Potterton Promax SL range Installation & Service Instructions Manual page 13

Boiler
Fig. 9
1000mm
Boiler
Typical Low Head Installation
Fig. 10
Automatic Air
Vent
1000mm
Boiler
Fig. 11
Boiler
Fig. 12
Alternative Low Head Installation
© Baxi Heating UK Ltd 2014
Copper
Copper
0.5m
0.5m
Copper
1m
22mm
Open Vent
45°
15mm
Min
400mm
Cold
Min Head
Feed
150mm
Max
Pump
Return
22mm
Open Vent
45°
15mm
400mm
Cold
Min Head
Feed
Min
150mm
Max
Return
If Conditions Require,
This System Possible
22mm
200mm
Feed & Vent
Min
Pipe
Air
Separator
Pump
Return
6.0 System Details
Flow
6.3
Return
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 on the boiler
are 22mm.
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 30 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).
Flow
6.4
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
2. For heads below 400mm then a combined vent and feed
Pump
pipe may be connected. This must be a minimum of 22mm
diameter. It is recommended that an air separator is fitted
Flow
when using a combined feed and vent pipe.
6.5
1. Providing that the cold feed and open vent pipe are
positioned correctly (e.g. the system is not prone to
pumping over, air entrainment etc.) the pump may be fitted
on the primary return pipe.
Flow
Pipework
Low Head Installation
(Fig. 12)
Pump
13