High School Reaps Benefits of Replacing Steam Heating System with Hydronic One

Case Study

  • Company: South Portland High School
  • Industry: Education
  • Location: South Portland, Maine
  • Profile: Replace the high school’s steam heating system with a hydronic one.
  • Challenge: Hydronic system had to be capable of dual return advantage.
  • Solution: Install four ClearFire®-C fully condensing boilers.
  • Results: Notable increase in efficiency and reduction in fuel bill.

South Portland High School in South Portland, Maine, recently underwent a major renovation to upgrade and expand its facility, constructed in 1952. More than 100,000 feet was added to the school for a total of 300,000 square feet, providing space to meet a projected increase in enrollment and to fulfill major design criteria desired by the community. In addition to modernizing and expanding the high school, the renovation provided the opportunity for the school to implement a number of energy-saving initiatives.

Retrofitting the entire building envelope enabled the engineering team of Harriman Associates to recommend that the high school switch its heating system from a traditional steam one to a highly efficient hydronic one. A hydronic boiler system can achieve efficiencies up to 99%. 

When it came time to select a hydronic boiler system, Harriman Associates consulted with Chuck Cyr, sales engineer for The Blake Group in Portland, Maine. Cyr recommended that they only evaluate boilers capable of dual return advantage to meet multiple demands, thereby maximizing energy efficiency. 

Most hydronic systems blend returns from different loops, compromising the performance of a condensing boiler system. One with a dual return advantage provides a 6% + efficiency gain over hydronic boilers without this feature.

In the case of South Portland High School, the boilers with dual return advantage were designed to meet both central heating and domestic hot water needs. 

When the team set out to compare hydronic systems capable of dual return advantage, they analyzed water temperature parameters of the terminal units. They wanted to select the unit that was capable of achieving the lowest water temperature to ensure the system operated in condensing mode as much as possible. In addition, they wanted the boilers to be zero-flow tolerant, capable of handling low- and zero-flow situations.

Cleaver-Brooks ClearFire® units best met the engineering firm’s requirements. The building team was familiar with the manufacturer because the school had been operating Cleaver-Brooks 250 HP steam boilers, which had proven to be very reliable over the years.  

Cyr worked with the engineers to develop the piping diagram for the dual return feature of the hydronic boilers. In the summer of 2012, four Cleaver-Brooks ClearFire-C fully condensing boilers were installed at South Portland High School.  

Cyr explained, “Dual return on this job allows us to do domestic hot water with the boilers. That fundamental capability coupled with the primary/secondary piping is what elevates this job to world-class status. Of the four boilers, two are capable of doing domestic hot water simultaneously.” 

Russ Brigham, director of building and grounds for the South Portland School District, said the high school will realize a significant fuel savings. During the one-and-a-half years of construction, with doors and windows open and plastic over many of these openings in the construction areas, the school ran heat to help the sheetrock, paint and other construction materials dry. Its fuel bill with the new hydronic boiler system while the school was under construction was about the same as it was when it ran the steam system. 

“We increased the size of the school by 100,000 feet,” said Brigham. “If the average energy requirements that I have for the past few years remain the same, I’m going to have a wonderful savings.”

In addition, Brigham said the new boiler system’s minimal emissions will help South Portland High School on its path toward LEED certification.