Patent ID: 6909843

Claim:
A tankless liquid heater comprising: a first inlet manifold; a first outlet manifold; a first plurality of liquid heaters each having a liquid inlet and a liquid outlet, the liquid inlets of the first plurality of electric liquid heaters being connected in a parallel flow relationship by the first inlet manifold, the liquid outlets of the first plurality of electric liquid heaters being connected in a parallel flow relationship by the first outlet manifold; a second inlet manifold; a second outlet manifold; a second plurality of liquid heaters each having a liquid inlet and a liquid outlet, the liquid inlets of the second plurality of electric liquid heaters being connected in a parallel flow relationship by the second inlet manifold, the liquid outlets of the second plurality of electric liquid heaters being connected in a parallel flow relationship by the second outlet manifold; and a valve assembly joining the first inlet manifold to the second inlet manifold, the valve assembly containing a valve configured to open and permit liquid flow into the second inlet manifold in response to a difference in liquid pressure between the first inlet manifold and the second inlet manifold, wherein each of the first plurality of liquid heaters and each of the second plurality of liquid heaters having one or more electrical resistance heating elements for heating liquid flowing through said liquid heater, and wherein the first plurality of liquid heaters and second plurality of liquid heaters are configured such that the tankless liquid heater is capable of delivering liquid having a temperature of greater than about 90 degrees Fahrenheit at a flow rate of greater than about 12 gallons per minute.