XTherm® Condensing Water Heaters, 2505-4005

The all-new XTherm - vertical modulating condensing heater in sizes to 4000 MBTU. XTherm combines time-honored high-recovery copper fin technology with cutting edge control and combustion advancements. The installer and building owner enjoy broad installation flexibility, easy commissioning, optimum seasonal efficiency, and long term reliability.

Remarkably small footprint saves space for those cramped retrofit projects. Built to last, with industrial grade construction and user friendly serviceability. Extreme burner turn down produces up to 99% efficiency at low fire when it's most needed. Now is the time to take a closer look at Raypak's XTherm.

XTherm products take their jobs seriously. On the outside the muscular powder coated steel cabinet provides clean proportions with a strong, unrivaled weather-resistant design. A look on the inside reveals the XTherm's hybrid heat exchanger system design. Our vertically stacked and robust copper main heat exchanger delivers maximum non-condensing efficiency that works seamlessly with our state-of-the-art-stainless steel commercial-grade secondary heat exchanger. Maximum synergy is maintained throughout the complete XTherm heat exchange system with Raypak's proven Cold Water Protection System, a proven design approach that ensures the XTherm is built for even the longest days of work, while saving the maximum amount of energy every time it is used.

The VERSA-IC control package units 7" touchscreen display provides on easy interface for control programming and monitoring while continuously monitoring the unit for faults and proper operating parameters. 

Model Number Full Input in
 Flue cat IV Dia.
WH7-2505 2501,000
WH7-3505 3,500,000
WH7-4005 4,000,000

  • 97% efficiency.  Condensing, Cat IV venting required
  • Brass headers with copper finned-tube primary heat exchanger.  Cupro-nickel tubes available as options.  CSA Low Lead Certified 5.25% lead
  • Minimum continuous inlet water temperature (50°F)
  • Electronic modulating gas valve and burner, up to 12.5:1 turndown
  • On-board diagnostic center, real English, no codes
  • All models indoor/outdoor construction
  • Complete cabinet protects all controls and wiring
  • Certified under BAA!MD rule 7 - LowNOx
  • Suitable for altitudes up to 10,000 ft. (derate above 5,000 ft.)
  • Primary-secondary piping required.
  • 0-10 VDC Remote set-point BMS Interface
  • 0-10 VDC Direct Drive
  • Available for natural gas or propane.
  • VERSA IC® control package with built-in outdoor reset function. 7" touchscreen display, including system sensor, indirect sensor & indirect supply sensor.
  • Built-in cascade function for up to 4 heaters
  • Modbus® RTU port (RS485).


  • BACNet IP, BACnet MS/TP, Modbus TCP, N2 Metasys (B-85)
  • Lonworks (B-86)
  • Alarm with 4” Bell (E-5)
  • Low Water Cutoff (F-10)
  • Condensate Neutralizer (Z-12)