Electric Water Heater Energy Consumption Determination Using Outlet Temperature and Volumetric Estimation

Abstract

This paper presents the use of outlet temperature and water meter data as inputs to a physical model of a domestic electric water heater (EWH) for estimating the energy consumption for various control settings. Four sets of actual household data, consisting of at least 7 consecutive days each, is used to determine the accuracy of the energy consumption estimates in comparison to measured energy consumption. Both the outlet temperature and water meter data inputs used were able to estimate the total energy input with an error of less than 10 percent for 3 of the 4 datasets considered. Additionally, both methods are also implemented as a smartphone application that can be used to obtain input from users, as well as provide instantaneous feedback on the impact of control changes.

Non-invasive estimation of domestic hot water usage with temperature and vibration sensors

“…Thermal mass (or thermal dispersion) flow measurement was used by Huijsing et al (1988) to measure low flow rate liquid flows (below 0.6 L min −1 ) in small diameter pipes (the measuring tube has an inner diameter of 13 mm). Thermal event detection and volumetric estimation were incorporated in an EWH energy usage model by Nel et al (2015) using a non-invasive temperature sensor installed on the outlet pipe. The data sample rate used was 1 min and the described system was more effective for longer duration flow events (7 to 10 min) and the minimum duration of a detectable usage event was 3 min.…”