Question 46Refrigeration/AC - QMED70% to pass
If the needle and seat assembly is excessively eroded, the valve cage assembly can be replaced. In replacing the original valve cage assembly rated at 1/2 tons, what would be the result if the replacement valve cage was oversized at 5 tons? Illustration GS-RA-07
AI Explanation
The correct answer is C) The expansion valve would hunt excessively, alternately starving and overfeeding the evaporator coil.
If the replacement valve cage assembly is oversized at 5 tons compared to the original 1/2 ton rating, the expansion valve would not be able to properly control the refrigerant flow. The larger capacity valve cage would cause the expansion valve to constantly oscillate between starving and overfeeding the evaporator coil, resulting in excessive hunting behavior. This would lead to inconsistent superheat levels and poor system performance.
The other options are incorrect because:
A) The evaporator would not be starved, but rather would experience alternating starvation and overfeed conditions.
B) The expansion valve would not function normally with the oversized valve cage.
D) The evaporator would experience both insufficient and excessive superheat, not consistently insufficient superheat.
Related Questions
#44 The coil temperature measured at the expansion valve sensing bulb of an operating system is 10°F. The low side pressure with the compressor running as shown on the gauge illustrated indicates 15 psig. What adjustments or changes, if any, should be made to the system? Illustration GS-RA-16 #45 If the superheat value of the thermostatic expansion valve is adjusted too high, what would be the result? #47 What is true concerning frost build-up on the evaporator coils of a multi-box direct expansion refrigeration system? #48 The term 'oil foaming' in refrigeration practice, is used to describe what event? #49 The "tare weight" of a refrigerant storage cylinder refers to what weight?