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6.0 System Details
12
© Baxi Heating UK Ltd 2011
6.3 Pipework
1. The sizes of flow and return pipes from the boiler
should be determined by normal methods, according to
the requirements of the system.
2. The connection tails for the boiler are 28mm diameter.
The 28mm section of the tails can be cut back to 22mm if
required.
3. The flow & return tails are push - fit ‘O’ ring
and clip connections within the boiler case.
4. A 20 °C drop in temperature across the system is
recommended for condensing boilers. Existing radiators
may be oversized and so allow this, but where radiator
sizing is marginal it may be advisable to retain a system
temperature drop of 11°C.
5. 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 (Fig. 9).
6. This boiler does not require a bypass.
6.4 Low Head Installation
1. Using a close couple arrangement the minimum head is
as shown in the diagrams (Figs. 10 & 11) subject to the
following conditions:
a) The pump being adjusted to give a 20°C drop across
the boiler.
b) The pump must be fitted on the flow.
c) The pump must be fitted in accordance with the
pump manufacturer's instructions.
d) The open vent pipe must be taken up from a tee in a
horizontal section of the flow pipe.
2. For heads below 400mm then an alternative utilising a
combined vent and feed pipe may be connected (Fig. 12).
This must be a minimum of 22mm diameter. It is
recommended that an air separator is fitted when using a
combined feed and vent pipe.
6.5 Air Vents
For correct operation of the flow switch the boiler
and system MUST be completely vented.
1. A manual air vent is fitted on the flow pipe, to enable
complete venting of the boiler. The pipe access panel
must be removed to do this.
2. Additional vents should be fitted at suitable points on
the system as required.
Boiler
Boiler
Boiler
Typical Low Head Installation
If Conditions Require,
This System Possible
Alternative Low Head Installation
500mm
45°
22mm
Open Vent
1000mm
Min
150mm
Max
15mm
Cold
Feed
400mm
Min Head
Return
Pump
Flow
500mm
45°
22mm
Open Vent
400mm
Min Head
1000mm
Min
Boiler Air
Vent
15mm
Cold
Feed
150mm
Max
Return
Pump
Flow
Return
Pump
Flow
200mm
Min
Air
Separator
22mm
Feed & Vent
Pipe
Fig. 10
Fig. 11
Fig. 12
Boiler
Flow
Return
Copper
0.5m
Copper
1m
Copper
0.5m
Fig. 9
Boiler Air
Vent
Boiler Air
Vent
Boiler Air
Vent