Radiant Heating System Meets Challenge of Complex School Design

At 280,000 square feet, Edward Little High School in Auburn, Maine is one of the state’s largest. The school’s architecture and engineering firm, Harriman Associates, implemented a radiant floor heating system throughout the building to achieve comfort and efficiency.

“Radiant heat is a very comfortable, very satisfying heat compared to a forced air convection system, heating people and objects directly as opposed to blowing hot air on them,” explained Harriman principal and mechanical engineer David Story, PE, LEED AP. “It’s a lot like feeling the warmth of the sun. It’s more natural and I think people tend to feel better with it.”

The radiant system allows for lower water temperatures, around 130°F, compared to the 180°F required by traditional hydronic systems. Harriman designed the system to primarily use geothermal energy for heating the water. “Radiant heating delivers this very high-quality heat at lower energy costs,” Story said. “I think the technology is especially appropriate in a learning environment where maintaining comfort is especially important, and in a situation where spending is always under scrutiny.”

Designing a Complex System

The school’s architects divided the building into 193 individual heating zones, each with unique requirements based on room size, ceiling height, equipment, and furnishings. Designing the radiant system required meticulous mapping of the under-floor piping loops, water flow, temperatures, pump sizes, pressure, and manifold locations.

Harriman has long specified radiant heating and worked with REHAU, selecting their RAUPEX O2 barrier pipe for the Edward Little project. “REHAU sells the complete radiant heating system, but they are also the experts in piping design. And they provide us with this in-house engineering design knowledge that’s very valuable,” Story said. “We were very impressed by the radiant design work done for all the rooms. Our expectations frankly are very high and REHAU lived up to them in every way.”

Product Performance

Story highlighted the importance of tight bend radius in the pipe given the many small rooms and tight under-floor loops. “Contractors tell me REHAU pipe is tight and neat, fast to install and it can do the tightest U-turns even when it’s cold,” he said.

He also emphasized the robustness of REHAU RAUPEX O2 barrier pipe. “Before it gets put in the slab, when it’s laying around the construction site, pipe can be under constant attack—stepped on by heavy boots, getting run over by forklifts and more,” he noted. “Poor quality piping will squish or puncture more easily, but REHAU pipe stands up to these realities. We don’t hear about damaged pipe and leaks with REHAU.”

System Components and Support

The radiant system incorporates Taco circulator pumps, Tandem geothermal water-source heat pumps, and Viessmann gas-fired condensing boilers for backup energy. Located throughout the school, indoor air handlers provide ventilation and air conditioning.

“When we design a building, we basically own all the issues of the building for the life of the building—that’s our reputation,” Story said. “That’s why we look for partners like REHAU. They meet our high expectations, give us good support and help us look good. We succeed together.”

Project Details

• Project: Edward Little High School, Auburn, ME
• Type of construction: Education, opened 2023
• Scope of project: 110,000 ft of radiant heating pipe
• General contractor: AC Dudley
• Mechanical contractor: ABM Mechanical
• Mechanical engineer & architect: Harriman Associates
• Systems used: Radiant heating (RAUPEX O2 barrier pipe, PRO-BALANCE manifolds, EVERLOC+ R-20 connectors)