Heatrae Sadia Megaflo Eco SolaReady, Instructions Manual

Page: 18 / 52

INST
ALLA
TION
18
Indirect Model
Boiler Selection
The Megaflo Eco SolaReady Indirect models are supplied with an auxiliary heating coil and are suitable for use with most gas
or oil fired boilers compatible with unvented systems i.e. fitted with a temperature control thermostat and thermal cut-out. If
in doubt consult the boiler manufacturer. Solid fuel boilers or any other boiler in which the energy input is not under effective
thermostatic control, unless additional and appropriate safety measures are installed, SHOULD NOT be used. The boiler used
can either be a sealed system or open vented type, maximum primary circuit pressure 0.3Mpa (3 bar). The primary flow
from the boiler MUST be pumped. Gravity circulation will not work due to the special design of the primary heat exchanger.
It is recommended that an air bleed point or automatic air vent is incorporated in the primary return pipework close to the
Megaflo Eco SolaReady unit. The boiler flow temperature should usually be set to 82ºC (maximum flow temperature to
primary heat exchanger 89ºC). The boiler cannot be vented through the Megaflo eco Solar unit.
Indirect Thermal Cut-Out And 2-Port Motorised Valve
To comply with Building Regulations, and to prevent the Megaflo Eco SolaReady from overheating the 2-port motorised valve
supplied MUST be fitted to the primary flow to the indirect coil (see Figure 6).
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 Megaflo Eco SolaReady Indirect combined thermostat and thermal cut-out are factory pre-wired. The 2-port motorised
valve supplied MUST be wired in series with the Indirect controls such that the power supply to the valve is interrupted should
either the Thermostat or Thermal cut-out operate. Figure 16, diagrams A, B, D and E detail the wiring required between these
controls and the motorised valve. 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.
Should the Megaflo Eco be used in conjunction with a boiler that controls the water temperature via a sensor
connected to the boiler controls it should be noted that the factory fitted indirect thermostat and thermal cut-out
MUST NOT be disconnected or bypassed. To do so would invalidate the product approvals and warranty and it would
not comply with Building Regulations. Should this method of control be adopted the Megaflo Eco Indirect thermostat
should be set at maximum and the boiler cylinder control temperature set at 60
o C to avoid the thermostat over-riding
the boiler control.
Where the boiler control does not directly power the 2 Port Motorised Valve supplied with the Megaflo Eco, the
wiring should ensure that in the event of the thermal cut-out on the Megaflo Eco Indirect controls operating power
will be interrupted to the 2 Port Motorised Valve such that it closes and prevents flow of the primary heating fluid
around the Megaflo Eco primary heat exchanger coil.
For further details of wiring the boiler, consult the boiler manufacturer’s installation instructions.
Heating System Controls
The controls provided with the Megaflo Eco SolaReady will
ensure the safe operation of the Megaflo Eco SolaReady
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 Eco SolaReady is compatible with most heating
controls, examples of electrical circuits are given in the block
wiring schemes. However, other systems may be suitable,
refer to the controls manufacturers’ instructions, supplied
with the controls selected, for alternative system wiring
schemes.
The auxiliary indirect heating source can be controlled via the
Solar Differential Controller – refer to block wiring schemes
B and E and Commissioning Section for setup details.
NOTE: The auxiliary backup immersion heater must have a
separate 13 amp fused supply and cannot be operated via the
Solar Differential Controller on indirect models.
Immersion Heater(s)
The Megaflo Eco SolaReady indirect units (Indirect models) are supplied with an immersion heater which can be used as an
alternative heat source should the boiler supply need to be isolated from the Megaflo Eco SolaReady unit. The immersion
heater is located within the upper controls housing. Refer to page 17 “Wiring and Operation” for details of wiring and
operation of the immersion heater.
L N 1 2 3
Control Housing Details
Element Connections
1.5mm² 3 Core
HO5 VV-F sheathed
cable Indirect control
wiring
Figure 15 – Control housing details