BENSON HEATING RS/UHA2 50 Manual

Gas room sealed unit heaters 2 stage
TECHNICAL INFORMATION ASSEMBLY
INSTRUCTIONS, USE AND MAINTENANCE
RS/UHA-2
BENSON HEATING
LUDLOW ROAD
KNIGHTON
POWYS
LD7 1LP
MAY 2003 Benson Heating is a divison of
Benson Climate Systems Ltd

COMPLIANCE NOTICES
The Benson RS/UHA2 range of warm air heaters detailed herewith are manufactured for Benson Heating within the
parameters of ISO 9002.
The Benson RS/UHA2 Range has been independently tested and assessed, and has been found to meet the Essential
Requirement of the following European Directives:
Gas appliance Directive (90/396/EEC)
Machinery Directive (89/392/EEC) 91368/EEC 93/44/EEC 93/65/EEC
Low Voltage Directive (73/23/EEC
Electromagnetic Compatibility Directive (98/336/EEC and 91/31/EEC)
Product Liability Directive (65/374/EEC)
The manufacturer has taken reasonable and practical steps to ensure that Benson RS/UHA2 Range of Heaters are safe
and without risk when properly used. These heaters should therefore only be used in the manner and purpose for which
they were intended, and in accordance with the recommendations detailed herewith.
The heaters have been designed, manufactured, assembled, inspected, and tested, with safety and quality in mind, there
are certain basic precautions which the installer and user should be aware of, and they are strongly advised to read the
appropriate sections of the information pack accompanying the heater, prior to installation or use.
Benson Heating supports all new products being supplied to their customers with a comprehensive information pack; this
clearly defines mandatory instructions for the safe installation, use, and maintenance, of the appliance(s).
Where proprietary items are incorporated into Benson Heating products, detailed information and instructions are also
provided as part of the information pack.
It is the responsibility of the installer, owner, user, or hirer, of such products supplied by Benson Heating, to ensure that
they are familiar with the appropriate information/manuals, supplied by the manufacturer, and that they are suitably
aware of the purpose of the manuals and the safety instructions. In addition, operators must be suitably trained in the use
of the appliance so as to ensure its continued safe and efficient use.
Benson Heating has a commitment to continuous improvement, and therefore reserves the right to amend or change the
specification of the RS/UHA2Heater range subject to agreement from The Notified Body.
Contained within the text of the manual, the words 'Caution' and 'Warning' are used to highlight certain points.
Caution is used when failure to follow or implement the instruction(s) can lead to premature failure or damage to the
heater or its component parts.
Warning is used when failure to heed or implement the instruction(s) can lead to not only component damage, but also
to a hazardous situation being created where there is a risk of personal injury.
Notified Body PIN Reference is
RANGE
Type Model Code
1 RS/UHA2 50
3TAIT2C016
2 RS/UHA2 80
3TAIT2C026
3 RS/UHA2 105
3TAIT2C036
4 RS/UHA2 140
3TAIT2C046
5 RS/UHA2 200
3TAIT2C066
6 RS/UHA2 260
3TAIT2C086
7 RS/UHA2 325
3TAIT2C106

INDEX
GENERAL
Description of equipment page.
Identification “
Description “
Identification “
Description “
Technical data “
Wiring diagram “
Remote control connections “
Regulating air flow “
FOR THE USER
Operation “
Servicing “
Heater indication lights “
Receipt of product “
Transport “
Dimension “
FOR THE INSTALLER
Location “
Wall bracket dimensions “
Gas connection “
Flue and combustion options “
Electrical control panel “
Electrical connections “
TECHNICAL ASSISTANCE SERVICE
Pre commissioning checks “
Initial start up “
Gas conversion “
Thermostat operation “
Control “
Maintenance “
Fault finding “

Heaters type 1-2-3-4-5
C
FAN 1
C
FAN 2
IMT
J6
NL
F2
F1
N
J5
II°
I°
SF
230V 50Hz
EF
SE
J4 J8
IGN1
PA
COMCOM
NA NC
ION
EA1
J11
J17
J2
J14
VM
TA
J16 J13
J7
RSTR
MS
EVG1-I°
EVG1-II°
RST
LB
LL
LF
J10
J9 J12
SND
LM
TR
J15J18
J1
KEY:
SND Temperature probe
TR Regulatory control thermostat (auto reset)
LM LIMIT thermostat (manual reset)
EVG1-I° Gas solenoid valve1
EVG1-II° Second stage gas valve 2
CFan capacitor
FAN 1 Axial fan 1
FAN 2 Axial fan 2 (type 5)
F1-F2 Line fuse (6,3 A)
LF Green working light
LL High temperature indication light
LB Lockout indication
RST Lockout reset
EF Flue venter
PA Differential pressure switch
IGN1 Ignition transformer
EA1 Spark electrode
ION Ionisation probe
SE Electrical control board
IMT (*) Fused isolator
MS (*) Fire damper connection (accessory)
RSTR (*) Remote reset connection
TA (*) Room thermostat connection
VM (*) Fan switch connection
SF (*) Second stage gas valve connection
(*) External to the heater customer supply.

Heater type 6-7
IGN2
EA2
EF
SE
J4 J8
IGN1
PA
COMCOM
NA NC
ION
EA1
J11
J17
J2
J14
VM
TA
J16 J13
J7
RSTR
MS
EVG2-I° EVG1-I°
EVG2-II° EVG1-II°
RST
LL
LB
LF
J10
J9 J12
SND
LM
TR
J15J18
J1
IMT
J6
230V ~50Hz
NL
F2
F1
N
J5
II°
I°
SF
C
FAN 1
C
FAN 2 FAN 3
C
KEY:
SND Temperature probe
TR Regulatory control thermostat (auto reset)
LM LIMIT thermostat (manual reset)
EVG1-I° Gas solenoid valve 1
EVG2-I° Gas solenoid valve 2
EVG1-II° Second stage gas valve 1
EVG2-II° Second stage gas valve 2
CFan capacitor
FAN 1 Axial fan 1
FAN 2 Axial fan 2
FAN 3 Axial fan 3(Type 7)
F1-F2 Line fuse
LF Green working light
LL High temperature indication light
LB Lockout indication
RST Lockout reset button
EF Flue venter
PA Differential pressure switch
IGN1 Ignition transformer 1
IGN2 Ignition transformer 2
EA1 Spark electrode 1
EA2 Spark electrode 2
ION Ionisation probe
SE Electrical control board
IMT (*) Fused isolator
MS (*) Fire damper connection (accessory)
RSTR (*) Remote reset connection
TA (*) Room thermostat connections
VM (*) Fan switch connections
SF (*) Second stage gas valve connection
(*) External to the heater customer supply.

GAS CONVERSION
The heaters are supplied ready for use with (G20) Natural Gas as per the table below Conversion kits are available from
the manufacturer:
Natural Gas (G20)
TYPE 1 234567
Number of injectors 1 1 1 1 2 2 4 N°
Diameter of injectors 3,10 410 480 555 500 540 450 mm/100
Gas supply pressure 20 mBar
Head pressure high fire 11,0 13,0 13,0 13,0 10,0 13,0 10,5 mBar
Head pressure low fire 6,0 7,0 6,5 6,5 7,0 6,5 5,0 mBar
BEFORE CHANGING INJECTORS ENSURE GAS SUPPLY IS ISOLATED
INSTRUCTIONS FOR CONVERSION TO PROPANE GAS G(31)
1. Change the injectors
2. Adjust the gas inlet pressure
3. Adjust the head pressure
4. Fit primary air diaphragm (if required )
5. Fit adhesive label supplied with kit indicating gas type
6. Ensure settings are correct as per the manual and data plate
CHANGE INJECTORS:
To change injectors:
Unscrew the natural gas injectors and replace them with the correct size injectors for propane as shown in table below:
Propane gas (G31)
TYPE 1 234567
Number of injectors 1 1 1 1 2 2 4 N°
Diameter of injectors 190 250 280 335 285 320 255 mm/100
Replacing injectors single manifold (type 1-2-3-4-6)
Replacing injectors 2 per manifold (type 5-7)
Check the size stamped on the side of the
injector is correct to the data in the manual.
Ensure that the new injectors are correctly fitted
in the manifold and are gas tight, When the
conversion is complete fix the transfer supplied
with the kit showing the correct gas pressure on
to the manifold
Test for gas soundness on completion
Ensure that the aluminium washers supplied for
(types 5–7) are fitted when changing the
injectors.

If the gas line has not been correctly purged ignition
may not take place at the first attempt resulting in
the heater going to lockout
Reset the lockout before re starting ignition sequence
Before each attempt at ignition it is necessary
to wait at least 10 seconds
•Connect the manometer on to the pressure test
point PM and check inlet gas pressure if correct
connect manometer to test point PV and start heater
with heater running ensure the gas pressure
corresponds to that shown on the data plate adjust
by altering the screws RP1 and RP2 on the gas
valve
•Check that the gas consumption reading
corresponds with that indicated in the TECHNICAL
DATA section Set on/standby switch to standby
when heater is sufficiently cool isolate gas supply
•Remove manometer ensure the screw at the test
point is tightened test for gas leaks
•Open the gas isolating cock switch on the electrical
supply set the room thermostat to the desired
temperature.
•The heater is now ready for operation
GAS VALVE
Model SIT 843 (two stage)
The heater must only be operated with the
burner compartment door(s) closed
STOPPING
To stop the heater use only the room thermostat Set it
to the minimum temperature The fan will stop after 3
minutes or when the heat exchanger is sufficiently cool
If required switch off the electricity supply at the isolator
!
The main electrical supply must not be switched off
or used as a method of stopping the heater except
in an emergency until the heater has cooled down
sufficiently preventing damage to the heat
exchanger
Interruption of electrical supply whilst heater is in
operation will cause it to go to overheat and may
damage the heat exchanger the LIMIT thermostat
will operate and this will have to be manually re set.
PM Inlet pressure test point.
PV Head pressure test point
RP1 Cross cut screw low fire adjuster
RP2 Hexagonal screw high fire adjuster

Assembly of primary air diaphragm:
Diagram showing the fitting of a primary air
diaphragm to single burner manifold (1-2-3-4-6) Diagram showing the fitting of a primary air
diaphragm for a two burner manifold type (7)
Warning the diaphragm plates should only
be used when using propane gas G31.
Gas conversion adhesive label:
Once the heater has been converted to propane ensure
that the correct label is fitted to the burner overtop of
the factory fitted one covering it completely. It is
recommended that the diameter of the nozzles be
checked also that the pressure corresponds to that
shown on the data plate provided
Ensure that all of the additional gas components are
correct for the installation (including storage tank, pipes
and pressure valves etc
Ensure that the pressure regulators are sealed after
carrying out the conversion.
GAS PRESSURE REGULATION
To regulate the gas inlet pressure :
•Connect a manometer onto the gas valve test
point (PM)
•Adjust the inlet gas supply regulator (customer
installation) to pressure indicated on data
plate:
To regulate the gas head pressure to the burner:
•Connect a manometer onto the gas valve test
point (PV)
•Adjust the pressure regulating adjusters RP1/
RP2 as detailed on next page to obtain correct
pressures indicated in table below:
Propane gas (G31)
TYPE 1 234567
Gas supply pressure 37 mBar
Head pressure max 35,5 35,0 35,5 35,5 34,5 35,5 34,5 mBar
Head pressure min 20,0 18,0 18,5 18,0 18,0 18,0 18,5 mBar
Gas inlet pressure must not exceed 60 mbar at the gas valve inlet.

Gas valve head pressure setting high fire Propane G31:
When setting the gas pressure for propane high fire
(second stage ) contact SF should be closed the high
fire pressure adjusting screw on the gas valve must be
excluded.
Connect a manometer on test point PV
Remove the plastic cover from the adjuster RP1 RP2
With a screw driver hold the adjuster RP1 stationary
and using a spanner, screw adjuster RP2 clockwise to
the bottom of the thread until the correct pressure
according to the data plate is achieved .
Gas valve head pressure setting low fire Propane G31 :
When setting the gas pressure for propane low fire
(first stage) contact SF should be open. The low fire
pressure should be adjusted to the settings shown on
the data plate and the data in the manual provided by
adjusting screw RP1
Clockwise increases the pressure
Anti clockwise to decrease the pressure
On completion replace the plastic cover and seal with
paint
Remove manometer ensuring that the test point screw
is gas tight
Gas valve gas SIT 843
On heaters with 2 gas valves the pressure regulation must be carried out on both gas valves

FAULT FINDING
If the heater is not working firstly check the following :
•Check electrical supply
•Check voltage is as stated +15%, -15%
•Check gas supply is on
•Check that the pressure is as stated in the TECHNICAL DATA
FAULT CAUSE SOLUTION
No operation No electrical supply 
Check main isolator.
Check supply cables
Check line fuses.
Check electrical connections
No spark ignition.
Flue venter working
No indication lights on
Differential pressure switch not
working Check flue pipe and combustion air pipe are clear.

Faulty differential pressure
switch Replace differential pressure switch

Poor connection at pressure
switch Check air pipe to switch is
connected and not damaged
Check electrical connections
Check that pipes are
condensate free .

Faulty flue venter Replace flue venter

Faulty control panel Replace control panel

Faulty ignition electrode Check ignition probe is not
cracked or damaged
Replace the ignition probe
No ignition
Flue venter working
No indication lights on Room thermostat open Check room thermostat.

Faulty flue venter Replace flue venter

Faulty control panel Replace control panel

Burner lights but locks out
after 5 seconds Live and neutral inverted
Poor earth Check electrical connections

Faulty ionisation probe 
Check electrical connection on
probe.
Check probe for cracks or
damage.
Replace ionisation probe .

Faulty ignition 
Check the gas type is suitable
for the heater.
Check the inlet gas pressure.
Check the head pressure.
Check the gas supply pipes
have been properly purged of
air .
Explosive start up. Faulty ignition electrode Replace ignition electrode

Incorrect electrode position Reposition electrode correctly
over the burner bar.

Faulty burner tube Replace the burner tube

Faulty ignition transformer Replace ignition transformer

Faulty ignition 
Check the gas type is suitable
for the heater.
Check the inlet gas pressure.
Check the head pressure.
Check the gas supply pipes
have been properly purged of
air .

heat exchanger dirty Check / clean heat exchanger
Burner shuts down then
re lights automatically .
No indication lights on.
Pressure differential switch not
operating correctly 
Check that air pipe to switch not
damaged or blocked.
Check that the flue and
combustion air pipes are clear.
Check that the thermal overload
on the flue venter has not
operated

Faulty pressure differential
switch Replace differential switch

Room thermostat in warm air
flow Check position of thermostat

Burner goes out due to the
intervention of the SND
thermostat and is restarted
automatically when the heater
has cooled down .
Yellow indication light on.
Excessive heat exchanger
temperature 
Check inlet gas pressure
Check burner head pressure
Check that gas type is suitable
for heater
Check injector size is correct for
the heater.

Excessive air temperature due
to insufficient air flow over heat
exchanger. 
Check the fan blades are clean
Check that the horizontal and
(vertical if fitted) louvers are
sufficiently open. (see in
installation section of manual)
Check that the fan speed is
correct and the air flow over the
chamber is sufficient.

Faulty SND thermostat or
control panel Replace SND thermostat or control panel
Burner goes out due to the
intervention of the TR
thermostat and is restarted
automatically when the heater
has cooled down .
Yellow indication light on.
Excessive heat exchanger
temperature 
Check inlet gas pressure
Check burner head pressure
Check that gas type is suitable
for heater
Check injector size is correct for
the heater.

Excessive air temperature due
to poor air flow 
Check the fan blades are clean
Check that the horizontal and
(vertical if fitted) louvers are
sufficiently open. (see in
installation section of manual)
Check that the fan speed is
correct and the air flow over the
chamber is sufficient.

Faulty thermostat Replace thermostat

Burner goes out due to the
intervention of the LIMIT
thermostat (LM).
Yellow light flashing
Excessive heat exchanger
temperature. 
Check inlet gas pressure
Check burner head pressure
Check that gas type is suitable
for heater
Check injector size is correct for
the heater.

Excessive air temperature due
to poor air flow over heat
exchanger 
Check the fan blades are clean
Check that the horizontal and
(vertical if fitted) louvers are
sufficiently open. (see in
installation section of manual)
Check that the fan speed is
correct and the air flow over the
chamber is sufficient..

Faulty thermostat Replace thermostat

Faulty fan Check fan capacitor
Check fan motor.

Intervention of thermal overload
on fan Check electrical absorption Replace fan motor

Faulty fan operation Change fan control or SND
thermostat
Heater at lockout
Red lamp illuminated Faulty ignition 
Check inlet gas pressure
Check burner head pressure
Check that gas type is suitable
for heater
Check that gas line has been
purged correctly.

Faulty ionisation probe 
Check electrical connection to
the probe.
Check probe is not cracked or
damaged
Change probe or probe lead

Faulty ignition electrode Replace ignition electrode.

Faulty solenoid Replace solenoid

Dirty gas filter Clean filter

The control panel will not
reset .
Red light on
Faulty flame control module Replace the flame control
module after first checking the
electrical connections
Fan works intermittently Defective fan control Change fan control or SND
thermostat

Insufficient gas pressure 
Check that the gas type is
suitable for the heater .
Check the gas pressure
Check burner head pressure.
The fan does not work. Defective fan control Change fan control or SND
thermostat

Faulty fan Check fan capacitor.
Check the fan motor .
The heater works
continuously with out
reaching the required
temperature
Heater to small for application
Insufficient gas pressure

Re check heat output required
for the application
Check that the gas type is
suitable for the heater .
Check gas pressure.
Check burner head pressure.

Dirty heat exchanger Clean heat exchanger

B22: Single flue option with condensate tee and roof terminal combustion air from
inside the room
Type 1 – 2 – 3 – 4

MIN 300
MAX 10000
140
132
U
970
410
*
Ø100
A
T
V
✴157 mm type 1 – 2 – 3
165 mm type 4
ITEM DESCRIPTION
A Pipe M/F ∅100 L=1000 with seal
T Terminal with guard
∅
100
U Condensate Tee with drain point
V Pipe M/M ∅100 L=200 without seal
NOTE IMPORTANT:
MODEL 1-2-3-4
∅FLUE SPIGOT
∅
100 female
∅COMBUSTION AIR SPIGOT
∅
100 female
INSTALLATION Flue should be adequately supported
each bend corresponds to approx 0,8-1 meter of horizontal pipe work

B22: Single flue option with condensate tee and roof terminal combustion air from
inside the room
Type 5 – 6 – 7
A
T
410
970
Ø100
Z
U
MIN 340
MAX 10000
132
165
ITEM DESCRIPTION
A Pipe M/F ∅100 L=1000 with seal
T Terminal with guard
∅
100
U Condensate tee with drain point
Z Pipe M/F ∅100 L=250 with seal
NOTE IMPORTANT:
MODEL 5-6-7
∅FLUE SPIGOT SIZE
∅
100 male
∅COMBUSTION AIR SPIGOT SIZE
∅
150 male
INSTALLATION Flue should be adequately supported
Each bend corresponds to approx 0,8-1 meters of horizontal pipe work

MAX 10000
Ø100
Ø100
H
H
U
175
132
970
235
140 *
MIN 300
A
Ø150
L
A
V
C32 Installation showing Vertical co axial flue terminal with condensate drain
Type 1 – 2 – 3 – 4
✴157 mm type 1 – 2 – 3
165 mm type 4
ITEM DESCRIPTION
A Flue pipe M/F ∅100 L=1000 with seal
H Bend 90° M/F ∅100 with seal
L Vertical co axial roof terminal kit
∅
100-100
U Condensate tee with drain point
V pipe M/M ∅100 L=200 without seal
NOTE IMPORTANT:
MODEL 1-2-3-4
∅FLUE SPIGOT SIZE
∅
100 female
∅COMBUSTION AIR SPIGOT SIZE
∅
100 female
INSTALLATION Flue should be adequately supported
each bend corresponds to about 0,8-1 meters of horizontal pipework

MIN 10000
115
970
410
MIN 340
185
U
Ø100
Ø150
165
Z
A
NØ160
C32 Installation showing Vertical co axial roof terminal with condensate drain
Type 5 – 6 – 7
ITEM DESCRIPTION
A Pipe M/F ∅100 L=1000 with seal
F Pipe M/F ∅150 L=1000 with seal
I Bend 90° M/F ∅150 with seal
N Vertical co axial roof terminal kit
∅
100-150
P Adaptor F/F ∅150 L=200 with seal
Q Bend 45° M/F ∅150 with seal
R Pipe M/F ∅150 L=140 with seal
S Bend 90° F/F ∅100 with seal
U Condensate tee with drain point
Z Pipe M/F ∅100 L=250 with seal
NOTE IMPORTANT:
MODEL 5-6-7
∅FLUE SPIGOT SIZE
∅
100 male
∅COMBUSTION AIR SPIGOT SIZE
∅
150 male
INSTALLATION Flue should be adequately supported
each bend corresponds to about 0,8-1 meters of horizontal pipework