Energy usage display unit

An energy usage display unit for displaying energy usage of gas used for a water heater, water used for the water heater or electricity used in a housing where the water heater is set, comprising:

• a clock section for having a clock and calendar function;
• a counting section for counting usage of gas, water or electricity, the counting section having an hourly counting section, a daily counting section, and a monthly counting section;
• a memory section for storing a count value of usage counted by the counting section retroactive to past by a predetermined number with a predetermined time unit and rewriting the count value of the oldest usage with the predetermined time unit to the count value of the latest usage with the predetermined time unit, the memory section having an hourly memory, a daily memory, and a monthly memory;
• a counting control section for writing the count value of usage from the counting section to the memory section;
• a display control section for reading either or both of the count value of the counting section and a stored value in the memory section to prepare display data of usage, in accordance with a period unit required by a user;
• and
• a display section for displaying usage based on the display data prepared by the display control section, wherein
• the hourly counting section for adding up usage of gas, water or electricity sent through the water heater from previous 0 minute to current 0 minute at time 0 minute,
• the daily counting section counts, as one day usage of yesterday from 0:00 to 24:00, the one day count value obtained by adding a count value of one hour usage of one hour from 23:00 to 24:00 of yesterday counted by the hourly counting section to stored values of usage with an hour unit from 0:00 to 23:00 of yesterday stored in the hourly memory at 0 o'clock 0 minute,
• the monthly counting section counts, as one month usage of last one month from the first day to the last day, stored values of usage with a day unit from the first day to the last day of the last month in the daily memory at 0 o'clock 0 minute of the first day of the month,
• the hourly memory for storing the count value of usage counted by the hourly counting section retroactive to past by a predetermined hour number with the hour unit at time 0 minute and rewriting the count value of the oldest one hour usage with the hour unit to the count value of the latest one hour usage with the hour unit at time 0 minute,
• the daily memory for storing one day count value of usage counted by the daily counting section retroactive to past by a predetermined day number with the day unit at 0 o'clock 0 minute and rewriting the count value of the oldest one day usage with the day unit to the count value of the latest one day usage with the day unit at 0 o'clock 0 minute,
• the monthly memory for storing one month count value of usage counted by the monthly counting section retroactive to past by a predetermined month number with a month unit and rewriting the count value of the oldest one month usage with the month day unit to the count value of the latest one month usage with the month unit at 0 o'clock 0 minute of the first day of the month,
• the counting control section controls such that at 0 minute every hour, the count value added up usage from previous 0 minute to current 0 minute at the hourly count section is written in the hourly memory as the latest one hour usage with the hour unit and the count value of the oldest one hour usage with the hour unit stored in the hourly memory is rewritten to the count value of the latest one hour usage with the hour unit,
• the counting control section controls such that the one day count value of usage counted by the daily counting section is written in the daily memory as the one day usage of yesterday with the day unit at 0 o'clock 0 minute and the count value of the oldest one day usage with the day unit stored in daily memory is rewritten to the count value of the one day usage of yesterday with the day unit at 0 o'clock 0 minute, and
• the counting control section controls such that the one month count value of last one month usage counted by the monthly counting section is written in the monthly memory as the one month usage of last one month with the month unit at 0 o'clock 0 minute of the first day of the month and the count value of the oldest one month usage with the month unit stored in the monthly memory is rewritten to the count value of the latest one month usage with the month unit at 0 o'clock 0 minute of the first day of the month.