Where shall a shut-off valve be located when a single tank and a single burner are installed?

The correct answer indicates that a shut-off valve should be installed in the supply line at the tank and another at the burner. This placement is crucial for both safety and maintenance reasons.

Installing a shut-off valve near the tank allows for quick access to stop the flow of oil in case of an emergency or maintenance requirement without needing to disrupt the entire system. By also placing an additional valve at the burner, it ensures that the burner can be isolated from the oil supply for servicing or in case of a malfunction.

This configuration enhances safety by allowing operators to manage the flow of oil effectively and ensures they can perform maintenance on the burner safely without risking oil leakage from the supply line. It is a standard practice in heating and oil burner systems to have this dual shut-off option as a measure to protect both equipment and personnel.

The other options suggest inadequate or restrictive locations for the shut-off valve, which may not provide the necessary control that operators require for safe and effective operation of the oil burner system.