Baxi Solo 2 PF Installation And Servicing Instruction page 8

3.0 System Details – Page 8
3.3 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. An 11º C (20º F) drop in temperature across the
system is recommended.
3.4 System Controls
1. For optimum operating conditions, the heating system
into which the boiler is installed should include a control
system.
2. Such a system will comprise of a timer control and
separate room or cylinder thermostats as appropriate.
3. The boiler should be controlled so that it operates on
demand only.
4. Operation of the system under control of the boiler
thermostat only does not produce the best results.
5. A frost thermostat is fitted integrally to the appliance
controls and will protect the boiler from frost damage by
operating the burner when the water temperature in the
boiler drops towards freezing point. The boiler will fire as
necessary to maintain a temperature above freezing.
NOTE: The frost thermostat operates even if the
boiler thermostat is in the OFF ('0') position and it is
necessary therefore, if the system is drained, for the
external electrical and gas supplies to be isolated. It
is recommended that a label be affixed to the
appliance to draw attention to the fact that the system
has been drained.
3.5 Low Head Installation
For boilers up to 50,000 Btu/h output
1. Using a close couple arrangement the minimum head
is as shown in the diagrams (Figs. 5 & 6) subject to the
following conditions:
a) The correct heat input.
b) The pump being adjusted to give an 11º C drop
across the boiler.
c) The pump must be fitted on the flow.
d) The pump must be fitted in accordance with the
pump manufacturers instructions.
e) The open vent pipe must be taken up from a tee in a
horizontal section of the flow pipe.
Alternative Low Head Installation for all Sole 2 PF
(Fig. 7)
2. If less height is available 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.
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