Manhattan Co-op Finds Solution to Noisy Radiators, Saves on Energy Bills

A Manhattan co-op has solved two problems in one stroke by taking steps to silence its noisy steam radiators and, in the process, reap savings on its energy bills. And shareholders long frustrated by the banging and clanging are breathing a sigh of relief.

The culprit — a missing part. “The building’s steam heat system was very, very old,” says Ramez Afifi, principal of E4P Consulting Engineering, the firm brought in to figure out how to reduce the radiator noise. The eight-story, eight-unit co-op has an oil-fired boiler with steam distributed in a two-pipe system. This means steam is delivered to radiators in one pipe and the condensed water returns to the boiler in another pipe. Two-pipe systems typically have steam traps on the radiators to discharge the liquid that condenses in the pipes, and if this is working properly it will prevent banging. But in this co-op, the building’s steam system was installed before the invention of steam traps.

Mix-up upon mix-up. Renovations in individual apartments had contributed to the noise problem, because some contractors who noticed the two-pipe system added the missing steam traps. Others had seen the absence of steam traps, assumed it was a one-pipe system and had cut or sealed the second pipe on the radiator. This lack of consistency throughout the building made the banging worse. “It sounds like metal against metal every few seconds,” Afifi says. 

A two-part fix. The first step in reducing the radiator noise was to convert the system into a two-pipe system with steam traps. Steam traps had, at one point, been added near the boiler in the basement, but it was clear they were not working and needed to be replaced. Steam traps were also needed on individual radiators. Because each radiator had two valves — the twisting mechanism that allows you to control how much heat you want your radiator to give out — one of the valves was replaced with a steam trap.

The next step was to remove the radiator air vents and have a central vent near the boiler. The old system had air vents on each radiator, which is in fact a characteristic of a one-pipe system. Air in a steam system can slow the flow of steam and create noise. “Removing the vents from each radiator allows the system to operate as a true two-pipe system and avoids confusing future contractors as to what type of steam system is in the building,” Afifi explains.

Going above and beyond. Having silenced the banging, shareholders only heard “acceptable sounds of water flowing,” Afify says. In search of quelling this noise even further, Afify focused on the boiler’s pressure, which was not operating optimally. “The pressure in a steam boiler is similar to blood pressure in the body,” Afifi says. “It’s better for the system to operate at lower pressure, which is more efficient, and less noise is produced and more energy saved.” The pressure was lowered in phases, with adjustments made using a pressuretrol, a control that sets when the boiler should begin and end firing..

The de-bang cost.  The project’s price tag was $50,000 and the co-op tapped into reserve funds to pay for it. However, budget constraints meant the radiator repairs were carried out only in apartments at the front of the building, where shareholders had the most noise complaints. When the co-op has the money, work will be carried out in the back of the building. All told, the retooling is expected to generate winter savings of between 10-15% for the building.