# US 12,222,136 B2 · Field conversion electric water heater > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,222,136 B2 - Document ID: US12222136B2 - Status: Granted - Kind: B2 - Application number: 17/379,039 - Filed: 2021-07-19 - Published: 2022-01-13 - Granted: 2025-02-11 - Earliest claimed: 2018-07-12 - Assignees: Rheem Manufacturing Company - Applicants: Rheem Manufacturing Company - Inventors: Matthew S. Park; Timothy D. Scott; William Jason Hall - Web page: https://patentgrep.com/patent/US12222136B2 ## CPC - F24H 9/2021: {Storage heaters} - F24H 1/202: {with resistances} - F24H 9/1818: Arrangement or mounting of electric heating means - F24H 15/407: using electrical switching, e.g. TRIAC - F24H: FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL (steam generation F22) ## Abstract An electric water heater has upper and lower electric resistance type heating elements respectively controlled by a single pole, double throw upper thermostat and a single pole, single throw lower thermostat. The upper and lower thermostats are operatively interconnected by a wiring harness having outer conductor end portions that are connected to a terminal block portion of an external junction box to provide the water heater with a variety of heating element operating modes without having to replace either of the thermostats, vary the wiring harness interconnections therebetween, or vary the connection between the outer conductor end portions and the terminal block. The water heater may thus be advantageously manufactured in a single variant that may be easily and quickly modified in the field to selectively alter the heating element control mode of the water heater. ## Claims ### Claim 1 A liquid heating apparatus comprising: a tank configured to hold a liquid; a first electric heating element configured to provide heat to the liquid; a first thermostat configured to control the first electric heating element; a second electric heating element configured to provide heat to the liquid; a second thermostat configured to control the second electric heating element; a terminal block having (i) line side terminals configured to interchangeably connect to electrical power supply conductors and (ii) heating side terminals; and wiring connected to the first and second thermostats and the heating side terminals in a manner such that, without replacing either of the first and second thermostats or altering the wiring to either of the first and second thermostats or the heating side terminals, a selective portion of the electrical power supply conductors is connected to the line side terminals to provide the liquid heating apparatus with a plurality of heating element control modes, the plurality of heating element control modes including: a dual independent branch circuit element control mode; and single-phase and three-phase simultaneous dual element and non-simultaneous dual element control modes. ### Claim 2 (depends on 1) The liquid heating apparatus of claim 1, wherein the first and second electric heating elements are located at different heights within the tank. ### Claim 3 (depends on 1) The liquid heating apparatus of claim 1, wherein the first and second electric heating elements are resistive heating elements. ### Claim 4 (depends on 1) The liquid heating apparatus of claim 1, wherein: the first thermostat is a single pole double throw thermostat, and the second thermostat is a single pole single throw thermostat. ### Claim 5 (depends on 1) The liquid heating apparatus of claim 1 further comprising one or more jumpers interchangeably connectable to the line side terminals or the heating side terminals to enable each of the plurality of heating element control modes. ### Claim 6 (depends on 5) The liquid heating apparatus of claim 5, wherein each of the one or more jumpers is of a uniform size. ### Claim 7 (depends on 1) The liquid heating apparatus of claim 1, wherein the terminal block is incorporated in a junction box removably securable to the liquid heating apparatus. ### Claim 8 (depends on 1) The liquid heating apparatus of claim 1, wherein the single phase simultaneous dual element and non-simultaneous dual element control modes comprise a single phase simultaneous dual element control mode and a single phase non-simultaneous dual element control mode. ### Claim 9 (depends on 1) The liquid heating apparatus of claim 1, wherein the single phase non-simultaneous dual element control modes comprise a single phase non-simultaneous dual element control mode with four wire outlet operation and a single phase non-simultaneous dual element control mode with three wire outlet operation. ### Claim 10 (depends on 1) The liquid heating apparatus of claim 1, wherein the three phase simultaneous dual element and non-simultaneous dual element control modes comprise a three phase simultaneous dual element control mode and a three phase non-simultaneous dual element control mode. ### Claim 11 A liquid heating apparatus comprising: a tank configured to hold a liquid; a first electric heating element configured to provide heat to the liquid; a first thermostat configured to control the first electric heating element; a second electric heating element configured to provide heat to the liquid; a second thermostat configured to control the second electric heating element; a terminal block having (i) line side terminals configured to interchangeably connect to electrical power supply conductors and (ii) heating side terminals; and wiring connected to the first and second thermostats and the heating side terminals in a manner such that, without replacing either of the first and second thermostats or altering the wiring to either of the first and second thermostats or the heating side terminals, a selective portion of the electrical power supply conductors is connected to the line side terminals to provide the liquid heating apparatus with a plurality of heating element control modes, the plurality of heating element control modes including: a dual independent branch circuit element control mode; and single phase and three phase simultaneous dual element control and non-simultaneous dual element control modes. ### Claim 12 (depends on 11) The liquid heating apparatus of claim 11, wherein the first and second electric heating elements are located at different heights within the tank. ### Claim 13 (depends on 11) The liquid heating apparatus of claim 11, wherein the first and second electric heating elements are resistive heating elements. ### Claim 14 (depends on 11) The liquid heating apparatus of claim 11, wherein: the first thermostat is a single pole double throw thermostat, and the second thermostat is a single pole single throw thermostat. ### Claim 15 (depends on 11) The liquid heating apparatus of claim 11 further comprising one or more jumpers interchangeably connectable to the line side terminals or the heating side terminals to enable each of the plurality of heating element control modes. ### Claim 16 (depends on 15) The liquid heating apparatus of claim 15, wherein each of the one or more jumpers is of a uniform size. ### Claim 17 (depends on 11) The liquid heating apparatus of claim 11, wherein the terminal block is incorporated in a junction box removably securable to the liquid heating apparatus. ### Claim 18 (depends on 11) The liquid heating apparatus of claim 11, wherein the single phase simultaneous dual element and non-simultaneous dual element control modes comprise a single phase simultaneous dual element control mode and a single phase non-simultaneous dual element control mode. ### Claim 19 (depends on 11) The liquid heating apparatus of claim 11, wherein the single phase non-simultaneous dual element control modes comprise a single phase non-simultaneous dual element control mode with four wire outlet operation and a single phase non-simultaneous dual element control mode with three wire outlet operation. ### Claim 20 (depends on 11) The liquid heating apparatus of claim 11, wherein the three phase simultaneous dual element and non-simultaneous dual element control modes comprise a three phase simultaneous dual element control mode and a three phase non-simultaneous dual element control mode.