Sunday, September 22, 2019
RED Calc Free Help DHW Average Daily Usage
DHW Average Daily Usage Tool User Guide

DHW Average Daily Usage
Red Calc Tool User Guide

What this tool can do for you

This tool calculates average daily hot water use based on the amount of hot water used by various appliances and use incidents. Default usage values are included.

This tool is helpful in determining the value for the "Daily hot water usage" input in the DHW Systems Comparison tool.

Photo of Gas Storage Water Heater
Source: US Department of Energy

Calculated values

  • Average daily hot water usage


  • Clicking the label for any input or result will cause a popup help box to appear. This help box includes the allowed and normal values (for inputs). Read more.
  • This tool uses number of times per week a hot water appliance is used. The weekly value is divided by seven to determine the average daily hot water use.

Inputs and field measurements

  • Hot water use for each appliance each time it is used.
  • Times per week each appliance is used.

Related tools

  • DHW Systems Comparison: This tool allows you to calculate the annual cost of heating domestic hot water. In addition, you may compare the annual costs of up to three systems to a base system. Four water heating fuel types are available; electricity, natural gas, LPG, and #2 oil. You can use this tool for any system for which you have an energy factor (EF), including electric resistance and heat pump systems, and various types of oil- and gas-fired systems.
  • DHW First Hour Rating: This tool helps you determine the First Hour Rating for the purpose of sizing a storage water heater. This method is based on guidance from the Air-Conditioning, Heating and Refrigeration Institute (AHRI), the industry standard for sizing storage water heaters.
  • DHW Instantaneous Sizing: This "solve-all" tool is used for sizing an instantaneous (tankless) hot water heater. It can also be used to determine the maximum hot water flow rate for a given system and temperature rise.
  • DHW Volume per Use: This tool determines the volume of hot water used given an amount of mixed (hot + cold) water used and the temperatures of the hot, cold, and mixed water. The amount of mixed water can be specified by volume directly, or from a flow rate and duration.
  • Water Flow Rate: This is a "solve-all" tool that relates the volume of water drawn, the duration of the water draw, and the flow rate. The primary expected use case is determining flow rate using a test container with known volume and a stop watch.

Related external resources

Version 2016-07-06_01:30
© 2013 Residential Energy Dynamics, LLC

Home   |   About Us   |   Services
Copyright 2018 Residential Energy Dynamics, LLC