Compact in-line tankless double element water heater

A compact "in-line" tankless double element water heater includes a top connected to a manifold having a cold water inlet and a hot water outlet for connection to the cold, and hot water lines of a faucet. The compact water heater includes a body with a passageway through which cold water travels, from the top towards the bottom, where it is fed into four separate chambers, two each separated on opposed sides of the body and of a diaphragm. A first of the two chambers on each side has no outlet, and the pressure of cold water therein presses against a first side of the respective diaphragm, while the second of the two chambers on each side includes an outlet to a separate hot water chamber on each side, having a separate heating element therein. A second of the two chambers on each side also includes a plunger, biased by a spring against a second side of the diaphragm, and a plunger rod, which contacts an operating member of a microswitch. When the hot water handle of a faucet is opened, water travels from each of the separate hot water chambers to lower the cold water pressure in each of the second chambers and flex each of the diaphragms toward its respective microswitch, to move the abutting operating members and actuate the microswitches so that each of the heating elements is switched on. When the hot water handle is closed, the pressure in each of the two chambers will be equalized, and the springs will force the diaphragms to their starting positions to shut off the two heating elements. A sheet metal stepped plate is held in a fully sealed enclosure and secured to temperature limit switches for added safety and security.