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EP-4741730-A1 - HEAT PUMP WATER HEATER SCHEDULING

EP4741730A1EP 4741730 A1EP4741730 A1EP 4741730A1EP-4741730-A1

Abstract

An implementation of the disclosed technology provides a method of controlling a hot water system that includes a heat pump and a hot water tank. The method includes estimating the hot water usage over a past time period based on the heat production of the heat pump during the past time period, without relying on data from sensors measuring actual usage of hot water and/or sensor measurements associated with the hot water tank. The method further includes estimating hot water usage over a future time period based on the estimated hot water usage over the past time period, accessing external data for the future time period, generating a schedule for operating the heat pump to optimize energy costs based on the estimated hot water usage over the future time period and the external data, and operating the hot water system according to the schedule.

Inventors

  • EL ABIBI, Amal
  • RODOPOULOS, Charalampos
  • ABDOLLAH, Mohammad Abdollah Fadel

Assignees

  • BDR Thermea Group B.V.

Dates

Publication Date
20260513
Application Date
20251112

Claims (15)

  1. A method (300) of controlling at least a hot water system (200), the method implemented on a controller (100, 210), the hot water system comprising a heat pump (202) and a hot water tank (204), wherein the method (300) comprises: estimating (302) a hot water usage over a past time period based at least in part on a heat production of the heat pump (202) during the past time period, without relying on data from a sensor measuring actual usage of hot water and/or sensor measurements associated with the hot water tank (204); estimating (304) hot water usage over a future time period based at least in part on the estimated hot water usage over the past time period; accessing (306) external data related to a cost of operating the heat pump for at least a portion of the future time period; generating (312), by the controller (100, 210), a schedule for operating the heat pump (202) to optimize an energy cost function based at least in part on the estimated hot water usage over the future time period and the external data for the future time period; and operating (314), using the controller (100, 210), the hot water system (200) according to the schedule.
  2. The method (300) of claim 1, further comprising: estimating a heat demand over the future time period; wherein estimating (304) hot water usage over a future time period comprises using the estimated heat demand over the future time period as a proxy for the hot water usage.
  3. The method (300) of claim 2, wherein generating (312) a schedule for operating the heat pump (202) to optimize energy costs comprises generating a heat production target for a plurality of time slots within the future time period, the heat production target specifying an estimated heat production to be achieved by the heat pump by an end of the time slot associated with the heat production target.
  4. The method (300) of claim 3, wherein operating (314) the hot water system (200) according to the schedule comprises using hysteresis control based on a temperature of hot water in the hot water tank (204) by, for each time slot in the future time period: transforming the heat production target for the time slot into a temperature setpoint for the hot water tank (204), and, in relation to the time slot, setting the hot water tank temperature setpoint based on the transformed heat production target for the time slot; setting, at the start of the time slot, a hot water tank hysteresis value to a value low enough to cause the heat pump (202) to start operating to heat the water in the hot water tank (204) to the hot water tank temperature setpoint; and setting, at the end of the time slot, the hot water tank temperature setpoint and the hysteresis value to values sufficient to stop the heat pump (202) from further heating the water in the hot water tank (204), and to prevent heating from starting again except in accordance with the schedule.
  5. The method (300) of any one of the preceding claims, wherein the heat pump (202) uses outdoor air, and wherein the method (300) further comprises: accessing (308) outdoor air temperature predictions for the future time period; estimating (310) a coefficient of performance (COP) of the heat pump (202) over the future time period based at least in part on the outdoor air temperature predictions and on performance characteristics of the heat pump (202); and generating (312) the schedule based at least in part on the estimated COP.
  6. The method (300) of claim 5, wherein accessing the air temperature predictions comprises accessing weather forecast data from a cloud-based weather service, the weather forecast data comprising the air temperature predictions or data from which the air temperature predictions can be derived.
  7. The method (300) of any one of the preceding claims, wherein the hot water system (200) includes photovoltaic energy generation, and wherein the accessing external data related to a cost of operating the heat pump comprises: accessing weather predictions for at least a portion of the future time period; and wherein generating (312) a schedule for operating the heat pump (202) comprises: using the weather predictions to predict an amount of photovoltaic energy available for use by the hot water system (200) over the future time period; and generating (312) the schedule based at least in part on the predicted amount of photovoltaic energy available.
  8. The method (300) of claim 7, wherein accessing weather predictions for the future time period comprises accessing solar irradiance predictions for the future time period.
  9. The method (300) of any one of the preceding claims, wherein accessing (306) external data on a cost of operating the heat pump comprises accessing energy tariff data for at least a portion of the future time period.
  10. The method (300) of any one of the preceding claims, wherein heat production of the heat pump (202) during the past time period is determined based at least in part on a temperature and a flow volume of liquid into the heat pump (202) and on a temperature and a flow volume of liquid out of the heat pump (202).
  11. The method (300) of any one of the preceding claims, wherein the heat production of the heat pump (202) during the past time period is determined based at least in part on energy usage of the heat pump (202) over the past time period.
  12. The method (300) of any one of the preceding claims, wherein generating a schedule for operating the heat pump (202) to optimize energy costs comprises using an optimization algorithm with an energy cost function (402) based at least on estimated energy usage and energy tariff data to optimize energy costs.
  13. A controller (100, 210) configured to operate at least a hot water system (200), the hot water system (200) comprising a heat pump (202) and a hot water tank (204), the controller (100, 210) being arranged to carry out the method (300) of any one of claims 1 to 12.
  14. A hot water system (200), comprising a heat pump (202) and a hot water tank (204), the hot water system (202) characterized in that the hot water system further comprises a controller (100, 210) according to claim 13.
  15. A computer-readable medium (110, 125) carrying instructions for operating a hot water system (200) to carry out the method (300) of any one of claims 1 to 12.

Description

TECHNICAL FIELD The disclosed technology relates to heat pump water systems for use in production of hot water and/or heating systems, and in particular to control of such a heat pump water heating system to operate on a schedule to optimize energy costs based on external information, such as dynamic energy tariff information and/or weather or solar irradiance predictions. BACKGROUND Water heating systems are means of producing hot water for heating applications, in particular central heating with, e.g., radiators, underfloor heating or other heating means, water heating systems may alternatively or additionally be used in the production of domestic or sanitary hot water, also referred to as tap water. It will be understood that while much of the discussion here will center on heat pump water heaters that are used for the production of domestic hot water (DHW), similar systems may be used for other heating and/or cooling applications. Similar systems and methods may be applied to a wide range of applications in which water or other liquids are heated and/or cooled for use in a wide range of heating and/or cooling applications. A heat pump water heater is a water heater with at least one heat pump as a water heating element. A heat pump water heater may have other associated heating means such as an electric resistive element or heat exchangers associated with a hot water circuit or, more generally, with other suitable refrigerant fluids. Supplementary heating, such as a gas-powered boiler, pellet boiler, thermal solar panel, and/or other heating systems may also be used. Heat pump water heaters need an available energy/heat source to transfer heat to the water to be heated. Different sources can be used. The type of source can be used to differentiate and designate different types of heat pump water heaters. For example, ambient air heat pump water heaters use ambient air as an energy source. Ambient air entering and leaving the heat pump is drawn in and returned to the volume of air available at the installation site. The place of installation is often an unheated, frost-free room such as a utility room in a building (e.g., a cellar, garage, attic, etc.), though controlled temperature rooms may also be used. Ambient air heat pumps provide a simplified product compared to other heat pump types. This is because, e.g., the ambient air used has a limited and positive temperature range. In addition, the pressure losses in the air flow are low as the air is pulled in and discharged in the same space as the product location. Ducted air heat pump water heaters use outside air as an energy source - i.e., air that is drawn in and/or discharged from and/or to the outside. This type of heat pump water heater offers greater flexibility in installation modes and allows the user to choose a configuration that provides for comfort throughout the year. For example, it is possible to choose to discharge the air from the heat pump to the outside when the outside temperature is below the comfort temperature of the room. Alternatively, one can choose to recirculate the air from the heat pump at the installation site when this provides comfort. This type of heat pump water heater may be susceptible to significant pressure drops due to lengths, bends, and height differences in the ducts. A heat pump system could also be split, with an outside portion (e.g., an outdoor unit (ODU) with a mono-block or split-block heat pump) and an indoor portion (e.g., an indoor unit (IDU) with the tank or heating/cooling circuit). Extracted air heat pump water heaters use air extracted from a ventilation network of the installation building as an energy source. This air has a relatively constant and high temperature, as it comes from living areas of a dwelling. In general, this air may be particularly humid and can contain significant levels of dust or other debris, because it may come from damp rooms, such as bathrooms or kitchens. Heat pumps using this type of air must be able to operate with a relatively low air flow rate (that of the building's ventilation system). A fan may be included in the heat pump water heater. Alternatively, the fan of the ventilation system of the installation building may be used, removing the need for a fan in the heat pump water heater. Water or ground source heat pump water heaters use an open (e.g., for underground water pumping) or closed (e.g., for soil) water circuit as an energy source. The water circuit may be the return of a heating circuit, a geothermal circuit or any other closed or open water circuit. For all above-mentioned heat pump water heater types, the heat pump includes at least one closed refrigerant circuit. The refrigerant circuit includes a first heat exchanger with the source medium (an evaporator), a compressor, a second heat exchanger with the destination medium (a condenser), in particular water or other liquids (e.g., for use in heating and/or cooling applications, and/or domestic hot wat