Single Pipe System; Two Pipe System - Grant Combi 70 V3 User's Installation Manual

6 The flexible fuel lines supplied should be inspected
annually when the boiler is serviced and replaced
at least every two years.
5.3.3 Single pipe system - (See Fig. 5)
1 Where the storage tank outlet is above the burner
the single pipe system should be used. The height
of the tank above the burner limits the length of
pipe run from the tank to the burner.
2 As supplied the burner is suitable for a single pipe
system.
5.3.4 Two pipe system - (See Fig. 6)
1 When the storage tank outlet is below the burner, the
two pipe system should be used. The pipe runs should
be as shown in Fig. 5. The return pipe should be at the
same level in the tank as the supply pipe, both being
75 to 100 mm above the base of the tank. The pipe
ends should be a sufficient distance apart so as to
prevent any sediment disturbed by the return entering
the supply pipe.
5 - GENERAL BOILER INFORMATION
Fig. 5 - Single pipe system
Combi V3, Combi Max and Vortex Combi models
2 Avoid the bottom of the tank being more than 3 m
below the burner.
3 A non-return valve should be fitted in the supply pipe
together with the filter and fire valve. A non-return
valve should be fitted in the return pipe if the top of
the tank is above the burner.
4 To be used with a two-pipe system, the burner
must be fitted with an additional flexible fuel line
(a flexible fuel line (600 mm) and
male adaptor are available from Grant Engineering
(UK) Limited - Part No. RBS104).
See Section 5.3.6.
5 The pump vacuum should not exceed 0.4 bar.
Beyond this limit gas is released from the oil. A
vacuum gauge must be fitted to the fuel pump to
check the vacuum reading.
For guidance on installation of top outlet fuel tanks and
suction oil supply sizing, see OFTEC booklet T1/139.
Available at www.oftec.org.uk
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