Converting Steam Heated Buildings to Hot Water Heat: Practices, Savings and Other Benefits

As part of an effort to gather reliable information on conservation measures for multifamily buildings, the conversion of steam heating systems in older buildings to hot water heating systems was investigated. The purpose was to determine how common conversions are in Minneapolis, what modifications are typical, how much it costs, and how much energy is saved. The study is based on interviews, site visits and PRISM analysis of monthly gas data.

In all the conversions studied, the boiler was replaced. Other work done depended on the building's existing system. In two pipe steam (TPS) systems, the existing distribution system was retained. In single pipe steam (SPS) systems new piping and radiation was installed and other changes were made to allow the buildings to be zoned. These changes make SPS systems more expensive and difficult to convert. As a result, SPS buildings are converted less often, even though SPS systems are much more common than TPS systems in Minneapolis.

The final sample was ten buildings, four SPS conversions and six TPS conversions. They include seven multifamily buildings, one commercial building, one church rectory, and one duplex. The SPS buildings showed savings of 13% to 27% of total weather normalized gas use and the TPS buildings had savings of 17% to 39%

In addition to energy savings, other benefits help to make conversion attractive. These benefits include more even heating, fewer tenant complaints, reduced maintenance and increased building values.

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Converting Steam Heated Buildings to Hot Water Heat: Practices, Savings and Other Benefits