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5

FLUE TERMINAL POSITION

Position Minimum 

spacing

Directly below an openable window,  300mm 12in

air vent, or any other ventilation 

opening

B

Below gutter, drain/soil pipe

75mm

3in

Below eaves

200mm

8in

D

Below a balcony

200mm

8in

*2500mm 98in

From vertical drain pipes and 

150mm

6in

soil pipes

F

From internal or external corners

300mm 12in

*internal corners

*1000mm 40in

Above adjacent ground or 

balcony level

300mm 12in 

From a surface facing the terminal

600mm 24in

*2500mm 98in

Facing terminals

1200mm 48in

*2500mm 98in

From opening (door/window) in 

1200mm 48in

carport into dwelling

*not recommended

Vertically from a terminal on the 

1500mm 60in

same wall

Horizontally from a terminal on the 

300mm 12in

same wall

M

Adjacent to opening

300mm 12in

N

Below carport

600mm 24in

*not recommended

O

From adjacent wall

300mm 12in

P

From adjacent opening window

1000mm 40in

Q

From another terminal

600mm 24in

Minimum height

300mm 12in

• •

• •

• •


A

B,C

G

K

M

A

E

F

F

K

B,C

G

G

K

K L

L

J

F

H,I

D,N

C

Q

O

O

P

R

SPECIAL REQUIREMENTS FOR A
VERTICALLY BALANCED FLUE

300mm

Min

430mm

Min

10

d)

If the appliance is installed in a room or internal space with other

opened flued appliances, the aggregate maximum rated input shall
be used to determine the air vent free-area. (BS 5440-2 Table 2).

e)

Where an open flued system is used, and the flue duct air

inlet is within a compartment then high and low level air vents are
necessary in the compartment, the size of the vents should be
calculated in accordance with BS 5440-2 Table 2.

3.5

CONDENSATE DISPOSAL

The condensate drain connection is suitable for either 21.5 mm or
22 mm plastic push fit or adhesive overflow pipes and fittings. It
should be piped to drain, preferably within the building, maintaining
a continuous 2.5° fall away from the appliance. If the drain is routed
to outside it should be to a drain or soak away, and any external
pipe work should be in 32 mm. Insulation to protect from freezing in
cold weather conditions is also advisable.

3.6

GAS SUPPLY

a)

The Gas Supplier should be consulted at the installation planning

stage in order to establish the availability of an adequate supply of gas.

b)

An existing service pipe MUST NOT be used without prior

consultation with the Gas Supplier.

c)

A gas meter can only be connected by the Gas Supplier or by their

contractor.

d)

An existing meter and/or pipe work should be of sufficient size to

carry the maximum appliance input plus the demand of any other
installed appliance. (BS 6891: 1988).

A minimum of 22 mm diameter pipe work is
recommended within 1000 mm of the appliance gas cock.
e)

Natural gas appliances: The governor at the meter must give a

constant outlet pressure of 20 mbar (8 in.wg) when all appliances on
the system are running. 
Propane appliances: The regulator must give a constant outlet pressure
of 37 mbar (14.9 in.wg) when all appliances on the system are
running.

f)

The gas supply line should be purged. WARNING: Before purging

open all doors and windows, also extinguish any cigarettes, pipes, and
any other naked lights.

g)

The complete installation must be tested for gas tightness.

3.7

CENTRAL HEATING SYSTEM

a)

The appliances are designed for open vented central heating

water systems, but may be fitted to a sealed central heating
system provided the necessary components, such as expansion
vessel and pressure safety relief valve are fitted to the system.
Refer to Figure 8 for a typical open vented system design, which
incorporates radiators, and a drain facility that must be provided
at the lowest point in the system to allow complete drain down.

b)

The installation should be designed to operate with a flow

temperature of up to 95°C.

*Recommended by the boiler manufacturing industry to prevent
pluming nuisance and damage to buildings.

If the appliance is installed in a garage all pipe work
should be in 32 mm. Ensure that the condensate discharge
system complies with any local regulations in force.

LED CODE FAULT/EFFECT

REASON

ACTION

Check no air is in heat exchanger/CH system 

1

Overheated appliance

Water temperature greater than 105 °C

Check external pump operation

Check PCB/X1C connector

Check flow thermistor

Water flow failure or

Check water pressure

Differential check faulty/

Check external pump/ CH system blockage

2

Flame for a short

Sensor temperature differential incorrect

Check no air is in heat exchanger/CH system

period only

Check flow, and return sensors

Check wires to sensors not crossed

Check gas supply

Check gas service cock

Check gas valve and lead

No gas or Lockout flame  Low gas pressure.

Check detection electrode/lead

3

signal/ No flame, Lockout No flame signal on ignition,

Check gas supply

after 5 ignition attempts

or loss of signal during operation

Check gas valve and lead

Check PCB/X2A & X2B connectors

Check spark generator/spark electrode

Check mains earth lead continuity

Check flue sensor

Check flue system

4

Flue gas sensor/No flame Flue gas temperature greater than 95 °C

Check no air is in heat exchanger/CH system

Check external pump

Check PCB/PCB connectors

Check flow, return and flue sensors

5

Defective sensor/No flame Defective flow, return or flue sensor

Check wiring to sensors

Check PCB/X6 & X8 connectors

Defective gas valve/

5 sec flame signal after burner

Check gas valve and lead

6

Flame continues after

is switched off

Check PCB

demand ends

Check fan

7

Defective fan/No flame

Missing or Erroneous RPM signal

Check mains fan lead & connector

Check low voltage fan lead & connector

Check PCB/X3 connector

A

PCB error/No flame

Internal error

Check PCB

b

Activate BCC/No flame

New BCC

Turn CH control knob to reset twice to activate

C

Safety system failure/

Failure of internal self checking system

Check PCB

No flame

Check BCC is initialised

E

BCC error/No flame

Incorrect /missing BCC

Reseat or replace BCC

h

No flame

Faulty connector

Check PCB/X1A connector

Check water pressure

Differential check faulty/

Check external pump/ CH system blockage

O

Flame for 15 seconds

Water flow rate too low

Check no air is in heat exchanger/CH system

Check flow, and return sensors

Check wires to sensors not crossed

P

Error in power supply/

Low mains voltage

Check mains voltage

No flame

Check PCB connectors

Check power supply

No light indication

Defective power supply

Check PCB/X1B connector

Check PCB fuse

27

Summary of Contents for VBX 18

Page 1: ...T R A I N I N G 0 1 9 2 6 8 3 4 8 3 8 Halstead Boilers Limited 20 22 First Avenue Bluebridge Industrial Estate Halstead Essex C09 2EX Telephone 01787 272800 Sales Direct Line 01787 475557 Fax 01787 47...

Page 2: ...nctional Flow Wiring Diagram 25 8 FAULT FINDING 26 8 1 General 26 8 2 Diagnostic LED Indicators 26 8 3 Faulting Finding Codes 26 8 4 Central Heating Fault Finding 26 9 REPLACEMENT OF PARTS 28 9 1 Igni...

Page 3: ...appliance are cured and give no known hazard in this state Insulation Pads These can cause irritation to skin eyes and the respiratory tract If you have a history of skin complaints you may be suscept...

Page 4: ...8 9 kg h 2 36 1 43 Seasonal Efficiency 90 4 91 0 92 4 93 1 Seasonal Efficiency SEDBUK Band A Nox Classification Class 5 Min Central Heating System Pressure Bar 0 1 1 m H2O Max Central Heating System P...

Page 5: ...ue max rate Propane 0 019 0 005 Flue products mass flow rate Nat Gas g s 13 7 8 3 Flue products mass flow rate Propane g s 13 7 8 3 Gas Valve Offset min rate Pa 3 0 Connections Gas 15 mm compression C...

Page 6: ...user interface from its housing see figure 22 c Lower the controls front d Unplug the electrical leads from the PCB Refer to section 7 e Unplug the BCC boiler chip card if fitted f Remove the PCB pla...

Page 7: ...m Roof terminal with rain cover and pitched roof flashing kit a b 3c If the standard horizontal terminal is likely to cause nuisance to neighbours or buildings because of excess pluming then this part...

Page 8: ...ded that to prevent dust the insulation be dampened prior to removal and that a protective mask is worn when changing or handling the insulation material Refer to Figure 43 a Ensure supply voltage is...

Page 9: ...me equivalent length 45 Extension Elbow Allows an additional bend in the flue and has an equivalent length of 775 mm Vertical Turret Socket For use with elevated horizontal flues and vertical terminal...

Page 10: ...e that all joints and seals are correctly re fitted Note The gas control valve is factory set and sealed and is not adjustable If the gas control valve is changed then when the appliance is running th...

Page 11: ...imitations MUST be observed when siting the appliance a The appliance is not suitable for external installations The position selected for installation should be within the building unless otherwise p...

Page 12: ...The complete installation must be tested for gas tightness 3 7 CENTRAL HEATING SYSTEM a The appliances are designed for open vented central heating water systems but may be fitted to a sealed central...

Page 13: ...INDER SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE The domestic hot water cylinder must be of the double feed fully indirect coil type 3 15 SEALED WATER SYSTEMS The installation must comply with th...

Page 14: ...cuit to ensure pump over run functionality 3 18 PRESSURE GAUGE A pressure gauge with a set pointer and covering at least 0 to 4 bar 0 to 60 lb in shall be fitted permanently to the system in a positio...

Page 15: ...plete electrical isolation of the appliance Either a 3A fused three pin plug and un switched shuttered socket outlet both complying with BS 1363 or a 3A fused double pole switch having a 3 mm contact...

Page 16: ...per template in the required position ensuring that the necessary clearances are achieved Ensure squareness by hanging a plumb line b Mark the position of the wall mounting plate fixing holes 4 c Mark...

Page 17: ...products are available from Grundfos Pumps Ltd on 01525 850000 and Pump House on 0115 922 2211 22 ROUTINE SERVICING 6 6 1 COMBUSTION CHECK The appliance incorporates a flue sampling point on the appli...

Page 18: ...flue elbow e Fit the flue terminal to the flue system ensuring that the duct joints are not disturbed and that the external sealing ring is seated against the outside wall f Finally use the internal...

Page 19: ...cluded in the appliance specification ANTI CYCLE DEVICE When the appliance cycles on its central heating control thermostat a slow cycle device operates The timer set to 5 minutes is activated after t...

Page 20: ...s tightness in accordance with BS 6891 1988 Open all doors and windows extinguish naked lights and DO NOT SMOKE whilst purging the gas line It is recommended where possible to flush the CH system with...

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