Humidifier with water valve control

1. A humidifier for adding humidity to an air stream in response to a call for humidity, the humidifier comprising:

an air intake configured to fluidically interface with an HVAC duct;

a humidifier pad in fluid communication with the air intake;

a water valve for selectively delivering water from a water source to the humidifier pad; and

a controller for controlling the water valve, wherein the controller is configured to cause the water valve to deliver water to the humidifier pad in a water delivery pattern having a period and a duty cycle, wherein the period/duty cycle combination is configured to achieve a humidity transfer rate from the humidifier pad to the air stream that is substantially the same as a humidity transfer rate resulting from an always-on delivery of water to the humidifier pad during the call for humidity.

2. The humidifier of claim 1 , wherein the period is greater than 120 seconds and the duty cycle is greater than 50%.

3. The humidifier of claim 1 , wherein the period is greater than 180 seconds and the duty cycle is greater than 30%.

4. The humidifier of claim 1 , wherein the period is greater than about 240 seconds and the duty cycle is greater than 40%.

5. The humidifier of claim 1 , wherein the period is greater than 60 seconds and the duty cycle is greater than 30%.

6. The humidifier of claim 1 , wherein the period is greater than 180 seconds and the duty cycle is greater than 20%.

7. The humidifier of claim 1 , wherein the period and/or duty cycle are field programmable by a user.

8. A humidifier for adding humidity to an air stream of an HVAC system during a call for humidity, wherein the call for humidity has a call duration, the humidifier comprising:

a humidifier housing;

an air intake configured to fluidically interface with an HVAC duct of the HVAC system;

a humidifier pad within the humidifier housing, wherein humidifier pad is in fluid communication with the air intake;

a water valve for controlling delivery of water from a water source to the humidifier pad; and

a humidifier controller within the humidifier housing and configured to receive the call for humidity signal from an HVAC controller that is external to the humidifier housing, wherein the humidifier controller is configured to send control signals to activate/deactivate the water valve such that water is delivered to the humidifier pad during the call for humidity but for less time than the call duration of the call for humidity, and

wherein the humidifier controller is configured to cause the water valve to deliver water to the humidifier pad in a water delivery pattern having a period and a duty cycle, wherein the period/duty cycle combination is set to achieve a humidity transfer rate from the humidifier pad to the air stream that is substantially the same as a humidity transfer rate resulting from an always-on delivery of water to the humidifier pad during the call for humidity.

9. The humidifier of claim 8 , wherein the period and the duty cycle of the water delivery pattern are fixed during the call for humidity.

10. The humidifier of claim 9 , wherein the period is greater than 120 seconds and the duty cycle is greater than 50%.

11. The humidifier of claim 9 , wherein the period is greater than 180 seconds and the duty cycle is greater than 30%.

12. The humidifier of claim 9 , wherein the period is greater than about 240 seconds and the duty cycle is greater than 40%.

13. The humidifier of claim 9 , wherein the period is greater than 60 seconds and the duty cycle is greater than 30%.

14. The humidifier of claim 9 , wherein the period is greater than 180 seconds and the duty cycle is greater than 20%.

15. The humidifier of claim 8 , wherein the humidifier controller is configured to cause the water valve to deliver water to the humidifier pad for greater than 30% of the call duration of the call for humidity.

16. The humidifier of claim 8 , wherein the humidifier controller is configured to allow a user to field program one or more parameters that effect an amount of time that water is delivered to the humidifier pad during the call for humidity.

17. A humidifier for adding humidity to an air stream, the humidifier comprising:

an air intake configured to fluidically interface with an HVAC duct;

a humidifier pad in fluid communication with the air intake;

a water valve for selectively delivering water from a water source to the humidifier pad; and

a controller for controlling the water valve, wherein the controller is configured to:

cause the water valve to deliver water to the humidifier pad in a water delivery pattern having at least one “on” cycle and at least one “off” cycle during a call for humidity such that:

the at least one “on” cycle and the at least one “off” cycle combination is set to achieve a humidity transfer rate from the humidifier pad to the air stream that is substantially the same as a humidity transfer rate resulting from an always-on delivery of water to the humidifier pad during the call for humidity, and

less than about 70% of the water delivered to the humidifier pad from the water valve drains from the humidifier pad during the call for humidity; and

allow a user to program in the field one or more water delivery pattern parameters that effect the water delivery pattern.

18. The humidifier of claim 17 , wherein the one or more water delivery pattern parameters include a period and/or a duty cycle, and the controller is configured to allow a user to program in the field one or more of the period and duty cycle.

19. The humidifier of claim 18 , wherein the period is greater than 180 seconds and the duty cycle is greater than 30%.

20. The humidifier of claim 17 , wherein the water delivery pattern is fixed during the call for humidity.