Specs and Docs


Commercial Boiler and Volume Water Heater

The Rheos boiler / water heater is a unique commercial heating system design. Engineers and heating contractors can choose a single high-efficiency, low-cost system for commercial installations requiring up to 2.4 million BTU/hour. Plus, the Rheos features one of the highest density and smallest footprint available, so it takes up far less floor space. In fact, it's so compact, it can fit through a standard 3'-0'' doorway. 

Rheos boiler technology saves fuel costs

The innovative Rheos boiler technology controls the boiler operation by automatically down-firing to as low as 50% of full input. In addition, the system boasts up to 86% combustion efficiency - one of the highest ratings in its class. Taking full advantage of high-efficiency combustion in addition to the boiler modulation, Rheos can cut operating costs by as much as 30% over conventional, non- modulating systems. The result is fuel cost savings that can amount to tens of thousands of dollars over the life of the equipment. In fact, in most installations, the Rheos will virtually pay for itself in a short period of time. Optional control packages are available to comply with regional code requirements. 

Control it your way

Rheos boilers and water heaters use a PI control system that allows for interfacing with a variety of system types:

  • The Laars M4-LHS mutliple boiler control integrates easily via a 0-10VDC signal, allowing for control of multiple boilers - up to 16, with the use of the M4 extension modules.
  • Rheos will accept a 0-10V DC signal and a call for heat from a building automation system or other types of external controllers. Simply flip the switch on the Rheos, and connect your signal wires. 

Patented double-row heat exchanger

Rheos is a compact and cost-effective heating system in its rating
class. The system uses a patented double-row coil configuration to create maximum heat transfer surface area and balanced water flow. Coupled with a powerful burner, the Rheos is
able to provide industrial grade service for hydronic and volume water applications.

For water conditions requiring an upgrade, a cupro-nickel heat exchanger is available as an option.