Stop valves before and after a pressure-reducing valve allow servicing of the pressure-reducing valve.

A(n) ___ is a hot water boiler fitting that serves as a boiler water setpoint temperature control system with an outside air thermostat.

___ is the condition where a flame travels upwind and into the burner assembly.

Oxygen in boiler water is used to remove nonadhering sludge.

A ___ is a dynamic pump with a rotating impeller inside a cast iron or steel housing.

A ___ is a dynamic pump with a rotating impeller inside a cast iron or steel housing.

Scale acts as an insulating material and reduces the transfer of heat to water.

___ is heat transfer that occurs when currents circulate between warm and cool regions of a fluid.

A common cause of problems in a hot water system is air in the system.

The purpose of a safety valve is to prevent the pressure in a boiler from ___.