Rain Master RME EAGLE EG Series, User Manual

Page: 87 / 132

Rain Master Eagle User Manual 8.0 ET PROGRAMMING
- 81 -
8.0 ET PROGRAMMING
8.1 INTRODUCTION
Evapotranspiration (ET) is defined as the water loss that takes place on irrigated zones due to
evaporation and transpiration. Evaporation is the water transfer from the soil to the air and
transpiration is the water transfer from the plant to the air.
The main factors that influence ET includes incoming radiation (energy from the sun), outgoing
radiation (sensible energy leaving the earth), the amount of moisture in the air, air temperature
and wind speed.
ET is a feature that resides in the Rain Master Eagle controller. Its purpose is to improve irrigation
efficiency on a daily basis by re-computing station runtimes based on any one of the following
inputs:
1. Historical weather information
2. Manual operator entered ET values
3. Weather station measured ET
4. Internet supplied ET
Any of the four irrigation programs within the Rain Master Eagle controller can be configured
to utilize the ET feature or to conform to a conventional programming model. If conventional
programming is desired, please disregard this chapter and do not use the front panel key labeled
“ET”.
In order to utilize the ET feature for a program, you must input information before your
water savings may be realized. This information includes entering site specific historical ET
information, generating a reference program, and selecting a source device which will supply the
ET information.
Once the data is established, the RME controller will automatically compare the daily ET source
value to the ET Reference value. Station runtimes are adjusted by the controller each day based
upon the daily ET (weather conditions). Water savings are achieved because the controller now
responds to environmental conditions. In a conventional program model, the station runtimes
never change unless the operator “reprograms” the controller. The ET feature allows the controller
to make intelligent decisions as if an operator were present every day.
The remainder of this chapter addresses the setup and programming steps required to utilize your
Rain Master Eagle controller with ET scheduling.