ET percent 4000%/hr!

[DC]

The percentage displayed Areas Setup screen for Zone 1 is 4000%/hr. (I think that's the ET rate, correct)?

All the other zones show 2%/hr which seems more reasonable.

[Michael McSharry]

These numbers will vary wildly when you first play with the software because they are based on the cycle patterns. When a zone is cycled often then it looks as if the soil moisture goes from 100% to its on-threshold (0%) very quickly. This yields high cycle rates. As the software is introduced to a real-world cycle pattern then the rates will decline to a reasonable level such as the 2%

[DC]

Can you add a variable for MIN and MAX ET?

[Michael McSharry]

Min ET will always be 0. There is a variable for max light over past 30 days. The ET will track this value reasonably well. What period of time is the max intented to span. The max 1 hour, the max 1 day, etc? At what point is the max reset. The max light is a 30 day moving window.

[DC]

OK, I may not understand what the variable is but 4000% per hour couldn't be correct even in the most extreme conditions, could it? Wouldn't that mean that the moisture level would go from 100% to 0% in less than two minutes? What I meant by a max ET is some sort of "sanity check value" that can never be exceeded. Maybe assume that it couldn't possibly exceed 100% per hour, for example. (And even that would probably be impossible). Maybe I don't understand what that variable means.

[Michael McSharry]

The actual equation used for this is the inverse of

Y = (Elapsed Minutes) / (Number of Zone Valve Cycles - 1) / (100 - Soil Moisture Threshold Percentage)

This is intended to indicate how fast the soil moisture goes from 100% to the threshold set for the area. With a very small number of minutes between cycles the rate will be large. When the cycles are caused by actual soil moisture loss rather than manually experimentation then it is a good indicator. What I did do in the last posting was to limit the display to 99, but this is still an unreasonable number.

This number is intended to augment the graphic to provide a numerical value for the slope of the lines being seen. It is similiar to the other number on the right side of the graphic that reflect the current value. The number is not intended to represent ET, however in a normal hands-off scenario the net (ET-Rain) will track this slope.

The plugin does provide *** ET status devices for periods of 1 Hour and 1 Day. It is possible to add other *** values. The 1 Hour is the computation interval for ET. The 1 Day is the simple sum over the day. Both of these are useful quantities to assess the calibrations that one may desire to make. I did not find *** ET for longer periods to be useful for control purposes so I never generated them. I did store the information to the database so it could be used for historical data observation. They can also be easily generated via Homeseer with a once a day event sometime between sunset and midnight that will accumulate the contents of the DevceValue of the 1 Day ET.