15
Secondary circulation
If secondary circulation is required it is recommended
that it be connected to the cylinder as shown (see figs.
9 and 9b).
`
The secondary return pipe should be in 28mm pipe
and incorporate a check valve to prevent backflow.
`
A suitable WRAS approved circulation pump will
be required.
`
On large systems, due to the increase in system
water content, it may be necessary to fit an
additional expansion vessel to the secondary
circuit. This should be done if the capacity of the
secondary circuit exceeds 10 litres.
Pipe capacity (copper):
15mm O.D. = 0.13 l/m (10 litres = 77m)
22mm O.D. = 0.38 l/m (10 litres = 26m)
28mm O.D. = 0.55 l/m (10 litres = 18m)
Note: Plastic pipe capacities may be reduced due to
thicker wall sections.
In direct electric installations where a secondary
circulation is required particular attention should be
paid by the installer to maintain the returning water
temperature (guidelines state that a minimum of 55°C
return temperature is advisable). Factors such as,
but not limited to, secondary circulation flow rates,
minimising heat loss of all secondary circuit pipework
and timed operation during periods of high demand
are critical to the correct operation and longevity of the
heating element(s) and thermostats.
Secondary circulation is not recommended for
direct electric units using off-peak tariffs where the
secondary circulation is not controlled in conjunction
with the heat source as performance can be affected.
Figure 9: Secondary circulation schematic
IMPORTANT INFORMATION:
HOW TO INSULATE YOUR T&P RELIEF VALVE
TO SAVE HEAT AND ENERGY A SET OF INSULATING PARTS FOR
THE T&P RELIEF VALVE HAVE BEEN SUPPLIED WITH THIS WATER
HEATER. INSTALL THE HEATER FIRST THEN FIT THE INSULATING
PARTS BY FOLLOWING THE DIAGRAMS BELOW.
A
B
C
D
T&P RELIEF
VALVE
DISCHARGE
PIPEWORK
TUNDISH
LEFT HAND
INSULATING PIECE
PLASTIC COVER
DISCHARGE PIPE
RIGHT HAND
INSULATING PIECE
CLIP INTO
PLACE !
T&P Relief valve insulation
A set of insulating components are supplied with the
cylinder and should be installed to gain maximum heat
and energy saving benefits by insulating the exposed
metal parts of the T&P Relief Valve. See Figure 10
below for installation instructions.
Figure 10: T&P Relief Valve insulation set installation
Secondary Return
WRAS approved
pump
Check Valve
Cold Water
Inlet
To Hot Outlets
Figure. 9b Indirect models
Cold Water
Inlet
To Hot
Outlets
Check Valve
Swept Tee
Secondary
Return
Secondary
Circulation Pump
Summary of Contents for Megaflo Eco 125DD
Page 34: ...34 Benchmark checklist...
Page 35: ...35 Commissioning service records...
Page 38: ...38 NOTES...
Page 39: ...39 NOTES...
