Baxi Barcelona Installation And Servicing Instructions page 10

6.0 System Details – page 10
Fig. 7a
Fig. 8 Typical Low Head Installation
Fig. 9 If Conditions Require,
This System Possible
Fig. 10 Alternative Low Head Installation
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 connection to the
boiler is 28mm (compression).
2. Due to space requirements within the boiler outercase,
pipework should comprise of solder fittings.
3. A 20ºC (36ºF) 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 11ºC (20ºF).
4. 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. 7a).
6.4 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.
(An integral twin channel programmer is available as an
optional extra).
3. The boiler should be controlled so that it operates on
demand only.
4. Operation of the system under control of the boiler
thermostat & TRV's only does not produce the best
results.
6.5 Low Head Installation
1. Using a close couple arrangement the minimum head is
as shown in the diagrams (Figs. 8 & 9) subject to the
following conditions:
a) The pump being adjusted to give an 20ºC drop across
the boiler.
b) The pump must be fitted on the flow.
c) The pump must be fitted in accordance with the pump
manufacturers 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. 10)
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.
6.6 Thermal Stores
1. The Barcelona must not be fitted to thermal stores
which override the boiler control system.