RED A10-UHE, Installation And User Manual

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User’s Manual Code 001 Page 10-55 Rev 0819
10.2.5 Heat pump supply circuit
The Heat Pump coil inlets and outlets are identifiable by labels positioned at each of the
connections. The INC inlets and outlets should be plumbed directly to the heat pump
distribution manifold as shown in, Chapter 6, and plumbed from the top pumped port of the
manifold. The maximum operating pressure for the heat pump coil is 3 bar. If the hot water
storage tank is to be connected to an old or existing system with steel pipework or is heated
by a cast iron boiler, slurry and sludge may enter the hot water storage tank which can cause
blockages and corrosion. To prevent possible damage, it is recommended the system is
power flushed before filling the heat exchanger coil and a dirt filter or sludge separator is
fitted. Corrosion inhibitor should also be added to the associated pipework - this will need to
be checked periodically. Any pipework and fittings used should withstand a maximum
pressure of 6 bar at a temperature of 95 degrees. To reduce heat loss, insulation with
thickness equal to the outside diameter of the supply pipework should be used.
10.2.6 Secondary return
Ideally the INC tank should be installed as close as possible to all hot water outlets however,
where this is not possible, and the pipe runs to tap outlets are excessive a secondary return
may need to be fitted. Figure 27 details a typical schematic of how to fit a secondary return
to the tank, in addition to a pump suitable for sanitary hot water it is recommended that a
pipe thermostat or time clock is fitted to prevent the pump running constantly. To prevent
excessive heat loss the sanitary distribution pipework must be well insulated with expanded
nitrile foam insulation of not less than 13mm thick. It is also essential that the check valves
shown in the diagram are fitted to prevent the cold mains feed back flowing up the secondary
return pipework.
10.2.7 Overflow pipework
The overflow pipework should be configured in such a way as to allow any discharge from the
tank to be conveyed to a safe visible position. The overflow pipe should discharge directly via
a short length of pipe (<500mm) to a tundish which should be positioned lower than the
overflow pipe. The tundish should have a suitable air gap so any discharge becomes apparent.
Figure 27 Secondary return schematic