Method and system for determining heat loss of a building and sizing HVAC equipment

• US 7,072,727 B1
• Filed: 12/16/2002
• Issued: 07/04/2006
• Est. Priority Date: 12/16/2002
• Status: Active Grant

• Current Assignee: Tom G. Davis
• Original Assignee: Tom G. Davis
• Inventors: Davis, Tom G.
• Primary Examiner(s): CABRERA, ZOILA E
• Application Number:
  US10/320,146
• Time in Patent Office: 1,296 Days
• Field of Search: 700/97, 700/117, 700276-278, 700209-210, 379/102.05, 165200-303, 236/1
• US Class Current: 700/97
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving

Abstract

A method for determining proper size of HVAC equipment, recording on and off cycling data associated with equipment within a structure for a period of time, recording inside temperature data of the structure for the period of time, recording outside temperature data outside of the structure for the period of time, and determining a minimum size of the HVAC equipment needed to maintain a desired internal temperature at least partially based on an outdoor design temperature, the on and off cycling data, the inside temperature data and the outside temperature data. The present invention also provides for a system of determining the proper size of the HVAC equipment.

Claims

1. A method for determining proper size of HVAC equipment using load measurement, comprising:

recording on and off cycling data associated with equipment associated with a structure for a period of time;

recording inside temperature data of the structure for the period of time;

recording outside temperature data outside of the structure for the period of time;

selecting one complete cycle from the on and off cycling data of the HVAC equipment, wherein each complete cycle is defined as a cycle beginning when the HVAC equipment turns to an on state and which continues as the HVAC equipment remains in the on state and then turns to an off state and remains in the off state with the cycle ending when the HVAC equipment turns to the on state again, each change of state triggered by the thermostat;

determining a total time from the on and off cycling data for the one complete cycle;

determining a percentage of the total time during which the HVAC equipment was on from the on and off cycling data for the one complete cycle;

determining a heat loss based on load measurement from characteristics of the HVAC equipment, an outdoor design temperature, the inside temperature data, and the outside temperature data and

determining a minimum size of the HVAC equipment needed to maintain a desired internal temperature at least partially based on the outdoor design temperature, the heat loss based on load measurement, efficiency of the HVAC equipment, and the percentage of the total time during which the HVAC equipment was on from the on and off cycling data for the one complete cycle.

2. The method of claim 1 wherein the HVAC equipment includes a furnace.

3. The method of claim 1 wherein the step of recording on and off cycling data being performed with a first data logger operatively connected to the HVAC equipment and wherein the first data logger is adapted for recording a time of each change of state of the HVAC equipment.

4. The method of claim 3 further comprising downloading the on and off cycling data from the first data logger to a computer.

5. The method of claim 1 wherein the step of recording outside temperature data being performed with a second data logger and wherein the second data logger is adapted for recording a time associated with each recorded outside temperature.

6. The method of claim 1 wherein the step of recording inside temperature data being performed with a third data logger operatively connected to a thermostat within the structure and wherein the third data logger is adapted for recording a time associated with each recorded inside temperature.

7. The method of claim 1 wherein the step of determining a minimum size of the HVAC equipment being performed by software.

8. The method of claim 1 further comprising calculating a percentage of over/under sizing of the HVAC equipment.

9. The method of claim 1 wherein the step of determining the minimum size of the HVAC equipment needed to maintain the desired internal temperature includes compensating for supplemental heat.

15. The method of claim 1 wherein the step of determining a minimum size of the HVAC equipment needed to maintain a desired internal temperature is further at least partially based on a second complete cycle from the on and off cycling data.

10. A method for determining heat loss of a building and sizing a furnace having a burner based on load measurement of heat loss, comprising:

setting a thermostat associated with the furnace to a desired indoor temperature;

recording on and off cycling data of at least one cycle associated with the furnace of the building for a period of time, the on and off cycling data including a time the furnace cycles on, a time the furnace cycles off, and a time the furnace cycles on again;

recording outside temperature data outside of the building for the period of time;

synchronizing the outside temperature data with the on and off cycling data;

determining a total time period for at least one complete on/off cycles from the on and off cycling data, wherein each complete cycle is defined as a cycle beginning when the burner turns to an on state and which continues as the burner remains in the on state and then turns to an off state and remains in the off state with the cycle ending when the burner turns to the on state again, each change of state triggered by the thermostat;

determining a percentage of the total time during which the burner was on from the on and off cycling data;

determining a heat loss based on load measurement from the characteristics of the furnace, an outdoor design temperature, the inside temperature data, and the outside temperature data,

determining a minimum size of the furnace needed to maintain the desired internal temperature at least partially based on the outdoor design temperature, the heat loss based on load measurement and the percentage of the total time during which the burner was on from the on and off cycling data for the one complete cycle.

11. The method of claim 10 wherein the furnace is a variable speed furnace.

12. The method of claim 10 wherein the step of determining is performed by software.

13. The method of claim 10 wherein the step of recording on and off cycling data is performed by a data logger.

14. The method of claim 10 further comprising replacing the furnace with a second furnace of at least the minimum size.

16. The method of claim 10 wherein the step of determining a minimum size of the furnace needed to maintain the desired internal temperature is further at least partially based on a second complete cycle from the on and off cycling data.