Question

which item is not essential for the safe operation of a conventional gas - fired water heater?
thermocouple
t - r valve
thermostat
pressure limit switch
flue
question 16
1 pts
which of the following is a common problem with combination heating systems?
oversizing
inadequate combustion air
inadequate heat and/or hot water
excess pressure at faucets
increased fuel consumption and cost

Explanation:

1. For the first question about gas - fired water heater: A thermocouple senses flame and shuts off gas if flame is out, a TPR (Temperature - Pressure Relief) valve relieves excess pressure and temperature, a thermostat controls water temperature, and a flue vents combustion gases. A pressure limit switch is not essential for basic safe operation of a conventional gas - fired water heater.
2. For the second question about combination heating systems: Oversizing can lead to short - cycling and inefficiency, inadequate combustion air can cause poor combustion, inadequate heat/hot water is a common issue if not sized or installed correctly, excess pressure at faucets is not a typical main problem, and increased fuel consumption and cost can occur due to inefficiencies like oversizing or poor combustion. Inadequate heat and/or hot water is a very common problem.

Answer:

1. pressure limit switch
2. inadequate heat and/or hot water