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3 KEY FEATURES
3 .11 The APU Midi comprises of the following main components:-
1 .
Moulded tank – Main body of the APU, comprising of an integrated water
tank with warning pipe and weir overflow and mounting the brass pump
assembly, manifold and controller .
2 .
Pump assembly – One or two brass peripheral pump units powered by
induction motors, with integrated non return valves and venting screw .
Mounted into the moulded tank with vibration isolating rubber mounts .
3 .
Outlet manifold – Brass manifold with pressure transducer used to monitor
system pressure and connection to the pump(s) .
4 .
Programmable controller – Intuitive, user set controller allowing system set up
and easy alarm connection .
5 .
Wall mounting plate – Robust stainless steel wall mounting plate allowing
quick, easy installation and removal if needed .
6 .
Moulded cover – Moulded acrylic capped ABS cover retained to the
moulded tanks with Dual Lock
TM
fastening system for quick and easy
access .
3 .12
Principle of operation: The pressurisation unit consists of a break tank and
one/two peripheral pumps . The break tank is supplied with mains water from
either the left or right through a flexible hose connected to a float valve and
includes an overflow and weir to maintain an AB air gap in the tank . The unit is
connected to the heating/chiller system via another flexible hose which can
exit the unit on either the left or right . The pumps are connected to the tank
via a rubber connector .
A pressure transducer monitors system pressure and if a reduction in system
pressure is detected, the controller runs the pumps until the system is re-
pressurised to the required pre-set level . If the unit only has a single pump
connected it will run continuously until this level is reached, if the unit is a
twin pump model the pumps run in duty standby mode (the controller will
alternate which pump starts first to even the wear on the pumps) . The pumps
are fitted with non-return valves to ensure system pressure is maintained once
pressurised .
4 INSTALLATION
4 .11
Fill valve flow restrictor guidelines: The side entry fill valve must be fitted
with the correct filter and flow restrictor combination (dependant on the
mains water pressure) into the G ½ threaded tail as outlined below:
Coloured insert - To be used for water pressure between 1 and 4 bar
White insert - To be used for water pressure above 4 bar
4 .12
Cold mains feed connection: The connection to the cold water mains inlet is
made using the 15 mm compression flexible hose supplied . Ensure the rubber
sealing washer supplied with the hose is installed when the hose is fitted .
When tightening ensure the fill valve within the tank is not rotated . If the
valve is rotated it may not function correctly with the risk of flooding . The
hose is made water tight with a sealing washer on assembly, nip tight to
4 to 5 Nm for water tight seal .
(Do not overtighten) . See Fig . 6 .
1
Fig. 3
2
3
4
5
6
Fig. 4
Fig. 5
Fig. 6
