Water Heaters

ST Series Semi-Instantaneous Water Heaters

The Diversified Heat Transfer (DHT) ST Series Semi-Instantaneous Water Heaters are the engineered solution for facility managers, mechanical contractors, and engineers who need high recovery capacity in a small space. They are constructed with a stainless steel shell and other non-ferrous materials to ensure long leak-free operation. Designed for continuous high-peak loads, the DHT ST Series is ideal for high-demand applications, such as hospitals and dormitories.

Units are custom engineered using steam or boiler water as the heating medium. Semi-instantaneous operation provides high output by channeling the incoming cold water directly over the heat exchanger tubes in a controlled manner to maximize the heat transfer rates compared to conventional stratified heat exchanger convection systems. Velocity of water and pressure drop are controlled by changing water flow directly across the heat exchanger, which increases heat transfer and inhibits scale formation.

Perfect for mechanical rooms where space is limited, the water heating systems feature vertical configurations so they require less than four square feet of floor space. Plus, the tube bundle can be removed straight out or downward from the bottom of the unit to eliminate the need for overhead space or extra clearances for service or maintenance.

  • Steam-to Water and Water-to-Water configurations
  • Available in single and double wall construction.
  • Copper (standard) and optional CuNi or SS bundle material of construction.
  • Copper, Cu-Ni or SS material in contact with water (potable water).
  • Fully packaged solution for quick and easy single point connections.
  • Available in vertical or horizontal (optional) construction.
  • Compact foot print- Fits through a standard doorway
  • Standard trim is available up to 200 psi and optional up to 250 psi.
  • Fully modulating energy input for precise temperature controls.
  • Available in electronic or pneumatic controls.
  • NEW Advanced Electronic PID controls with touchscreen user interface and compatible with Building Management System via ModBus IP or built-in BacNet IP
  • Domestic Water Pressure Drop: Less than 5 PSI
  • Low Lead Complaint
  • Made in America
  • ASME- B&PV Code Sec. VIII, Div. 1 Stamped
  • Warranty: Tube Bundle (5) years, Shell (10) years


  • Ideal for new or retrofit installations
  • Suitable for both single or multiple unit installations
  • No storage tanks required for instantaneous applications
  • Support variety of applications including:
    • Apartment Complexes
    • Prisons / Correctional Facilities
    • Hospitals/ Nursing homes/ Medical Centers
    • Hotels/ Entertainment Facilities
    • Schools/ Colleges/ Universities/ Dormitories
    • Commercial laundries
    • Government & Office buildings
    • Industrial applications