IDEAL HE15 Installation And Servicing page 10

3 OPEN VENT SYSTEM REQUIREMENTS
The system should be vented directly off the boiler flow pipe,
as close to the boiler as possible. The cold feed entry
should be inverted and MUST be positioned between the
pump and the vent, and not more than 150mm (6") away
from the vent connection.
Note. Combined feed and vent pipes may also be fitted.
There should be a minimum height 450mm (18") of open
vent above the cistern water level. If this is not possible refer
to
Frame 5. The vertical distance between the highest point of
the system and the feed/expansion cistern water level MUST
not be less than 450 mm (18"). The pump must be fitted on
the flow side of the boiler.
A suitable pump is a domestic circulator capable of
providing a maximum 11
across the boiler with the whole of the heating circuit open
(e.g. Grundfos UPS 15/50, 15/60 or equivalent). With the
minimum flow circuit allowed by the controls the differential
o
must not exceed 25 C. (18
The vertical distance between the pump and feed/expansion
cistern MUST comply with the pump manufacturer's
minimum requirements, to avoid cavitation. Should these
conditions not apply either lower the pump position or raise
the cistern above the minimum requirement specified by
Caradon Ideal Limited. The isolation valves should be fitted
as close to the pump as possible.
4 SCHEMATIC PIPEWORK AND SYSTEM BALANCING
The boiler does not normally need a bypass but at least some
radiators on the heating circuit, of load at least 10% of the
minimum boiler output, must be provided with twin lockshield
valves so that this minimum heating load is always available
(see footnote re. thermostatic radiator valves).
Balancing
1. Set the programmer to ON for both CH and HW.
Turn the cylinder thermostat down. Close the
manual or thermostatic valves on all radiators,
leaving the twin lockshield valves (on the radiators
referred to above) in the open position. Turn up the
room thermostat and adjust these lockshield valves
to give boiler flow and return temperatures not more
o
than 20 C apart. These valves should now be left
as set.
2. Open all manual or thermostatic radiator valves and
adjust the lockshield valves on remaining radiators
o
to give around 11 C temperature drop at each
radiator.
3. Turn up the cylinder thermostat and adjust the
cylinder balancing valve so that the cylinder
achieves a maximum flow consistent with adequate
flow to the radiators. Check that with only the
domestic hot water loop in circuit a differential
o
temperature of 20 C across the boiler is not
exceeded.
4. Adjust room and cylinder thermostats and
programmer to NORMAL settings.
10
o o
C (20 F) temperature differential
o
C for the HE15)
GENERAL
Return & flow
connections
load 30 - 60 = 22 mm
load 70 - 80 = 28 mm
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mexico HE -
Installation & Servicing