System and method for measuring duct leakage in a HVAC system
A system and method of measuring duct leakage in an HVAC system including an indoor unit assembly operably coupled to a processing device, wherein at least one supply air conduit, and at least one return air conduit are coupled to the indoor unit assembly by operating a blower system at a nominal airflow rate, restricting airflow in each of the at least one supply air conduits, and each of the at least one return air conduits; operating the blower system, within the indoor unit assembly, at a first airflow rate; and operating the processing device to calculate a duct leakage airflow and duct leakage measurement.
1. A method for measuring duct leakage in an HVAC system including an indoor unit assembly including an indoor unit assembly control and a blower system, at least one supply air conduit coupled to the indoor unit assembly, at least one return air conduit coupled to the indoor unit assembly, and a processing device operably coupled to the indoor unit assembly, the method comprising:
(a) circulating air through the at least one supply air conduit and the at least one return air conduit;
(b) operating the processing device to determine a nominal static pressure;
(c) restricting airflow in each of the at least one supply air conduits, and each of the at least one return air conduit;
(d) operating the processing device to determine a static pressure of the HVAC system;
(e) operating the processing device to calculate a duct leakage airflow, wherein the duct leakage airflow is determined in response to the nominal static pressure, the static pressure and the airflow; and
(f) operating the processing device to calculate a duct leakage measurement wherein the duct leakage measurement is determined in response to the duct leakage airflow.
2. The method of claim 1 , wherein the processing device comprises a system control element.
3. The method of claim 1 , wherein step (c) comprises closing a register coupled to each of the at least one supply air conduits and each of the at least one return air conduits.
4. The method of claim 1 , wherein step (a) further comprises operating the indoor unit assembly control to operate the blower system at a nominal airflow rate.
5. The method of claim 1 , wherein step (a) further comprises operating the indoor unit assembly control to operate the blower system at a first airflow rate.
6. The method of claim 1 , wherein the blower system comprises a motor and a blower.
7. The method of claim 6 , wherein the motor comprises a variable speed motor.
8. The method of claim 1 , wherein the duct leakage airflow is calculated using the formula:
Q leak =Q 1×sqrt( ESP nom ÷ESP 1).
9. The method of claim 1 , wherein the duct leakage measurement comprises a duct leakage rate.
10. The method of claim 9 , wherein the duct leakage measurement comprises a duct leakage percentage.
11. The method of claim 10 , wherein the duct leakage percentage is calculated using the formula:
Duct leakage percentage=(2× Q leak )÷ Q nom ×100.
12. The method of claim 9 wherein the duct leakage rate is calculated using the formula:
Duct leakage rate=2× Q leak .
13. An HVAC system comprising:
an indoor unit assembly comprising:
an indoor unit assembly control; and
a blower system configured to circulate air;
a processing device operably coupled to the indoor unit assembly;
at least one supply air conduit coupled to the indoor unit assembly, the at least one supply air conduit configured to distribute the air; and
at least one return air conduit coupled to the indoor unit assembly; wherein the processing device is configured to:
(a) determine a nominal static pressure when the blower system operates at a nominal airflow rate;
(b) determine a static pressure when the blower system operates at a first airflow rate, the first airflow rate different than the nominal airflow rate;
(c) calculate a duct leakage airflow, wherein the duct leakage airflow is determined in response to the nominal static pressure, the static pressure and the first airflow rate; and
(d) calculate a duct leakage measurement, wherein the duct leakage measurement is determined in response to the duct leakage airflow.
14. The HVAC system of claim 13 , further comprising a register coupled to each of the at least one supply air conduits, and each of the at least one return air conduits.
15. The HVAC system of claim 13 , wherein the indoor unit assembly is selected from the group consisting of: an air handler and a furnace.
16. The HVAC system of claim 13 , wherein the processing device comprises a system control element.
17. The HVAC system of claim 13 , wherein the blower system comprises a motor and a blower.
18. The HVAC system of claim 17 , wherein the motor comprises a variable speed motor.
19. The HVAC system of claim 13 , wherein the indoor unit assembly control is to operate the blower system at the nominal airflow rate.
20. The HVAC system of claim 13 , wherein the indoor unit assembly control is to operate the blower system at first airflow rate.
21. The HVAC system of claim 13 , wherein the processing device calculates the duct leakage airflow using the formula:
Q leak =Q 1 ×sqrt( ESP nom ÷ESP 1 ).
22. The HVAC system of claim 13 , wherein the duct leakage measurement comprises a duct leakage rate.
23. The HVAC system of claim 22 , wherein the duct leakage measurement comprises a duct leakage percentage.
24. The HVAC system of claim 23 , wherein the duct leakage percentage is calculated using the formula:
Duct leakage percentage=(2× Q leak )÷ Q nom ×100.
25. The HVAC system of claim 22 , wherein the duct leakage rate is calculated using the formula:
Duct leakage rate=2× Q leak .