A probe-type low water fuel cutoff uses ___ to complete a burner control circuit.

A ___ boiler is a boiler in which water passes through tubes surrounded by gases of combustion.

In a feedwater system, a ___ supplies the extra capacity to handle changing loads and peak flows of condensate.

Water cannot be used as a secondary refrigerant in any application where the temperature is below ___°F.

A ___ is used to prevent a dangerous vacuum from forming in a boiler when it is taken out of service.

A ___ boiler is a boiler in which water passes through tubes surrounded by gases of combustion.

In a feedwater system, a ___ supplies the extra capacity to handle changing loads and peak flows of condensate.

A ___ is used to prevent a dangerous vacuum from forming in a boiler when it is taken out of service.

Common types of hot water system valves include diverter fittings, three-way valves, and centrifugal valves.

A strainer should be installed before an RPZ backflow preventer to remove any foreign matter that could cause the preventer to malfunction.