COMBAT CUHA, CUHB, CUHA/A, CUHC, CUHB/A Installation, Commissioning, Service & User Instructions

SUITABLE FOR: GB, IE, IT & ES

UNIT HEATERS

Installation, Commissioning,

Service & User Instructions

Models

CUHA, CUHB, CUHC & CUHD

60 to 240 (Manual Ignition)

CUHA/A, CUHB/A, CUHC/A & CUHD/A

60 to 380 (Automatic Ignition)

October 1999

Part No. X404C

Price £5.00

Page 1

UNIT HEATER

T

hese appliances have been tested and certi fied 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.

This A ppliance 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 distri bution conditions, nature of gas
and pressure, and adjustment of the appliance are compatible.

Page 2

UNIT HEATER

CONTENTS

The parts of this manual are numbered by section, clause and sub-clause. Hence 1:2:3 refers to Section
1, 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

THESE AIR HEA TERS ARE FOR USE WITH NATURAL GAS OR L.P.G ONLY AS ST ATED
ON THE HEA TER DAT A PLATE

(Conversion between gasses must be carried out in accordance with section

10 of these instructions)

THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR NEAR THE HEATER

Note: Every eff ort is made to ensure that the information contained in this Manual is accura te. Howe ver,

Combat Engineering Ltd. reserves the right to alter specifications without prior notice.

Combat 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 W arranty (subject to terms and conditions).

Page 3

UNIT HEATER

Section 1. GENERAL SPECIFICATION- CUH RANGE

l.l Basic Information

There are eight types of heater in the CUH... range covered by these instructions.

1. CUHA 60 to CUHA 240 Manual ignition with axial fans.

(22.5kW (76770 Btu/hr) to 89kW (303668 Btu/hr) Gross heat input)

2. CUHB 60 to CUHB 240 Manual ignition with centrifugal fans.

(22.5kW (76770 Btu/hr) to 89kW (303668 Btu/hr) Gross heat input)

3. CUHC 60 to CUHC 240 Manual ignition as CUHB but with the fans encased to allo w inlet ducting .

(22.5kW (76770 Btu/hr) to 89kW (303668 Btu/hr) Gross heat input)

4. CUHD 60 to CUHD 240 Manual ignition without fan for installing into ducting.

(22.5kW (76770 Btu/hr) to 89kW (303668 Btu/hr) Gross heat input)

5. CUHA/A 60 to CUHA/A 380 Automatic ignition axial fans.

(22.5kW (76770 Btu/hr) to 140kW (477680 Btu/hr) Gross heat input)

6. CUHB/A 60 to CUHB/A 380 Automatic ignition ,with centrifugal fans.

(22.5kW (76770 Btu/hr) to 140kW (477680 Btu/hr) Gross heat input)

7. CUHC/A 60 to CUHC/A 380 as CUHB/A but with the fans encased to allow inlet ducting.

(22.5kW (76770 Btu/hr) to 140kW (477680 Btu/hr) Gross heat input)

8. CUHD/A 60 to CUHD/A 380 Automatic ignition, without fans for installing into ducting .

(22.5kW (76770 Btu/hr) to 140kW (477680 Btu/hr) Gross heat input)

Combat CUH... ranges of unit Air Heaters are type B11 appliances for vertical flue whi ch are designed
to be suspended or shelf mounted.

These heaters are Cat II

2H3+

appliances for use with natural gas or L.P.G. as stated on the heater data

plate, and are intended for indoor installation only.

They 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 the Combat range of control consoles,
or by the use of individual controls as per the circuit diagrams in Section 5.

Page 4

UNIT HEATER

1.2 Heater Operation

1.2.1 Automatic Ignition Burner

Combat CUH.../A range warm air heaters are fitted with an automatic ignition control which ignites
the gas and monitors for the safe operation of the burner each time the exter nal controls call for the
heater to operate.

1.2.2 Manual Ignition

Combat CUH... range heaters are fitted with a permanent pilot w hi ch requires manual ignition. Once
ignited the pilot remains alight so long as the thermocouple is detecting a flame. i.e. the multifunctional
control or isolating gas valve is not turned off and the electrical power supply is not interrupted.

1.2.3 Common Operation - All Heater Types

When the external controls call for heat, the burner operates 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 b uilding.

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.

Note: F or CUHD... versions supplied without a fan, for installation in ducting with a customer supplied
fan unit, it is essential that the control of the f an incorporates a system for allowing the fan to run on at
close down of the burner as described above.

WARNING

The electrical isolator should only be used in an emergency and should not be used for

closing down the burner, as this switches off the fan prematurely and may damage the heat

exchanger invalidating the warranty and causing a potential fire hazard.

Operating the electrical isolator on a CUH... manual ignition heater will also

turn off the pilot burner.

Page 5

UNIT HEATER

Fig 2.1 Dimensions etc. CUHA... 60 to 300

Gas Connection

Access to Second

Limit Thermostat

WARNING !

Isolate Before

Removing Cover

Electrical Connections

for Main Fan, Gas

Valve and Interrupter

Relay

Lighting

Instructions

Data Plate

Electrical Supply via Cable

Gland

Pilot viewing

via cut out

Combustion

Air Slots

Honeywell

Combination Fan/

Limit Stat.

Burner

Compartment

Air Deflection

Grille

Model

Ref.

60 80 100 120 140 160 180 200 240 280 300

A Width

mm

(ins)

519

(20½)

519

(20½)

589

(23)

589

(23)

729

(28½)

729

(28½)

869

(34)

869

(34)

1009

(39¾)

1219

(48)

1219

(48)

B Support

Spacing

mm

(ins)

479

(18)

479

(18)

549

(21¾)

549

(21¾)

689

(27¼)

689

(27¼)

829

(32¾)

829

(32¾)

969

(38¼)

1179

(46½)

1179

(46½)

C Flue Dia.

mm

(ins)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

229

(9)

229

(9)

254

(10)

254

(10)

254

(10)

Weight kg 91 91 110 110 130 130 150 150 190 200 200

Page 6

UNIT HEATER

Fig 2.2 Dimensions etc. CUHA... 340 to 380

Air Deflection GrilleBurner Compartment

WARNING !

Isolate Before

Removing

Cover

Lighting

Instructions

Electrical Supply

via Cable Gland

Access to Second

Limit Thermostat

Combustion

Air Slots

Data Plate

Gas

Connection

Pilot viewing

via cut out

Electrical

Connections for

Main Fan, Gas

Valve and

Interrupter Relay

Flue

Connections

Assembled on Site

Honeywell

Combina-

tion Fan/

Limit Stat.

Model

Ref.

340

380

A Width

mm

(ins)

1359

(53½)

1499

(59)

B Support

Spacing

mm

(ins)

1319

(52)

1459

(59)

C Flue Dia.

mm

(ins)

305

(12)

305

(12)

Weight kg 210 210

Page 7

UNIT HEATER

Fig 2.3 Dimensions etc. CUHB... 60 to 300

Burner

Compartment

Electrical Supply

via Cable Gland

Access to Second

Limit Thermostat

Data Plate

Combustion

Air Slots

Lighting

Instructions

Pilot viewing

via cut out

Gas

Connection

Electrical

Connections for

Main Fan, Gas

Valve and

Interrupter Relay

WARNING !

Isolate Before

Removing

Cover

Honeywell

Combina-

tion Fan/

Limit Stat.

Air Deflection

Grille

Model

Ref.

60 80 100 120 140 160 180 200 240 280 300

A Width

mm

(ins)

519

(20½)

519

(20½)

589

(23)

589

(23)

729

(28½)

729

(28½)

869

(34)

869

(34)

1009

(39¾)

1219

(48)

1219

(48)

B Support

Spacing

mm

(ins)

479

(18)

479

(18)

549

(21¾)

549

(21¾)

689

(27¼)

689

(27¼)

829

(32¾)

829

(32¾)

969

(38¼)

1179

(46½)

1179

(46½)

C Flue Dia.

mm

(ins)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

229

(9)

229

(9)

254

(10)

254

(10)

254

(10)

Weight kg 111 111 130 130 150 150 170 180 220 270 270

Page 8

UNIT HEATER

Fig 2.4 Dimensions etc. CUHB... 340 to 380

Air Deflection GrilleBurner Compartment

Electrical

Supply via

Cable Gland

WARNING !

Isolate

Before

Removing

Cover

Combustion

Air Slots

Access to Second

Limit Thermostat

Data

Plate

Lighting

Instructions

Gas

Connection

Pilot viewing

via cut out

Electrical

Connections for

Main Fan, Gas

Valve and

Interrupter Relay

Honeywell

Combina-

tion Fan/

Limit Stat.

Model

Ref.

340

380

A Width

mm

(ins)

1359

(53½)

1499

(59)

B Support

Spacing

mm

(ins)

1319

(52)

1459

(59)

C Flue Dia.

mm

(ins)

305

(12)

305

(12)

Weight kg 276 276

Flue

Connections

Assembled on Site

Page 9

UNIT HEATER

Fig 2.5 Dimensions etc. CUHC... 60 to 300

Air Deflection

Grille

Burner

Compartment

WARNING !

Isolate

Before

Removing

Cover

Access to Second

Limit Thermostat

Combustion

Air Slots

Honeywell

Combina-

tion Fan/

Limit Stat.

Electrical Supply via

Cable Gland

Lighting

Instructions

Data

Plate

Gas

Connection

Pilot viewing

via cut out

Electrical

Connections for

Main Fan, Gas

Valve and

Interrupter Relay

Model

Ref.

60 80 100 120 140 160 180 200 240 280 300

A Width

mm

(ins)

519

(20½)

519

(20½)

589

(23)

589

(23)

729

(28½)

729

(28½)

869

(34)

869

(34)

1009

(39¾)

1219

(48)

1219

(48)

B Support

Spacing

mm

(ins)

479

(18)

479

(18)

549

(21¾)

549

(21¾)

689

(27¼)

689

(27¼)

829

(32¾)

829

(32¾)

969

(38¼)

1179

(46½)

1179

(46½)

C Flue Dia.

mm

(ins)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

229

(9)

229

(9)

254

(10)

254

(10)

254

(10)

E Duct

Spigot Width

mm

(ins)

438

(17¼)

438

(17¼)

508

(20)

508

(20)

648

(25½)

648

(25½)

788

(31)

788

(31)

928

(36½)

1137

(44¾)

1137

(44¾)

Weight kg 128 128 148 148 169 169 191 201 243 295 295

Page 10

UNIT HEATER

Fig 2.6 Dimensions etc. CUHC... Models 340 to 380 Range

WARNING !

Isolate

Before

Removing

Cover

Electrical Supply

via Cable Gland

Honeywell

Combina-

tion Fan/

Limit Stat.

Access to

Second

Limit

Thermostat

Combustion

Air Slots

Air Deflection GrilleBurner Compartment

Data

Plate

Lighting

Instructions

Gas

Connection

Pilot viewing

via cut out

Electrical

Connections

for Main Fan,

Gas V alve and

Interrupter

Relay

Model

Ref.

340 380

A Width

mm

(ins)

1359

(53½)

1499

(59)

B Support

Spacing

mm

(ins)

1319

(52)

1459

(59)

C Flue Dia.

mm

(ins)

305

(12)

305

(12)

E Duct

Spigot Width

mm

(ins)

1277

(50¼)

1417

(55¾)

Weight kg 303 304

Flue

Connections

Assembled

on Site

Page 11

UNIT HEATER

Fig 2.7 Dimensions etc. CUHD 60 to 300

Burner

Compartment

25mm Mez. Flange

Duct Connection Spigot

Electrical Supply via

Cable Gland

Honeywell

Combina-

tion Fan/

Limit Stat.

WARNING !

Isolate

Before

Removing

Cover

Combustion

Air Slots

Access to Second

Limit Thermostat

Lighting

Instructions

Data

Plate

Pilot viewing

via cut out

Gas

Connection

Electrical Connec-

tions for Gas Valve

and Interrupter

Relay

Rear Honeywell

Combination Fan/

Limit Stat.

Model

Ref.

60 80 100 120 140 160 180 200 240 280 300

A Width

mm

(ins)

519

(20½)

519

(20½)

589

(23)

589

(23)

729

(28½)

729

(28½)

869

(34)

869

(34)

1009

(39¾)

1219

(48)

1219

(48)

B Support

Spacing

mm

(ins)

479

(18)

479

(18)

549

(21¾)

549

(21¾)

689

(27¼)

689

(27¼)

829

(32¾)

829

(32¾)

969

(38¼)

1179

(46½)

1179

(46½)

C Flue Dia.

mm

(ins)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

178

(7)

229

(9)

229

(9)

254

(10)

254

(10)

254

(10)

D Duct

Spigot Width

mm

(ins)

438

(17¼)

438

(17¼)

508

(20)

508

(20)

648

(25½)

648

(25½)

788

(31)

788

(31)

928

(36½)

1137

(44¾)

1137

(44¾)

Weight kg 82 82 92 99 104 114 124 134 154 180 180

Page 12

UNIT HEATER

Fig 2.7 Dimensions etc. CUHD 340 to 380

Access to Second Limit

Thermostat

Data

Plate

Lighting

Instructions

Honeywell

Combina-

tion Fan/

Limit Stat.

Combustion

Air Slots

WARNING !

Isolate

Before

Removing

Cover

Rear

Honeywell

Combination

Fan/Limit Stat.

Burner

Compartment

25mm Mez. Flange

Duct Connection Spigot

Gas

Connection

Pilot viewing

via cut out

Electrical

Connections

for Gas Valve and

interrupter relay

Electrical Supply

via Cable Gland

Model

Ref.

340 380

A Width

mm

(ins)

1359

(53½)

1499

(59)

B Support

Spacing

mm

(ins)

1319

(52)

1459

(59)

C Flue Dia.

mm

(ins)

305

(12)

305

(12)

D Duct

Spigot Width

mm

(ins)

1277

(50¼)

1417

(55¾)

Weight kg 190 190

Flue

Connections

Assembled

on Site

Page 13

UNIT HEATER

Table 2.1 General Technical Data - All Models

ECNEREFERLEDOM0608001021041061081002042082003043083

EGNAR'A'

-daoLlacirtcelElatoT

sttaW

1911911918.7228.7224444442.4832.4838.8488.8488.8488.848

epyTnaF

nafiSnafiSnafiSnafiSnafiSnafiSnafiSnafiSnafiSnafiSnafiSnafiSnafiS

GMPGMPGMPGMPGMPGMPGMPGMPGMPGMPGMPGMPGMP

101-14053101-14053101-14053101-14093101-14093101-14024101-14024101-14053101-14053101-14024101-14024101-14024101-14024

dettiFsnaFforebmuN

1111111222222

fµroticapaC

5.25.25.23344 5.2x25.2x24x24x24x24x2

sttaW-gnitaR

071071071012012081081071071081081081081

spmA-tnerruCnuR

7.07.07.068.068.08.18.145.145.165.365.365.365.3

spmA-tnerruCtratS

9.19.19.13.23.24.34.32.42.47.67.67.67.6

rh/³M-wolFriA

0962096200330283440460743834065405360139013967396739

nim/³tf-wolFriA

3851385124918422083207720852486273730845084591559155

gk-thgieW

1919011011031031051051091002002012012

SEGNAR'C'&'B'

-daoLlacirtcelElatoT

sttaW

00900900210021571157110571002200420042004200530053

dettiFsnaFforebmuN

FFO1FFO1FFO1FFO1FFO1FFO1FFO2FFO2FFO2FFO2FFO2FFO3FFO3

epyTnaF

072-072NIROT072-072NIROT072-072NIROT072-072NIROT072-072NIROT072-072NIROT142-142NIROT142-142NIROT072-072NIROT072-072NIROT072-072NIROT072-072NIROT072-072NIROT

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

EVIRDTCERIDEVIRDTCERID

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

TCERID

EVIRD

sliateDrotoM

sttaWeziS

055x1055x1055x1055x1055x1055x1055x2055x2055x2055x2055x2055x3055x3

DEEPSTESLAMRON

WOLWOLMUIDEMMUIDEMMUIDEMMUIDEMWOLMUIDEMMUIDEMMUIDEMMUIDEMMUIDEMMUIDEM

-tnerruCnuRlamroN

spmA

9.39.32.52.51.51.55.74.93.013.013.015151

-tnerruCtratSlamroN

spmA

8.48.44.64.6663.96.118.21277.21277.216.816.81

deepShgiHtasmumixaM

spmA-tnerruCnuR

1.61.69.69.61.51.54.114.117.317.317.319.719.71

spmA-tnerruCtratS

88 6.86.877 6.316.311.711.711.711.221.22

tuohtiwdesuebottoN

tabmoCotecnerefer

rh/³M-wolFriA

0052006200130023052306230844007500260076008600490049

nim/³tf-wolFriA

1741035152813881319191917362553394633493200433553355

gkthgieW-egnaR'B'

111111031031051051071081022072072672672

gkthgieW-egnaR'C'

131131051051071071591502542003003603603

EGNAR'D'

deriuqeR

rh/³mwolFriAmuminiM

0052006200130023052306233834065400260086008667396739

nim/³tf

1741035152813881319191910852486294632004200491559155

taehssorcassolerusserP

riaderiuqertaregnahcxe

wolf

rabm

34.034.034.034.034.034.034.034.034.034.034.034.034.0

gkthgieW-egnaR'D'

28282999401411421431451081081002022

eziSnoitcennoCsaG

egnaRnoitingIlaunaM

½R½R½R½R½R½R½R½R½RA/NA/NA/NA/N

egnaRnoitingIcitamotuA

½R½R½R½R

Page 14

UNIT HEATER

Table 2.2 Technical Data CUHA, CUHB, CUHC and CUHD

Manual Ignition Range

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)

ONLEDOMNOITINGILAUNAM0608001021041061081002042

Wk-vcssorGtupnItaeH

5.225.92733425955.664798

rh/utB-vcssorGtupnItaeH

07767456001442621617641424771803102898622884252866303

Wk-vcteNtupnItaeH

3.026.623.337.839.642.359.957.662.08

rh/utB-vcteNtupnItaeH

0719698609647311191231958951973181534402294722506372

Wk-tuptuOtaeH.xorppA

87.7113.3232.9279.3380.1416.6445.2564.8513.07

rh/utB-tuptuOtaeHxorppA

846067159733799609511561041330951942971664991898932

srenruBforebmuN

4456789 0121

SAGLARUTAN

ezisrotcejnI

49.x749.x749.x749.x749.x749.x749.x749.x749.x7

kramdna

048048048048048048048048048

rabm-erusserPrenruB

9.5016.017.0121215.218.219.41

GWsni-erusserPrenruB

4.242.43.48.48.40.51.50.6

rh/³M-etaRsaG

41.218.235.301.469.426.543.650.784.8

rh/³tf-etaRsaG

7.573.995.4217.4410.5715.8918.3220.9425.992

EPYTEVLAVSAG

avoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.S

450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0

oNTRAP

134L134L134L134L134L134L134L134L134L

SAGGPL

eziSrotcejnI

A/N45.x745.x745.x745.x745.x745.x745.x745.x7

kramdna

A/N052052052052052052052052

rabm-erusserPtelnIenaporP

A/N7300.737300.737300.737373

GWsnI-erusserPtelnIenaporP

A/N8.4108.418.4108.418.4108.418.418.41

rh/³MetaRsaGenaporP

A/N11.193.126.169.122.205.297.253.3

rh/gketaRsaGenaporP

A/N11.246.270.327.322.457.492.563.6

rabm-erusserPtelnIenatuB

A/N9200.929200.929200.929292

GWsnI-erusserPtelnIenatuB

A/N6.1106.116.1106.116.1106.116.116.11

rh/³MetaRsaGenatuB

A/N48.060.132.194.196.109.121.255.2

rh/gketaRsaGenatuB

A/N51.296.231.387.392.448.493.584.6

EPYTEVLAVSAG

A/NavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.SavoN.T.I.S

A/N450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0450.028.0

)ROTALUGERON()ROTALUGERON()ROTALUGERON()ROTALUGERON()ROTALUGERON()ROTALUGERON()ROTALUGERON()ROTALUGERON(

oNTRAP

134L134L134L134L134L134L134L134L

Page 15

UNIT HEATER

Table 2.3 Technical Data CUHA/A, CUHB/A, CUHC/A and CUHD/A

Automatic Ignition Range

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)

NOITINGICITAMOTUA

ECNEREFERLEDOM

06A/08A/001A/021A/041A/061A/081A/002A/042A/082A003A/043A/083A/

Wk-vcssorGtupnItaeH

5.225.92733425955.664798301011521041

rh/utB-vcssorGtupnItaeH

07767456001442621617641424771803102898622884252866303634153023573005624086774

Wk-vcteNtupnItaeH

3.026.623.337.839.642.359.957.662.088.291.996.2111.621

rh/utB-vcteNtupnItaeH

0719698609647311191231958951973181534402294722506372446613361833772483093034

Wk-tuptuOtaeH.xorppA

87.7113.3232.9279.3380.1416.6445.2564.8513.0773.1809.6857.8906.011

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846067159733799609511561041330951942971664991898932436772305692539633763773

srenruBforebmuN

4456789 012141517191

SAGLARUTAN

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49.x749.x749.x749.x749.x749.x749.x749.x749.x749.x749.x749.x749.x7

kramdna

048048048048048048048048048048048048048

rabm-erusserPrenruB

7.56.92.01016.015.015.015.015.015.015.010.114.11

3.28.31.40.42.42.42.42.42.42.42.44.46.4

rh/³M-etaRsaG

41.218.235.301.469.426.543.650.784.818.984.0119.1143.31

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7.573.995.4217.4410.5715.8918.3220.9425.9926.6432.0736.0241.174

EPYTEVLAVSAG

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mednaTmednaTmednaTmednaTmednaTavoNavoNavoNavoNavoNavoN

0402MG

1009

0402MG

1009

330.038.0330.038.0330.038.0330.038.0330.038.0711-228-0711-228-0711-228-0711-228-0711-228-0711-228-0

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114L114L114L114L114L124L124L124L124L124L124L950L950L

SAGGPL

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A/Nmm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7mm45.0x7

kramdna

A/N052052052052052052052052052052052052

ENAPORP

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A/N737373737373737373737373

GWsnI-erusserPtelnI

A/N8.418.418.418.418.418.418.418.418.418.418.418.41

rh/³M-etaRenaporP

A/N11.193.126.169.122.205.297.253.388.341.407.472.5

rh/gk-etaRenaporP

A/N11.246.270.327.322.457.492.563.663.768.739.810.01

rh/rtLdiuqiL-etaRenaporP

A/N1.42.50.63.73.83.94.014.214.414.515.716.91

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A/N6.116.116.116.116.116.116.116.116.116.116.116.11

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A/N48.060.132.194.196.109.121.255.259.251.385.310.4

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A/N51.296.231.387.392.448.493.584.605.700.801.991.01

rh/rtLdiuqiL-etaRenatuB

A/N47.396.454.506.684.734.893.992.1160.3159.3168.5167.71

EPYTEVLAVSAG

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020.038.0020.038.0020.038.0020.038.0711-228-0711-228-0711-228-0711-228-0711-228-0711-228-0

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Page 16

UNIT HEATER

2.1 Gas Controls - Automatic Ignition

The heaters may be fitted with one of two types of gas control v al ves dependent upon the model, each
giving the same control elements as follows (see Section 4).

2.1.1 Main Gas Burner

The multifunctional main gas val ve contains a gas regulator and two automatic shut off va lves. When
set up as defined in Section 4 the valves will have a step opening operation on the main gas to give
smooth lighting. Settings of the valves are given in Section 4 and tables in Section 2.

2.1.2 Start Gas Burner

There is one solenoid valve to contr ol the pilot burner gas supply which is designed to operate at inlet
pressure and therefore does not need a regulator.

2.2 Gas Controls - Manual Ignition

The multifunctional gas valve contains a main gas regulato r, a safety gas valve controlled by the
thermocouple, and a solenoid valve to operate the main gas.
The manual control knob and Piezo electric igniter incorporated in this control allow for the safe
manual ignition of the pilot and selection for automatic oper ation of the main burner.

2.3 Main Fan

The main air moving fan(s) fitted to these heater s 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 used for distributing unheated air.

2.4 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 Honey well combination thermostat and the second is situated on the
side of the heater towards the rear. Note: on models 340 and 380 B & C versions there is an extra
secondary limit thermostat protecting the third fan unit.

2.4.1 Honeywell Combination Fan/Limit Thermostat

The combination fan/limit thermostat is a dual function control and safety device (see Fig. 2.7). There
are two of these fitted to CUHD versions, the second one on the inlet spigot at the rear of the heater.

Page 17

UNIT HEATER

2.4.2 Second Limit Thermostat

This is a manual reset device - see Figs. 2. 1 to 2.7.
Note: On CUHB and CUHC models 340 and 380 there are two of these fitted.

To reset this thermostat:

a) Remove the screw on cover of the thermostat where it protrudes from the cabinet side.

b) Push in the button in the centre of the thermostat. Note: the heat exchanger must be cooled to

allowthis to happen.

c) Replace the cover.

Fan Thermostat

The fan thermostat controls the operation of the main fan during the heater operating cycle. This
control also ensures that the main fan continues to run after the burner tur ns of f 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 CD100 type
control consoles this feature is catered for b y the fan on position of the control switch.

Limit Thermostat

The limit thermostat operates in overheat conditions caused by insufficient air passing over the heat
exchanger. T his is a manual reset de vice and is reset by pressing in the red reset button on the thermostat.
Note the heat exchanger must have cooled to below the operating temperature for reset to be possible.

Fig. 2.8 Combination Fan/Limit Thermostat

WARNING: IT IS ESSENTIAL THAT THE BREAK OFF LINK SHOWN IS REMOVED

IN THE EVENT OF THERMOSTAT REPLACEMENT

Page 18

UNIT HEATER

2.5 Thermocouple Interrupter Relay

All manual ignition heater s are fitted with a thermocouple interrupter relay to interface between the
limit thermostats and the thermocouple. This r elay is fully encapsulated and if faulty must be replaced
with the same type as it is specially produced to operate with burner thermocouples.

For normal operation the limit thermostats provide a constant voltage to the coil connections making
the relay permanently energ ised unless the limit thermostats operate or the electrical supply is interrupted.
In the event of interruption of the electrical supply to the interrupter relay then the contact opens and
the safety valve of the m ultifunctional gas va lve closes. The pilot will then need to be manually relit.

2.6 Automatic Ignition - Burner Control Box

2.6.1 DESCRIPTION OF SATRONIC TFI 812 2B Mod 10 CONTROL BOX

The fully automatic gas burner fitted to all CUHA/A, CUHB/A, CUHC/A and CUHD/A models is
controlled by a Satronic TFI 812 2B Mod 10 plug-in control box. This control ensures the safe start
and stop sequence and also monitors the safe presence of a flame.

Fig 2.9 Satronic TFI 812 Control Box Sequence

Page 19

UNIT HEATER

2.6.2 Sequence of Events

With the external controls on and calling f or heat, the control box will self check and then begin a start
sequence.

Electric Ignition ON

Start Gas Valve Energises

The start 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.

Electric Ignition Off

Five seconds later the electric ignition turns off, leaving the start gas flame to be proved as stable.

Main Gas Valve Energises

Following a short delay the main gas valves ener gise and the main flame cross lights from the start gas.
The control is now in its normal run position.

Close Down

When the external controls are satisfied the control box turns of f all outputs simultaneously and returns
to rest position for the beginning of the next sequence.

2.6.3 Fault Conditions

If at any stage the flame fails the control will go to ‘lockout'. The red light will glow and the control
will need to be manually reset before any further start attempt can be made.

Minimum flame probe current 1 µA DC.
Typical flame probe current 3-5 µA DC

2.7 External Control s

CUH... range heaters may be operated from external controls or consoles supplied by Combat
Engineering Ltd. which ar e described in their own instructions book.

The wiring diagrams for the external controls are shown in Section 5.

Page 20

UNIT HEATER

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 requir ements 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 Insatallation of Low Pressure Pipes up to 28mm (R1) or
Institute of Gas Engineers Documents IGE/UP/1 and IGE/UP/2 as appropriate;

BS 5588 Parts 2 and 3 Fire Precautions In the Design and Construction of Buildings;

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.

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 21

UNIT HEATER

3.2 General

All models must be installed with the base level and may be suspended from above or from specially
prepared wall brackets of sufficient strength to adequately support the weight of the hea ter as listed in
Section 2. Data Tables. Drop r ods should be a minimum of 10 mm diameter mild steel. The four
hanging brackets are located on top of the heater, for all models. All heaters may be mounted on a shelf
of NON combustible mate rial.

Heaters 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 combustib le materials does not exceed 65°C.

It is important to ensure that at all times there is adequate air circulation around the heater to supply air
for combustion ,ventilation and distribution.

Consideration should also be given when siting a heater to allo w for the proper location of the flue .

It is important that the gas supply pipe and the electrical connections do not support any of the heaters
weight

Fig 3.1 Typical Installation

C le ara nc e s fo r ins ta llation a ll mo d e ls

CUHA.... CUHB... CUHC... CUHD...

"A " Re ar o f fan to wa ll 0.6 M 0.6 M Se e B e low Se e B e low

"B " C le a r an c e at si de s 0.8 M 0.8 M 0 .8 M 0.8 M

"C" He ight to base 2.75 to 3.0 M 2.75 to 3.75 M N/A N/A

Clearance in front of heater See Below See Below

"D " T o re m o ve b ur ne r 1.1 M 1.1 M 1.1 M 1.1 M

"E" From combustible mater ial 3.0 M 3.0 M N/A N/A

"F" Clea r a n c e ab o ve h e ate r 0.6 M 0.6 M 0.6 M 0.6 M

CUHC & CUHD inlet and outlet ducts
Dime n sion "A" Minimum le ng th o f inle t d uct 2 x large st dimension
Minimum le ng th of o utlet duct 1.1 m or 2 x largest dimen sion whichever is gre ater.

Page 22

UNIT HEATER

3.3 Gas Supply

General

The installation must compl y with local laws and re gulations, and the complete installation including
the meter where fitted, must be purged and tested for soundness.
The gas supply must be via metal pipes and terminate at the heater with a service gas cock 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 at the specified
inlet pressure under all load conditions.
It will generall y be required to use installation pipes of a larger diameter than the hea ter inlet connection.
On suspended heaters it is recommended that an approved metal flexible connection is used betwe e n
the service cock 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.

L.P.G.

For L.P.G. applica tions each heater must be provided with g as with the inlet pressure closely controlled
to 37 mbar for Propane (G31) or 29 mbar for Butane (G30). T his is best provided by the installation of
a suitable re gulator controlling the inlet to each heater to ensure tha t variations in system pressure are
not transferred to the individual heaters.

3.4 Flue

Each heater must be fitted with at least one metre of an individual and correctly sized stainless steel
flue (see Section 2 Tables) .which is designed to carry the products of combustion outside of the
building in accordance with B.S. 6230 or B.S.5440 Part 1 as appropriate.

Suitable flue may be supplied by Combat Engineering Ltd.

A separate draught div erter is not required as the heaters have one b uilt in. No other appliance may be
connected to the flue.

Page 23

UNIT HEATER

Models 340 and 380 only

The models 340 and 380 heaters are provided with two outlet spigots on top of the heater and a flue
assembly as shown in Fig 3.2 to combine these two flue outlets into a single vertical flue for the
appliance.

The combination piece is supplied in three pieces for ease of transportation and must be assembled on
site.

The same assembly is used for both Model 340 and 380 units.

T o assemble the flue combination piece on site the two bends provided must be secured to the branch
arms of the centre section as shown in Fig 3.2 using 'Monel' blind rivets or sheradised PK screws.
T o do this offer the female end of each bend in turn to the branch arm and secure to the tw o components
together ensuring that the dimension "F" shown on Fig 3.2 is correct. Also ensure that when the
assembly is standing on a flat surface the central flue section is exactly vertical.

The assembled unit is then fitted to the heater. Ensure that the combination flue is sealed into the two
heater spigots using heat resistant rope and fire cement.

The remainder of the vertical flue is then installed from the spigot at the top of the combination
assembly in accordance with the instructions for all other models.

All Models

The flue must be terminated at least one metre higher than the section of the roof it intersects (see Fig

3.1). Furthermore if the point of intersection with the roof is within 2.5m of a nearby structure the
terminal must be at least 1m above that structure.

It is important that flues are designed to pre vent the adv erse ef fects of down draughts which cause the
products of combustion to spill from the draught diverter and it is essential that the spilla ge test in
Section 4.6 is carried out. If spillage is occurring then it is recommended that the flue is terminated at
least one metre above the highest point of the roof or any close obstruction.

If the flue extends more than 2 M above the roof it should be adequately supported by guy wires
(see Fig. 3.1).

The top of flues with a diameter of 200mm or less should be fitted with an approved ter minal and flues
of larger diameter should be fitted with a "Rain Cap".
90º bends and horizontal pipe must not be used in flues. As a guide, if 135º bends are used to offset
the flue, then at least one metre of vertical flue must be added to the minimum height to overcome the
resistance of each 0.33 m of none vertical flue or each two 135º bends.

Flues should be assembled with their sockets facing upwards inside of the building up to the rain
collar, and with their sockets facing downwards outside of the building above the rain collar. T he
sections should be secured together using "Monel" blind rivets or sheradized P.K. screws and be
supported so that the heater does not carry the weight of the flue.

Page 24

UNIT HEATER

Fig 3.2 Flue assembly of models 340 and 380 only

3.5 Air Supply

It is important to ensure that there is adequate air supply at all times for both combustion and heating
requirements. Particular attention must be paid to this point when the heater is installed in a separate
room. Ventilation should prevent the Plant r oom temperature exceeding 32°C and any negative air
pressure within the room containing the heate r.

Any plant room containing air heaters will require permanent air v ents direct to outside air in compliance
with BS 6230.

Most traditional building constructions will provide air changes of at least 0.5/h without the need for
ventilation openings. In the case of a building having an air change rate less than 0.5/h, low level
ventilation will be necessary in accordance with B.S.6230.

If the flue passes through a wall or ceiling of combustible mate rial it must be enclosed by a sleeve of
noncombustible material and be separa ted from the sleeve by at least a 25 mm air ga p. The temperature
of any combustible ma terial near the flue or heater must not exceed 65°C when the heater is in oper ation.

The flue must be at least 50 mm from any other comb ustible material.

The joints between the flue and the roof or wall must be made good to prevent water ingress.

The joint between the flue and the female spigot of the heater must be sealed using a heat resistant rope
and fire cement.

Dimension E = 405

Dimension F = 372

Page 25

UNIT HEATER

For buildings with a design air chang e rate 0.5/h or greater and where the v olume of the heated space
is greater than 4.7 m

3

per kilowatt of total rated heat input, as appropriate, additional high and low le vel

ventilation will not be required.

Where natural ventilation is used for compartment/plant r ooms, suitable permanent openings at low
and high level, communicating directly with the outside air, must be provided.

Where mechanical ventilation is used, it must be by mechanical inlet and with either natural or
mechanical extraction. Systems of ventilation employing mechanical extraction and natural air inlet
must not be used.

Automatic means, such as interlocks, must be provided for installations where equipment failures can
lead to hazardous situations developing.

3.6 Building Ventilation

Air must be taken from an outside point w h ere 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 must be a t least that required for personnel
within the building.

Where the heaters are located in the heated space the air supply requirement is not necessarily the sum
of the individual requirements for combustion, v entilation and dilution air, and fresh air , but the gre ater
individual requirement.

Where there are any open flued appliances in the room and where outside air is supplied mechanically
and there is mechanical extraction, the design extr act rate must be 5% to 10% less than the design inlet
rate so that the room will be at a higher pressure than outside air.

3.7 Distribution Ductwork CUHC and CUHD Heaters

CUHD range heaters are supplied with inlet and outlet duct spigots for mounting the heater into a
customer designed duct system .

CUHB range heaters may be supplied to special request with the outlet flanged for connecting to
customer designed duct systems.

CUHC range heaters are as CUHB range but with the fans enclosed so that the heater may be connected
to inlet ducting.

It is important when ducted systems are required that only the flanges made and fitted at the factory are
used at the heater to ensure that the integrity of combustion zone and draught diverter is not impaired.
Also it isimportant that the lower front and rear panels remain accessible for burner routine maintenance
and repairs. The burner may only be removed from the front lower panel and the rear lower panel
needs to be removed to do this.

Provision should be made so that the complete heater may be removed from the duct system.

Page 26

UNIT HEATER

It is recommended that f lexible duct connectors are used to reduce duct born noises.

The dimensions of the connecting ducts must be maintained to those of the heater spigot for at least
twice the major duct dimensions. T his should ensure that adequate air flow will pass ov er the whole of
the heat exchanger cross sectional area. Also there must be a duct length of at least 1.2m in front of the
heater before any downward vertical turn in the ducting to ensure that the burner may be withdrawn
from the front of the heate r.

All joints between the heater and the ductwork should be made as air tight as possible.

When installing a CUHB or CUHC heaters 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) to force
the fan to run and not rely on the fan thermostat to turn it on (see suggested scheme in Section 5).
Any such de vice must be in parallel with the fan thermostat so that the fan run-on operation will still
take place. CUHD heaters are fitted with tw o combination thermostats, at the front and in the rear inlet
spigot to cater for this effect.

Contact Combat Engineering Limited Design Department for advice regarding duct resistance
and design.

3.7.1 CUHD Heaters

For CUHD heaters it is essential that the airflow in the duct system is at least that specified in the Dat a
Sheets in Section 2 and in the correct direction across the heat e xchanger as indicated by the ar row 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 a bove to ensure that there is a homogenous
air flow across the whole of the heat exchanger . F ailure to provide a suita ble air flo w 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

3.8 Electrical Supply

A constant 230 volt 50 Hz single phase supply is required for all heater models connected to terminals
L, N & Earth.
It is important that the "L & N " polarity is correct, particularly for automatic ignition heaters as
incorrect polarity will prevent the burner control box from operating correctly. It is also important on
these heate rs that the voltage between N and Earth does not exceed 15v.

All heaters and controls must be correctly earthed.

All external wiring must comply with the relevant IEE regulations and be carried out by a qualified
electrician.

Page 27

UNIT HEATER

3.9 Remote Controls

Burner Controls

The heaters are designed to be operated by controls installed remote from the heater. Any controls
intended to operate the burner must be voltage free contacts connected between terminals 2 & 3 of the
main terminal block on the side of the heater.

Fan Controls

The fan is designed to operate automatically providing there is a constant 230v supply to the main
terminals. However, a switch wir ed between terminals L & 1 in the terminal block at the side of the
heater will provide for summer running of the fan/s.
It is acceptable for the fan to operate continuously from an external control, with the burner c ycling on
and off, providing that the fan run-on at close down is not impared.

3.9.1 Siting of Combat Control Consoles or Room Thermostats

The Combat control consoles or room thermostats 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 door s, 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.

Where CD100 type controls are fitted these also need to have the same constant 230v 50Hz.

An isolator with a contact separation of at least 3 mm on all poles should be installed adjacent to,
but not fixed to the heater to disconnect all supplies to the heater and where necessary to isolate any
remote control.

The final connection to the heater should be made in metal sleeved flexible cable or flexible conduit
to the main terminal block on the side of the heater using 1 sq. mm cable on all models.

A fuse size of 5 Amp must be used for all models CUHA and CUHA/A up to and including model
240, and 10 Amp for all remaining CUHA , CUHA/A ,CUHB, CUHC,CUHB/A and CUHC/A
models except for models CUHB… CUHC … 340 and 380 where the fuse size should be 20 Amp.

CUHD and CUHD/A models must have the external fan, or its control connected to Terminal 1 so
that the fan run on function at close down operates correctly.

Page 28

UNIT HEATER

3.9.2 Remote Room Thermostat

A remote room thermostat may be connected to terminals 2 & 3 in the main terminal block on the side
of the heater (see Section 5).

3.9.3 Remote Frost Thermosatat

Where a remote frost thermostat is required to override the operation of a time switch during its "off"
periods, this may be connected to terminals 2 and 3 in the main terminal block on the side of the
heater. It should be sited within the heated space adjacent to the most vulnerable equipment that
requires protection.

Page 29

UNIT HEATER

Section 4. COMMISSIONING THE HEA TER - ALL TYPES

Before starting to commission a heater read this section through and fully understand its contents.
Only competent engineers should carry out the work.

4.1 Pre Commission Checks

Checks before lighting the unit heater

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 Checks

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.

Check the correct fuse size is fitted; 5 Amp must be used for all models CUHA and CUHA/A, and 10
Amp for CUHB, CUHC, CUHB/A and CUHC/A models, except for models 340 and 380 where th e
fuse size should be 20 Amp. This must be connected in the live conductor (see Polarity Test below).

Earth Continuity Test

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.

Polarity Test

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 AC 50Hz should be found.

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 v olts. If these tests
do not conform to the above there is a fault whi ch must be rectified before progressing further with the
commission. An electrician should be consulted to carry out this work.

Note: For Automa tic Ignition models the burner control box will not operate with a neutral to earth
voltage above 15v and may be unreliable at any reading other than 0.

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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
val ve inlet test nipple before the start gas burner will ignite.

4.3 Mechanical checks

1. Check that the fan(s) are free to run and delivery louvres are turned to give required air deflection.

2. Check that the flue is installed in accordance with these instructions and local regulations.

3. Check that the Settings of the Combination Fan/Limit thermostat are correct - see below .
Note: The limit thermostat is preset and sealed a t the works and will need no adjustment.

To set the combination fan/limit thermostat first remove the co ver by releasing the co ver 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. 2.8.

Front combination thermostat (All Models) Rear thermostat on CUHD ... Only

HAND 1 FAN OFF SET TO 38°C SET TO 30ºC
HAND 2 FAN ON SET TO 57°C SET TO 55ºC
HAND 3 LIMIT SET TO 95°C SET TO 90ºC

Always refit the cover and tighten the cover scr ew after adjustments.

To continue with the Commissioning follow 4.4 f or Automatic Ignition models or 4.5 for Manual
Ignition models. Then continue with 4.6 for all appliance types

4.4 Automatic Ignition Unit Heaters

4.4.1 Carry Out a “Dry Run”

To ensure that all the controls are in safe working order it is advisable to operate the fully automatic
controls for the first time with no main gas.

To do this unplug the electrical plug from the main gas valves (there are two plugs for Nov a automa tic
valves). Now, using the installed external control turn on the burner.

The automatic sequence will now begin as described in Section 2. The electric ignition will be heard
and the spark may be observed via the gas inlet port in the rear panel.

The start gas flame will then ignite on the opening of the start gas valve. If the flame does not ignite
then the control will go to the “lockout” condition.Wait one minute, then press in the control box reset
button, or the remote reset button if fitted and repeat until the start gas flame ignites.

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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.

There is no adjustment for the start gas burner.

Once the start gas flame has ignited it will be monitored by the flame probe and should remain on until
the controls turn it off.

Turn off the burner at the external control and refit the electrical plug/s to the main gas val ve.

Inlet Pressure

Step Opening
adjustment

Electrical connection

Fig. 4.1 S.I.T. Tandem 0.830.033 Gas Valve (Natural gas)

0.830.020 valve (L.P.G)

Burner Pressure

Regulator adjusting screw under cover.
(Note: on L.P.G. heaters this is a throughput adjuster
and must be fully open )

Gas Outlet

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Inlet Pressure "E"

Burner Pressure "A"

Manual control knob

Regulator adjusting screw

Thermocouple interrupter
relay connections

Thermocouple
connection

Pilot Gas pipe
connection

Electrical connection

Gas Outlet

Pilot gas outlet of valve
Blanked off

Fig. 4.2 S.I.T. Nova 0.822.177 Automatic Ignition Gas Valve

Fig. 4.3 S.I.T. Nova 0.820.054 Manual Ignition gas Valve

Burner pressure

Inlet Pressure

Regulator (under cover)

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2

3

1

Dungs MBDLE 405 BO1 Main gas valve

Johnson GM 2031 0240 Main gas valve

4

5

The main gas control valve used on all versions of the models CUHA/A, CUHB/A, CUHC/A and
CUHD/A 340 and 380 is the Johnson GM 240 9001 combination gas valve or alternative Dungs
MBDLE 405 BO1 (see Fig 4.4). These controls contain two main safety shut off valves and burner
pressure regulator.

1. Pressure regulator under swivel cover

2. Slow opening adjustment

3. Throughput adjuster (Always fully open)

4. Inlet flange with inlet pressure test point

5. Outlet flange with outlet pressure test point

Fig 4.4 Main gas valves for Models 340 and 380

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4.4.2 Commissioning the Gas Valves - Natural Gas

Depending on the model of the heater there will be an S.I.T Tandem valve, an S.I.T Nova va l ve or a
Johnson controls gas valve (see Data Table in Section 2 and Figs 4.1 to 4.4).

Connect a manometer to the outlet (burner) pressure test point of the g as val ve after f irst removing its
screw cover.

To set the burner pressure remove the regulator cover and, with the burner firing, turn the regula tor
adjustment screw to set the required burner pressure as stated in the data tables in Section 2.

Note: If any difficulty is found in obtaining the correct burner pressure then check that there is a
sufficient inlet pressure available to the valve, with the bur ner firing.

Under no circumstances should a regulator be set to a pr essure ov er that wher e the pressure is
no longer being changed.

If the inlet pressure is too lo w to allow correct burner setting then the problem will be on the installa tion
and must be corrected before completing the commission. T he inlet pressure must be 20mbar with the
main burner firing.

To set the step opening adjustment, first turn off the burner at the external controls or unplug the
electrical connection to the main gas valv e and w ait for one minute for the valve to settle. Turn on the
burner again and as the main b urner turns on set the step opening pressure to approximately 2.5 mbar.
As the step opening lasts for only a few seconds its setting may need to be checked two or three times
to ensure satisfactory starting of the main burner.

Following burner pressure adjustment, allow the heater to operate for at least 15 minutes and then re­check settings. Remove the manometer and refit all covers to the val ve.

Wherever possib le a reading of the gas rate timed through the gas meter should be taken and compared
with the nominal rating in the Data Table, Section 2. The burner pressure should be adjusted to give
this nominal gas rate.

4.4.3 Commissioning the Gas Valves - L.P .G.

In all cases the gas v alves for L.P.G either have no re gulator or have the regulator put out of action (see
Section 10). The heater is therefore set on the inlet pressure to the gas va lve w hich must be maintained
at 37 mbar (25 - 45) for G31 (Propane) or 29 mbar (20 - 35) for G30 (Butane).

Note: Although the appliances are tested to operate safely between the minim um and maximum pressures
show n, they are designed to give the correct heat input only at th especified inlet pressure.

No further adjustments are necessary.

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4.5 Manual Ignition Unit Heaters

All CUH manual ignition unit heaters are controlled by an S.I.T No va 0.820.054 multifunctional gas
valve (see Fig 4.3).

First remove the electrical plug from the multifunctional gas valve to ensure that main gas cannot be
released.

T o ignite the pilot press in the manual control button of the g as valve and turn anticlockwise to the star
symbol. Press the button fully in and hold whilst continuously pressing and releasing the Piezo ignition
device to create the spark ignition.

Note: IF AT ANY TIME THE PILOT FAILS TO LIGHT OR GOES OUT, EITHER
INTENTIONALLY OR UNINTENTIONALLY, WAIT A FULL 3 MINUTES BEFORE
ATTEMPTING TO RELIGHT.

Once the pilot flame has been seen to light continue to hold in the control valve b utton for a further 30
seconds, and then release. The pilot flame should now remain on.

Should the pilot flame go out check that the limit thermosta ts have not operated and that there is an
electrical supply to the main terminal blo ck. Also ensure that the leads to the thermocouple interrupter
relay are connected to their connections on the gas valve (see Fig 4.3). Observe the 3 minute waiting
time and retry .

Once the pilot flame has been established it will remain on constantly providing that the gas or electricity
supplies are not interrupted and the limit thermostats do not operate.

To Operate the Main Burner

Replace the electrical plug onto the gas valve. Press in slightly and turn the valve control knob a
further quarter turn anticlockwise to the "flame" symbol. With the external contr ols in an on position
and calling for heat the main burner will now fire

Connect a manometer to the outlet (burner) pressure test point of the gas v a lve after first removing its
screw cover (see Fig. 4.3).

To Set the Main Burner - Natural gas

T o set the burner pressure r emove the regulator cov er scre w and with the burner fir ing, turn the regulator
adjustment screw to set the required burner pressure as stated in the Data Tables in Section 2.

Note: If any difficulty is found in obtaining the correct burner pressure then check that there is a
sufficient inlet pressure available to the valve, with the burner firing.

Under no circumstances should a regulator be set to a pressure over tha t where the pressure is
no longer being changed.

If the inlet pressure is too low then the problem will be on the installation and must be corrected before
completing the commission. The inlet pressure must be 20mbar with the main burner firing.

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Wherever possib le a reading of the gas rate timed through the gas meter should be taken and compared
with the nominal rating in the Data Table, Section 2. The burner pressure should be adjusted to give
this nominal gas rate.

4.5.2 Commissioning the Gas Valves - L.P .G.

In all cases the gas val ves for L.P.G. ha ve the re gulator put out of action. The heater is therefore set on
the inlet pressure to the gas valve wh ich must be maintained at 37mbar for G31, (Propane) or
29 mbar for G30 (Butane).

No further adjustments are necessary

4.6 Commissioning Tests - All Heater Types

W ith the main burner opera ting for at least 15 minutes carry out a spillage test on the draught diverter
in accordance with BS 5440 Part 1 ensuring that all doors and windows in the area are closed and that
any extract f ans are turned ON.

One method is to hold a lighted taper or smoke match just inside of the draught diverter and observe
that the smoke or flame is not drawn away from the heater.

Should it be indicated that the products of combustion are continuously entering the b uilding from the
draught diverter then correctiv e action MUST be taken before leaving the heater to operate nor mally.

4.7 Combustion Testing - All Heater Types

Although there is no adjustment availa ble 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.

T o do this the flue gas is sampled at the test point on the flu e, within 1 metre of the heater and tested for
contents of CO2 (carbon dioxide), CO (carbon monoxide) and temperature rise. The values of CO

2

should be between 5.5% and 6.5% . CO should be no more than 0.0015% ( 15 PPM) and the temperature
rise of the flue gasses above ambient should be approximately 160°C to 180°C.

Combustion testing must be carried out with all covers etc. fully fitted as designed.

4.8 Pilot Drop-Out Test - Manual Ignition Models

Carry out the Pilot Drop-Out Test as described in Section 6.4 and ensure a positive result.

4.9 Turning Off the Heater - All Heater Types

To turn off the heater operate the external controls to the off position and the main burner will stop.
Allow the fans to run on until they are stopped automatically by the fan thermostat. The heater will
then be at rest until the controls call for heat once more. For long term closing down for summer etc.
then when the fans ha ve stopped automatically, turn off the g as and electrical supplies at the isolator s .

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WARNING

The electrical isolator should only be used in an emergency and should not be

used for closing down the burner, as this switches off the fan prematurely and may damage

the heat exchanger invalidating the warranty and causing a potential fire hazard.

Operating the electrical isolator on a CUH Manual Ignition heater

will also turn off the pilot burner.

4.10 External Controls

Operate the External Controls as installed which may include time switch, room thermostat and manual
switch to ensure that they function correctly. Set the time switch (if fitted) and room thermostat to the
users requirements.

See Sections 2 and 9.

4.11 Handing Over

Ensure that all covers are fitted correctly and all test points are properly sealed before leaving the
appliance.

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 of f, using the controls fitted on site. Hand over these instructions
to the user.

Ensure that the user is shown and understands the emergen cy instructions in Section 9 of this book.

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Fig. 5.1 Wiring for CUHA Manual Ignition Range

Section 5. WIRING DIAGRAMS

MANUAL IGNITION

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Fig 5.2 Wiring for CUHB & CUHC models 60 to 160

MANUAL IGNITION

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Fig 5.3 Wiring for CUHB & CUHC models 180 to 300

MANUAL IGNITION

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Fig 5.5 Wiring to CUHD Manual Ignition Range (All models)

MANUAL IGNITION

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Fig. 5.6 Wiring Diagram for CUHA/A Range of Heaters Models 60 to 240

AUTOMATIC IGNITION

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Fig. 5.7 Wiring Diagram for CUHA/A Range of Heaters Models 280 to 380

AUTOMATIC IGNITION

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Fig 5.8 Wiring For CUHB/A & CUHC/A Models 60 to 160

AUTOMATIC IGNITION

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Fig 5.9 Wiring For CUHB/A & CUHC/A Models 180 to 300

AUTOMATIC IGNITION

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Fig 5.10 Wiring For CUHB/A & CUHC/A Models 340 to 380

AUTOMATIC IGNITION

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Fig 5.12 Alternative wiring of external motor for CUHD Range - All Models

Fig 5.11 Wiring of CUHD/A Range - Automatic Ignition - All Models

AUTOMATIC IGNITION

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Fig 5.13 Individual controls for all CUH Range heaters

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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 of f as the
fan can start automatically at an y time.

NOTE 1: After any maintenance wor k always test fire the heater in the prescr ibed 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. A n y 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

Burner maintenance is essentially the same for manual and automatic ignition heate rs. Where there is
a significant difference the two types are referred to separately:

1. Remove the Burner Assembly as in 7.1.

2. Check condition of the ignition burner, ignition electrode and flame probe (for automa tic), or
thermocouple (manual) as appropriate. Clean off any deposits which may have been formed on
the thermocouple or flame probe. Replace as necessary.

3. Check that the ignition gas pipe is clear of any deposits and that all joints are sound (See 7.3)

4. Check condition of ignition electrode and flame probe for erosion and damage to the ceramic
insulation (see 7.3). Replace as necessary.

5. Clean any deposits from the main burner paying particular attention to fluf f etc. which may have
formed in the injectors or venturi of the burner (See 7.2).

6. Check the condition of the thermal insulation lagging at the bottom of the burner compartment
and replace if necessary . Pay particular attention to the condition of the foil face of this insulation
which must be complete and unbroken.

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6.2 Fan/Motor Assembly all Models

The main fan requires very little maintenance as the bearings ar e sealed for life and need no lubrica tion.
If the fan blades need cleaning re m ove the fan guards and use a small brush or duster to clean the fan
blades from each side of the fan(s).

6.2.1 For CUHB & CUHC Centrifugal Fan Models

CUHB and CUHC models are fitted with thermally protected three speed direct dive fans. The data
table indicates the normal number of fans and their standard running speed for each model .They
require very little servicing other than cleaning of the fan blades.

It is essential th a t the fans are not operated at higher speeds than the original setting on the heater
without prior consultation with Combat Engineering Ltd. Such action may cause the fan motor s to be
over loaded.
Overloading the motor will cause the built in thermal overload protection device to operate.

Where two or three fans are fitted they must be all operating at the same speed and they will be
switched using a fan contactor built into the heater see the wiring diagrams.

The "HIGH" speed option is available to g ive the normal required air f low against higher static pressures
and is not intended to be operated free blowing or against low resistance . Use of the fans under these
conditions may cause the fan thermal o verload to operate and the f an thermostat to cyc le due to a lower
temperature rise.

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 liv e. The other tw o windings are "parked" separately in spare terminals

High speed: White N, Black liv e. The other two windings are "parked" se parately in spare

terminals

For CUHC models the fans may be accessed via the re movable panels in the top, bottom and sides of
the inlet spigot compartment as required.

6.3 Heat Exchanger

The heat exchanger should remain clean unless some problem has de veloped with comb ustion. Howev er,
an inspection of the condition of the heat exchanger is w ell worth while especially looking for signs of
overheating at the lower edges with may indicate burner over firing or persistently lo w air flows. An y
deposits in the heat exchanger may be removed with a small flue brush and vacuum cleaner from the
burner compartment after first removing the burner tray.

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Manual Ignition

There is no regular maintenance required on these devices. To change gas control valves, see
Section 7.4.

Pilot Drop Out Test - Manual Ignition Models

During the routine service a check must be made that the flame failure device operates correctly
To do this:-

I) With the pilot flame alight and running for at least 10 minutes, turn off the gas isolating

val ve and watch the pilot flame.

II) Measure the time taken from the pilot flame going out until the gas safety valve operates

(can be felt and heard as a dull click). This must be less than 60 seconds.

If the above test fails, replace the thermocouple (see Section 8) with one of the correct type.

Repeat the test to confirm a positive result.

It is not recommended for gas control valves to be repaired or disassembled on site.
Any faulty gas valve should be changed for the correct replacement.

6.4 Gas Control Valves

Automatic Ignition

There is no regular maintenance required on these devices. To change gas control valves, see
Section 7.4.

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Section 7. REMOVAL AND 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 remov ed from the heater only from the front.

It may be rem oved complete with the gas valve train assembly or on its own leaving the gas valves in
the heater.

These instructions indicate how to remove the burner tray and valves separately.

7.1.1

Remove the front lower cabinet panel. Remove the rear lower cabinet panel.

7.1.2

Dependant on the heater size and if it is manual or automatic ignition the main val ve will be connected
to the main burner inlet manifold using a navy union or the angled flange outlet of the valve.
The pilot gas supply will be in 4mm OD steel pipe and be connected to the pilot gas valve or pilot port
of the main gas val ve using a suitable compression fitting.

Undo the pilot supply compression fitting

Automatic Ignition

Unplug the flame probe lead from its socket and the HT lead from the spark generator.

Manual ignition

Unscrew the thermocouple from its connection with the gas valve and pull off the leads to the
thermocouple interrupter relay from their receptacles.
Disconnect the main burner gas supply pipe at the union or gas valve flange

7.1.3

Unscrew the two scre ws securing the b urner tray at the fr ont, (Fig .7. 1 ) and pull out the tray forward s
from the front of the heate r.

7.1.4

To replace the tray reverse the a bove steps ensuring that the tray is firmly in its correct place with the
two fixing screws tight and that the gas pipe work is sound.

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7.2.2

To remove the burner bars first remove the screws securing the retaining bar at the front end of the
burner and pull off the retaining bar (see Fig. 7.1).

Remove the screws securing the burner rear baffle and pull it upwards to remove.

7.2.3

The individual bars may now be removed by pulling up the front end 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 misplacement.
It will be found easier to remove burners starting from the opposite end of the burner tray.

7.2.4

If the injectors are being removed they ar e now accessible, ea ch one is screwed into its port of the
manifold with a soft metal sealing washer and may be remov ed using a 13mm spanner.

7.2.5

On replacing injectors ensure that they seat onto the soft metal washer to effect a tight seal and that the
correct one is fitted for gas being burned. See marking stamped onto the injector and ta bles in Section

2. It is recommended that new sealing washers ar e used when replacing injectors to ensure a gas tight

seal.

7.2.6

When re fitting 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.

Finally replace the retaining bar and its fixing screws.

7.2 Main Burner Bars/injectors

7.2.1

Remove the burner tray as in 7.1.

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Fig 7.1 Burner Tray Assembly

Fig 7.2 Optional versions of pilot burner

7.3 Ignition Burner Assembly

CAUTION: Do not kink or tightly bend the pilot gas pipe or thermocouple (where fitted).

There are two options to the pilot burners used for the complete range of heaters.
These are sho wn belo w in Fig 7.2. Howe v er a different pilot injector is used f or natural g as and L.P.G.
The pilot burner for use on natural gas is fitted with an injector marked 34.
The pilot burner for use on L.P.G. is fitted with an injector marked 19.
The difference between manual and automatic ignition is:

Manual Ignition heaters are controlled with a thermocouple .
Automatic ignition are controlled with a flame probe.

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7.3.1 Removal of pilot burner

i) Remove the rear lower panel of the heater.
ii) Unscrew the pilot gas pipe at its compression fitting with the pilot gas valve or main gas v alve as

appropriate.

iii) Unplug the H.T cable from the Piezo electric igniter or spark generator, as appropriate.
iv) Either unplug the flame probe from its jack socket or unscrew the thermocouple from the gas

valve.

v) Using a 10mm spanner undo the two set scre ws securing the pilot bracket assembly to the main

burner manifold.

The assembly will now come free by pushing it slightly forward and then allo wing it to drop so that it
will pull clear of the main burner .

7.3.2

Using the appropriate spanners undo the thermocouple /flame probe, ignition electrode and gas pipe
from the rear of the ignition burner.

7.3.3

To replace directly rever se the above.

All manual ignition models use the S.I.T Nova multifunctional valv e for main gas and pilot g as control.
Electrical connection is by a plug on a flying lead.
There are also ¼" receptacles for the connection of the thermocouple interrupter.

NOTE: It is important that the correct injector is used and that when assembling the gas pipe to the
pilot burner that the injector is fitted onto the special compr ession nut so that as the gas pipe is withdrawn
the injector is drawn out of the burner.Failure to fit the injector correctly will cause gas leaks and
permanent damage to the injector.

The Ignition electrode has a small tag connector for connecting the H.T/lead and ALWA YS fits into the
centre hole of the pilot burner.

The thermocouple or flame probe (with permanently connected P.T . F.E. insulated wire) is fitted in the
end hole of the pilot burner

7.4 Gas Control Valves

7.4.1

The gas control valves of all heater types are accessible from the rear of the heater without further
disassembly or may be withdrawn as part of the b urner assembly as convenient.
These instructions assume that the valves are removed with the burner tray remaining in place.
Section 2 tables give details of the gas valve specified for use on the various options available.

IT IS MOST IMPORTANT THAT O NLY THE CORRECT GAS VALVES SPECIFIED FOR
EACH MODEL TYPE ARE USED WHEN REPLACING THESE CONTROLS.

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7.4.2 Removal of Gas Valves - Automatic Ignition

There are two mounting systems used for the automatic ignition gas valves.
i) S.I.T Tandem valves

These are connected to the main gas manifold using a navy union.
Electrical connection is by a plug on the end of a flying lead.

ii) S .I.T Nova automatic gas valves

These are connected to the main gas manifold using the valve manufacturers angled outlet flange.
Electrical connection is by two pre-wired plugs on a flying lead.

The pilot gas valves are supported on the ¼ BSP inlet pipe and the outlet is a 4mm OD compression
fitting. Electrical connection is by a small three pin plug.

To remove gas valves

i) Disconnect the pilot gas pipe at the compression fitting at the pilot gas valve.
ii) Disconnect the union between the gas supply pipe and the gas valve.
iii) Disconnect the electrical plugs to all gas valves.
iv) Disconnect the navy union or valve outlet flange between the gas va l ve and the burner.

This allows the gas valves to be removed from the heater

Disassemble gas train for automatic ignition

To separate the start and main gas v alves hold the main gas v alve f irmly in a vice and unscrew the pilot
line from the main gas line at the ¼ m & f elbow by ¼ turn. This will allow the pilot or the main gas
val ve to be unscrewed from the main gas pipe.

Refitting is a direct re versal of the above.

It is important when refitting gas valves that only a minimum amount of none hardening gas seal is
used on the pipe threads so that excess sealant is not carried into the valve mechanisms.
It is also important that the val ves are assembled with the marked gas flo w in the correct direction, and
that the "O" ring seals are fitted to the inlet and outlet flanges where appropriate.
See Section 10 for converting between natural gas and L.P.G.

7.4.3 Removal of gas Valves - Manual Ignition.

All manual ignition models use the S.I.T Nova multifunctional v alve for main g as and pilot gas control.
Electrical connection is by a plug on flying lead.
There are also ¼" receptacles for the connection of the thermocouple interrupter relay.

To remove gas valves

i) Disconnect the pilot gas pipe at the compression fitting at gas valve pilot port.
ii) Disconnect the union between the gas supply pipe and the gas valve.
iii) Disconnect the electrical plugs to all gas valves.
iv) Unscrew the thermocouple from the valve and pull off the leads to the interrupter relay.
v) Disconnect the outlet flange between the gas valve and the burner.

This allows the gas valves to be removed from the heater.

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7.4.4 Thermocouple

The thermocouple is fitted into the pilot burner body by pushing fully home against the shoulder and
then tightening the retaining nut to hand tight plus ¼ turn with a spanner.
The thermocouple must be bent gently into its original path being careful not to kink or crack it.
The valve end of the thermocouple is connected using the screw nut. This connection is an electrical
one and must be clean and without the use of compounds.
The Connecting nut must be screwed hand tight plus no more than ¼ turn with a spanner to create a
sound electrical connection.

7.4.5 Thermocouple Interrupter Relay

All manual ignition heaters are fitted with a thermocouple interrupter relay to interface betw een the
limit thermostats and the thermocouple. This relay is fully encapsula ted and if faulty m ust be replaced
with the same type, as it specially produced to operate with burner thermocouples.

It is important that the 230v supply to the relay is provided from the specified terminals in the terminal
block, and that following replacement the operation of the limit thermostats is checked to ensure that
on operation the pilot is extinguished.

NO ATTEMPT SHOULD BE MADE T O OPERATE THE HEATER WITHOUT THIS RELAY .
FAILURE TO COMPLY WILL CAUSE A SEVERE FIRE HAZARD

7.5 CUHA Axial Fan/Guard/Motor Assembly

The Axial fan unit for the CUHA range of heaters is supplied completely assembled and balanced.
These components are not replaceable separately

7.5.1 To Remove the Fan Assembly:

Disconnect the electrical cables from the fan terminal box at the rear or side 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.

7.5.2 To Replace the Fan Assembly:

T o replace the f an assembly re ver se the above procedure ensuring that the rubber washers are fitted to
the guard mountings to reduce vibration.

Check that the fan blades are free to rotate without catching before turning on the power to the fan.

It is also most important that the colour code of the fan wires is strictly observed to ensure correct
operation.

It is sound practice to replace the fan capacitor when changing a fan.

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UNIT HEATER

7.6 CUHB & CUHC Centrifugal Fan/Guard/Motor Assembly

The direct drive fan/s for the CUHB & CUHC range is supplied as a complete assembly and therefore
does not need to be disassembled. Each fan is fitted to the rear of the cabinet secured with four fixing
screws and washers.

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 CUHC versions 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 obser ved to ensure correct operation,
and being careful to use the correct neutral connection. The Blue Neutr al is for the main fan; the Blue/
White neutral is for the burner controls and must not car ry the load of the main fan .This is because the
burner electr ical supply is protected from mains bourne interference by the use of a special conditioning
filter which is not ca pable 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 Li ve The other two windings are "par ked" separately in spare ter minals
Medium speed: White N, Blue live. The other two windings are "parked"separately in spare terminals
High speed: White N, Black li ve. The other two windings are "parked" separately in spar e terminals

7.7 Combination Fan/Limit Thermostat

7.7.1

To gain access to this thermostat, remove the cover retaining screw and pull of the cover.

7.7.2

Disconnect the electrical connections by pushing in with a small screwdri ver and pulling out the wires.
(see Fig. 2.8).

The earth wire is held under a screw connection.

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UNIT HEATER

7.8 Second Limit Thermostat

7.8.1

Remove the mounting nut securing the thermostat to the heater side.

7.8.2

Remove the heater low er rear panel to gain access to the body of the thermostat and its electrical
connections.

Disconnect the push-on electrical connections from the thermostat.

7.8.3

Remove the fan assembly from the heater rear (see 7.5 or 7.6).
Note: On models 340 and 380 B & C versions the secondary limit thermostats are mounted on the fan
mounting panel. The relevant fan will need to be rem oved to gain access to these thermostats.

7.8.4

Carefully pull the capillary sensing probe through its access hole in the side of the heater heat e xchanger
being careful not to damage the capillary tube.

7.7.3

Unscrew two fixing screws and withdraw the unit from the cabinet feeding the cables through the
plastic conduit connection.

7.7.4

To refit, reverse the above procedur e reusing the plastic conduit connection 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. 2.7). Permanent damage will be caused by leaving this link in.

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UNIT HEATER

7.8.5

To refit a thermostat, first carefully straighten the capillary tube, it is important not to kink or crack
it. Proceed to replace by rever sing the above pr ocedure ensuring that the sensing bulb at the end of the

capillary tube is positioned against the base of the heat exchanger to w ards the centr e 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).

Secure the capillary tube re -using the metal bra cket from the original one.

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UNIT HEATER

Section 8. FAULT FINDING

Following the replacement of parts
carry out the Commissioning procedure as in Section 4.

Should these procedures not resolve any problem, please contact Combat Engineering Ltd.

NO NO

Is " Lockout " Check external co ntrols

St art warni n g light are on & supply is sound

Assuming gas & el ectrical ON ?

supp l ies are on

YES

T est bur ner as

in 8.2

NO NO

Does the fan run? Press i n white button Use 8.5 to t est fa n

on com bination

thermostat.

Fan runs now?

YES

S ee sect ion 4.3 to Rep lace com b inat ion

che ck fan s t at ther m o stat

setti ngs

YES

YES NO NO

Do es b urn er sto p after Has burner Check for correct Ch eck operation &

Runnin g for several "Locked out" ? operation of fan setting of
minutes ? (wi th the combi nation stat.

c o ntrols still on) YES YES Re p a ir or repla c e

as necessary

NO

Use 8.2 to t est burner

YES

Heater operating

8.1 General for Automatic Ignition

Warning

Fault finding should 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.

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UNIT HEATER

STAR T

Assuming gas & electrical

supplies are ON

NO NO
Do es p ilot f lame l ight when Try ign it ing pil o t with Ensure th at t h ere is a gas
gas valve button is pressed a lighted taper & electricity supply.

in & piezo i gniter i s Ensure that the limit

re pe ate dly pressed Y ES the rm ostats have not

opera te d.

YES Se e 8.3

Piezo faulty. Replace

NO

Does pilot remain on when Use 8.3.1 to trace fault

start button is released

YES

NO NO

Do es main b urner come ON C heck all co n t rols ar e ON Use 8.4 to t race f ault

& that the gas val ve knob

YES i s in the BURNER ON

position

NO

Do es f an r un after b u rner Use 8.5 to t race f ault

has run for several minutes ?

YES

Heater Working

8.1.1 General - Manual Ignition

Warning

Fault finding should 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.

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UNIT HEATER

START

All cont rols O N

Y E S

NO

Is Green light ON ? Check for electr ical su pp ly

o p er ation o f ext ernal con tro ls

Y E S & limit therm os ta t s

YES

Is RED lockout warning Press in reset button on

li ght ON ? con trol bo x or r emote re set

NO

NO NO

Ignition spark operating ? Remove pilot burner as in 7.3 replace spark generator

& i nspect electr o d e and

Y E S H .T. lea d. Rep la ce if faulty

NO YES

Pilot flame igniting Pilot solenoid va lve ope ning ? Ch eck gas is on

and purged of ai r

Y E S NO

NO

Use 8.4 to t est so lenoid v alve C on t rol box fault y

Replace

YES NO

Red "Lockout" li ght Check flam e current i s at Check Inlet pressure of gas

comes ON ? least 1 µ amps DC wh en i s cor rect for gas type.

pilo t lights

YES YES

Remove pilot bu rner as in 7.3

in sp ec t f lame p ro be and

lea d. Rep lace if faulty

NO

Control box faulty

Rep lace wi th correct type .

NO NO

Main burne r fires ? Check for 2 30v at output Control box faulty

from c ontrol box Replace with corre ct type

YES

YES

Use 8.4 to chec k val ves

YES

B urner operating

T o measure flame current, connect
a 0 - 50 µA DC meter in series with
The flame probe by using the flame
probe jack plug.
If the meter reads Negative values
then reverse the test leads.

WARNING Ignition output fr om the
spark generator is 160 kv to earth.
Extreme care must be taken

8.2 Fault Finding For Automatic Ignition Burner Systems

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UNIT HEATER

To measure flame current, connect
a 0 - 50 µA DC meter in series with
The flame probe by using the flame
probe jack plug.
If the meter reads Negative values
then reverse the test leads.

Maximum fl ame current Mi nimum flame current

with no flame with pilot only

0 to 0.5 µA D.C. 1.0 µA D.C.

Typical flame current

3.0 to 5.0 µA with main
Burner ON

Connect a D.C. ammeter i n

ser ies w it h th e flame pro be

using the jack plug provi ded

Turn on all cont rols an d

ensure that there i s a supply

to the burner

Green l i ght ON

YES

Is there a curren t flowing in Repair or r eplace

the flame probe cir cuit I nspect and test the flame probe as necessary

with no flame present and wiring for damaged

insul at ion and short circuits

to earth

NO

YES

Does "l ockout" occur when Check adequate ga s pressure Control box f aulty

there is a flame present ?. Replace flame probe and en sure Replace with correct type

that it is fitted correctly.

Check f ro correct eart hing o f

heater

Check th at live and n eutral

NO polarity are correct

Burner Op erat ing

8.3 Flame Supervision System

8.3.1 Automatic Ignition Systems

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UNIT HEATER

NO NO

Doe s pilot flame ligh t ? Chec k gas supply a nd pilo t Ch e c k if pilot flame will light

gas pipe for blo ckag e using a taper

YES YES

Che ck piezo i gni ter, lead
and ignition electro de for

damage. Replace as

necessary

NO NO

Does pilo t f lame rem ain On Wait 3 minutes Check that t here is power t o

When s t art b utto n is rele a se d Try again .Butt on must be fully c oil term ina ls sup plying the

on gas valve ? depressed in "start " positi on ther mocoupl e interru pt er

and held f or at l east 20 s econds relay.

a ft e r pilo t fla m e ha s lit.

T e s t the thermocou ple Ch ange i nterrupte r

output to the saf e ty valve. relay

there shoul d be 5 to 7 mV
between the thermocoup le
sheath and the valv e input

terminal

Chang e thermocoup le

Bu rner Operat ing

8.3.2 Flame Supervision Systems - Manual Ignition

8.4 Fault Finding for Solenoid Valves

Note For manual ignition valves the gas will not
pass to the main burner until the pilot flame has
been lit and accepted and the valve knob has been
turned to main flame position.

Sta rt

NO

T est for 230v across val ve Fault elsew here

su pply termin als at the Check all con n ections and

appropriate ti me controls incl uding

lim it the rmosta ts

YES

NO

Test gas pressure at inl et of val ve Fault elsewhere

Test gas pressure at outl et of val ve. NO

Pressure should rise on outlet Sol enoid valve faul ty

when valve energises Replace as necess ary

YES

Valve Work ing

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UNIT HEATER

8.5 Fault Finding for Main Fan

NO NO

Fan does not run automatically? Check fo r electrical supply Fault elsewhere

230v L to N

YES

NO NO

Press in manual switch o f Test for 230v bet ween terminals Fau lt elsewhere

combination therm o stat 1 a nd N in te rminal block

Fan runs now ?

YES

YES Fan m otor or ca pacitor faulty

R epl ace as necessar y

Check sett ings o f combinat ion

ther mostat

fan now operates

Page 67

UNIT HEATER

Section 9. USER INSTRUCTIONS

The CUHA/A, CUHB/A, CUHC/A & CUHD/A ranges of heaters are fully automatic and operate
from the remote controls fitted on site.

The only user controls situated on the heater are:

The burner lockout reset button See 9.3.1
The fan run button See 9.2.1
The limit thermostat reset See 9.2.1
The second limit thermostat reset button See 9.2.2
(there are tw o of these on the models 340 & 380)

The CUHA, CUHB, CUHC & CUHD ranges of heaters are manual ignition of the pilot, but operate
automatically from the remote controls fitted on site providing that the pilot flame remains alight.

The user controls on these heaters are:

The main gas valve controls for lighting the pilot and main burner see 9.6.1 and Fig 9.1
The fan run button see 9.2.1
The limit thermostat reset see 9.2.1
The second limit thermostat reset button see 9.2.2
(there are tw o of these on the models 340 & 380)

All heaters require a constant gas and electricity supply which must not be interrupted during the
normal operation.

9.1 Heater Operation

When the heater has been switched on by the remote controls installed on site (see Controls Instructions)
the main burner will automatically turn on to heat the heat exchanger.

For Automatic ignition heaters the burner control box will control the safe ignition of the pilot and
main flame.

For manual ignition the pilot flame must be manually ignited and constantly alight to enable the
remote controls to operate the main burner.

When the heat exchanger is suf ficiently heate d, the fan thermostat turns on the main fan(s) and warm
air is discharged from the front of the heater.

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.

For manual ignition models interrupting the electrical supply also turns off the pilot flame.

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UNIT HEATER

9.3.1 Burner Lockout Reset Button

This manual reset button which is built into the burner contr ol box, and will illuminate the red warning
light on the elctrical terminal box 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.

Note: On some fully ducted heate rs the fan will come on during the burner firing cycle and not w ait for
the temperature rise. This is to ensure that there is always a proper oper ation of the heater under all
possible duct conditions.

When the remote controls turn of f the heater, the b urner turns off immediately lea ving the f an(s) to run
on to cool the heat exchanger. When cooled sufficiently the fan thermo s tat will turn off the fan(s).

9.2.1 Combination Fan/Limit Thermosatat

This is located on the top right hand side of the heater, see Fig.1.1.
This control ensures the heater does not blo w cold air in the normal heating cycle and protects the heat
exchanger against overheating.

Fan Thermostat (White Button)

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 (Red Button)

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 red manual reset button is operated. The combination fan/limit thermostat is preset
during commissioning (see 4.3). Note: the heat exchanger must ha ve cooled for reset to be possible.

9.2.2 Secondary Limit Thermostat

There is also a secondary limit thermostat situated on the heater side panel at the rear .There are two of
these thermostats on models 340 and 380 which are sited on the rear panel below the fans. These are
hand reset devices 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.

9.2 User Controls Common to All Versions

9.3 User Controls Automatic Ignition Versions

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UNIT HEATER

9.4 Lighting Instructions for Automatic Ignition Heaters
Types CUHA/A, CUHB/A, CUHC/A and CUHC/A

(See 9.6. for lighting manual ignition heaters)

9.4.1

Ensure that the electrical and gas supplies to the heater are on. Check that the time switch is in an
“ON” period and that the thermostat is set to the required temperatu re (which must be above the
ambient temperature for the heater to operate).

9.4.2

Operate the Installed remote controls to the “heat on” position and the automatic firing sequence will
begin as described in Section 2 of this manual.

The heater will now operate fully automatically under the control of the time switch and thermostats,
as installed.

Following long shut down periods the control may go to “lockout” (indicated by the red “lockout
light” being illuminated on the heater). To r eset 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

Do not operate the 'Lockout' reset button more than three times.

Turn off the heater and consult a competent heating engineer to correct the fault.

9.4.3 To Turn the Heater Off (short periods):

Operate the installed remote controls to the “OFF” position. The b urner will tur n off immediately, but
the distribution fan will continue to run for a few minutes to dissipate the heat from the heat exc hanger .
To restart turn the control used above to “ON”.

9.4.4 To Turn the Heater Off (long periods):

Carry out the operations of 9.4.3. 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 reset the time
switch as described in the manufacturers instructions. Carry out the operations in 9.4.1.

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 70

UNIT HEATER

Fig 9.1 Features of the S.I.T. Nova valve for Manual Ignition Versions

9.5 User Controls for Manual Ignition Versions

9.5.1 Multifunctional Gas Valve

The S.I.T.Nov a multifunctional gas v a lve fitted to all man ual ignition unit heate rs is shown in Fig 9.1.
and is used to control the gas supply whilst lighting the pilot flame by hand.
Follow the instructions in 9.6 to light the pilot and operate the main burner.

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.

Press in and hold
to light pilot

Press in and turn
to start

Press in and turn
to run burner

Press in and
turn to stop

Press in and turn
to stop

OFF Position START Position BURNER RUN

Position

Page 71

UNIT HEATER

9.6 Lighting Instructions for Manual Ignition Heaters

Types CUHA, CUHB,CUHC and CUHD

(See 9.4. for lighting automatic ignition heaters)

9.6.1

Ensure that the electrical and gas supplies to the heater are on.
Check that the remote controls are set to “OFF”.
All CUH manual ignition unit heaters are controlled by an S.I.T No va 0.820.045 multifunctional gas
valve (see Fig 9.1).

TO LIGHT PILOT

T o ignite the pilot press in the manual control button of the g as valve and turn anticlockwise to the star
symbol.
Press the button fully in and hold whilst continuously pressing and releasing the Piezo ignition de vice
to create the spark ignition.

Note: IF AT ANY TIME THE PILOT FAILS TO LIGHT OR GOES OUT, EITHER
INTENTIONALLY OR UNINTENTIONALLY, WAIT A FULL 3 MINUTES BEFORE
ATTEMPTING TO RELIGHT .

Once the pilot flame has been seen to light (visible through the rear panel of the heater near to the gas
pipe to the burner) continue to hold in the control valve button for a further 30 seconds, and then
release.The pilot flame should now remain on.
Should the pilot flame go out check that the limit thermosta ts have not operated and that there is an
electrical supply to the main terminal block.
Also ensure that the leads to the thermocouple interrupter relay are connected to their connections on
the gas valve (see Fig 4.3).

Observe the 3 minute waiting time and retry.

Once the pilot flame has been established it will remain on constantly providing that the gas or electricity
supplies are not interrupted and the limit thermostats do not operate.

To Operate The Main Burner

Press in slightly and turn the valve control knob a further quarter tur n anticlockwise to the "flame"
symbol.
Operate the remote controls to ON ensuring that the thermostat is set to the required temperature,
(which must be above the ambient temperature for the heater to operate).

The main burner will now operate automatically pro viding that the pilot flame remains alight.

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.

Interrupting the electrical supply also turns off the pilot flame.

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UNIT HEATER

9.7 Simple Fault Finding - General

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. One or both of the limit thermostats may have operated. This may be caused by

inadvertent rem oval 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 Figs in Section 1).

Limit thermostat 2 is under the screw on cover on the side or rear of the heater
(see Figs in Section 1).

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.

Any other problem will require the assistance of a Service Engineer.

9.6.2 To Turn the Heater Off (Short Periods):

Operate the remote controls to the “OFF” position.
The burner will tur n o ff immediately, but the distr ibution fan will continue to run for a few minutes to
cool the heat exchanger before turning off automatically.
The heater will then be at rest until the controls are turned on again.

9.6.3 To Turn the Heater Off (Long Periods):

Carry out the operations in 9.6.2 and allow the fan to stop automatically.
When the fan has stopped, turn off the gas and electricity supplies at the isolators.

To restart follow from 9.6.1

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UNIT HEATER

9.7.1 Simple Fault Finding - Automatic Ignition Heaters

5. If under fault conditions the burner fails to ignite for an y reason then it will g o to the

lockout condition this will be indicated b y the red lockout warning light on the heater
or remote control

To reset press in and release the lockout reset button after waiting for one minute
(see Figs 2.1 & 2.2).

"Lockout" should not occur during normal operation of the heater and indicates ther e is a fault condition
which must be corrected.

9.7.2 Simple Fault Finding - Manual Ignition Heaters

Ensure that the pilot flame is alight by following the instructions in 9.6.
Ensure that the control knob of the gas valve is turned to the main f lame position.

Should the pilot flame fail regularly ensure that the electrical supply to the heater is not being
interrupted.
Electrical interruption for ev en a few seconds will cause the interrupter relay to turn off the pilot.

9.8 Service Requirements

This heater will require servicing at least once per year except when operating in a dirty or 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 abrasives.

“

WARNING

Do not operate the 'lockout' reset button more than three times.

Turn off the heater and consult a competent heating engineer to correct the fault.

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. ventilate the

area and contact your local gas supply undertaking immediately.

DO NOT SEARCH FOR GAS LEAKS WITH ANY NAKED FLAME

Page 74

UNIT HEATER

Section 10. Conversion Between Gasses

10.1 General

Note all versions of models CUH...60 may not be operated on L.P.G

All versions of the heaters use the same main burner bars and pilot burners.

Natural gas

All natural gas versions use the same main burner injectors, marked 840, and pilot injectors marked

34.

The gas valves vary accor ding to the models size and method of control i.e. manual or automatic
ignition but in all cases the 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 250, and pilot injectors marked 19.
The gas valves vary accor ding to the models size and method of control i.e. manual or automatic
ignition but in all cases the valve DOES NOT contain a gas pressure regulator.
The correct operation of the heater de pends on the close control of the gas inlet pressur e to the appliance.

10.2 Burner Conversion

To convert the burner assembly from one gas to the other is the same for all types of heater.

i) Remove the burner tray as in Section 7 of these instructions and remove all of the main burner

injectors.
ii) Replace with the ones for the new gas.
iii) Remove the pilot burner assembly retaining the flame monitor , and spark electrode.
iv) Fit the new pilot burner injector following the instructions in Section 7.

Fig 10.1 Pilot Burner Options

Page 75

UNIT HEATER

10.3 Gas Valves - Automatic Ignition

There are three type of valve used for this range of heaters (see Data Tables in Section 2 for part
numbers and specification numbers).
CUH.../A 60 to 140 use the S.I.T. Tandem gas valve.
Note: Model CUH.../A 60 heaters only cannot be operated on L.P.G.
CUH.../A 160 to 300 use the S.I.T. Nova gas valve.
CUH.../A 340 to 380 use the Johnson multifunction gas valve.

10.3.1 T andem Range Valves

T andem range main gas v a lves cannot be con verted between gasses as they are constructed either with
or without a governor. These valves must be changed for the correct type as listed in the data tables.

10.3.2 Nova Range Valves

Nova range main valves may be converted to operate with or without a burner gas pressure regulator.
Follow the instructions in Section 7 of this manual for removal of gas valves.

To convert Nova valve from Natural Gas to L.P.G. (see Fig 10.2)

i) Remove the cov er of the pressure regulator.
ii) Completely unscrew the regulator adjusting screw and remove it complete with its spring.
iii) Replace the adjusting screw and original cover with the blanking nut attachment.
This device screws fully into the body of the re gulator until it stops and puts the regulator out of action.
The step opening feature of the main valve will still operate.

To Convert Nova Valve from L.P.G. to Natural Gas

Reverse the instructions a bove.

Blanking screw Governor spring
For L.P.G. assembly

The valve shown is the Nova manual
ignition version, however conversion
of the automatic ignition version is
exactly the same.

Fig 10.2 Conversion of Nova Family Valve

Page 76

UNIT HEATER

10.3.3 Conversion of Johnson Valve to L.P.G.

For the Models 340 and 380 the va lve for use on L.P . G. Propane or Butane is exactly the same Johnson
valve as for natural gas however the pressure regulator must be put out of service.

To do this for the Johnson gas valves an ada ptor pipe is fitted to connect the pressure regula tor
breather port to one of the valve centre test points (see Fig 10.3).
This is achieved by f irst removing the plastic re gulator breather plug by unscrewing it and screwing in
one of the compression couplers.

Remove the centre test point that coincides with the adaptor pipe length and again replace with the
other compression coupler.
Link the two couplers with the adaptor pipe and tighten the compression fittings.

The internal re gulator is now out of action and the heater must be supplied with gas closely contr olled
at the correct inlet pressure of 37mbar for Propane or 29mbar for Butane.

Fig 10.3 Conversion of Johnson Gas Valve for L.P.G.

Regulator Breather Port

Pipe Link to Put
Regulator Out of Action

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UNIT HEATER

10.4 Conversion of Manual Ignition Valves

All CUH... range manual ignition unit heaters use an S.I.T Nova multifunctional gas valve.

The Models CUH... 60 only cannot be operated on L.P.G.

Nova Range valves

Nova range main valves may be converted to operate with or without a burner gas pressure regulator.
Follow the instructions in Section 7 of this manual for removal of gas valves.

To convert Nova valve from Natural Gas to L.P.G. (see Fig. 10.2)

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 re gulator until it stops and puts the regulator out of action.
The step opening feature of the main valve will still operate.

To Convert Nova Valve from L.P.G. to Natural Gas

Reverse the instructions a bove.

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UNIT HEATER

DESCRIPTION P ART NUMBER

Axial Fan S4E 350 A 262

Axial Fan S4E 400 A 263

Axial Fan S4E 420 A 264

Manual ignition gas valve. S.I.T. Nova (All gasses) L 431

Thermocouple L 432

Thermocouple interrupter relay L 434

Automatic ignition gas v alve: S.I.T. T andem (Nat gas) L 411

Automatic ignition gas valve: S.I.T. Tandem (L.P.G gas) L 413

Automatic ignition gas valve: S.I.T. Nova (All gasses) L 421

Exclusion screw for No va valves (All Types) for L.P.G. L 425

Automatic Ignition pilot solenoid valve L 085

Main burner injectors, natural gas B 094

Main burner injectors, L.P.G. gas B 095

Sealing washers for main burner injectors B 210

Pilot burner injector for natural gas B 184

Pilot burner for all gas types B 186

Pilot burner injector for L.P.G. gas B 088

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.

Section 11. PARTS LIST

Parts available from:

Combat Engineering Ltd.

Oxford Street, Bilston, West Midlands

WV14 7EG

SERVICE
Service Department
Tel: [phone]
Fax: [phone]

SPARES
Trade Counter
Tel: [phone]
Fax: [phone]

SWITCHBOARD
Tel: [phone]
Fax: [phone]

Page 79

UNIT HEATER

INLET GAS PRESSURE mbar

BURNER GAS PRESSURE mbar
GAS RATE MEASURED AT METER M

3

/hr (ft3/hr)

AMBIANT TEMPERATURE °C

GROSS STACK TEMPERATURE °C

NET STACK TEMPERATURE °C

CARBON DIOXIDE IN FLUE CO

2

%

CARBON MONOXIDE IN FLUE CO.. P.P.M.

ESTIMATED EFFICIENCY % (State net or gross)

COMMENTS

CUSTOMER

SITE ADDRESS

HEATER LOCATOIN

MODEL SERIAL NUMBER

GAS TYPE NATURAL/L.P.G.

ENGINEER SIGNATURE DATE

Section 12. COMMISSIONING DATA SHEET

Page 80

UNIT HEATER

Page 81

UNIT HEATER

CONTACTS

SERVICE

Tel: [phone]

Fax: [phone]

SPARES

Tel: [phone]

Fax: [phone]

MAIN SWITCHBOARD

Tel: [phone]

Fax: [phone]

Combat Engineering Ltd.

Oxford Street, Bilston, West Midlands WV14 7EG

Tel: [phone] Fax: [phone]

e-mail: [e-mail]

www.combat.co.uk

A Roberts-Gordon Company