Air Supply; Sealed System - Worcester 35CDi Installation And Servicing Instructions

5.3. The terminal must not cause an obstruction nor the
combustion products a nuisance.
5.4. Under some climatic conditions the terminal might steam.
Positions where this might be a nuisance should be avoided.
Combustion products must not enter the roof space.
5.5. If the terminal is within 1m of a plastic or painted gutter or
within 500mm of painted eaves then an aluminium shield at
least 750mm long should be fitted to the underside of the gutter
or painted surface.
5.6. If the terminal is less than 2m above a surface to which
people have access then a guard must be fitted. The guard must
be evenly spaced about the terminal and fixed with plated
screws.
5.7. A guard, Type K2, can be obtained from Tower Flue
Components, Vale Rise, Tonbridge, TN9 1TB.

6. Air Supply

6.1. A separate vent for combustion air is not required.
6.2. If the appliance is in a cupboard or compartment then,
because of the low casing losses, it is not necessary to have
additional ventilation for the boiler.
6.2.1. There must be proper clearance around the appliance to
allow the free movement of the air. Refer to Table 8.

7. Sealed System

7.1. The system must comply with requirements of BS6798 and
BS5449.
7.2. The appliance must not be operated without the system
being full of water and correctly pressurised.
7.3. The pressure relief valve will operate at 3 bar. The discharge
pipe must be directed away from any electrics and from where it
might be a hazard.
7.4. The pressure gauge shows the required system pressure and
the actual system pressure.
7.5. The expansion vessel, to BS4814, has a capacity of 10 litres
charged to 0.5 bar, which is suitable for a static head of 5 metres.
A schraider type valve allows the pressure to be increased if the
static head is greater than 5 metres.
7.5.1. If the expansion vessel fails then it must be replaced with
the designated spare part.
7.6. Refer to BS 7074:1, BS5449 and Table 9 for a guide to the
available system capacity.
7.7. The maximum system design pressure is 1.5 bar. If the
pressure is above 2.6 bar when the appliance is at maximum
temperature then another expansion vessel must be fitted as
near to the appliance as possible in the return pipe.
7.8. The filling point must be at a low level.
7.8.1. Water lost from the system must be replaced. The make-
up connection must be close to the appliance in the heating
return pipe through an approved non-return valve.
7.8.2. The system and the appliance must be properly vented.
Repeated venting loses water from the system and usually
indicates that there is a leak.
7.8.3. The connection to the mains water supply must have the
approval of the local water company.
7.9. The integral by-pass should be adjusted to balance the
system when commissioning the appliance.
7.10. The CH pump is set at maximum and must not be
adjusted.
7.11. All connections in the system must withstand a pressure of
up to 3 bar.
7.12. The radiator valves must conform to BS2767:10 and other
valves to BS1010.
Supplied By www.heating spares.co Tel. 0161 620 6677
Fig 6 - Sealed system
13
Static Head
of System
3
4
12
5
11
6
7
DHW
8
Cold Water
10
9
1. Make-up Bottle
2. Non-return Valve
3. Domestic Hot Water
Pump
4. Central Heating Pump
6. Relief Valve
7. Drain Tap
8. Bypass Adjuster
9. Water Main
Fig 7 - System Fill
1
2
3
1.Central Heating Return
2.Non-return Valve
3.Test Cock
5.Stop Cock
6.Temporary Hose
7
1
2
A Drain Cock Should be Fitted at the
Lowest Point of the System
Radiator
Valve
10. BS Stop Valve
11. Domestic Hot Water
Flow Regulator and
Switch
12. Domestic Hot Water
Expansion Vessel
(Optional)
13. Auto Air Vent
4
2
5
Lock
Shield
Valve