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INSTALLATION OPERATIONS AND MAINTENANCE MANUAL - VORT NRG MEGA-R SERIES
13.8 Hydraulic connection to the exchange coils
13.8.1 Water coils
The following requirements for water connections are also applicable for coils with other fluid, such as glicole solutions, dia-
thermal oil, etc. The following minimal requirements are recommended for any type of installations.
a) Provide appropriate supports for external circuit and thermal expansion joints with vibration isolators; avoid to load coil
connections.
b) Position water pipes and water circuit devices not to impede coil slide out, inspection panel openings and access to any
unit sections.
c) Avoid damages to coil connection solderings by fastening mechanical connections with care without applying any torsions
to the same especially when the exchangers are small.
Coil performance is normally rated for counter-flow circuit arrangement, consequently coils are provided with
water inlet at the bottom and downstream air flow, outlet at the top and upstream air flow.
This rule is ensured by following the applied plates indicating “
Water in
” and “
Water out
”.
Furthermore, water circuit should be provided with:
1) water drain to be positioned at the unit lowest point (obligatory);
2) vent valve at the circuit highest point to allow easy replenishment (recommended);
3) shut-off valves, on water inlet and outlet, to allow coil disassembly for extraordinary maintenance;
4) for hot water coils, water pump electric interlock with the fan cycling device or circuit bypass, to avoid damages resulting
from overheated stagnating air, during fan shutdown periods.
Installer must obviously guarantee the requested value of water flow.
13.8.2 Direct expansion coils
Instructions given at points a) and b) of previous paragraph for water coils should be followed also in this case, bearing in mind
that the best coil performance is always obtained with the counter-flow arrangement. In this case coil supply is evidently the
one provided with the distribution header where the liquid line must be connected.
The refrigerant circuit must be made in accordance to the best state-of-the-art practice; in any case, the following recommen-
dations are to be followed:
1) coil is supplied with a holding charge of refrigerant or dehydrated nitrogen;
2) only refrigeration copper tubes should be used, tubes must be thoroughly cleaned, dehydrated and sealed until their use;
3)
coil distributor should be cut only immediately before proceeding to brazing, which must be carried out in dehydrated nitrogen
atmosphere which must be forced inside tube to prevent undesired oxidation;
4) same criteria described in point 3) must be used when brazing liquid line to distributor;
5) refrigerant circuit must include appropriate controls and devices to guarantee proper system operation, coil is only a part
of the system.
