The boilers, powered by either natural gas or diesel, produce steam that is then transported through a 71,540-foot distribution network to approximately 180 different buildings, providing heat for more than 37 million square feet of office space in the Tenderloin, Union Square, the Financial District and parts of SoMa.
According to a Department of Public Works newsletter, supply pipes carry steam from the network into radiators that heat San Francisco City Hall. When the loop opened in 1915, a power plant at Larkin and McAllister streets provided its energy until the mid-1990s.
Today, teams from the Bureau of Building and Street Repair handle the portion of the network beneath the four main streets surrounding City Hall: Grove, Larkin, McAllister and Polk Streets.
“We just feed it out of our system. We treat it like a service, like any other building,” Eurkus told The Standard.
Eurkus said about 95% of the network's steam comes from the 460 Jessie plant, using not only groundwater piped from the Powell BART station but also another source: “The other part is that we actually recycle condensation “After the buildings use the steam, some of it condenses, turns into water and is pumped back to the Cordia Energy Plant, he explained.
The oldest functioning parts of the network date back to 1913 and serve the use of several boiler systems. The Meacham Plant in the city's Tenderloin began operations in the 1960s, offering additional boilers to meet steam demand.
“Now, if there is a problem, 99% of the time we get a call from DPW or even the fire department, often because it's something that happened. If it’s abnormal, there’s too much steam coming out of the ground,” Eurkus said.
“We can respond within an hour and take care of it. In normal operation you'll see it burst and a little steam come out, but if it's an unusual situation where it's too much, and you know, then we'll get the call and we'll take care of it.”
