If a system has 80% of the condensate returning at 200º F with 20% make up at 60º F, the blended feedwater temperature would normally be about 170º F. This should be adequate temperature for most firetube or commercial watertube boilers.
If, for example, the system has 50% make-up at 60º F and 50% returns at 200º F, the blended feedwater temperature would be about 130º F at normal operating conditions. This system would normally require feedwater heat to protect the boiler.
A sparge tube with a temperature switch and steam supply valve is available. This is an inexpensive way to heat the feedwater to acceptable levels.
The heater assembly has a solenoid or self-contained type control valve with a 250 lb. screwed body up through 2" (the 2-1/2" has a 125 lb. flanged body), heater tube, y-strainer, and required piping. The selection is determined by percentage make-up, type of heater valve (solenoid or modulating), and pressure level of steam (low pressure of 15 lb. versus high pressure of 100 lb.). Heater assembly options are listed as part of the select and customization process.