Technical data
6.0 System Details
13
© Baxi Heating UK Ltd 2006
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. The connections to the
boiler will accept 22mm pipe.
2. A 20 °C (36°F) 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 (20°F).
NOTE: On 100/2 HE Plus models 28mm pipe should
be used to connect to the boiler flow and return.
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 (Fig. 9).
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.
An alternative Low Head Installation (Fig. 12)
2. For heads below 400mm then a combined vent and
feed pipe may be connected. 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 Thermal Stores
1. When the boiler is fitted in conjunction with a
thermal store, both jumpers must be removed from the
PCB, see Fig. 32 Section 8.8.
Typical Low Head Installation
If Conditions Require,
This System Possible
Alternative Low Head Installation
Boiler
500mm
45°
22mm
Open Vent
1000mm
Min
150mm
Max
15mm
Cold
Feed
400mm
Min Head
Return
Pump
Flow
Boiler
500mm
45°
22mm
Open Vent
400mm
Min Head
1000mm
Min
Automatic Air
Vent
15mm
Cold
Feed
150mm
Max
Return
Pump
Flow
Return
Pump
Flow
Boiler
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