Technical data

ManualsBrandsBaxi ManualsBoilerBermuda BBU 15 HE

4.0 System Details

4.7 Sealed Systems (Figs. 6, 7 & 8)

1. SAFETY VALVE - A safety valve complying with the

requirements of BS 6750 Part 1 must be fitted close to the

boiler on the flow pipe by means of a horizontal or vertically

upward connection with no intervening valve or restrictions

and should be positioned to facilitate testing. The valve should

be pre-set and non-adjustable to operate at a pressure of 3

bar. It must be arranged to discharge any water or steam

through a pipe to a safe outlet position.

2. PRESSURE GAUGE - A pressure gauge of minimum range

0-4 bar with a fill pressure indicator must be fitted to the

system, preferably at the same point as the expansion vessel in

an easily visible position.

3. EXPANSION VESSEL - An expansion vessel complying with

the requirements of BS 4814 must be fitted to the system by

means of a connection close to the inlet side of the circulating

pump in accordance with the manufacturers instructions, the

connecting pipe being unrestricted and not less than 15mm

nominal size. The volume of the vessel should be suitable for

the system water content and the nitrogen or air charge

pressure should not be less than the system static head (See

Fig. 7).

Further details of sealed system design can be obtained from

BS 5449 and the British Gas publication entitled 'Specifications

for Domestic Wet Central Heating Systems'.

4. FILLING POINT - A filling point connection on the central

heating return pipework must be provided to facilitate initial

filling and pressurising and also any subsequent water loss

replacement / refilling. The sealed primary circuits may be filled

or replenished by means of a temporary connection between

the primary circuit and a supply pipe provided a ‘Listed’ double

check valve or some other no less effective backflow

prevention device is permanently connected at the inlet to the

circuit and the temporary connection is removed after use. The

filling method adopted must be in accordance with all relevant

water supply regulations and use approved equipment.

Your attention is drawn to, for GB: Guidance G24.2 and

recommendation R24.2 of the Water Regulations Guide. for IE:

the current edition of I.S. 813 “Domestic Gas Installations”.

5. MAKE UP SYSTEM - A method of replacing water lost from

the system should be provided either by means of a make up

vessel of not more than 3 litres (5 pints) capacity, mounted

above the highest point of the system, or by re-pressurisation

of the system.

6. VENTING - A method of venting the system during filling

and commissioning must be provided by fitting automatic air

vents or by venting manually.

7. HOT WATER STORAGE - The hot water storage vessel

must be of the indirect coil type. All components used in the

system must be suitable for operation at 110°C and at the

pressure allowed by the safety valve.

Safety

Valve

Pressure

Gauge

Pump

Filling

Point

Air

Vent

3 Litre

Top Up Bottle

(if required)

Radiator

Circuit

Expansion

Vessel

System Drains at

Low Point

Max Boiler Flow

Temp = 75° C

Boiler

Vessel Charge

Pressure (Bar)

0.5

1.0

1.5

Initial System

Pressure (Bar)

0.5

1.0

1.5

2.0

1.0

1.5

2.0

1.5

2.0

Multiply Total

Water Content Of

System By (Litres)

0.067

0.112

0.207

0.441

0.087

0.152

0.330

0.125

0.265

System Volume = 75 litres

Vessel Charge Pressure = 1.0 bar

Initial System Pressure = 1.5 bar

75 x 0.152 = 11.4 litres

Expansion Vessel Volume

Example :-

Then :

NOTE

Where a vessel of the calculated size is not obtainable then

the next available larger size should be used.

Fig. 7

Fig. 6

Fig. 8

Stop

Valve

Double

Check

Valve

Mains

Cold

Supply

Return

Temporary

Hose

Stop

Valve