Screw Plug Circulation Heaters

Screw Plug Circulation HeaterCirculation heaters are highly efficient heating cells designed to heat liquids and gases as they flow through a pipe body. These units are 100% energy efficient, compact, and easy to install. They offer primary heating or act as a backup/start up heating source to natural or forced circulation systems.

The core of a circulation heater is a screw plug immersion heater or a flanged immersion heater that is installed into a pipe vessel. The vessel is thermally insulated and a stainless steel or rust proof painted outside metallic jacket protects the insulating material. The vessel is connected to a system through inlet and outlet NPT threaded fittings or flange connections.

Circulation heater design concept at Bucan incorporates all the rugged and durable features of a tubular heater with the flexibility of a heat exchanger.

Design specifications may require a unit to meet the boiler and pressure vessel code. Bucan can supply the unit designed, built and registered to the ASME code, with the applicable code stamps.



  • Sheath materials - selected to suit the liquid or gas being heated
  • Connections - NPT nipples or flanged inlet and outlet connections
  • Flange pressure ratings -  selected based on the temperature and pressure design conditions
  • Terminal Enclosures
    • General Purpose (NEMA 1)
    • Weather Resistant (NEMA 4)
    • Hazardous Location (NEMA 7)
  • Passivation - when required
  • Support frames - for stand-alone mounting
  • Vessel materials - steel, stainless steel, or other specialty metals
  • Cross flow baffles - to improve heat transfer characteristics, when required
  • Controls - built in thermostats, thermocouples, and high limit thermocouples
Nominal vessel size A B D E F G Inlet/outlet size (NPT)
3" Heater insertion length, from standard flange heater tables 4 7.5



10 6 1"
4" 4 9.0 11 6 1"
5" 4.0 10.0 11 7 2"
6" 4.0 11.0 12 7 1"
8" 4.5 13.25 13.5 9 2.5"