Mounting a temperature sensor outside

[BrettS]

I just got my order of one wire stuff from Hobby Boards and had no problems getting a few temperature sensors connected and working (which is a bit of a micacle considering that 90% of my one wire network consists of pairs that I split out of existing CAT5 cable that's also being used for phone and network connections)

In any case, I want to mount one of my sensors outside, but being in a townhouse I'm pretty limited in the places I can mount it. I know that it's best to mount the sensor away from the house, but unfortunately that is not an option for me. I am also limited to mounting on the east or west side of the house (and west would be best for running the cable). There is no shade to speak of on either side and being in Florida solar radiation is a big concern.

Any suggestions about where or how to mount this? Is there some sort of a pagoda or shade that I can easily build or buy to block the solar radiation and also the heat from the building it will be next to? I'm thinking of maybe trying to make something out of white styrofoam cups or bowls, but I'm not sure how the styrofoam would hold up in the weather.

Thanks,
Brett

 

[litemyster]

Usually they are just covered by a "z" shaped piece of metal that sits a couple of inches off the wall to prevent it from receiving direct sunlight.

 

[JeffCharger]

Regardless of where you locate a sensor outside, consider enclosing it in a DIY pagoda. I constructed one from a set of plastic bowls found at a $ store and a bit of hardware. The sensor enclosed is very accurate (although it is not in direct sunlight)

 

[Michael McSharry]

With the pagoda your objective is to create something that will disipate the heat generated by the direct sunlight. With a set of plastic dishes or bowls stacked on top of each other with a series of small air gaps then most of the direct sunlight heat is disipated before it gets down to the bottom bowl under which the sensor is placed. It is never perfect as there will still be some energy hitting the bottom bowl at lower sun angles, but it is a marked improvement over taking no action or simply putting a single barrier up. The plastic is also pretty good because it does not heat up the same way metal will. You also want to elevate the sensor sufficiently so that it is not affected by ground radiation which could be either cold or hot depending upon your environment. When I built mine I used two sizes of PVC pipe. The smaller size was my mast and I ran the wire up its center and out at the lower plate position. The larger size was cut into spacers that separated the plates.

 

[Quixote_1]

With the pagoda your objective is to create something that will disipate the heat generated by the direct sunlight. With a set of plastic dishes or bowls stacked on top of each other with a series of small air gaps then most of the direct sunlight heat is disipated before it gets down to the bottom bowl under which the sensor is placed. It is never perfect as there will still be some energy hitting the bottom bowl at lower sun angles, but it is a marked improvement over taking no action or simply putting a single barrier up. The plastic is also pretty good because it does not heat up the same way metal will. You also want to elevate the sensor sufficiently so that it is not affected by ground radiation which could be either cold or hot depending upon your environment. When I built mine I used two sizes of PVC pipe. The smaller size was my mast and I ran the wire up its center and out at the lower plate position. The larger size was cut into spacers that separated the plates.

Any chance we can see some simple diagrams of different solutions? I think that would help tremendously. I'm also considering this, but I also have to take into account rain, snow and ice accumulation.
Thanks in advance!

 

[Photon]

Here's the concept: http://www.ambientweather.com/amwesrpatera.html

 

[BrettS]

The plastic is also pretty good because it does not heat up the same way metal will.

Hmm... how important do you think the plastic is? I went out last night and purchased six metal pipe covers (like this... http://www.acehardware.com/product/index.j...ductId=1273254) and I had planned to spray paint them white and build a pagoda with them.

I'm really trying to go for something reasonably small and unobtrusive, and this should only be two or three inches in diameter as opposed to nearly seven and a half inches like that ambient weather one. I'm certainly not doing anything scientific with it and I'm OK with sacrificing a bit of accuracy for a smaller footprint, but if we're talking 2 or 3 degrees difference when the sun is shining on it, then I think it would be worth putting in something bigger and/or plastic.

You also want to elevate the sensor sufficiently so that it is not affected by ground radiation which could be either cold or hot depending upon your environment.

I'm definitely worried about ground radiation. I'm in Central florida, so things get hot here, and this is going to be mounted near my garage and over the blacktop, so I imagine that there will be a bit of heat coming off of the ground. I can probably put it at least 8 or 10 feet high. Do you think that will be enough to help? Do you think it would be worth making the bottom plate solid to try to deflect some of the heat radiation coming from the ground?

Thanks again,
Brett

 

[Quixote_1]

Here's the concept: http://www.ambientweather.com/amwesrpatera.html

Thanks for the link. That should help me out a bit.

 

[BrettS]

Looks like I might be going back to the drawing board on this one. There's just too much heat radiating off of the building for me to mount the sensor anywhere near the building. I had a little indoor/outdoor thermometer from radio shack with a sensor on a long wire and I played around with it a bit today. I got a reading of about 84 degrees out in the yard in the shade of a tree, but even in the pagoda I built I was getting a reading of 89 degrees within a few inches of the building (where I would mount the sensor). 5 degrees is just way too far off for me. And I imagine that it would only be worse in the middle of summer.

The good news is that I tried it both in and out of the pagoda back out in the yard and I was definitely getting good readings with the pagoda in direct sun (within a fraction of a degree of a reading in the shade in the yard).

Even though I'm in a townhouse I'm thinking that I should be able to mount something reasonably small and unobtrusive out in the yard, but there's no way for me to run a wire out there, so it will have to be wireless. Any suggestions on a reasonably inexpensive wireless temperature sensor that I can use with homeseer? Alternately, I may give up on getting my own outdoor reading and just use one of the scripts or plugins that pulls the temperature off of the web site of a local weather station. I'm not sure how accurate my own reading will be, so if I can find a weather station that's reasonably close I'll probably be about as accurate as my own reading would be anyway.

Thanks,
Brett

 

[Quixote_1]

Even though I'm in a townhouse I'm thinking that I should be able to mount something reasonably small and unobtrusive out in the yard, but there's no way for me to run a wire out there, so it will have to be wireless. Any suggestions on a reasonably inexpensive wireless temperature sensor that I can use with homeseer? Alternately, I may give up on getting my own outdoor reading and just use one of the scripts or plugins that pulls the temperature off of the web site of a local weather station. I'm not sure how accurate my own reading will be, so if I can find a weather station that's reasonably close I'll probably be about as accurate as my own reading would be anyway.

My plan is to use some RFXCom sensors ( http://www.rfxcom.com/sensors.htm ) that will be read by my W800RF ( http://www.wgldesigns.com/w800.html ). I've decided to use a cut of drainage pipe, capped at both ends, that I'll be using to house a number of other devices, which I will suspend from my balcony. Inside the drainage pipe, I'll stack disks of insulation styrofoam that I've cut +to hold the various pieces. The styrofoam and plastic drain pipe should be enough to insulate the temperature reader from the sun after I paint it white. I'm going to work with the design from the link to allow adequate air flow, while preventing water damage/interference.