72
EN/06.2016/i01 © STULZ S.p.A. – all rights reserved
WPA ExPlOrEr OrIGINAl INSTrUCTIONS
auxiliary contactor in the electric cabinet. For the 140W heater the ohmic resistance should
approximately be 1,1 kOhm, 1,3 kOhm for the 120W heater and 1,8 kOhm for the 90W heater.
8.4 Air circuit
8.4.1 Condenser
To be checked: condenser coils
The air-cooled condenser consists of a microchannel coil with aluminium fins. Through the
microchannel coil flows outside air which is eventually polluted. Particles of polluted air may set-
tle at the fins and reduce the heat transmission the same as raise the air resistance. This could
probably identified by a increase of the fan current.
The heat exchanger can be cleaned by pressurized air or steam blasting (maximum 2 bar) which
has to be blown to the normal air flow direction along the fins.
WArNING
• Do not bend the fins during such an operation, in order not to limit the exchange efficiency
and increase the pressure drop on the air side.
• Do not use chemicals, these could cause corrosion at the coils.
8.4.2 Condenser Fan
To be checked: fans
The bearings of the fans are lifetime lubricated and do not need maintenance. Check the opera-
tion current. An increased operation current indicates either a higher air resistance by a clogged
condenser coil or a winding short circuit in the fan motor.
8.4.3 Filter
To be checked: air filters
The filters (optional) are made of metal, therefore they can be washed with water, once removed
from their seats.
8.5 Water circuit
• Be sure that the cooling medium respect the limit and the specification required (see "5.2
Chilled water quality" at page 36 ).
• Check the cleanliness and wash with water if necessary
• Check for any leaks and for proper sealing of fittings
• Check the presence of air in the water circuit. In case bleed the circuit following the instruc-
tions given in paragraph "6.7 Filling and bleeding air" at page 59
8.5.1 Tightness
Check the water circuit visually for tightness. Beyond that a level indication at the storage tank,
