Position of Rain Detector

[Gina]

I have a Reichelt Rain Detector and just wondered where would be the best place for it to detect rain and automatically close the roll-off-roof on my observatory.  I'd be interested to hear where others have put theirs. TIA for any replies.

Edited August 2, 2019 by Gina

[daz]

Outside......

 

 

 

Sorry, I'll get my coat! Taxi for one....!!!!

[tekkydave]

Anywhere in the open where it wont get dripped into should be good.

[Gina]

28 minutes ago, daz said:

Outside......

 

 

 

Sorry, I'll get my coat! Taxi for one....!!!!

Not necessarily - it could go in the scope room.  I'm most interested if it starts raining when I have the roof open so that rain will set the roof closing.  Outside may be best though...

[Geoff Barnes]

Can it go here Gina, look like a good spot for it?....

[Dr_Ju_ju]

I don't know how large\sensitive it is?, but one of the things that struck me was the small target area, for rain to hit. So to increase the capture area, I was thinking of some sort of funnel with super slick top layer, to ensure the water ran off very quickly..... 

[Gina]

1 hour ago, Geoff Barnes said:

Can it go here Gina, look like a good spot for it?....

It could do.

[Gina]

1 hour ago, Dr_Ju_ju said:

I don't know how large\sensitive it is?, but one of the things that struck me was the small target area, for rain to hit. So to increase the capture area, I was thinking of some sort of funnel with super slick top layer, to ensure the water ran off very quickly..... 

It's pretty small and I was thinking of a funnel or similar.

[Gina]

Regarding using a funnel :-  Been trying to find out the hydrophobic properties of various plastics including those used in 3D printing.  Polyethylene seems about the best with PETG being similar.  PLA seems less hydrophobic.  I guess a funnel with steep sides should let water droplets run down onto the rain detector.  I may try some experiments with 3D printed funnels of varying steepness (ie. height).

[Gina]

I think a steep sided funnel may not need a hydrophobic spray to stop droplets sticking to the sides but we shall see.

OTOH if a single rain droplet triggers the detector, I won't need a funnel (though I have plenty of PLA and PETG to make a nice big one!).

Edited August 2, 2019 by Gina

[Dr_Ju_ju]

Its the odd occasion when the wind\rain comes from a different direction, so 'misses' the detector.....

[Gina]

I can certainly arrange that the rain detection is independent of wind direction.  I don't know if the bare sensor is dependent on wind/rain direction.  It has to be set on a slope so that rain runs off in the direction of the points on the sensor according to the instructions.  Over all, I think some sort of funnel is indicated.

[tekkydave]

I guess the answer is good ol' experimentation 🙂

 

[sloz1664]

7 hours ago, Dr_Ju_ju said:

I don't know how large\sensitive it is?, but one of the things that struck me was the small target area, for rain to hit. So to increase the capture area, I was thinking of some sort of funnel with super slick top layer, to ensure the water ran off very quickly..... 

The only issue here is when dew forms on the funnel sides and drips onto the sensor.

Steve

[Gina]

Ah, yes!!  Hadn't thought of that.  So the funnel would need a dew heater!!  This is getting complicated!

[Geoff Barnes]

I think you're over complicating this Gina. I would simply fix it to the top of the facia board so that rain can land on it from any direction, and bob's your uncle!  

[Starlight 1]

I do have one  , It do not like clean water  so off the roof good, and you have to off set the unit , not flat .

[Gina]

I'll try various arrangements with data feed indoors in some form and see what works.  No doubt we'll have some rain in the next week or so.

If there's some pollution in the air the rain detector will work on its own but this may depend on wind direction.  Wind from the usual SW should have pollution from Honiton but other directions are rural and may not have enough.  Rainwater off the observatory roof should be fine.

Edited August 2, 2019 by Gina

[sloz1664]

Gina, set it near to your Obsy, in a clear space, away from where it could receive any random splashes and set it at an angle of around 20 degrees for "run off"

Steve

Edited August 2, 2019 by sloz1664

[Stargazer33]

Would it be worth getting 3 or 4 and setting them in a pyramid shape so that all directions are covered? Or would the cost be prohibitive?

[Gina]

It's a thought but shouldn't be necessary.  Cost £22 each so not prohibitive.

[DaveL59]

On 02/08/2019 at 20:29, Starlight 1 said:

I do have one  , It do not like clean water  so off the roof good, and you have to off set the unit , not flat .

That's an interesting point, re clean water. When I was rigging up a couple of water/flood sensors for the house alarm I used a couple of panic buttons and ran a trailing wire from the push switch to act as remote trigger. Fresh tap water - no response at all, input trigger not sensitive enough. Add a contaminant and triggers just fine once damp. For that I found a dry cat biccie with a bare wire each side and wrapped in kitchen paper did the job just fine.

I'm not sure the air pollution would make the same difference, after all tap water has a number of things in it at low ppm. Hopefully a rain sensor would have much more trigger sensitivity but is that adjustable on the unit at all? Certainly worth a test with tap water to see at what point it'd trigger.

 

[Gina]

The one I have is not adjustable.

[JAS]

I have mounted the same sensor onto a small pole inside my obsy at a small angle to allow the rain drops to run across the sensor surface, it is only exposed to the weather when the roof is open. 

It quickly activates my roof when it starts raining, but the roof started closing when there was no rain! After several false alarms I realised that dew was forming on the sensor and activating it. From what I remember the inboard due heater only activates once rain has been detected to dry it off, obviously this is not of any use as far as dew is concerned !

I have not done anything about it yet, but I thought is was worth mentioning.

Jason .

[Gina]

I was thinking of mounting mine in a similar way.  If dew is a problem, I guess a small dew heater would be wanted.