___ boilers do not retain any water internally except for what is in the heat exchanger coil.

Protective ___ protect workers by resisting penetration and absorbing the blow of impact.

A ___ system provides the air necessary for combustion.

The method for controlling draft is determined by the boiler equipment.

Chilled water systems are classified as indirect cooling systems because chilled water is used as a medium to transfer heat and cool a building space.

There are four main causes of natural circulation in a boiler.

There are four main causes of natural circulation in a boiler.

An operating pressure control starts and shuts down a burner based on steam pressure.

Equipment in chemical feed systems varies but usually includes a mixing tank, a pump, control valves, piping, and a control mechanism.

A natural-circulation hot water heating system uses circulating pumps to transport water in the system.