Operating instructions

20 IMM AGSB-60
The piping should be designed with a minimum number of bends and changes in elevation to
keep system cost down and performance up. It should contain:
1. Vibration eliminators to reduce vibration and noise transmission to the building.
2. Shutoff valves to isolate the unit from the piping system during unit servicing.
3. Manual or automatic air vent valves at the high points of the system and drains at the low
parts in the system. If the evaporator is the highest point in the piping system, it must be
equipped with an air vent.
4. Some means of maintaining adequate system water pressure (i.e., expansion tank or
regulating valve).
5. Water temperature and pressure indicators located at the unit to aid in unit servicing.
6. A strainer to remove foreign matter from the water before it enters the pump. The strainer
should be placed far enough upstream to prevent cavitation at the pump inlet (consult
pump manufacturer for recommendations). The use of a strainer will prolong pump life
and help maintain high system performance levels.
NOTE: A 40-mesh strainer must also be placed in the supply water line just prior
to the inlet of the evaporator. This will aid in preventing foreign material from
entering the evaporator and causing damage or decreasing its performance. Care
must also be exercised if welding pipe or flanges to the evaporator connections to
prevent any weld slag from entering the vessel.
7. Protected water piping to the unit to prevent freeze-up if below freezing temperatures are
expected. See page 21 for further information on freeze protection.
CAUTION
If a separate disconnect is used for the 115V supply to the unit, it should
power the entire control circuit, not just the evaporator heaters. It should be
clearly marked so that it is not accidentally shut off during cold seasons.
Freeze damage to the evaporator could result. If the evaporator is drained
for winter freeze protection, the heaters must be de-energized
to prevent
heater burnout.
8. If the unit is used as a replacement chiller on a previously existing piping system, flush the
system thoroughly prior to unit installation. Then regular chilled water analysis and
chemical water treatment is recommended at equipment start-up.
9. In the event glycol is added to the water system as a late addition for freeze protection,
recognize that the refrigerant suction pressure will be lower, cooling performance less, and
water side pressure drop greater. If the percentage of glycol is large, or if propylene is
employed in lieu of ethylene glycol, the added pressure drop and loss of performance
could be substantial.
10. For ice making or low temperature glycol operation, the freezestat pressure value will need
to be checked and probably lowered. The freezestat setting can be manually changed
through the MicroTech II controller.
Make a preliminary leak check prior to insulating the water piping and filling the system.
Include a vapor barrier on piping insulation to prevent moisture condensation and possible
damage to the building structure. It is important to have the vapor barrier on the outside of the
insulation to prevent condensation within the insulation on the cold surface of the pipe.