CHUNLAN -B, Service Manual

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Typical case analysis
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insulation.
Case IV: A user installed 11 sets of Chunlan FR260/S, FR180/S and FR125/S air duct type air
conditioners. During test run, it was found that heating effect was poor and highest air
delivery temperature in rooms was only 28
℃
. Measurement showed that current, voltage and
system pressure were all normal.
Analysis: (1) Design of air return was not reasonable. Air return ports provided were as small
as half a book and in some rooms, even no such port is provided; (2) Fresh air port was
normally open and not controlled by air damper; (3) Room area/space was too large.
Solution: (1) Provide effective air return with sufficient area; (2) Fabricate effective air
damper to control fresh air port or block fresh air port; (3) Increase number of air conditioning
units or add auxiliary heating.
Case V: A user installed 26 sets of Chunlan air duct type air conditioners, in which 23 were
FR260/S. Now the user complains high noise in many units beyond what he can accept.
Analysis: (1) All units adopt air duct return air to ensure efficiency. Air delivery hose of each
unit adopts 3
φ
120mm round plastic air ducts and return air duct adopts 5
φ
180mm round
plastic air ducts. Calculation shows that total air delivery area is 0.0989m
2
, less than 0.135 m
2
recommended by instruction manual; and total return air cross sectional area is 0.127 m
2
, also
less than 0.3 m
2
recommended by instruction manual. Calculated air speed in air delivery
branch hose and air return branch hose are 5.3/s and 4.15m/s respectively. By consulting
tables, noise level is apparently high; (2) Unit installed on support angle steel by hard contact
causes resonance and hard contact between metal air duct and ceiling running water pipe
aggravates the resonance; (3) Some indoor units are directly installed in operating
environment, e.g. ceiling of offices, and rooms in which the units operate are too near sound
sources, hence higher noise.
Solution: (1) Increase air delivery/return branch hose cross sectional areas or number of such
branch hoses so that sum of cross sectional area of air delivery/return hoses meets instruction
manual specification; (2) Avoid hard contact at unit support faces, add wood or rubber pads to
isolate vibration; (3) Rooms where air conditioners are used shall be at a longer distance from
indoor unit, outdoor unit and other sound sources; if this is not feasible, wrap a 5cm thick
sound absorbing sponge plus plastic cloth on indoor unit (except air return port).
Case 6: A user installed two sets of FR180/S air duct type air conditioners early 2003. These
share an air system. In summer of the year, it was found that cooling effect was not good and
room temperature cannot be brought under 26
℃ .
Analysis: Measurement showed that one unit was not operating and further inspection showed
that there was no display on wire controller of this unit. After replacement of wire controller,
there was still no display on wire controller. By swapping wire controller cards on indoor
main control boards of two units, the originally failed unit now operated normally while there
was no display on the originally normal unit. Measurement of wire controller connecting
cable showed that there were m any extension connections on it and the cable had been wetted
and had large resistance.