Heatrae Sadia Megaflo Eco Solar Series Product Manual page 15

Drain Tap
A drain tap is supplied and should be installed in the cold water supply to the MEGAFLO Eco Solar unit between the 8 Bar Pressure Relief Valve
and the heater at as low a level as possible (see Figure 1, p. 5). It is recommended that the outlet point of the drain pipe work be at least 1 metre
below the level of the heater (this can be achieved by attaching a hose pipe to the drain tap outlet spigot). The drain tap supplied provides very
good water flow control and blanking cap for extra security.
Outlet Pipework
Ideally the pipework from the MEGAFLO Eco Solar to the outlet fittings should be in 22mm pipe with short runs of 15mm pipe to showers and
basin taps. Small bore pipe can also be used to suit some taps, but runs should be of minimum length. Pipe sizes may vary due to system design.
Expansion Vessel
The Expansion Vessel accomodates expansion that results from heating the water inside the unit. The unit is pre-charged at 0.35MPa (3.5 Bar).
The Expansion Vessel must be connected between the 8 Bar Pressure Relief Valve and the MEGAFLO Eco Solar cylinder (See Figure 1, p. 5). The
location of the Expansion Vessel should allow access to re-charge the pressure as and when necessary, this can be done using a normal car foot
pump. It is recommended that the Expansion Vessel is adequately supported. An Expansion Vessel wall mounting bracket is supplied for this
purpose.
NOTE: DO NOT USE THE POTABLE WATER EXPANSION VESSEL SUPPLIED WITH THE MEGAFLO Eco SOLAR FOR ANY OTHER
PURPOSE. IT MUST NOT BE USED IN PLACE OF THE SOLAR PRIMARY SYSTEM EXPANSION VESSEL.
Secondary Circulation
The secondary return pipe should be in 15mm pipe and incorporate a check valve to prevent backflow. A suitable WRAS approved bronze
circulation pump will be required. On large systems, due to the increase in system water content, it may be necessary to fit additional expansion
volume to the secondary system by fitting an external expansion vessel to the circuit. This should be done if the capacity of the secondary circuit
exceeds 10 litres.
Indirect models
If a secondary circulation system is required on an indirect model, it is recommended that it be connected as shown in Figure 8a below.
Direct models
If a secondary circulation system is required on a direct model, it is recommended that it be connected as shown in Figure 8b via a swept tee
(spares code 95605812). Particular attention should be paid by the installer to maintain the return water temperature (guidelines state that
a minimum of 55° C is advisable). Factors such as, but not limited to secondary circulation flow rates, minimising heat loss of all secondary
pipework and timed operation during periods of high demand are critical to the correct operation and longevity of the heating element(s) and
thermostats.
Pipe capacities (copper)
15mm o/d = 0.13 litres per metre run (10 litres = 77m)
22mm o/d = 0.38 litres per metre run (10 litres = 26m)
28mm o/d = 0.55 litres per metre run (10 litres = 18m)
Secondary Circulation Connection
TO HOT OUTLETS
CHECK VALVE
SECONDARY RETURN
WRAS APPROVED
BRONZE PUMP
Fig. 8a INDIRECT MODELS
TO HOT OUTLETS
COLD WATER
INLET
Fig. 8b DIRECT MODELS
Unvented Hot Water Cylinder
COLD WATER
INLET
SWEPT TEE
SECONDARY
CIRCULATION PUMP
SECONDARY
RETURN
CHECK VALVE
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