Technical information

Installation and servicing instructions strictly reserved
for qualified gas installers
19
4.7 Open (Vented) Water System
The boiler must be supplied from an unrestricted
water supply taken from a feed and expansion
cistern situated at a maximum height of 27 metres
(90ft) above the boiler.
The cold feed must be 15mm minimum size.
The vent must rise continuously and be
unrestricted.
It is important that the relative positions of the
pump, cold feed and open vent are as shown in
diagram 4.2.
4.8 Combined Feed and Vent
For combined feed and vent, a 22mm pipe must
be fitted in accordance with BS 5449.
4.9 Domestic Hot Water Cylinder
SINGLE FEED INDIRECT CYLINDERS ARE
NOT SUITABLE
The domestic hot water cylinder must be of the
double feed fully indirect coil type.
4.10 Domestic Hot Water System -
unvented
General - All domestic hot water circuits,
connections, fittings must be in accordance
with the relevant standards and water supply
regulations.
For GB: Guidance G17 to G24 and recommendation
R17 to R24 of the Water Regulations Guide.
For IE: The current edition of I.S.813 “Domestic
Gas Installations”.
Diagram 4.3
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