Specifications

5.7
Sealed
systems
Sealed
systems
do
not
require
leed
and
exDansion
cisterns,
open
vents
etc'
only
gooo
ouitiW
raOiator
valve's
and
fittings
should
be
Jsed
in order
to
prevent
excessive
detrlmenlal
topping-uP.
5.7.1
Pressure
lelief
valve
This
is required
on
all
sealed
systems
and
is
connected'as
shown
in
4'3.4'
5.7.2
Pressure
gauge
This
is
factory
fitted
to
the
boiler
and
shows
the
pressure
in
the
Primary
circuit.
5.7.3
Expansion
vessel
A
1 5
litres
expansion
vessel
is incorporated
into
ihe combi
b6iler
suitable
for
a sealed
heating-
iuit".
with
a
maximum
water
contents
of
260
litres
(57.2
lmP.
galls')
lf the
nominal
capacity
of
the
built-in
expansion
vessel
is not
sufficient
for
the
heating
sys,tem.
itor-instance
in
case
of
modernization
of
old
iioen
Jvstems)
an
additional
expansion
ve-ssel
cin Oe
instatt6d
to
the
side
connection
of
the
ieturn
service
cock
in connection
with
the
pressure relief
valve.
5.7.4
Filling
and
make
uP
The
svstem
should
be
filled
with
water
via
a
seoar6te
lilling
point
fitted
at
a convenientpoint
on'
the
neati-nb
circuit.
Where
local
Water
Authority
Regulation
allows,
a
temporary
connection
to-the
mains
may
b,e
used'
The
connection
must
be
removecl
when
lllllng
ls
completed.
Where
local
Water
Authority
Reqirlation
does
not
allow
temporary
corinection,
a sealed
system
filler
pump
with
break
tank
must
be
used.
The
heating
system
witt
not
be
filled
automatically
from
the
domestic
side.
ln
principle,
sealed
systems
do
not
require
waier
mat<e-up
faciliti6s,
but
experience
has
shown
that
some
make-up
may be
necessary'
Methods
of
filling
sealed
systems
are
given in
appendix
A
of
BS 5376:2.
22
3
Fig.32
5.7.5
Pipework
All oioework
shall
be securely
supported,
shall
run'n'eatly
and
be
concealed
where
possible'