Section SPS 341.47 - Multi-boiler installationsWhen hot-water heating boilers are installed in multiples with a common header and a common return, isolation valves may be eliminated between units and the units may be considered as one boiler provided all of the following conditions are met:
(1) OUTPUT LIMIT. No single unit exceeds 500,000 Btu per hour output.(2) PRESSURE RELIEF. Each unit has a pressure relief device as required by the ASME code, or the common header has a pressure relief device with sufficient relieving capacity for all units in the installation.(3) CONTROLS. Each unit has operating controls and safety controls acceptable to the department.(4) LOW-WATER CUTOFF. The fuel supply to each unit is shut off by a low-water cutoff in the event of low water in the system.Wis. Admin. Code Department of Safety and Professional Services SPS 341.47
Cr. Register, February, 1988, No. 386, eff. 3-1-88; CR 11-047: am. (intro.), (1) to (3) Register May 2012 No. 677, eff. 6-1-12.