Final answer:
The recovery process on an R-12 or R-134a A/C System should continue until a stable vacuum is held for 20 minutes. For your company's scheduling, using the standard deviation and average service time to create a confidence interval will help ensure sufficient time is budgeted per technician. The standard deviation indicates that 1.1 hours might be close and EER is critical for understanding efficiency in A/C systems. correct answer is 4.
Step-by-step explanation:
The recovery process on an R-12 or R-134a A/C System should continue until a stable vacuum is held by the system for 20 minutes. In regards to your company's preventive maintenance planning, to determine if the average of 1.1 hours per technician will be enough, you should use the standard deviation and the average time from past records to calculate the confidence interval for the average servicing time. If the upper bound of this confidence interval is less than or equal to 1.1 hours, then you will have budgeted enough time per technician. However, given the previous average is 1 hour with a standard deviation of 1 hour, budgeting only 1.1 hours may be cutting it close, especially if there is significant variance in service times, which the standard deviation suggests.
Discussing the energy efficiency of air conditioners, the energy efficiency rating (EER) is important. It is defined as the number of British thermal units of heat transfer from a cold environment per hour divided by the watts of power input. A 4-ton air conditioner with an EER of 12.0 shows that for every joule of work done, 12 joules of heat are removed from the environment. Additionally, considerations for heat transfer, such as air infiltration, turnover time, weather stripping, and caulking are significant for achieving energy efficiency in homes and structures.