Instant Heat Exchanger

REX Tank Heat Exchangers

Instantaneous Indirect Water Heaters

The new generation REX instantaneous indirect water heaters are engineered for high heating efficiency. REX heaters use the boiler to heat domestic water instantly upon demand. As the boiler water enters the tank (not the coils) it is stored, ready for a domestic water call.

REX heaters also act as a buffer tank to eliminate boiler short cycling. The boiler water is circulated in a closed loop system, thus extending boiler life.

The REX indirect instantaneous system offers high efficiency, long life and an economical way of heating domestic water as there is no stagnant water in the coils. It virtually eliminates bacterial growth.

Specifications Brochure
Superior Hydrodynamics
Improved Heat Transfer


  • Domestic
  • Commercial and industrial institutions (hotels, apartments, schools, hospitals)
  • Excellent for close temperature approach applications

Maximum Working Pressure

  • Up to 150 PSI (1.03 MPa)

Maximum Working Temperature

  • Up to 375°F (190°C)

Standard Materials

  • Completely passivated stainless steel construction.
Instant Heat Exchanger
Our stainless steel indirect water heaters are ideal for use with hydronic, radiant heat, and steam heating systems.

The stainless steel distributor is the key to proper distribution of the boiler water over the coil tubes to give peak heat transfer as the hot water cascades through the coils, providing greater turbulence as it reaches the bottom distributor plate.

Constructed from stainless steel, the REX water heaters are built to last. All of the REX tanks are designed to be used for modular installations and all will fit through a 30 inch doorway.

The REX heaters are an efficient solution for new projects and are ideal for retrofit applications to improve existing system performance and reduce installation costs.

Instant Heat Exchanger

The product information and literature on this website are intended as a guideline for general purposes only. Models, dimensions, and operational parameters are subject to change at AIC's discretion. Contact AIC directly for updated design specifications.

Rex Technical Product Specifications

Heat Exchanger Model Characteristics Geometrical Dimensions Weight Connections
  Tank Capcity Heat Transfer A B   Domestic Water Water Boiler
l g m2 sq ft mm in mm in kg lbs in in
REX 150 151 40 3.2 34.4 504 19.8 5767 61.7 46.3 102 1 1
REX 190 189 50 3.7 39.9 595 23.4 1300 51.2 53.5 118 1.5 1.5
REX 300 303 80 3.7 39.9 595 23.4 1923 75.7 81.6 180 1.5 1.5
REX 435 435 115 6.8 72.5 714 28.1 1955 77.0 129.3 285 2 2