Invisible History

How hard could it be to replace an old steam heating system? When I saw the inside of the elegant rococo theater, I understood. Unfortunately, the radiators were concealed within elaborately paneled walls with sill grilles about 11 ft above the floor. Cutting and patching was out of the question.

“We knew we would need to replace the old steam system pretty soon,” the business manager said. “No one has been able to figure out how to redo the heat and keep the character of the space, never mind air conditioning.”

“Even if we could get the new heat in, I don't know how you could get those huge radiators out,” the director of facilities said. “The only access is through little holes from the pipe tunnels below, barely big enough to change a trap.”

“Pipe tunnels below?” I asked. “How big?”

“Pretty good size,” he said. “They used to bring return air from the back of the theater to the ventilating fan, but the fan hasn't run since World War II.”

“I think I have an idea how to solve your problem,” I said. “Let's look at that fan and the old drawings.”

We climbed up to a mechanical loft 35 or 40 ft above the stage. The fan had been idle for years, but the wheel spun with the touch of a finger. It was part of a built-up air-handling unit with a full-size outside-air connection, steam preheat and reheat coils, and supply ducts above the auditorium ceiling. With a new motor, heating/cooling coils, and economizer dampers/controls, it would make quite a neat new system.

The drawings showed me how to deliver air with an invisible system. We could reverse the duct connections, converting the return duct system under the floor, including the big ducts and pipe tunnels, to supply. Then we could abandon the radiators, blank off the floor-level wall intake grilles, and cut slots in the concrete floor, letting conditioned supply air from the rebuilt fan system flow over the dead radiators and out of the grilles beneath the windows. The old ventilation supply grilles would become the returns. There even was existing ductwork up to a cupola over the entry that could provide economizer relief. Even before the theater had a chiller, it could have invisible economizer cooling much of the year.

David M. Elovitz, PE
Energy Economics Inc.
Natick, Mass.

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