8.2OPERATION BELOW 48°F
A.A chiller typically operates with a setpoint of 50°F or higher. However, if setpoints between 20° - 48°F are required, special precautions must be taken to prevent freezing and possible damage. Attention must be given to freeze protection, water supply and safety adjustments.
B.FREEZE PROTECTION
1.It is understood that untreated water freezes at 32°F. Therefore, an inhibited propylene glycol and water solution must be used in lieu of ordinary water. Prescribed amounts are listed in figure 8.2A.
OPERATING |
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TEMPERATURE | GLYCOL | WATER |
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40°F | 20% | 80% |
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25°F | 25% | 75% |
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30°F | 30% | 70% |
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Figure 8.2A
2.On initial installation of the unit, the water/glycol solution should be premixed, then added to the reservoir. After the pump has been started, water lines filled and air purged, it may be necessary to add more water/glycol solution to maintain the recommended reservoir level. Note: a hygrometer should be used on a regular basis to determine the mixture strength according to freeze point. The freeze point temperature should be 25° below the lowest required setpoint. Water will evaporate from the mixture, and if you continue to add a premixed solution eventually you will have too much glycol. It is necessary to add water or glycol to maintain proper freeze point temperature.
3.PLEASE NOTE THAT A CHILLER IS NOT DESIGNED TO ACCOMMODATE AUTOMOTIVE TYPE
C.WATER SUPPLY
1.The automatic water supply (if equipped) restores the reservoir water level as needed. However, if untreated water is added to an water/glycol solution, dilution will occur decreasing the freeze protecting ability of the solution.
UGH020/0301 | VL Series Portable Chillers, 0.25 to 1.5 Tons | Page: 35 |
