The _______ limit of the firing rate of a flame-retention head burner is governed by the flue gas temperature leaving the furnace or boiler:

One cubic foot of natural gas contains about _____ of energy:

Natural gas has a specific gravity of _____

Which of the following fuel is used in Direct Gas-Fired Heating Systems:

In Quartz lamp heating, the elements of this type of heater operate at about _______ and consist of a tungsten wire coil sealed within a quartz tube

When the carbon dioxide (CO2) content of the flue gas is too low (less than 8 percent), heat is lost up the chimney:

Boilers that meet or exceed an _______ efficiency rating are labelled as Energy Star compliant:

_______ is the measurement of the actual amount of available energy that transfers into the heating medium: