Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 0105-E • 11 •
INSTALLATION - TRANSPORT - HANDLING
3.4.3 - Antifreeze protection
3.4.3.1 : Use glycol/water solution
ADDITION OF GLYCOL IS THE ONLY EFFICIENT WAY TO PROTECT AGAINST FREEZING
The glycol/water solution must be sufficiently concentrated to ensure proper protection and prevent formation of
ice at the lowest outdoor air temperatures expected on an installation. Take precautions when using non passivated
MEG antifreeze solutions (Mono Ethylene Glycol or MPG Mono Propylene Glycol). Corrosion can occur with these
antifreeze solutions with oxygen.
3.4.3.2 : Drain the installation
It is important to make sure that manual or automatic air bleeders are installed at all the high points of the water
circuit. To enable drainage of the circuit, make sure that drain cocks are installed at all the low points of the circuit.
To drain the circuit, the drain cocks must be opened and an air inlet ensured.
Note : air bleeders are not designed to admit air.
FREEZING OF AN EVAPORATOR DUE TO COLD WEATHER CONDITIONS IS NOT COVERED BY LENNOX
WARRANTY.
3.4.4 - Electrolytic corrosion
We would like to draw your attention to the problems of corrosion due to electrolytic corrosion caused by an
imbalance between earthing points.
AN EVAPORATOR THAT IS PUNCTURED BY ELECTROLYTIC CORROSION IS NOT COVERED BY THE UNIT
WARRANTY
3.4.5 - Minimum water capacity
The minimum volume of the chilled water circuit must be calculated with the formula here under. If necessary, install
a buffer tank. Proper operation of regulating and safety devices can only be ensured if the volume of water is
sufficient.
The theoretical volume of the water loop for a proper air conditioning operation can be calculated using the formula
hereafter:
Q ! Cooling capacity of the chiller in kW
N ! Number of capacity stage of the chiller
Dt ! Water temperature Delta T.
Vt = 72 x Q/(n x dt) litres
Example, for a chiller with 400kW, water conditions 12°C/7°C and 4 capacity stages, the minimum volume is :
Vt = 72 x 400/(5 x 4) = 1440 l.
This formula will give the minimum water capacity of the installation that will ensure a temperature rise of the water
loop of (dt/n)°C during anti short cycle of compressors.
This formula is only applicable for air-conditioning installation and must not be used for process cooling
where temperature stability is required.
3.4.6 - Flow switch
A flow switch must be installed on the evaporator water inlet or outlet, so as to enable detection of water flow through
the heat exchanger before the unit is started up. This will protect the compressors against any eventual liquid
slugging during the starting phase and prevent accidental ice formation in the evaporator, if the flow of water is
interrupted.
Flow switches are available on option.
The normally open contact of the flow switch should be connected to the terminals provided to that effect in the unit
electrical box. (See the wiring diagram supplied with the unit).
The normally closed contact can be used as an indication of a lack of flow condition.
Warranty is void if a flow detection device is not fitted and connected to the LENNOX control panel.
3.5 - ELECTRICAL CONNECTIONS
First of all, make sure that power supplies from the building to the place where the unit is installed are properly
established and that wire gauges are in keeping with the start up and running currents.
Check tightness of all electrical connections.
You MUST make absolutely certain that the power supplies applied to the power and control circuits are those for
which the electrical panel was manufactured.
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