15
intelligently applied technology
© Baxi Heating UK Limited 2005
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
0
5
10
15
20
25
30
35
40
Min. 11°C
Max. 20°C
l/min
11.5
15.2
19.2
22.9
26.7
30.5
mbar
21.2
34.1
53.0
73.5
97.5
124.6
m
0.22
0.35
0.54
0.75
0.99
1.27
30 HE
40 HE
50 HE
60 HE
70 HE
80 HE
Water
level
22mm
Flow
Return
Top of
casing
Boiler
Max.
30.5m (100ft)
Min.
150mm (6")
Optional
2 port
valves
Indirect HE
Cylinder
Auto air vent
Alternative existing
by-pass arrangement
using the bathroom
radiator fitted with two
lockshield valves
Typical Fully Pumped System fitted with a Close Coupled Feed and Open Vent
** If plastic pipe is used for the central heating circuit there must be a run of at least
2 metres of uninsulated copper pipe from the
boiler flow and return connections
including any branches.
2m **
Automatic
by-pass or
existing
by-pass
balancing
valve
Optional
3 port
valve
Auto air vent
150 mm
Max.
Boiler drain off
point inside casing
Pump with
isolating valves
Table 2
3.9.5 Boiler Protection
• A frost thermostat is fitted within the boiler controls
which operates even if the temperature control knob
is at the ( ) position. The boiler will operate as
necessary to maintain the boiler temperature above
freezing.
• The boiler is fitted with a timed pump overrun that will
operate for around 2 minutes after boiler shutdown.
• The boiler control will operate the pump for around 2
minutes every 24 hours to maintain free running of
the pump.
3.9.6 Pump Requirements
• Resistance through the heat exchanger is shown in
the graph and Table 2 opposite.
• If other control valves are used in the system the
resistance through them, quoted in their
manufacturers literature must be taken into account.
3.9.7 Further Details
• Further details on systems are shown in BS5449 and
BS6798.
Fig. 10
l/min
6.3
8.4
10.6
12.6
14.7
16.8
mbar
6.3
10.8
16.9
23.7
31.9
41.2
m
0.06
0.11
0.17
0.24
0.32
0.42
Water Flow Rate (l/min) and Boiler Resistance (mbar/m)