Section 10, "Conversion Betwen
Gasses"), but with the Pressure regulator put out of action.
2.2 Main Fan
The main air moving fan/s fitted to these heaters are operated automatically by the fan thermostat within the
Honeywell combination fan/limit thermostat. When suitably connected to site wiring (see Section 5) the fan/s
may also be operated manually to distribute unheated air.
2.3 Limit Thermostats
There are two limit thermostats on these heaters to protect them from overheating, should the fan fail for any
reason.
One is within the Honeywell combination thermostat and the second one being situated on the rear of the
heater.
2.3.1 Honeywell Combination Fan/Limit Thermostat
The combination fan/limit thermostat is a dual function control and safety device (see Fig. 2.4). There are two
fitted to FRSD ducted heaters, the extra one being fitted at the rear inlet spigot.
Fan Thermostat
The fan thermostat controls the operation of the main fan during the heater operating cycle and ensures that
unprogrammed cold air is not circulated. This control also ensures that the main fan continues to run after the
burner turns off to dissipate the residual heat from the heat exchanger.
The white button on the fan thermostat should be pulled to its “out” position for normal operation. In the
“pushed in” position the fan will run continuously. However, when connected to suitable site wiring this feature
may be catered for by the remote fan on facility of remote controls.
Limit Thermostat
The limit thermostat operates in overheat conditions caused by insufficient air passing over the heat
exchanger. This is a manual reset device and is reset by pressing in the red button on the thermostat.
Note:
the heat exchanger must have cooled to below the operating temperature for reset to be possible.
2.3.2 Second Limit Thermostat
This is a preset, manual reset device and is designed to be fail safe (see Figs. 1.1 & 1.2).
To reset this thermostat:
a) Remove the screw on cover of the thermostat where it protrudes from the mounting plate.
b) Push in the Black button in the centre of the thermostat, (note the heat exchanger must be cooled to allow
this to happen).
c) Replace the cover.
Page 11
Page 9
ROOM SEALED UNIT HEATERS
Fig. 2.4 Combination Fan/Limit Thermostat
WARNING: IT IS ESSENTIAL THAT THE BREAK OFF LINK SHOWN IS
REMOVED IN THE EVENT OF THERMOSTAT REPLACEMENT
Fig. 2.5 Satronic DMG 970 MOD 03 Control Box Sequence
Page 12
Page 10
ROOM SEALED UNIT HEATERS
2.4 Burner Control Box
2.4.1 Description (DMG 970 MOD 03 CONTROL BOX)
The fully automatic gas burner fitted to all models is controlled by a Satronic DMG 970 MOD 03 plug-in control
box. This control ensures the safe start and stop sequence and also monitors the safe presence of a flame
and operation of the flue fan.
2.4.2 Sequence of Events
With the external controls on and calling for heat, and the flue proving air pressure switch at rest (contacts
open), the flue fan will switch on after a 5 second wait.
Note:
If the air pressure switch contacts are closed there will be no start.
2.4.3 Air Pressure Switch Contacts
With the flue fan now running, the air pressure switch contacts have to close within the next 10-15 seconds to
indicate the availability of sufficient combustion air or lockout will occur.
2.4.4 Purge
The sequence continues with a purge time with just the flue fan running.
2.4.5 Electric Ignition ON
The electric ignition switches ON at the end of this purge time.
2.4.6 Main Gas Valve
As these appliances are designed for direct main flame ignition ,the main gas valve opens and once a flame
has been established this remains on until close down. The flame probe is now continuously monitoring for the
safe presence of flame.
2.4.7 Electric Ignition OFF
Five seconds later the electric ignition turns off, leaving the flame to be proved as stable.
2.4.8 Close Down
When the external controls are satisfied the control box turns off all outputs simultaneously and returns to rest
position for the beginning of the next sequence.
2.4.9 Fault Conditions
If at any stage the flame fails or the air pressure switch detects a loss of air pressure, the control will go to
‘lockout’. The red light will glow and the control will need to be manually reset (either at the conrol or at a
remote reset button ,if installed) before any further start attempt can be made.
Minimum flame probe current 1 ,mA . DC.
Typical flame probe current 3-5 ,mA . DC.
2.5 Flue Proving (Air Pressure Switch)
This device, which is housed inside the controls compartment at the side of the heater, monitors the flow of
flue products produced by the flue fan. It is factory set and the correct one must be fitted for the model (see
Section 4 and Data Tables in Section 2).
Page 13
Page 11
ROOM SEALED UNIT HEATERS
Section 3. Heater Installation
3.1 Required Standards
It is important that all gas appliances are installed by competent persons, in accordance with the relevant
requirements of the local laws and regulations. Failure to install gas appliances correctly could lead to
prosecution.
THE RELEVANT REGULATIONS ARE .......
Gas Safety (Installations and use) Regulations 1984.
BS 6230 Specification for the Installation of Gas Fired Forced Convection Air Heaters for
Commercial and Industrial Space Heating of Rated input Exceeding 60kW.
BS 6891 Low Pressure Installation Pipes or Institute of Gas Engineers Document IGE/UP/2.
BS 5588 Parts 2 and 3 Fire Precautions In the Design and Construction of Buildings.
The Building Regulations ; The I.E.E Regulations ; The Health and Safety at Work etc Acts ; Any
Requirements of the Local Authority, Fire Officer and Insurance Company
The installation will be similar to the one shown in Figure 3.1.
3.2 General
All models must be installed with the base level and may be suspended from a ceiling or specially prepared
wall brackets of sufficient strength to adequately support the weight of the heater as listed in Section 2. Data
Tables. All heaters may be mounted on a NON combustible shelf. Drop rods should be a minimum of 12 mm
diameter mild steel. The four hanging brackets are located on top of the heater, for all models.
They will normally be installed at between 2.75m and 3.75m above the floor.
Clearances around the heater as indicated in Fig. 3. 1 must be maintained to ensure adequate access for
servicing and to ensure that the temperature of combustible materials does not exceed 65°C.
Note:
for servicing, the burner is removed only from the right hand side of the heater as viewed from the front.
Adequate clearance of at least the total width of the heater, or 0.8m which ever is greater, will be required on
this side between the heater and any obstruction to allow burner removal.
It is important to ensure that at all times there is adequate air circulation around the heater to supply air for
both ventilation and distribution.
Consideration should also be given when siting a heater to allow for the proper location of the flue and air
intake pipes.
It is important that the gas supply pipe and the electrical connections do not support any of the heater's
weight.
WARNING:
AIR HEATERS SHOULD NOT BE INSTALLED IN CORROSIVE ATMOSPHERES i.e. NEAR PLATING
OR DEGREASING PLANTS OR IN AREAS WHERE THERE IS A FIRE RISK.
CONSULT LOCAL REGULATIONS FOR FURTHER INFORMATION ON HAZARDOUS AREAS.
Page 14
Page 12
ROOM SEALED UNIT HEATERS
3.3 Gas Supply General
The installation must comply with local laws and regulations, and the complete installation including the meter
must be purged and tested for soundness.
The gas supply must be via metal pipes and terminate at the heater with a manual gas valve of the 90º turn
type and union as in Fig. 3.1 to facilitate servicing.
The gas supply pipes must be sized to supply the correct amount of gas to the heater inlet at the specified
inlet pressure under all load conditions. The pressure test point for measuring the inlet gas pressure is
situated at the top of the heater near to the connection point.
On suspended heaters it is recommended that an approved metal flexible connection is used between the
manual valve and the heater.
Note: due to the design of flexible connectors it is usually needed to use at least one pipe size larger than the
supply gas pipe to reduce the pressure loss through the connector.
Natural Gas
The gas meter and service must be checked by the local gas supply undertaking to ensure that it is adequate
to deal with the total connected load of the completed installation.
The maximum inlet pressure for natural gas is 25 mbar.
L.P.G.
For L.P.G. applications each heater must be provided with gas having the inlet pressure closely controlled to
37 mbar for Propane (G31) or 29 mbar for Butane (G30). This is best provided by the installation of a suitable
regulator controlling the inlet to each heater so as to ensure that variations in system pressure are not
transferred to the individual heaters.
The maximum inlet pressure for LPG is 45 mbar for Propane or 35 mbar for Butane.
3.4 Flue and Combustion Air Intake
Each heater must be fitted with airtight sealed flue and combustion air intake pipes of the correct size to fit
into the provided spigots and as supplied by Roberts-Gordon. These must be within the maximum length
stated in the Data Table on Fig. 3.1 and terminate with the special concentric balanced flue terminal into the
open air. The pipe sections must be assembled ensuring that each section seals correctly into the next.
It is most important that the maximum flue and inlet pipe resistance is not exceeded. As a guide for
estimating resistance each 90° of bend shortens the maximum flue and air intake length by 1m.
If the flue passes through a wall or ceiling of combustible material it must be enclosed by a sleeve of
noncombustible material and separated from the sleeve by at least 25 mm air gap. The temperature of any
combustible material near the flue or heater must not exceed 65°C when the heater is in operation.
The flue must be at least 50 mm from any other combustible material.
The joints between the flue and the roof or wall must be made good to prevent water ingress.
The flue and air intake pipes should be installed and supported so that the unit heater does not carry the
weight. The final section through the wall or roof must be the concentric balanced flue terminal connected with
the flue to the inside duct and the combustion air to the outside duct (see Figure 3.1).
There are two types of concentric terminal available, one for vertical mounting through the roof and one for
horizontal mounting through a wall.
The flue pipe must always be the inner pipe of the concentric flue terminal and must be installed in positions
which will not cause the products of combustion to be drawn back into the building through open doors,
windows or ventilation systems.
Page 15
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ROOM SEALED UNIT HEATERS
3.5 Air Supply
As these heaters are of room sealed design there is no need to provide a separate air supply for combustion,
however provision must be made for the main distribution air and for ventilation particularly when the heater is
installed in a plant room where the ambient temperature must be maintained below 32°C at all times.
3.5.1 Building Ventilation
Air shall be taken from an outside point where it is not likely to be contaminated, for example with smells,
road vehicle exhausts, dry cleaners, exhausts, solvents, etc.
The minimum quantity of outside air required for ventilation shall be at least that required for personnel within
the building.
3.6 Electrical Supply
The electrical installation must be carried out by a qualified electrician in accordance with the local regulations
using the Wiring Diagrams in Section 5.
THE HEATER AND ITS CONTROLS MUST BE PROPERLY EARTHED.
A constant 230 v 50 Hz single phase supply is required for all models which must be connected into the main
terminals as shown in Section 5.
For the correct operation of the burner control box it is essential that the electrical supply has the earth and
neutral wires at the same potential and that the supply is only connected to the correct terminals of the heater
E, N, L, in the connection block on the side of the heater as shown in Section 5.
The final connection to the heater should be in metal sleeved flexible cable, or flexible conduit, to the terminal
block. Cable size should be 1 sq.mm. Reusable cable ties are provided at the lower edge of the controls panel
inside the heater to ensure that site connecting cables are installed tidily and do not impede the removal of
the burner tray.
It is recommended that the length of the final connecting wires to the live terminal is shorter than the wires to
the Neutral or Earth so that in the event of the cable being pulled out of the terminals the Live will disconnect
first.
An isolator with a contact separation of at least 3 mm on all poles should be installed adjacent to the heater
and/or the control panel, to disconnect all supplies to the heater (see Section 5).
A fuse size of 5 amps must be used on all FRSA models and 10 amps or 15 amp fuses must be used on
FRSB models dependant on model size. FRSD heaters will require a 5 amp fuse for the heater and suitable
connection to the duct fan system in accordance with Section 5 and local regulations.
3.6.1 Remote Controls
The heaters are designed to be operated by controls installed remote from the heater. Any control intended to
operate the burner must have contacts that are free of voltage from external sources which are connected
between terminals 2 & 3 of the main terminal block on the side of the heater. The contacts will make to
energise the burner.
Burner Controls
The minimum control scheme must have a room thermostat.
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ROOM SEALED UNIT HEATERS
Fan Controls
The main fan is designed to operate automatically providing there is a constant 230v supply to the main
terminals. However a switch, free of voltage from external sources, wired between terminals L & 1 in the main
terminal block at the side of the heater will provide for summer running of the fan.
It is acceptable for the fan to operate continuously from external control, with the burner cycling on and off
providing that the fan run on at close down is not impaired.
3.6.2 Siting of Control Consoles or Room Thermostats
The Roberts-Gordon® control console or room thermostat should be mounted on a wall or column at a height
of approximately 1.5 metres from the floor of the building being heated. It is important for both comfort and fuel
economy that the control or thermostat is sited where it will monitor an average room temperature i.e. keep
clear of cold draughts from doors, windows etc., similarly it should be kept out of the direct path of warm air
from the heater. Areas of little air movement e.g. corners, should also be avoided.
3.7 FRSB Heaters, Distribution Ductwork and FRSD Heaters
3.7.1 FRSB Heaters
FRSB heaters are supplied with three speed direct drive centrifugal fans which have been connected to
operate with the heater free blowing into the heated space. Each of the fans has built in thermal overload
protection.
The data tables will indicate the normal number of fans and their standard running speed for each model .
It is essential that the fans are not operated at higher speeds than the original setting on the heater without
prior consultation with Roberts-Gordon. Such action may cause the fan motors to be overloaded.
Overloading the motor will cause the built in thermal overload protection device to operate.
If the heaters are to be connected to a duct distribution system then they must be specified to be
factory fitted with an outlet spigot as described below in 3.7.2.
Where two fans are fitted these will be switched using a fan contactor built into the heater see the wiring
diagrams in section 5
The three speed winding connections are:
Low speed White Neutral, Red Live. The other two windings are "parked" separately in
spare terminals
Medium speed White Neutral, Blue live. The other two windings are "parked" separately in spare
terminals
High speed White Neutral, Black live. The other two windings are "parked" separately in
spare terminals
FRSC heaters are FRSB heaters supplied with an inlet spigot to encase the fans and provide for connecting
to an inlet duct system.
Page 17
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ROOM SEALED UNIT HEATERS
3.7.2 Distribution Ductwork
It is important when ducted systems are required that only FRSB, FRSC or FRSD models are selected and
that the inlet and/or outlet flanges made and fitted at the factory are used at the heater to ensure that the
integrity of the sealed combustion zone is not impaired.
Provision should be made so that the complete heater may be removed from the duct system.
It is recommended that flexible duct connectors are used to reduce duct bourne noises.
The cross sectional dimensions of the connecting ducts must be maintained to those of the heater spigot for
at least twice the major spigot dimensions. This should ensure that adequate air flow will pass over the whole
of the heat exchanger cross sectional area.
All joints between the heater and the ductwork should be made as air tight as possible.
When installing a heater onto ducting it is possible for the duct installation to change the natural convected air
flow through the heater before the fan is turned on. Under these condition it is sound practice to use an
electrical design (such as a 60 second time delay relay - see Section 5) to force the fan to run and not rely on
the fan thermostat to turn it on. Any such device must be in parallel with the fan thermostat so that the fan run
on operation will still take place. FRSD models have two combination thermostats, with the extra one fitted at
the rear inlet spigot to cater for this effect.
Contact Roberts-Gordon design department for advice regarding duct resistance and design.
3.7.2 FRSD Heaters
For FRSD heaters it is essential that the airflow in the duct system is at least that specified in the Data
Sheets in Section 2 and in the correct direction across the heat exchanger as indicated by the arrow on the
heater. Higher air flows are acceptable but it should be remembered that as the air flow rises the temperature
rise across the heat exchanger will fall.
It is recommended that the fan is positioned to blow the air through the heat exchanger.
It is important that the duct is designed as described in 3.7.1. above to ensure that there is a homogenous air
flow across the whole of the heat exchanger.
Failure to provide a suitable air flow properly distributed across the heat exchanger will cause heat exchanger
failures
The fan motor or its control should contain a method of overload protection and be supplied via a local
electrical isolator if it is installed remote from the heater. Where such a local isolator is installed it should be
positioned and labelled to prevent inadvertent operation
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ROOM SEALED UNIT HEATERS
Sealed
Joints
M12 Hanging Points
3m Clearance
Clearance at side
at least 0.8m
Clearance at rear at least 0.6m from rear of
fan
Maximum Flue Length 8m straight (see text
for reducing length for bends etc.
Union Fitting
Isolating Gas Valve
Electrical Entry on rear panel
Minimum Clearance at this side, for
burner removal - heater width or 0.8m,
whichever is greater
Gas Supply
Clearance from floor:
2.75m to 3m for FRSA
2.75m to 3.75m for FRSB
Special Concentric Terminal Horizontal and Vertical Versions
Available
Clearance above heater from
combustible material: 0.6m
Air Intake Pipe
Flue Pipe
Fig. 3.1 Typical Heater Installation for FRSA, FRSB, FRSC & FRSD
All clearances and distances in metres for the installation
Detail of Flue Components
* The maximum length of flue and air intake pipes must not be exceeded.
The effect of bends etc. must be taken into consideration and the total length of pipe reduced accordingly
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Page 19
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ROOM SEALED UNIT HEATERS
Section 4. Commissioning the Heater
Before starting to commission a heater read this section through and fully understand it's contents.
Only competent engineers should carry out the work.
Checks before lighting the unit heater
4.1 Pre-Commission Checks
Ensure that the heater and all controls are suitable for the gas, pressure and electrical supply that they are
being connected to.
4.1.1 Electrical Check
A preliminary electrical check should be carried out by a qualified engineer, after completion of the installation
and before commissioning the heater as follows:-
Check that all site wiring is connected in accordance with the appropriate wiring diagram of Section 5.
4.1.1.1
Check the correct fuse size is fitted, 5 amp for FRSA heaters and 10 amp or 15 amp (depending on model) for
FRSB or FRSC heaters. This must be connected in the live conductor, (see 4.1.1.4 below).
4.1.1.2
The appliance earthing must be tested using a suitable method according to local regulations. The resistance
of the earth circuit from the heater to the earth connection must be 0.1 ohm or less.
4.1.1.3
Connect one lead of a suitable voltmeter to earth and connect the other lead to the live supply terminal at the
heater.
Turn on power to heater. A reading of approximately 230 volts should be given.
4.1.1.4
The same result should be obtained by connecting the test leads from live to neutral.
Connecting the voltmeter between Neutral ‘N’ and Earth should give a reading of
0 volts. If these tests do not conform to the above there is a fault which must be rectified before progressing
further with the commission. An electrician should be consulted to carry out this work.
4.1.2 Flue Proving Switch Setting
The setting of the air pressure switch that proves the correct flow of air in the flue system is factory preset
and must not be adjusted. For checking that the device is operating correctly see Section 7.9.
Only pressure switches that have been calibrated by Roberts-Gordon for use on the specific model of heater
may be used.
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ROOM SEALED UNIT HEATERS
4.2 Gas Supply
The whole of the gas installation, including the meter, should be inspected, tested for soundness and purged
in accordance with local regulations.
It will be necessary to ensure that the air is fully purged from the heater inlet pipe up to the main gas valve
inlet test nipple before the gas burner will ignite.
The pressure test point for measuring the inlet gas pressure is situated at the top of the heater near to the
connection point.
4.3 Mechanical Checks
1. Check that the fan is free to run and delivery louvres are turned to give required air deflection.
2. Check that the flue and combustion air pipes are installed in accordance with these instructions and local
regulations.
Note:
the inner pipe of the concentric terminal MUST be the flue outlet.
3. Check that the Settings of the Combination Fan/Limit thermostat are correct (see below).
Note:
the limit thermostat is preset and sealed at the works and will need no adjustment.
To set the combination fan/limit thermostat first remove the cover by releasing the cover fixing screw and
pulling off the cover. The three hands from left to right should be set approximately as follows subject to site
conditions (see Fig. 2.4).
HAND 1 FAN OFF SET TO 38°C
HAND 2 FAN ON SET TO 57°C
HAND 3 LIMIT SET TO 80°C
Always refit the cover and tighten the cover screw after adjustments.
4.4 Carry out a "Dry Run"
To ensure that all the controls are in safe working order, operate the fully automatic controls for the first time
without the gas turned on.
To do this turn off the appliance gas isolating valve at the inlet to the heater.
Now using the installed external control turn on the burner.
The automatic sequence will now begin as described in Section 2. Following the purge period the electric
ignition will be heard and the spark may be observed via the viewing window on burner drawer at the side of the
heater.
As the gas is turned off, the main gas flame will not ignite on the opening of the main gas valve and the control
will go to the “lockout” condition. Press in the control box reset button, or the remote reset button if installed.
4.5 Fire the Burner
Turn on the appliance gas isolating valve and repeat the operations of 4.4 above.
Note at the first firing of the heater it may be necessary to repeat several times whilst purging the remaining
air from the gas train.
The main burner will be ignited directly by the spark ignitor.The main gas valve will start the main burner at a
preset step opening rate and then automatically proceed to the full rate within 45 seconds.
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ROOM SEALED UNIT HEATERS
Fig. 4.2 S.l.T Nova 0-822-177
Burner
pressure test
point
Inlet pressure test
point
Gas Inlet
230v electrical
connection valve 1
Regulator (under
cover)
Pilot gas outlet of valve
blanked off
230v electrical
connection valve 2
Gas outlet to
burner
Fig. 4.1 Controls Layout
Fans
Connections
Mains Filter for
Controls Only
Main Connection BoxBurner Control
Box
Air Pressure
Switch
Natural
Positive Pipe
Red
Negative
Pipe
Remote
Reset
Lockout
Device
(Built into
Control on
DMG)
Spark
Generator
Cable
Ties
Gas
Valve
Second
Limit
Thermostat
Fan
Capacitors
Page 22
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ROOM SEALED UNIT HEATERS
4.5.1 Commissioning the Gas Valves
All models of the heater are controlled by one S.I.T Nova 0-822-117 automatic gas valve.
Connect a manometer to the outlet (burner) pressure test point of the gas valve after first removing its screw
cover (see Fig. 4.2).
The step opening feature of these valves is preset by the manufacturer and is not adjustable.
Set Burner Pressure (Natural Gas)
The pressure regulator on the multifunctional gas valve is used which is situated under the screw on cover
(see Fig 4.2). Adjust the burner pressure to the value as stated in the data table by turning the adjusting
screw slowly clockwise to increase pressure and vice versa.
Note:
if any difficulty is found in obtaining the correct burner pressure then check that there is sufficient inlet
pressure to the valve, (20 mbar for G20) with the burner firing.
Under no circumstances should a regulator be set to a pressure over that where the pressure is no longer
being changed.
Check Gas Consumption
Wherever possible a reading of the gas rate timed through the gas meter should be taken and compared with
the nominal rating in the Data Table in Section 2. The burner pressure should be adjusted to give this nominal
gas rate.
Following burner pressure adjustment, allow the heater to operate for at least 15 minutes, turn the burner off
and on, and then re-check settings. Remove manometer and refit all covers to the valve.
Set Burner Pressure (L.P.G.)
For all L.P.G applications the pressure regulator in the S.I.T. Nova valve is put out of action, (see conversion to
L.P.G, Section 10) hence there is no adjustment at this valve.
The burner pressure is controlled by the appliance inlet pressure which must be 37 mbar for Propane (G31) or
29 mbar for Butane (G30). The pressure test point for measuring the inlet gas pressure is situated at the top of
the heater near to the connection point.
It is most important that the inlet pressure is closely controlled at these pressures under all load conditions.
4.6 Combustion Testing
Although there is no adjustment available to alter the combustion performance of the heater, other than burner
pressure, it is advisable to take combustion readings to determine the proper operation of the heater.
To do this the flue gas is sampled at the test point on the outlet of the flue and tested for contents of CO
2
(carbon dioxide), CO (carbon monoxide) and temperature rise. The values of CO2 should be between 6.5% and
7.5% . CO should be no more than 0.0015% ( 15 PPM) and the temperature rise of the flue gases above
ambient should be 180°C to 210°C.
Combustion testing must be carried out with all covers etc. fully fitted and sealed as designed.
Ensure that all covers are fitted correctly and all test points are properly sealed before leaving the appliance to
run normally.
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ROOM SEALED UNIT HEATERS
4.7 External Controls
It is important to ensure that all controls fitted on site operate correctly and allow the heater to function in
accordance with these instructions.
Where fitted, operate the time switch, room thermostat and manual switch to ensure that they function
correctly. Set the time switch and room thermostat to the user's requirements.
4.8 Handing Over
When the commission is complete explain to the user the controls of the heater, including how to operate the
heater and how to turn it off, using the controls fitted on site. Ensure that the user is shown and understands
the emergency instructions in Section 9 of this Manual.
Page 24
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ROOM SEALED UNIT HEATERS
Fig. 5.1 Wiring of FRSA Axial Fan Unit Heaters
Section 5. Wiring Diagrams
Page 25
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ROOM SEALED UNIT HEATERS
Fig. 5.2 Wiring Diagram for FRSB and FRSC Centrifugal Fan Unit
Heaters - Models 75 to 135
Page 26
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ROOM SEALED UNIT HEATERS
Fig. 5.3 Wiring Diagram for FRSB and FRSC Centrifugal Fan Unit
Heaters - Models 150 to 210
Page 27
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ROOM SEALED UNIT HEATERS
Fig. 5.4 Wiring Diagram for FRSD Ducted Unit Heaters With No
Built In Fan
Page 28
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ROOM SEALED UNIT HEATERS
Fig 5.5 Individual Controls for All FRS Range Heaters
Fig 5.6 Methods of Connecting Remote Fan Motor for FRSD
Page 29
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ROOM SEALED UNIT HEATERS
Section 6. Servicing Instructions
After commissioning, the heater will require maintenance to be carried out at least once per year to ensure
that peak performance and safety are maintained. If the heater is used in a dirty or dusty area, then more
frequent maintenance may be necessary.
WARNING
Only competent and Qualified Engineering Personnel should carry out servicing
and fault finding on this equipment.
Before any maintenance is carried out, ensure that both gas and electrical supplies are turned off as the fan
can start automatically at any time.
NOTE 1:
After any maintenance work always test fire the heater in the prescribed manner to make sure all
safety systems are in working order before leaving the heater to run normally.
NOTE
2: Check all pipe joints for gas soundness using an approved method. Any leaks found must be
repaired before leaving the heater to fire normally.
NOTE
3: After routine maintenance, the commissioning procedure Section 4, should be carried out to ensure
that peak efficiency and safety is maintained.
Minor faults may be traced by use of the fault finding charts, Section 8.
6.1 Burner Maintenance
1. Remove the Burner Assembly as in 7.1.
2. Check condition of , the burners and clean any deposits from theburner paying particular attention to
fluff etc., which may have formed in the injectors or venturi of the burner (see 7.4).
3. Check condition of ignition electrode and flame probe for erosion and damage to the ceramic insulation
(see 7.3). Replace as necessary.
6.2 Fan/Motor Assembly - All Models
The main fan requires very little maintenance as the bearings are sealed for life and need no lubrication. If the
fan blades need cleaning remove the fan guards and use a small brush or duster to clean the fan blades from
each side of the fan(s).
The heat exchanger should remain clean unless some problem has developed with combustion. However, an
inspection of the condition of the heat exchanger is well worth while especially looking for signs of overheating
at the lower edges which may indicate burner overfiring or reduced air flow over the heat exchanger. Any
deposits in the heat exchanger may be removed with a small flue brush and vacuum cleaner from the burner
compartment.
6.3 Heat Exchanger
A heat exchanger clean out panel is also provided at the top of the heater and is accessed by removal of the
side panel of the heater oposite to the controls.
The clean out panel doubles as the mounting plate for the flue fan assembly.
If it is necessary to use this access, remove all of the fixing screws securing the cover to the side of the fume
box. When replacing this cover it is most important that new gasket material is used to ensure the integrity of
the combustion zone which must be maintained as room sealed. It is also important to ensure that the flue
outlet of the fan unit is again sealed onto the outlet flue.
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ROOM SEALED UNIT HEATERS
6.4 Gas Control Valves
There is no regular maintenance required on these devices. To change gas control valves, see Section 7.2.
6.5 Flue Fan
The flue fan should be inspected to ensure that the fan impeller is in good condition and that no debris has
entered the flue system.
If the fan is found to be damaged, then a replacement unit must be fitted of the correct type (see Data Tables).
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ROOM SEALED UNIT HEATERS
Section 7. Removal & Replacement of Parts
See warnings and notes at the start of Section 6 before removing or replacing parts.
7.1 Burner Tray
The burner tray may be removed from the heater only from the right hand side of the heater when viewed from
the front. It is best removed along with the gas valve as an assembly. Clear access at this side of the heater is
required for at least the full width of the heater to allow burner withdrawal.
7.1.1 To Remove the Burner Tray
Open the heater right hand side panel to expose all of the controls. The burner drawer is held in place by the
series of set screws.
Disconnect the gas supply pipe at the gas valve inlet flange being careful to retain the four fixing screws and
"O" ring seal.
7.1.2 Remove Electrical Leads
Unplug the two elctrical connectors from the gas valve.
Unplug the flame probe lead from the Flame probe and the HT lead from the spark igniter.
7.1.3
Unscrew the set screws securing the burner tray (Fig.7. 1 ), and pull out the tray from the side of the heater.
7.1.4 Replace Burner
To replace the tray reverse the above steps ensuring that the tray is firmly in its correct place with the fixing
screws tight ,and that the gas pipe work is sound.
IT IS MOST IMPORTANT TO ENSURE THAT THE BURNER DRAWER IS PROPERLY FITTED TO PROVIDE
AN AIR TIGHT SEAL. THIS WILL REQUIRE THE REFITTING OF ALL OF THE FIXING SCREWS AND MAY
REQUIRE THE REPLACEMENT OF THE SEALING GASKET.
7.2 Gas Control Valves
Open the heater side panel as in 7.1.
7.2.1
Isolate and remove the gas supply at the inlet flange of the gas valve being careful to retain the four screws
and "O" ring seal..
Unplug the two elctrical connectors from the gas valve.
7.2.2
Using a short screwdriver , unscrew the outlet flange of the gas valve being careful to retain the four screws
and "O" ring seal..
The valve is now free to be removed.
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ROOM SEALED UNIT HEATERS
7.2.3 Refit Gas Control
Refitting is a direct reversal of the above ensuring that the "O" ring seals are correctly fitted and gas tight and
that the valve is installed with the gas flow in the correct direction
After changing a gas valve it is essential that the commissioning procedure (Section 4) is carried out in full.
7.3 Flame Probe or Ignition Electrode
The flame probe and ignition electrode are made to be different from each other so that they may not be
interchanged.
To gain access to either requires the same operations.
7.3.1
Remove the burner tray as in 7.1 (it will be possible to pull open the burner drawer by about 150mm to gain
access to the electrodes).
7.3.1.1 Ignition Electrode
The Ignition electrode is the one situated at the centre of the burner near to the cross lighting brackets. This
electrode is designed to give a spark gap of 4 to 6mm between the electrode tip and the centre flame ports of
the burner.
7.3.1.2
To remove, pull off the H.T. "Rajah" connector from the ignition electrode.
Using suitable spanners unscrew the securing nut that holds the electrode to the side of the burner drawer.
To replace directly reverse the above ensuring the proper spark gap and that the fixing of the electrode is air
tight to the burner drawer..
7.3.1.3
The flame probe is situated towards the front of the heater and is designed to have the end of the electrode
running parallel to the burner at a position to impinge with the edge of the flame.
To remove, pull off the tag connector from the flame probe.
Using suitable spanners unscrew the securing nut that holds the electrode to the side of the burner drawer.
To replace ,directly reverse the above ensuring the position of the flame probe and that the fixing of the
electrode is air tight to the burner drawer.
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ROOM SEALED UNIT HEATERS
First Burner with
no Crosslighter
Burner with
Crosslighter
Crosslighter
Injectors
Flame Probe Ignition Electrode Spark gap 4 to 6mm to Centre
Burner Ports
Rear Baffle
Manifold
Viewing
Window
Flame
Probe
Plug for Second
Valve
Ignition
Electrode
Burner Drawer
Fixing Screws
Burner Drawer
Fixing Screws
Plug for First Valve
Outlet
Flange
Inlet Flange
Fig 7.1 Burner Tray Details
Page 34
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ROOM SEALED UNIT HEATERS
7.4 Main Burner Bars/Injectors
Remove the burner tray as in 7.1.
7.4.1
To remove the burner bars first remove the screw securing the burner rear baffle and pull it upwards.
7.4.2 Remove Burner Bars
The individual bars may now be removed by pulling up the front end of each one clear of the mounting tray and
then pulling the burner forward off its injector.
Note:
the burners are all the same except the first burner on left from the front (see Fig 7.1). This burner has
no cross lighting bracket and has two mounting tongues to prevent incorrect fitting.
It will be found easier to remove burners starting from the opposite end of the burner tray.
7.4.3 Remove Injectors
If the injectors are being removed they are now accessible, each one is screwed into its port of the manifold
with a soft metal sealing washer and may be removed using a 13mm spanner.
7.4.4 Re-fit Injectors
On replacing injectors ensure that the correct ones for the gas in use are used as stamped on the injector
(see Data Tables). They must seat onto the soft metal washer to effect a good seal onto the manifold
shoulder. It is recommended that new soft washers are used at each refitting of the injectors.
7.4.5 Re-fit Burner Bars
When refitting the burner bars start by fitting the No.1 burner (without cross lighting bracket) and ensure that
the burner is pushed fully home against the injector and then pushed down to the bottom of its mounting slots.
Repeat for each burner in turn until all the burners are back in place.
Replace the rear burner baffle ensuring that it engages into the slot in the bottom of each burner tube inlet
bracket.
Replace the fixing screw for the rear baffle.
Continue to reassemble reversing the above instructions.
Note:
It is most important to ensure that the burner drawer is properly fitted to provide an airtight seal. This
will require the refitting of all the fixing screws and may require the replacement of the sealing gasket.
7.5 FRSA Axial Fan Guard/Motor Assembly
The fan guard & motor for the FRSA range is supplied as a complete assembly and therefore does not need to
be disassembled.
The assembly is secured to the heater using the four fixing screws securing the guard to the heater with
rubber washers to reduce noise and vibration..
7.5.1 To Remove the Fan Assembly
Disconnect the electrical cables from the fan terminal block at the rear of the heater, carefully noting the
colour code of the wires to the fan.
Remove the four screws securing the fan guard to the heater carefully retaining the rubber washers.
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ROOM SEALED UNIT HEATERS
7.5.2 To Replace the Fan Assembly
To replace the fan assembly reverse the above procedure ensuring that the rubber washers are fitted to the
guard mountings to reduce vibration.
It is also most important that the colour code of the fan wires is strictly observed to ensure correct operation
and being careful to use the correct neutral connection. The Blue Neutral is for the main fan the Blue/White
neutral is for the flue fan and must not carry the load of the main fan
This is because the burner electrical supply is protected from mains borne interference by the use of a special
conditioning filter which is not capable of carrying the full load of the main fan.
It is sound practice to replace the fan capacitor when changing a fan.
Check that the fan blades are free to rotate without catching before turning on the power to the fan.
7.6 FRSB and FRSC Fan/Guard/Motor Assembly
The direct drive fan for the FRSB range is supplied as a complete assembly and therefore does not need to be
disassembled.
7.6.1 To Remove the fan/s.
Disconnect the electrical connections from the terminal block at the rear of the heater making a careful note of
the positions of the connecting wires and identifying the current speed setting.
Remove the fan / motor assembly by removing the fixing screws whilst supporting the weight of the fan
(approx. 19 kg) and making a careful note of the fan orientation.
For the FRSC version fitted with an inlet spigot assembly the fan/s may be accessed through the removable
covers on the sides, top and bottom of the spigot, as required.
7.6.2 To refit the fan/s
To reassemble reverse the above ensuring that the correct motor connections are used as identified when
disconnecting and that new rubber seal is used between the fan flange and the heater rear panel. It is
important that the fan is fitted to the rear panel in its correct orientation with the curved surface upwards.
It is most important that the colour code of the fan wires is strictly observed to ensure correct operation, and
being careful to use the correct neutral connection. The Blue Neutral at the heater is for the main fan the Blue/
White neutral at the heater is for the burner controls and must not carry the load of the main fan .This is
because the burner electrical supply is protected from mains borne interference by the use of a special
conditioning filter which is not capable of carrying the full load of the main fan..
Check that the fan blades are free to rotate without catching before turning on the power to the fan.
The three speed winding connections are:
Low speed: White N, Red Live. The other two windings are "parked" separately in spare terminals
Medium speed: White N, Blue live. The other two windings are "parked"separately in spare terminals
High speed: White N, Black live. The other two windings are "parked" separately in spare terminals
Page 36
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ROOM SEALED UNIT HEATERS
7.7 Combination Fan/Limit Thermostat
To gain access to this thermostat, open the heater side panel. Remove the thermostat cover retaining screw
and pull of the cover.
7.7.1
Disconnect the electrical connections by pushing in with a small screwdriver and pulling out the wires (see
Fig. 2.1).
7.7.2
The earth wire is held under a screw connection.
7.7.3
Unscrew two fixing screws and withdraw the unit from the cabinet feeding the cables through the grommeted
hole in the thermostat base.
7.7.4
To refit, reverse the above procedure reusing the grommet and reset as in the commissioning instructions,
Section 4.
Note:
the new thermostat should have the limit setting sealed by a suitable method to prevent unauthorised
adjustment.
WARNING
When replacing a combination thermostat ensure that the link is removed (see Fig. 2.1).
Permanent damage will be caused by leaving this link in.
Page 37
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ROOM SEALED UNIT HEATERS
7.8 Second Limit Thermostat
Remove the fan assembly from the heater rear (see 7.6).
7.8.1
Release the sensing phial from its clamp on the bottom of the heat exchanger and carefully pull the capillary
sensing probe through its access hole in the side of the heater.
7.8.2
To refit a thermostat, first carefully straighten the capillary tube - it is important not to kink or crack it.
Proceed to replace by reversing the above procedure ensuring that the sensing bulb at the end of the capillary
tube is positioned against the base of the heat exchanger towards the centre of the fan outlet (where there are
two fans the position of the sensing bulb should be towards the centre of the fan on the opposite side of the
heater from the controls).
Any spare capillary tube should be left carefully coiled in a position that will allow the burner drawer to be
removed without snagging on it.
7.9 Air pressure switch (Removal)
To replace the air pressure switch pull off the two coloured air pressure tubes noting there position .
Disconnect the two push on electrical connections noting there position.
Remove the two corner fixings of the pressure switch.
7.9.1 Replacement
To replace reverse the above ensuring that one of the correct calibration is used as specified in the data table
for the model. Only pressure switches that have been calibrated by Roberts-Gordon for use on the specific
model of heater may be used.
There is no adjustment necessary as the pressure switch is factory preset.
7.9.2 To test operation
To test for correct operation of the pressure switch requires that an accurate micromanometer is connected to
read the same differential pressure as the pressure switch.
This will require two temporary tee pieces inserting into the pressure tubes so that the manometer may be
used.
With the burner running read the pressure indicated on the micromanometer, it should be well above the set
point as indicated in the data tables for the model.
Apply a suitable clamp to the RED coloured Negative sample tube on the heater side of the temporary tee and
slowly close off the pressure to the pressure switch and micro manometer.
The pressure switch should turn off the burner at a pressure indicated on the micromanometer within ± 0.3
mbar of the set pressure as indicated in the data tables.
If the pressure switch is outside of this tolerance it must be changed.
Page 38
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ROOM SEALED UNIT HEATERS
Section 8. Fault Finding
WARNING
Fault finding must only be carried out by experienced engineers who fully understand
the operation of the burners. There is a risk, including that of explosion, when burners are faulty
and not repaired correctly.
START
Assuming gas and
electrical supplies
are ON.
Is the
Green Light ON?
Check external
controls are ON and
supply is sound.
Check for operation of
Limit Thermostats
Is Red 'Lockout'
warning light ON?
Test Burner
as in 8.1.
Does the Fan run?
Press in White
button on
combination
thermostat.
Fan runs now?
Use 8.4 to test fan.
See Section 4.3 to
check Fan Stat
Settings.
Replace
Combination
Thermostat.
Does burner stop
after running for
several minutes
(with controls still
on)?
Has the burner
'Locked Out'?
Check for correct
operation of fan.
Check operation
and setting of
Combination Stat.
Repair or replace as
necessary.
Use 8.1 to test burner.
Following the replacement or adjustment of parts, carry out the commissioning procedure as specified in
Section 4.
Heater Operating
YES
NO
NO NO
YES NO NO
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
NO
←←
←←
←
→→
→→
→
→→
→→
→
→→
→→
→
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
↓↓
↓↓
↓
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
YES
←←
←←
←
→→
→→
→
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
NO
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
←←
←←
←
Page 39
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ROOM SEALED UNIT HEATERS
8.1 Gas Burner Fault Finding
Start assuming that there is proven fuel and electricity supply with all external controls on (Greeen light on).
START
Assuming gas and
electrical supplies are ON.
Green light ON.
Is the air pressure switch at
rest (contacts open)?
See Section 4.1.2 & 7.9
for testing
Test switch. Replace.
Does the flue fan run?
Does 'Lockout' occur before
the burner fan has run for
10 seconds?
Use 8.2 to check flame
monitoring
Does 'Lockout' occur after
the burner has run for 10
seconds, but before the
burner fires?
Check setting of air
pressure switch (see 4.1.2).
Check that the flue fan is
operating. Check gas valve
plugs are fitted.
Check that the flue system
and flue fan are clean.
Check ignition circuit, fuel
supply and automatic gas
valve.
Does the burner fire?
Does 'Lockout' occur?
Use 8.2 to check flame
monitoring.
Heater Working
NO NO
YES
NO
NO
NO
YES
←←
←←
←
YES
↓↓
↓↓
↓
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
→→
→→
→
↓↓
↓↓
↓
↓↓
↓↓
↓
NO
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
↓↓
↓↓
↓
↓↓
↓↓
↓
YES
←←
←←
←
→→
→→
→
↓↓
↓↓
↓
YES
←←
←←
←
→→
→→
→
NO
↓↓
↓↓
↓
←←
←←
←
Page 40
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ROOM SEALED UNIT HEATERS
8.2 Flame Supervision Systems
Gas fired heaters use a rectification flame probe to monitor the flame.
To connect a suitable meter into the circuit to measure the flame signal current.
Disconnect the lead from the flame probe, (push on tag connector).
Connect a suitable DC ammeter between the flame probe and the wire just disconnected.
Should the meter read backwards, then reverse its connection.
Maximum flame current
with no flame:
0 to 0.5 m A D.C.
Minimum flam current
1.0 m A D.C.
Typical flame current
3.0 to 5.0 m A with main
burner ON
Connect a D.C. ammeter in series
with the flame probe using the jack
plug provided.
Turn on all controls and ensure that
there is a supply
to the burner.
Green light ON.
Is there a current flowing in
the flame probe circuit with
no flame present?
Inspect and test the flame
probe and wiring for
damaged insulation and
short circuits to earth.
Repair or replace
as necessary.
Does 'Lockout' occur when
there is a flame present?
Check adequate gas
pressure.
Replace flame probe and
ensure that it is fitted
correctly.
Check for correct earthing
of heater.
Check that live and neutral
polarity are correct.
Control box faulty.
Replace with correct type.
Burner Operating
YES
YES
←←
←←
←
↓↓
↓↓
↓
↓↓
↓↓
↓
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
↓↓
↓↓
↓
NO
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
NO
↓↓
↓↓
↓
↓↓
↓↓
↓
←←
←←
←
The Satronic DMG control is able to provide
Flame Current and Lockout information via a
special reader from the built in Lockout Reset
Button (see 8.2.1).
Page 41
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ROOM SEALED UNIT HEATERS
8.2.1.2 Lockout Diagnosis
In case of a failure the LED is permanently illuminated. Every 10 seconds the illumination is interrupted by a
flash code, which indicates the cause of the error. Therefore the following sequence is performed which is
repeated as long as the unit is not reset.
8.2.1 Satronic DMG Control Information System
The information system is microprocessor based and reports on all aspects of burner control box operation
and flame supervision. It informs continuously about the actual programming sequence the unit is just
performing. Besides monitoring of the programming sequence it also allows to identify errors during start up of
operation without any additional testing devices. The automatically performed diagnosis is a valuable tool
which facilitates service/maintenance work and therfore saves costs. the analyses of the error cause can be
done directly on stage or if not possible afterwrds as the lockout reason is stored in a non volatile lockout
mode memory.
The information system communicates with the outside world using a LED (the used Flash Code is similar to
the Morse Code). The messages are optically transmitted by an appopriately flashing LED. Using an
additional terminal (optional), the messages can be recorded and displayed in easy readable form.
8.2.1.1 Programming Sequence Display
The built in microprocessor controls not only the programming sequence but the information system too. The
individual phases of teh programming sequence are displayed as Flash Code.
The following messages can be distinguished:
MESSAGE FLASH CODE
Waiting for air proving switch l l .
Pre purge tv1 l l l .
Pre-ignition tvz l l l l .
Safety time ts l .
Delay 2nd stage tv2 l l .
Running l
_
Low mains voltage l
_
Description:
l = short pulse
= long pulse
. = short pause
_ = long pause
Error Diagnosis
Error Message Flash Code Possible Fault
Lockout safety time l
within lockout safety time no flame establishment
Stray light l l stray light during monitored phase, detector may be faulty
Air proving switch in closed
position l l l air proving switch contact welded
Air proving switch opened l l l l air proving switch opens uring start or operation
Loss of flame l loss of flame during operation
Flash Code for Manual Lockout
manual/external lockout
l l _
Page 42
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ROOM SEALED UNIT HEATERS
8.3 Solenoid Valve Circuit
To test the operation of a solenoid valve requires both electrical and mechanical checking.
To test the mechanicl operation of a valve requires a suitable manometer to be fitted to the outlet of the valve
and the rise in pressure observed at the appropriate time.
START
Test for 230v across valve supply
terminals at the appropriate time.
Fault elsewhere.
Check all connections and controls
including limit thermostats.
Pressure should rise on outlet when
valve energises.
Test gas pressure at inlet of valve. Fault elsewhere.
Solenoid valve faulty.
Replace as necessary.
Test gas pressure at outlet of valve.
Valve working
NO
NO
NO
↓↓
↓↓
↓
↓↓
↓↓
↓
YES
→→
→→
→
←←
←←
←
→→
→→
→
→→
→→
→
YES
↓↓
↓↓
↓
←←
←←
←
8.4 Main Fan Circuit
Fault elsewhere
Check for electrical supply
230v L to N
Fan does not run
automatically.
Test for 230v between
terminals 1 and N in
terminal block.
Press manual switch of
combination thermostat.
Fan runs now?
Fault elsewhere
Fan motor or capacitor faulty.
Replace as necessary.
Check settings of
combination thermostat.
Fan now operates
NO NO
NO NO
YES
↓↓
↓↓
↓
→→
→→
→
→→
→→
→
→→
→→
→
→→
→→
→
↓↓
↓↓
↓
YES
↓↓
↓↓
↓
YES
←←
←←
←
↓↓
↓↓
↓
Page 43
Page 41
ROOM SEALED UNIT HEATERS
Section 9. User Instructions
The normal user controls are installed remote from the heater and as a minimum will consist of a room
thermostat. Where a Roberts-Gordon remote control unit is used the operation of the heater will be fully
automatic from this control as described in the instructions supplied with the control.
The only user controls situated at the heater are:
The burner lockout reset button see 9.2.1
The fan run button see 9.2.2
The limit thermostat reset see 9.2.2
The second limit thermostat reset button see 9.2.3
9.1 Heater Operation
When the heater has been switched on (see Section 9.3) and the remote thermostat and/or time switch calls
for heat, the automatic control box turns on the burner and constantly monitors its safe operation. (see
Section 2.2).
When the heat exchanger is sufficiently heated, the fan thermostat turns on the main fan(s) and warm air is
discharged from the front of the heater.
Note on some fully ducted heaters the fan will come on during the burner firing cycle and not wait for the
temperature rise.
This is to ensure that there is always a proper operation of the heater under all possible duct conditions.
When the environmental working temperature, as set on the remote thermostat is achieved, the burner shuts
off. The main fan runs until all the heat has been extracted from the heat exchanger and the fan thermostat
detects a drop in leaving air temperature sufficient to turn it off. The heater then is at rest until the beginning
of the next cycle.
WARNING:
The main electrical isolator should only be used in an emergency and should not be used for
closing down the burner, as this switches off the main fan prematurely and may damage the heat
exchanger. Such action may cause a fire hazard and invalidate the warranty .
9.2 User Controls
The following controls are available for the user, at the heater.
9.2.1 Burner Lockout Reset Button
This button which is built into the burner control box, and will illuminate the red warning light at the front of the
heater when the control has gone to safety shut down ‘lockout’. This may be caused by flame failure.
After lockout has occurred, a waiting time of one minute must be observed before an attempt to reset the
control is made by pressing in the reset button on the side of the heater.
WARNING:
If the control should go to ‘lockout’ again, do not make more than three attempts at restarting the
heater.
The fault must be traced and repaired by a competent person.
Page 44
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ROOM SEALED UNIT HEATERS
9.2.2 Combination Fan/Limit Thermostat
This is located on the top right hand side of the heater inside the opening side door, see Fig. 1.1.
This control ensures the heater does not blow cold air in the normal heating cycle and protects the heat
exchanger against overheating.
Fan Thermostat
Although it should not be necessary for the user to touch this control, it is worth noting that:
Pressing in the White button on the combination fan limit thermostat causes the main fan(s) to run
continuously.
For normal operation this button should be pulled to the out position.
Limit Thermostat
If for any reason the main fan should fail or the air flow is reduced the built in limit thermostat will cause the
burner to go to safety shut down ‘lockout’. This condition will persist until the fault is corrected and the manual
reset button is operated. The combination fan/limit thermostat is preset during commissioning (see 10.2.7).
9.2.3 Secondary Limit Thermostat
There is also a secondary limit thermostat situated on the heater rear panel near to the electrical cable entry
points. This is a hand reset device designed to fail safe and give further protection against fan failure.
To reset this thermostat unscrew the plastic cover and press in the central reset button.
Note:
the heat exchanger must have cooled for reset to be possible.
9.3 Operating Instructions
9.3.1 Turning on the Heater
Ensure that the electricity and gas supplies to the heater are on and (where fitted) reset the time switch as
described in the makers instructions.
Check that the external controls are ON i.e. check that the time switch is in an “ON” period and that the
thermostat is set to the required temperature, (which must be above the ambient temperature for the heater to
operate).
The green light will now be on, and the heater will operate fully automatically under the control of the burner
control box along with the time switch and thermostats, as fitted on site.
Following long shut down periods the control may go to “lockout” (indicated by the red “lockout light” being
illuminated). To reset press in the “lockout reset button” and the sequence will begin again automatically.
“Lockout” should not occur during normal operation of the heater and indicates that there is a fault condition
which must be corrected.
WARNING:
If the control should go to ‘lockout’ again, do not make more than three attempts at restarting the
heater.
The fault must be traced and repaired by a competent person.
Page 45
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ROOM SEALED UNIT HEATERS
9.3.2 To Turn the Heater OFF (Short Periods)
Operate the external controls (Time switch or room thermostat) to an off position. The burner will turn off
immediately, but the distribution fan will continue to run for a few minutes to dissipate the heat from the heat
exchanger.
To restart turn the control used above to “ON”.
9.3.3 To Turn the Heater OFF (Long Periods)
Carry out the operations of 9.3.2. Allow the fan to stop running automatically. Turn off the gas and electrical
supplies.
To start the heater again, turn on the gas and electrical supplies and carry out the operations in 9.3.1.
WARNING
The electrical isolator must not be used for turning the heater off other than in an emergency. This
will prematurely turn off the distribution fan and will seriously shorten the life of the heat
exchanger, invalidating the warranty. Such action may also cause a fire hazard.
9.4 Simple Fault Finding
Some possible reasons for the heater not operating are:-
1. Gas supply not turned ON.
2. Electricity supply not turned ON.
3. The installed time and/or temperature controls are not ON.
4. Green light will not come on, check 2 & 3 above or
One or both of the limit thermostats may have operated. This may be caused by inadvertent
removal of the electrical supply or failure of the distribution fan.
Limit thermostat 1 is on the combination thermostat. To reset, press in and release the red reset
button (see 9.2.2).
Limit thermostat 2 is under the screw on cover on the rear of the heater near the Electrical
cable entry glands (see 9.2.3).
To reset remove the screw on cover and press in the reset button. Replace the cover after use.
If the Limit thermostats persistently operate then there is a fault which must be investigated
by a competent engineer.
5. If under fault conditions the burner fails to ignite for any reason then it will go to the
lockout condition this will be indicated by the red lockout warning light on the front of the heater.
To reset press in and release the lockout reset button (see Fig. 1.1).
Any other problem will require the assistance of a Service Engineer.
WARNING:
If the control should go to ‘lockout’ again, do not make more than three attempts at restarting the
heater.
The fault must be traced and repaired by a competent person.
Page 46
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ROOM SEALED UNIT HEATERS
9.5 Service Requirements
This heater will require servicing at least once per year except when operating in a dirty of dusty area, when
more frequent service may be necessary. The service should be carried out by a competent engineer in
accordance with the requirements of this manual.
For service contact your Heating Supplier.
The heater cabinet may be cleaned using a damp cloth with a little domestic detergent.
Do not use excessive water or abrasive materials.
EMERGENCY INSTRUCTIONS
If a gas leak is suspected, turn off the gas supply and extinguish all naked flames.
DO NOT operate any electrical switches or machinery.
Evacuate and ventilate the area and contact your local gas supply undertaking immediately.
DO NOT SEARCH FOR GAS LEAKS WITH ANY NAKED FLAME
Page 47
Page 45
ROOM SEALED UNIT HEATERS
Section 10. Conversion Between Gasses
10.1 General
All versions of the heaters use the same main burner bars.
Natural Gas
All natural gas versions use the same main burner injectors, marked 594.
The gas valve contains a gas pressure regulator to allow for setting of the burner pressure.
L.P.G.
All L.P.G. versions use the same main burner injector, marked 54.
The gas valve DOES NOT contain a gas pressure regulator.
The correct operation of the heater depends on the close control of the gas inlet pressure to the appliance.
10.2 Burner Conversion
To convert the burner assembly from one gas to the other is the same for all models of heater.
Remove the burner tray as in Section 7 of these instructions and remove all of the main burner injectors.
Replace with the ones for the new gas following the instructions in Section 7.
10.3 Gas Valves
All of the MKII FRS range heaters are fitted with S.I.T. Nova main valves which may be converted to operate
with or without a burner gas pressure regulator.
To Convert NOVA Valve from Natural Gas to L.P.G.
Remove the cover of the pressure regulator.
Completely unscrew the regulator adjusting screw and remove it complete with its spring.
Replace the adjusting screw and original cover with the blanking nut attachment.
This device screws fully into the body of the regulator until it stops and puts the regulator out of action.
The step opening feature of the main valve will still operate.
Then carry out the commissioning procedure as detailed in Section 4.
To Convert NOVA Valve from L.P.G. to Natural Gas
Reverse the instructions above Refitting the regulator spring, adjuster and cover.
Then carry out the commissioning procedure as detailed in Section 4.
Fig 10.1 Conversion of S.I.T
Nova gas valve between
gasses
Page 48
Page 46
ROOM SEALED UNIT HEATERS
Section 11. Parts List
DESCRIPTION PART NUMBER
Axial Fan S4E 350 A 262
Axial Fan S4E 400 A 263
Axial Fan S4E 420 A 264
Torin 270-270 three speed centrifugal fan A 047
Torin 241-241 three speed centrifugal fan A 049
Torin AUO 76416 flue fan - models 75 - 135 A 993
Torin AUO 75125 flue fan - models 150 - 210 A 991
Automatic ignition gas valve .S.I.T. Nova (All gasses) L 421
Exclusion screw for Nova valves (All Types) for L.P.G. L 425
Main burner injectors, natural gas B 109
Main burner injectors, L.P.G. gas B 101
Sealing washers for main burner injectors B 210
Honeywell combination fan/limit thermostat. K 017
Second limit thermostat K 120
Note:
Always quote the model and serial number of the heater when ordering spare parts.
Parts available from:
Roberts-Gordon
Oxford Street, Bilston, West Midlands
WV14 7EG
SWITCHBOARD
Tel: 01902 494425
Fax: 01902 403200
SERVICE
Service Department
Tel: 01902 498733
Fax: 01902 401464
SPARES
Trade Counter
Tel: 01902 499051
Fax: 01902 492411
Page 49
Page 47
ROOM SEALED UNIT HEATERS
Section 12. Commissioning Data Sheet
GAS RATE MEASURED AT METER M3/hr (ft3/hr)
AMBIANT TEMPERATURE °C
GROSS STACK TEMPERATURE °C
NET STACK TEMPERATURE °C
CARBON DIOXIDE IN FLUE CO2 %
CARBON MONOXIDE IN FLUE CO. P.P.M.
ESTIMATED EFFICIENCY %
(State net or gross)
COMMENTS
HEATER LOCATION
MODEL SERIAL NUMBER
GAS TYPE:NATURAL/P.G.
CUSTOMER
SITE ADDRESS
INLET GAS PRESSURE mbar BURNER GAS PRESSURE mbar
ENGINEER SIGNATURE DATE
Page 50
Page 48
ROOM SEALED UNIT HEATERS
Page 51
Page 49
ROOM SEALED UNIT HEATERS
Page 52
CONTACTS
SERVICE
Tel: 01902 498733
Fax: 01902 401464
SPARES
Tel: 01902 499051
Fax: 01902 492411
MAIN SWITCHBOARD
Tel: 01902 494425
Fax: 01902 403200
Roberts-Gordon
Oxford Street, Bilston, West Midlands WV14 7EG
Tel: 01902 494425 Fax: 01902 403200
e-mail: enquiry@combat.co.uk
www.combat.co.uk
www.rg-inc.com
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