Question

which water heater has the fastest recovery rate?
a single - element electric heater
a double - element electric heater
an oil - fired water heater
a conventional gas - fired water heater
a direct - vent gas - fired water heater
question 22
1 pts
common problems for pumps with hot water circulating systems include all of the following except
inoperative
leaking
overheating
excess noise or vibration
controlled by an aquastat

Explanation:

1. For the first question, double - element electric heaters can heat water faster as they have two heating elements working simultaneously compared to single - element ones. Oil - fired, conventional gas - fired, and direct - vent gas - fired heaters have different combustion and heat transfer processes that are generally slower in recovery rate than double - element electric heaters in many cases.
2. For the second question, inoperative, leaking, overheating, and excess noise or vibration are common problems with hot water circulating system pumps. Being controlled by an aquastat is a feature of temperature control, not a common problem.

Answer:

Question 1: B. a double - element electric heater
Question 2: E. controlled by an aquastat