Programmable Thermostat Control for HVAC and Water Heater Setback
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Solution Overview
Problem
Existing programmable thermostats for water heaters add complexity and require additional features to manage recovery time, and users face extra effort in programming them independently of furnace or air conditioner thermostats, leading to inefficiencies in energy consumption.
Innovation Solution
A programmable thermostat system that controls both heating and cooling systems in conjunction with fossil fuel-powered water heaters, using a relay to disconnect electric power to the water heater during set-back modes, thereby enabling a power-conserving mode without additional user effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a programmable thermostat is used for water heater control, then energy savings can be achieved, but device complexity increases and requires additional learning features
Solution Approach 1:
The patent combines the water heater thermostat with the HVAC thermostat into a single unified device. The thermostat simultaneously controls both the heating/cooling system and the water heater, eliminating the need for separate control devices and reducing overall system complexity while maintaining energy-saving capabilities.
Solution Approach 2:
The thermostat is designed to perform multiple functions: it controls both the HVAC system and the water heater, and it automatically adapts to different usage scenarios (workday, weekend, holiday) without requiring separate programming for each scenario. This multi-functionality reduces the need for additional learning features.
2Measurement precision
If a programmable thermostat is programmed independently for water heater, then precise control is achieved, but user effort increases
Solution Approach 1:
By merging the water heater control with the HVAC thermostat, the system eliminates the need for independent programming. Users program the thermostat once for their typical daily schedule, and the system automatically applies these settings to both HVAC and water heater control, maintaining precision while reducing effort.
Solution Approach 2:
The thermostat automatically determines the appropriate control strategy based on the current day type (workday, weekend, holiday) and time of day. It self-adjusts the water heater control parameters without requiring user intervention or complex programming, achieving precise control through automated decision-making.
3Reliability
If electric power is continuously supplied to water heater, then hot water availability is maintained, but energy consumption increases during unoccupied periods
Solution Approach 1:
The system implements periodic control of the water heater based on predetermined schedules corresponding to different day types. During workday evening periods when occupants return home, the thermostat automatically activates the water heater to ensure hot water availability, while keeping it inactive during unoccupied periods. This periodic action maintains reliability when needed while reducing energy consumption during unoccupied times.
Solution Approach 2:
The thermostat activates the water heater in advance of anticipated occupancy periods. For example, during workday evenings, the system turns on the water heater before the typical return time of occupants, ensuring hot water is ready when needed. This preliminary action maintains hot water availability without requiring continuous operation.
Data Source
AI summary
A system and method of using a set-back or programmable thermostat for heating or cooling systems to also controlling a fast-recovery water heater such as a power-vented fossil fuel powered water heater such that the water heater is disabled during a set-back mode of the thermostat. The system sends a control signal to a relay module adjacent to the water heater, into which the water heater electrical power cord can be plugged into. The interlock mechanism of the water heater prevents operation of the water heater when power to the water heater is interrupted.