Caution
If
the
valve is closed
when
the
pump
is
running
the oil pressure can be increased sufficiently so
as to cause
damage
to the seals within the
pump.
The return oil should preferably be discharged through an elbow onto a tank plate situated within
the tank, this
should
be positioned so as not to introduce air
or
air bubbles into the
draw
off pipe.
2.5 Two pipe system
This is used
where
the oil storage tank is lower than the
pump.
Access for the fuel feed to the
burner
should
be via a suitable
tapping
made
in the top of the tank,
and
the fuel feed pipe
should
extend to
not
less than
lOOmm
above the bottom of the tank. A none return valve
with
a metal to
metal seat
should
be fitted, especially if the return
pipework
is terminated at a level above the
draw
off tube.
The
none
return valve
must
be removable for service
and
maintenance purposes,
and
the
return
pipe
from the
pump
must
therefore
be
extended
down
into the tank to the
same
level as the
suction pipe. The presence of a
tamper
proof isolating valve fitted within the return
pipe
is only
required if there is a risk that oil will
siphon
out
of the tank if the return pipe is disconnected at the
pump
during
maintenance
or
servicing
and
if the none return valve has been omitted.
2.6 Pressurised ring main system
This
system
is
used
to
supply
a
number
of
units from a
common
storage tank. A booster
pump
is
used
to
provide
the
pressure
storage tank. A booster
pump
is
used
to
provide
the pressure to
push
the oil
around
the ring main
and
back to the tank. Pressure reducing valves
should
be fitted
on
the delivery
pipe
to each heater to ensure that
the
pressure at the
burner
pump
is less
than
6 psi.
Caution
The internal by-pass
plug
must
be
removed
from the
pump
when
used
in a pressurised ring
main application.
2.7 Pipework and fittings
Caution
Galvanised
pipework
and
fittings
must
not
be
used.
All joints
must
be
sealed
properly,
if
necessary
using
PTFE
tape
or
other
approved
sealing media. The
pipework
must
be
effectively
sealed so as to
prevent
the ingress
of
air.
It
is advisable to check all
pipework
prior
to installation to
ensure
that there is no loose debris or
scale present. Black iron pipes can be
hammered
to assist in the removal
of
these contaminants.
Note
The oil feed to each heater
must
be fitted
with
a fire check valve
and
isolating valve. The fire
check valve
must
be
operated
by
way
of a fusible link positioned so
that
it is above the burner.
2.8 Electrical supply
Wiring external to the cabinet heater
must
be installed in accordance
with
any
local, national,
and
European
regulations, as well as meeting
the
appropriate
requirements
of
lEE regulations.
The
means
of
connection
to
the
main
electrical
supply
must
allow
for
complete
electrical
isolation
of
the heater(s), furthermore, in the case of heaters wired for a three
phase
supply, the
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