Rain Sensor

[jwglover]

I just replaced my Irritrol RD-900 with the Bluespray system.  So far I'm very satisfied with the change.  My old system didn't have a rain sensor but I'm interested in hooking one up the the Bluespray system.  Is there any particular one that is best?  Are there any wireless sensors that are compatible?  I'm somewhat of an sprinkler system rookie so I appreciate the help.  Thanks.

[bluespray_admin]

You can use any commercially available rain sensor that is either Normally Open or Normally Close type.

[jmz]

Related question: How long does the delay last when the sensor detects rain?

[bluespray_admin]

As long as the rain sensor dictates.  The controller just does what the rain sensor tells it.

[guinness]

Apologies for hijacking this thread, but it is seems relevant to this topic.  The system currently only detects whether the sensor is NO/NC and then ignores a run when not in that state.  Is this hardware driven, i.e. power is interrupted to the valves, or software driven?  I'm thinking it must be the latter as there is the "Bypass Rain Sensor" option.

Is it possible to monitor when the sensor detects rain, i.e. sensor is not NO/NC for a period of say at least 3 hours and then cancel any scheduled runs for the next 24/48 hours regardless of the rain sensor state (which may have subsequently dried out)?  This would help situations where county/state regulations stipulates outdoor landscapes cannot be watered after measurable rainfall.

This would be a great optional feature to add to the Sensor Settings page and it would help a lot of folks out trying to avoid getting fined.

[bluespray_admin]

It's all done in software.  As long as the rain sensor is tripped, the controller won't water.

This is what the controller can do because there is no way to tell how much rain has fallen, even with the rain sensor to satisfy the "measurable rain fall" requirement.  Even the requirement is vague - how much is measurable?

Software wise, we can detect when the rain sensor is tripped or dried out and take action.  But because the nature of the rain sensor operation, we cannot depend on it reliably. 

The rain sensor operates on the principle that when rain gets inside of it, a set of plates expands and pushes a switch.  Some sensors have settings "indicating" how many inches of rain before tripping the sensor and how long it takes after the rain for the plates to dry out. 

We've tested many different rain sensors to see if they work as advertised.  The results were all over the map.  First of all, because of the small opening in the rain sensor, it sometimes take torrential rain for a couple of hours before the sensor is tripped.  We built a funnel to put on top of the sensor and it did not speed it up.  In some sensor, we poured a glass of water directly into it in order to make it trip.

We tried different settings on the rain sensor to delay watering.  They were never consistent.  It largely depends on the weather.  Hotter climate makes it dry faster, obviously.

Basically, we just did not find the rain sensor to be a reliable instrument to depend on.  That's why we're reluctant to make decision based on it.  We believe to accurately measure how much water is in the ground, you cannot rely on data or instrument in the air, but put a moisture sensor in the ground.

[guinness]

Thanks for the detailed reply.  Interesting to hear about your observations with the various rain sensors that you have tried out.  I understand your reluctance to base decisions on the seemingly unreliable instrumentation, after all you need to set users expectations when using your controller.

However, I would still be interested know when the sensor has tripped and when it resets.  Is it possible you can implement syslog on the controller?  I was thinking you could add a menu item named Debug Server in the System menu where you could set an IP like 192.168.1.255 which would broadcast messages to the subnet, or alternatively set an IP to a specific host.

If you would be willing to enable syslog on the controller, you could generate either Informational or Debug messages like below which would be very useful for the advanced users out there.

May 07 12:01:53 BlueSpray Rain sensor tripped
May 07 15:11:14 BlueSpray Rain sensor reset

In addition, it would also be useful if syslog messages could be generated for when a run is started/stopped and also for when each individual zone is open/closed.  Thanks again.

[bluespray_admin]

Logs will be available in the next firmware release.

BTW, we're looking into moisture sensor technologies instead of rain sensor.

[guinness]

Awesome, look forward to the next release.

In addition to the moisture sensor, another option would be an optical sensor.

The Hydreon RG-11 at $59 is an interesting sensor w/ config settings (www.rainsensors.com/docs/rg-11_instructions.pdf).

[bluespray_admin]

Well, the manufacture of the RG-11 even says that it's not an accurate instrument.  But it does have open/close output, so you can certainly install it with BlueSpray.  But remember that the controller does not make any decision on how much has rained, it just detects an open or close operation from the sensor.

[auto_man]

In addition to BlueSpray, I also have a home automation system.  I connected my rain sensor to a pair of digital inputs on the home automation system, and then connected the rain sensor input on BlueSpray to a relay output on the home automation system.  With this setup, the home automation system sees when the rain sensor activates, and then can programmatically decide what to do about it.  In my home automation system, if the rain sensor activates, the home automation program sends me a text message, creates a log record, and the sets the relay out to BlueSpray, thereby shutting off the irrigation.  When the rain sensor deactivates, again the home automation system can decide what to do, but at a minimum it sends me a text message and creates a log record.  Typically, I decide when I want to re-initiate irrigation and clear the rain sensor relay manually.

[bluespray_admin]

FYI, in 2.0 we'll add an automatic delay after rain feature.  If the controller senses that the rain sensor has been tripped for an hour or more, it will automatically delay watering X number of days that you'd set. 

This feature is inspired by many water restriction rules from many water district in California that says residents cannot water for 48 hours after "meaningful" rain fall.

[p2gee]

Just want to be clear on rain sensor delay and what constitutes tripped.  Does the sensor delay begin when the sensor is wetted or when the the sensor is wetted and dried out??

[bluespray_admin]

The controller considers the rain sensor tripped when the rain sensor goes from dry to wet.

[p2gee]

The controller considers the rain sensor tripped when the rain sensor goes from dry to wet.

If I may make suggestion for a firmware update:  Should be option to start delay from dry to wet or from wet to dry.  I currently have my rain sensor delay set at 3 days. If I have a one day cloud burst, between the delay and my sensor drying out, my water schedule should start back up at just the right time.  Recently though, we had a stretch of rain that lasted for 5 days.  My 3 day delay was used up during that period and on day six when my sensor dried out ( takes about a day) my system started watering a yard that after 5 days of rain really didn't need it. Just a little more flexibility would be helpful.