The Modulatic is a once-through
waterube boiler with a positive displacement pump to provide a constant
flow of feedwater. The water by-pass regulator continuously regulates
the amount of feedwater that is sent to the coils in response to changes
in steam pressure. By-passed water is returned to the feedwater tank.
The servo control changes the
amount of fuel and combustion air in direct proportion to the flow
of water being sent to the coils. 90% of the water is converted into
steam in the coils. Dry steam is then produced in the steam separator.
The water remaining is removed by a steam trap..