US Patent 7088915 Modular tankless water heater

A tankless water heater module is disclosed and includes a casing having a first end, a second end and a plurality of conduits formed therein. A top head manifold is coupled to the first end of the casing and includes a port aligned with each of the plurality of conduits. A bottom head manifold is coupled to the second end of the casing and includes a port aligned with each of the plurality of conduits. An immersion heating element extends through each port of the top head manifold and into the conduit aligned therewith. A flow path extends through the plurality of conduits, the plurality of conduits coupled in fluid communication by channels between ports of the top head manifold and a channel between ports of the bottom head manifold.