In the spring of 2019, we received a call from our Greenville, South Carolina representative, Scott Houston. He explained that an engineering firm in Florence, South Carolina, was working on a unique 15,000,000 BTU hydronic project for a hospital with a challenging mechanical room layout. The space was extremely limited, with obstructive existing piping, low ceiling height, and the requirement that all current equipment remain in place.

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The original engineering plan called for a 30,000 lbs/hr steam pressure reducing station from 80 psig to 15 psig, two standard shell-and-tube heat exchangers, a flash tank, and a duplex electric condensate pump—essentially their standard design. The project also required four vertical domestic steam water heaters and a clean steam generator for humidification. As one might imagine, this room quickly became overcrowded.

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After several on-site surveys, Thermaflo developed a design that completely reimagined the system layout. Our approach eliminated the complex 220-inch-long steam PRV station, the flash tank and its wasteful roof vent, the duplex electric condensate pump, and the large low-pressure steam piping. By removing these elements, the equipment could finally fit within the mechanical room without compromise.

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The new design utilized two 20-inch Thermaflo Vacuflo Hydronic Heaters that accepted 80 psig steam at their inlets and controlled it to an energy-saving vacuum low pressure within the shell to perform the heating work. The original plan relied on standard exchangers using 5 psig steam at approximately 864 BTU per pound (90% steam quality), whereas the Vacuflo system provided full steam separator conditioning control at 995 BTU per pound. This improved efficiency reduced the steam usage flow from 1,736 lbs/hr to 1,507 lbs/hr, eliminating flash steam generation in the process.

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Condensate from the Vacuflo heaters was discharged at 180–190°F and was pumped directly back to the deaerator system using the 80 psig steam as a motive source, without exposing any vents to the atmosphere. In addition to these steam savings and the removal of the PRV station, the Vacuflo design incorporated a rear “back-side” steam inlet that reduced overall system height to just 78 inches, solving the headroom dilemma. This back-side inlet design also prevents wet steam impingement on the tube bundle, which helps avoid pinhole leaks and premature failures.

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The 80 psig steam supply was then extended to the clean steam generator, where 15 psig steam was required for humidification. Meanwhile, the four vertical Thermaflo TH750 domestic water heaters replaced older units and utilized the same low-pressure control system, operating with 1–2 psig steam that was subcooled to condensate before draining by gravity to the basement return system. The cooler condensate improved the performance of the elevated return pump, eliminating the cavitation problems that had plagued the previous design.

In the end, the consulting engineer achieved all project goals. The hospital gained a system that reduced installation costs by 30 percent, lowered steam usage by 15 percent, and eliminated wasteful flash steam and high-maintenance PRV equipment.

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For Thermaflo, this project was what we like to call a “Blind Flash of the Obvious,” a perfect example of how experience and innovative design can transform a complex challenge into a simple, efficient, and long-lasting solution. When it comes to steam and hydronic systems, experience counts.