Bosch Tronic US4-2R Pro Under-Sink Electric Tankless Dis

The Bosch Tronic 3000 US4-2R delivers a continuous on-demand supply of hot water at a single sink without a storage tank. Because it heats water only at the moment of use, there is no tank capacity limit on the duration of the hot water supply — the unit will continue delivering hot water for the full duration of the draw. The US4-2R is rated to serve one sink at a time and is not designed for simultaneous multi-fixture delivery. Output temperature is dependent on incoming cold water temperature and the flow rate being drawn at the time of use.

The US4-2R requires a dedicated hardwired electrical circuit and accepts both 240-volt and 208-volt supply voltages, making it compatible with standard residential 240-volt service as well as commercial 208-volt three-phase electrical systems. The unit does not plug into a standard household outlet and must be hardwired by a licensed electrician in accordance with applicable local electrical codes. The dedicated circuit must be appropriately sized and protected for the unit's electrical draw at the supply voltage used.

The US4-2R activates its heating element once water flow reaches a minimum of 0.4 gallons per minute. This low activation threshold makes the unit well suited for sinks equipped with low-flow faucets, which may not generate sufficient flow to trigger the activation threshold of tankless units with higher minimum flow requirements. In commercial, office, and industrial settings where low-flow faucets are commonly installed to meet water conservation standards, the 0.4 gpm activation threshold ensures the US4-2R will reliably trigger and deliver hot water when the faucet is opened.

The US4-2R is specifically engineered to support installation in standard upright orientation as well as sideways and upside-down orientations to accommodate existing plumbing configurations without requiring the plumbing to be rerouted. This installation flexibility is particularly useful in retrofit installations where under-sink cabinet space is limited or existing supply and return pipe locations make standard orientation impractical. The unit's performance and warranty coverage are not affected by the installation orientation used.

RuralEnergy.com carries four models in the Bosch Tronic 3000 2R under-sink electric tankless series: the US3-2R (part number 7736505867), the US4-2R (part number 7736505868), the US7-2R (part number 7736505870), and the US9-2R (part number 7736505871). The US4-2R is the second-lowest kilowatt model in the series. Customers with higher simultaneous demand or colder incoming water temperatures that reduce effective output should consider the US7-2R or US9-2R for greater heating capacity at the point of use.

The Bosch Tronic 3000 US4-2R carries a 5-year limited warranty on the copper heat exchanger and a 1-year limited warranty on parts. Both warranty periods apply to residential, commercial, and industrial applications from the date of installation. Warranty coverage requires installation by a licensed professional in accordance with the unit's installation requirements and applicable local codes. The temperature and pressure relief valve included with the unit must be installed as part of the installation to maintain safe operating conditions and warranty compliance.