test-boiler

from The Century Dictionary.

• noun A form of steam-boiler so designed and installed in its setting that it may be used as a testing-device to determine the evaporative capacity of different fuels, the efficiency of furnace types, the effects of changes in the rate of combustion, and the value of steam-making devices and apparatus of various sorts. Most experimental laboratories of institutions for the education of engineers are equipped with such an experimental boiler.
• noun A boiler capable of withstanding a high internal pressure so that pressure from it may be used to test the strength of other boilers.
• noun A boiler specially constructed to test some principle or claim.