Bosch Worcester GB162-100 V2, Installation, Commissioning And Servicing Instructions

Pre-Installation

6720814332 (2018/04)

11

Before cleaning the system:

▶ Ensure that the system and pipe work is in good working order.
▶ Where possible keep the existing boiler/circulating pump in place 

when flushing the system.

3.2

Water quality

Unsuitable or contaminated heating water can lead to faults in the boiler 
and can damage the heat exchanger, among other things, due to sludge 
formation, corrosion or lime scale deposits. Please get in touch with the 
manufacturer if you require additional information on the water quality. 
You will find the relevant addresses on the back cover of these 
instructions.

▶ Do not use any chemical additives (e.g. inhibitors or pH-increasing or 

reducing agents) other than those approved by Bosch 
Thermotechnology (



table 9). The pH of the heating system water 

must be between 7 and 8.5. If this is not the case, please contact 
Worcester Customer Service before proceeding.

3.3

Mains supply

3.3.1

Electrical supply

• Supply: 230V - 50 Hz, 130 Watts
• Cable: PVC insulated H05VVF 3G1 (3 x 1mm

2

) temperature rated to 

90 °C.

• External 3A fuse to BS1362.
• The boiler must be earthed.
• IPX4D.
• Wiring must comply with the latest edition of BS 7671 (IEE wiring 

regulations).

3.3.2

Gas supply

• Boilers using Natural Gas (NG) must be connected to a governed 

meter.

• Liquid Petroleum Gas (LPG) must be connected to a regulator.
• Installation and connection of the gas supply to the appliance must 

be in accordance with BS6891 or IGE/UP/2 as appropriate.

• Gas pipe sizing should be calculated to ensure no more than the 

permitted pressure drop between the meter/governor to the 
appliance inlet (



 Commissioning section).

• The meter or regulator and pipe work to the meter must be checked, 

preferably by the gas supplier.

• This is to ensure that the equipment is in good working order and can 

meet the gas flow and pressure requirements, in addition to the 
demand from any other appliance being served.

3.4

Water systems and pipe work

If the boiler is used in heating systems with natural water circulation or 
open systems (where heating water is in contact with outdoor air):
▶ Install a system separation solution (a plate heat exchanger for 

example) between the boiler and the heating system

If plastic pipes are used in the heating system, with an underfloor heating 
system for example,
▶ use plastic pipes with sufficient oxygen diffusion resistance

-or-

▶ Install a system separation solution (a plate heat exchanger for 

example) between the boiler and the heating system.

Plastic pipe work:

• Any plastic pipe work must have a polymeric barrier with 600mm 

(minimum) length of copper pipe before being connected to the 
boiler.

• Plastic pipe work used for underfloor heating must be correctly 

controlled with a thermostatic blending valve limiting the 
temperature of the circuits to approximately 50°C.

Primary systems connections/valves:

• All system connections, taps and mixing valves must at least be 

capable of sustaining a pressure equal to the opening pressure of the 
PRV used.

• Radiator valves should conform to BS2767:10.
• All other valves should conform to BS1010.
• Thermostatic radiator valves (TRV’s) must be fitted to all rooms 

except bathrooms and the room in which the room thermostat is 
fitted.

• A drain cock is required at the lowest point(s) in the system.
• An air vent is required at the high point(s) in the system.

Sealed primary system:

• The CH sealed system must be filled using a WRAS approved filling 

method or comply with figure 10 for system fill.

• An expansion vessel must be fitted as close as possible to the 

appliance in the central heating return. When a pump group is used, 
see Chapter 5.11. 

• Do not use galvanised pipes or radiators.

System fill:

Filling and refilling of the heating circuit must have been carried out by a 
method that has been approved by the Water Regulation Advisory 
Scheme (WRAS), for the type of heating appliances, i.e. Domestic (in-
house) Fluid Category 3. Non-Domestic (other than in-house) Fluid 
Category 4. Depending on the Fluid Category the approved method 
should comprise of the following:

Requirements Fluid Category 3 systems

• Control valve (stop valve) including a double check valve on the 

mains cold water supply pipe.

• Temporary connection to be removed after filling (filling loop).
• Control valve (stop valve) on the heating system pipework.

NOTICE: 

▶ Debris from the system can damage the boiler and 

reduce efficiency.
Failure to comply with water treatment guidelines 
will invalidate the appliance guarantee and 
contravene the Building Regulations.

▶ It  is  recommended  that  you fit a primary water 

cleanser to the system. Worcester recommends a 
filter that will help remove both magnetite and non-
magnetic debris.

Product 

Concentration

Fernox F1

See Fernox product data sheet

Sentinel X100

See Sentinel product data sheet

Table 9 Approved inhibitors by Bosch Thermotechnology Ltd.

NOTICE: 

This boiler must not be connected to a 3 phase supply.

An external automatic bypass should be used if the 
system flow can be significantly adjusted or stopped by 
zone valves and thermostatic radiator valves (TRV).

NOTICE: 

Artificially softened water must not be used to fill the 
central heating system.