UM / UM PLUS
Chillers and inverter air / water heat pumps with axial fans
17
9
SHUTDOWNS FOR LONG PERIODS
The types of shutdown depends on the weather of the site where the unit is installed and on the period of the stop. The antifreeze
system, if it’s installed, stay on work also with the on-board control unit in “OFF” position.
If the time of stop is long and the temperature is low, we recommend to drain the hydraulic circuits or use a mixture of water and
glycol.
Drain the hydraulic circuits and shutdown the unit with this passage:
•
Turn off the unit by placing the switch of each unit to "OFF" position.
•
Close the water valves.
•
Place the general differential circuit breaker to "OFF" position, if it is installed.
If the temperature drops below 0°C there is serious danger of frost: add a mixture of water and glycol in the
plant, otherwise drain the hydraulic circuits of the plant and of the heat pump.
WARNING: the operation, although it was transient, with water temperatures below +5°C is not guaranteed on
the basis of the limits set out in Paragraph 17.4. Before you turn the unit on after a long off period, make sure
that the temperature of the mixture of water and glycol is higher than or at least equal to + 5°C.
10
MAINTENANCE AND PERIODICAL CONTROLS
WARNING: All the operations described in this chapter HAVE TO BE CARRIED OUT BY TRAINED STAFF ONLY.
Before any operation or before entering the inner components of the unit, be sure that the power supply is
disconnected. The compressor’s heads and discharge piping are usually at high temperature levels. Be very
careful when operating in their surroundings. Aluminium coil fins are very sharp and can cause serious wounds.
Be very careful when operating in their surroundings. After maintenance operations, re-install the cover panels,
and fix them by means of screws.
The refrigerant circuits must not be filled with different gas other than that indicated on the nameplate. The use
of a different refrigerant can cause severe damage to the compressor.
It’s forbidden to use oils other than those specified in this manual. The use of a different oil can cause serious
damage to the compressor.
The temperatures of heads and discharge piping of the compressor are usually high.
Be careful when working near condensing coils.
The aluminum fins are very sharp and can cause serious injuries.
After the maintenance operations, close the panels tightly with the fastening screws.
It is a good rule to carry out periodic checks in order to verify the proper operation of the unit.
OPERATION
1 month
4 month
6 month
Filling the water circuit.
x
Presence of bubbles in the water circuit.
x
Check out that safety and control devices work correctly.
x
Check out possible oil leakage from compressor.
x
Check out possible water leakages from the hydraulic circuit.
x
Check out the proper working of the flow switches.
x
Check out that the crankcase electric heaters are properly supplied and functioning.
x
Clean the metallic filters of the hydraulic circuit.
x
Clean the finned coil by means of compressed air or water jet.
x
Check out that all the terminals on the electric board as well as on the terminals of the compressor are
properly fixed.
x
Tightening of water connections.
x
Check out the tightening and the balancing of the fan blades.
x
Correct voltage.
x
Correct absorption.
x
Check the refrigerant charge.
x
Check the operating pressure, and superheat and subcooling.
x
Check of the efficiency of circulation pump.
x
Check the expansion tank.
x
If the unit should be out of service for a long period, discharge water from the piping and from heat
exchanger. This operation is necessary if, during seasonal stoppages, ambient temperature is expected to
go down below the freezing point of the employed fluid.
x
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