What should a technician do about the water in the chiller tubes before pulling a deep vacuum on the machine?
Correct Answer
A) Drain the tubes or keep the water circulating through them
As refrigerant is pulled out of a low-pressure machine the saturation temperature inside the shell falls, and standing water in the evaporator or condenser tubes can freeze solid. Ice expands, splits the tubes, and turns a routine recovery into a retubing job that costs far more than the refrigerant ever did. The fix is simple: either drain the water side completely before evacuating, or keep pumps running so the water is always moving and carrying heat into the bundle. Both approaches are accepted practice on Type III work.
Why This Is the Correct Answer
Removing the water eliminates the freeze hazard entirely, and keeping it flowing supplies a steady heat load that holds the tube temperature above freezing while the vacuum deepens. Either step protects the bundle. Skipping both is the single most expensive mistake a technician can make on a low-pressure chiller recovery.
Why the Other Options Are Wrong
Option B: Add a corrosion inhibitor to the chilled water loop
Corrosion inhibitor protects metal from rust and scale over the long term. It does nothing to change the freezing point in any meaningful way and offers no protection during a deep evacuation.
Option C: Fill the tubes completely and close both isolation valves
Trapping a full bundle of standing water with the valves closed is the worst case. The water cannot move, it cannot pick up heat from anywhere, and it has nowhere to expand when it turns to ice.
Option D: Lower the chilled water setpoint to forty degrees F
The chilled water setpoint only matters while the machine is running and making cooling. Once recovery starts the controller is out of the picture and the setpoint has no effect on tube temperature.
Memory Technique
Drain it or drive it: the water either leaves the tubes or keeps moving through them.
Reference Hint
Freeze protection of the water side is standard Type III service practice during recovery under 40 CFR Part 82, Subpart F.
More epa-608-type-3 Questions
Which piece of equipment requires a technician to hold Type III certification before it may be serviced?
What property of the refrigerant is what actually places an appliance into the low-pressure category?
During normal operation, what condition exists inside the evaporator of a running low-pressure centrifugal chiller?
In what unit is the required final recovery vacuum for a low-pressure appliance normally expressed?
What happens if the internal pressure of a low-pressure chiller is driven past the rating of its rupture disc?
Which refrigerant was the original factory charge in most low-pressure centrifugal chillers built during the nineteen sixties and seventies?
A running low-pressure chiller develops an opening in a section of shell that is below atmospheric pressure. What passes through that opening?
A technician is assigned to recover the charge from a large water chiller holding nine hundred pounds of R-134a. Which certification does that job require?
Into which appliance category does a machine charged with R-13 for very low temperature service fall?
On a low-pressure centrifugal chiller running at load, how do the evaporator and condenser sit relative to atmospheric pressure?
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