Patent ID: 7088915

Claim:
A method of heating water comprising the steps of: providing a tankless water heater module including a casing having a first end, a second end, and a plurality of conduits formed therein, extending from the first end to the second end, a top head manifold coupled to the first end of the casing and including a port aligned with each of the plurality of conduits, a bottom head manifold coupled to the second end of the casing including a port aligned with each of the plurality of conduits, an immersion heating element extending through each port of the top head manifold and into the conduit aligned therewith, each immersion heating element coupled to the top head manifold, and a flow path from through the plurality of conduits, the plurality of conduits coupled in fluid communication by channels between ports of the top head manifold and between ports of the bottom head manifold; injecting water into the flow path, sensing a flow rate of water through the flow path; sensing temperature of water entering the flow path and temperature of water exiting the flow path; supplying power to selected heating elements determined by the flow rate, the temperature of water entering the flow path and the temperature of water exiting the flow path.