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5
Installation - Indirect units
5.1 BOILER SELECTION
The MegaLife Indirect models are suitable for use with most gas or oil fired boilers. The boiler used
can either be a sealed system or open vented type. The maximum primary circuit pressure is 3.5
bar. If an open vented type boiler is used it must be fed from a separate boiler feed and expansion
cistern, it MUST NOT be fed from the MegaLife cold water feed cistern.
The primary flow from the boiler should be pumped. Gravity circulation is not recommended due to its
reduced heating performance. It is recommended that an air bleed point or automatic air vent is
incorporated in the primary return pipework close to the MegaLife unit to aid in bleeding air from the
primary heating coil.
The boiler should be fitted with adequate thermal control. This will normally include a primary flow
thermostat and a safety over temperature cut-out. The boiler flow temperature should usually be set to
82
C (maximum flow temperature to primary heat exchanger 90
o
The boiler cannot be vented through the MegaLife unit.
5.2 INDIRECT THERMAL CONTROLS
Control of the storage temperature when indirectly heated is provided by the cylinder thermostat fitted.
The control is located under the grey plastic cover located between the indirect coil connections. The
cylinder thermostat is adjustable between 10
adjustment dial located under the control cover. Recommended storage temperature is 60
See Diagram 4.
5.3 WIRING
All electrical wiring should be carried out by a competent electrician and be in accordance with the
latest I.E.E. Wiring Regulations.
The MegaLife Indirect Thermostat and Thermal Cut-out are factory pre-wired. It is recommended that
these controls are wired in series with a suitable 2 or 3 port motorised valve to control the primary
flow through the heater coil. Wiring to external controls is made via the terminal block fitted. The cable
should be routed through the aperture in the terminal cover and secured using the cable grip provided.
The Indirect Thermal Cut-out MUST NOT be bypassed.
5.4 HEATING SYSTEM CONTROLS
The controls provided with the MegaLife will ensure the safe operation of the MegaLife within a central
heating system. Other controls will be necessary to control the space heating requirements and times
that the system is required to function. Depending on the boiler selected, heating circuit design and
controls used it may be beneficial to incorporate a system bypass in the heating system pipework.
The Megaflo is compatible with most heating controls, examples of electrical circuits are given in
Diagrams 5 and 6. However, other systems may be suitable, refer to the controls manufactur-
ers' instructions, supplied with the controls selected, for alternative system wiring
schemes.
10
10
C).
o
and 70
C, adjustment is made by rotating the
o
o
to 65
C.
o
o
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