10
221954D
7350
FEED AND
EXPANSION
CISTERN
22mm VENT
(MIN.)
15mm (MINIMUM)
COLD FEED
OPEN VENTED FULLY PUMPED WATER SYSTEM
RECOMMENDED RELATIONSHIP BETWEEN
PUMP COLD FEED AND VENT
450mm
MIN.
HEIGHT
1METRE
MIN.
RETURN
FLOW
CYLINDER
PUMP
HEATING
150mm
MAX.
There must always
be a cold water
path to the return
connection of the boiler.
BOILER
28mm (MINIMUM)
BY-PASS WITH
LOCKSHIELD VALVE
FLOW
RET.
Diagram 3.1
3.1 Frost Protection
If the position of the boiler is such that it may be vulnerable to
freezing it should be protected as specified in the current issue
of BS5422. It is recommended that a frost protection thermostat
be fitted.
3.2 Pump
The pump, with integral valves, should be fitted in the heating
flow pipework from the boiler, it should be set to produce a
temperature difference of 11
o
C (20
o
), between the flow and
return, with the control thermostat set at “MAX”, which is about
82
o
C (180
o
F).
The pressure loss of the boiler is 37.5 litre/min for the 100FF and
45litre/min for the 120FF to give 11
o
C temperature difference.
High resistance microbore systems may require a higher duty
pump.
3.3 Bypass - Fully Pumped and Sealed Water
System
A bypass MUST be fitted to a fully pumped and sealed water
system.
Where the water system allows the boiler and pump to operate
on bypass only, the bypass connection must be at least 2.5metres
away from the boiler.
The flow through the boiler must not be allowed to fall such that
there is a temperature difference greater than 20
o
C between the
flow and return.
3.4 Water System
For an open vented system the boiler must be supplied from an
unrestricted water supply taken from a feed and expansion
cistern fitted at a maximum height of 27metres above the boiler.
The cold feed must be 15mm minimum size.
It is important that the relative positions of the pump, cold feed
and open vent are as shown in diagram 3.1.
The unrestricted open vent from the boiler must rise continuously
to over the feed and expansion cistern.
3.5 Domestic Hot Water System
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".
3.6 Indirect Cylinder
For all systems supplying domestic hot water the cylinder must
be indirect. It is recommended that the indirect cylinder be fitted
with some form of temperature control.
3.7 Fully Pumped Heating and Domestic Hot
Water
The connections for this type of system MUST be as shown in
diagram 3.1 and 3.2.
It is recommended that plastic pipes for primary pipework
should not be used for this boiler.
3 Water Systems