Baxi Potterton BBU 15 HE - Manual (Page 12)

4.3 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 a
drop in temperature across the system of between
11& 20°C.
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. 4).
4.4 System Controls
1. 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.
4.5 Fully Pumped Open Vent System (Fig. 5)
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 form part of the vent
pipe. No part of the open vent may contain a valve.
4. Inverted pipe runs must be avoided.
5. On low capacity systems with a maximum available
flow rate of less than 8.3l/min (temperature differential
›25°C) an external bypass must be fitted .
6. The bypass must be of the automatic pressure
operated type.
4.6 Storage Systems
1. For information regarding the use of a Bermuda
BBU 15 HE boiler with a storage system, contact the
appropriate storage system manufacturer.
4.0 System Details
12
© Baxi Heating UK Ltd 2009
Air Vent
Boiler
Pump
Radiator
Circuit
Fully Pumped System
22mm
Open Vent
15mm
Cold
Feed
Indirect
Cylinder
Return
Flow
Fig. 5
Boiler
Flow
Return
Copper
0.5m
Copper
1m
Copper
0.5m
Fig. 4