12
fig. 7
GW 400/0
Pipework not forming part of the use-
ful heating surface should be insulated
to help prevent heat loss and possible
freezing, particularly where pipes are
run through roof spaces and venti-
lated underfloor spaces.
Draining taps must be located in
accessible positions which permit the
draining of the whole system including
the boiler and the hot water system.
Draining taps should be at least
1
/
2
in. BSP nominal size and be in
accordance with BS 2879.
The boiler is suitable for use with mini-
bore or microbore systems. Copper
tubing to BS 2871: Part 1 should be
used for water carrying pipework. All
capillary joints in the DHW pipework
must be made with lead free solder.
Particularly where a new boiler is to
be fitted to an existing system, it is
good practice that the system is
thoroughly cleansed. This cleansing
should take place prior to the fitting of
the new boiler and be in accordance
with BS 7593.
For advice on the application of
system cleansers contact sentinel,
Grace Dearbom Ltd.
Widnes., Cheshire, WA8 8 UD.
Tel.: 0151 495 1861
3.7.2 Filling and make up
The system should be filled with water
via a separate filling point fitted at a
convenient point on the heating cir-
cuit. Where local Water Authority
Regulation allows, a temporary con-
nection to the mains may be used
(fig. 7). The connection must be
removed when filling is completed.
Where local Water Authority Regula-
tion does not allow temporary connec-
tion, a sealed system filler pump with
break tank must be used.
The heating
system will not be filled automatically
from the domestic side.
(Alternative methods of filling sealed
systems are given in BS 5449).
Heating
circuit
return
Double check
valve assembly
Stop
valve
Test
valve
Hose
unions
Mains
water
supply
Temporary
Hose
fig. 8
GW 401/0
3.7.3 Pressure relief valve
A pressure relief valve is provided rea-
dy-assembled to the return C.H. ser-
vice valve (4, fig. 8). This safety devi-
ce is required on all sealed C.H.
systems and is pre-set at 3 bar and
provided with a 3/4 in. BSP connec-
tion for a discharge pipe (minimum
size 15mm).
