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3.3
Pipework
1. The sizes of the flow and return pipes from the
boiler should be determined by normal methods
according to the requirements of the system.
2. It is recommended that the system is
designed for an 11
°
C (20
°
F) drop in temperature
across the system.
3. In systems using non-metallic pipework it is
necessary to use copper pipe for the boiler Flow
and Return. The copper must extend at least 1
metre from the boiler and include any branches.
The copper pipe must not be insulated (Fig. 2a).
3.4
System Controls
1. For optimum operating conditions, the system
in which the appliance is installed should include
a control system.
2. Such a system would comprise a timer control
and a separate room and/or cylinder thermostat
as appropriate.
3. The boiler should be controlled so that it
operates on demand only.
4. It is not economical to rely on the boiler
thermostat to control operation of the system.
3.5
Fully Pumped System
(Fig. 3)
1. The sizes of the system pipes should be
determined by normal methods.
2. The open vent pipe should be a minimum of
22mm and must rise continuously to a point
above the feed and expansion tank.
3. The flow pipe from the boiler may form part of
the vent pipe. No part of the open vent should
contain a valve.
3.0 System Details
1
7
Air Vent
Boiler
Pump
Radiator
Circuit
Fully Pumped System
22mm
Open Vent
15mm
Cold
Feed
Indirect
Cylinder
Return
Flow
Fig. 3
Boiler
Flow
Return
Copper
0.5m
Copper
1m
Copper
0.5m
Fig. 2a
