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The unit is delivered in two packages (1) the cased boiler and (2) the flue 
terminal assembly. The same flue terminal assembly is used for both sizes of 
boiler. If required, extended flue tubes 1500 mm (59 in) long are available. A 
plug-in programmer kit is also available to fit inside the boiler casing. This 
programmer simplifies wiring and is suitable for use with all external control 
systems shown in this instruction. 

Gas supply 

The 38/5OF requires 1.84 m

3

/h (66 ft

3

/h) of natural gas, the 20/35F requires 

1.28 m

3/

h (46 ft

3

/h). The meter and supply pipes must be capable of delivering 

this quantity of gas in addition to the demand from any other appliances in the 
house. 

The complete installation must be tested for gas soundness and purged as 
described in CP331:3. 

Electricity supply 

240V 50Hz via a fused double pole switch with a contact separation of at least 
3 mm in both poles or preferably a fused 3-pin plug and shuttered outlet 
socket, adjacent to the boiler. 

Fuse the supply at 3 amp. 

Mains cable: 0.75 mm

2

 (24 x 0.20 mm). 

The external wiring between the appliance and the electrical supply shall 
comply with the latest lEE Wiring Regulations, and any local regulations which 
apply. 

The appliance must be earthed. 

In the event of an electrical fault after installation of the appliance, preliminary 
electrical systems checks can be carried out as described in the British Gas 
multimeter instruction book. 

Air supply 

1. The room in which the boiler is installed does not 

require a purpose provided air vent. 

2. If the boiler is installed in a cupboard or compartment, 

permanent air vents are required in the cupboard or compartment, one at high 
level and one at low level, either direct to the outside air or to a room. Both 
high and low level air vents must communicate with the same room or must 
both be on the same wall to outside air. Both the high level and low level 
vents must have a free area of 180 cm

2

 (28 in

2

) for the 38/5OF and 123 cm

Summary of Contents for 20/35F

Page 1: ...d from 5 86 to 10 26 kW 20 000 to 35 000 Btu h The boiler must be installed in accordance with The Gas Safety Regulations 1972 The Gas Safety Installation and Use Regulations 1984 Local Building Regulations By Laws of the local Water Undertaking I E E Wiring Regulations Detailed recommendations are stated in the following British Standard Codes of Practice CP331 3 1974 BS5376 2 1976 BS5546 1979 BS...

Page 2: ...both poles or preferably a fused 3 pin plug and shuttered outlet socket adjacent to the boiler Fuse the supply at 3 amp Mains cable 0 75 mm2 24 x 0 20 mm The external wiring between the appliance and the electrical supply shall comply with the latest lEE Wiring Regulations and any local regulations which apply The appliance must be earthed In the event of an electrical fault after installation of ...

Page 3: ... an aluminium shield of at least 750 mm 30 in in length should be fitted to the underside of the gutter pipe or painted surface If the terminal is fitted less than 2 m 6 6 ft above a balcony above ground or above a flat roof to which people have access then a suitable terminal guard must be provided A type K2 protective guard is available from Tower Flue Components Ltd at Vale Rise Tonbridge Kent ...

Page 4: ...e in Scotland with respect to the installation of the boiler in a room containing a bath or a shower Where the installation of the boiler will be in an unusual position special procedures may be necessary and BS5376 2 and BS5546 give detailed guidance on this aspect A cupboard or compartment used to enclose the boiler must be designed and constructed specifically for this purpose An existing cupbo...

Page 5: ...n is connected to the in connection under the boiler and the temperature rise across the boiler is 11ºC 20º F In the event of any fault occurring during the commissioning of the boiler a fault finding guide is available in the maintenance instructions Page 2 ...

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Page 13: ...VE FOR COMPLETE SAFETY OF OPERATION THAT THE OUTER CASE IS PROPERLY FITTED CHECK THAT THE FOUR CASE FIXING SCREWS ARE TIGHTENED SUFFICIENT TO COMPRESS THE SEALING GASKET DO NOT RUN THE BOILER WITH THE CASE REMOVED Back Page Page 11 ...

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