The Short and Sweet
I love being able to see the detailed current weather conditions from the comfort of my kitchen table. --and from my desktop computer, and from my phone wherever I am!
The Ambient WS-2902C WiFi Smart Weather Station gets very good reviews, and is near the top of several reviews as a capable, affordable,internet-enabled home weather station
This station provides indoor and outdoor temperature and humidity, rainfall measured several different ways, wind speed and direction, barometric pressure, solar radiation and UV index, and predictions based on barometric pressure over time.
The WS-2902C gets one repeated complaint: the outdoor sensor array doesn't always communicate reliably with its indoor display console (which in turn can pass data to wifi). So be sure to test communications between your intended locations in time to return it if you can't use it. (My indoor display easily gets data from a sensor array twenty-five feet higher and through two walls and a floor.)
Mounting the station high enough to get good wind data is a challenge in an area with trees and buildings. I took advantage of a flat part of our roof, and built a free-standing mount to raise the sensors to about the height of the peak of my roof.
However you mount it, make sure you can access the sensor array a few times a year for maintenance.
The Long--
I came unexpectedly into a few hundred loose dollars in December and decided to put up a home
weather station. This would be a kind of Christmas present to my wife and me. (She points out, “we like
data.”) We've had a series of electronic weather thingies over the years--at a minimum indoor and
outdoor thermometers, with sometimes hygrometers and a barometer. These always read out in the
kitchen: nerve center of our home.
But I have toyed for years with the idea of having a real station with a wind vane and anemometer, of
tracking data over time, and maybe even contributing data to Weather Underground or something like it.
Now we have all that, plus rainfall (replacing my sawed-off old paint can) and solar radiation.
The Ambient WS-2902C WiFi Smart Weather Station seems to be at or near the top of reviews for good,
capable, inexpensive stations, so I ordered one from Amazon. The station’s sensor array is meant to
mount to the top of some kind of pole or mast that makes it high enough to be useful. I spent the free
time intervening figuring out a way to mount the station clear of obstructing trees and buildings. We are
blessed with a flat rubber roof at the southern end of our house, and my first thought was to mount a tall
mast for the station to the outside wall of the second floor. But all the antenna mounts I found online
would hold a mast at most one foot from the wall--which would not clear the two-foot overhang of our roof
eaves. It would be possible to mount a mast to the chimney of the house, but we have a central chimney,
and there was no way I was going to risk my life on our steeply-sloping roof. In addition, the sensor array
needs occasional maintenance: cleaning dead leaves, etc from the rain collector, and replacing the
atteries that backup the photocell.
I settled on a free-standing mount made of crossed pressure-treated 2x4s with pressure-treated 2x2
struts extending up to support a mast of electrical conduit. As usual with my clever ideas, realizing it took
many hours more fussing than I'd anticipated. The finished mount is five feet wide at the base and the
struts from the ends of the 2x4s converge on the mast (which sets in a shallow hole in the center of the
base) about seven feet up. It sits on my rubber roof, leveled by bits of wood wedged beneath. I believe
the whole thing will be strong and stable enough to withstand considerable winds, though I haven’t done
any math as yet.
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| Pressure-treated lumber is very dense. I'm hoping wind pressure on the high sensor array won't topple the broad, heavy base. |
One puzzle was how high the sensor array needed to be. I wanted the anemometer and wind vane to be
accurate. The roof itself, and several trees near and far were problem candidates. A rule of thumb is that
any obstructions higher than the sensors must be at least four times farther away than than they are
higher. That works out to an angle of 14 degrees. (The tangent of 14 is 0.25.) I made a simple sighting
device that would give me that angle above the horizontal while hung from a string, and went as high up a
ladder as I dared with the thing, but my device swayed uselessly in the slightest wind. So I decided to
make the mast as tall as I thought I could get away with, and hoped it would be high enough.
Eventually I realized I could easily check for obstructions after the fact photographically: standing far from
my house and equidistant from the sensor mast and a potential obstruction, I could take a photo, put it on
a big computer screen, and use a ruler to compare heights and distance. (At distances much greater than
objects are tall, I could assume measured heights to be close to real. It helped that I could get good views
through winter's leafless trees. It also helped that my camera has an internal level, so I could take level
photos to take measurements from.) By that method, a single, unexpectedly distant but tall tree is the only
problem for my finished station.
The actual mast is electrical conduit. I intended to get rigid conduit, which is made for outdoor use, but
found it to be unavailable in single pieces (and very expensive) from my local home stores. Instead I
bought two ten-foot lengths of EMT (thin-walled) conduit--one that was ¾ inch inside diameter, the other 1
inch. The smaller telescopes into the larger, and can be held at a given height by a pin (really a nail)
through the larger tube, and kept from wobbling by two screws that steady it. Together, including about
four feet of overlap to keep everything straight, the mast raised the sensor cluster about seventeen feet
above the flat roof, which is at least twenty-five feet above the ground. An advantage of the telescoping
system is that I could make some adjustments to the rig at a more workable eleven-foot height from my
ladder. The sensor array itself is made to strap with U-bolts to any tubing between one and two inches in
diameter. (My ¾ inch tubing just made the cut--mainly because that was its internal diameter.) An
advantage of my rig being free-standing is that I can do maintenance simply by tipping the entire stand
over to bring the sensor array down to me. I did so several times over the last two months in the process
of fine-tuning to make the sensors level and accurately pointed north. This cheap thin-walled conduit will
probably be too weakened by rust to last much more than a year, but I hope can be replaced with only a
few hours’ work. In the end, I spent about as much building the stand as I did for the weather station itself.
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| The completed station holds the array at almost the height of the roof peak. |
The most consistent complaint I read in reviews of the Ambient WS-2902C is that it does not always
communicate properly with its base station. Because of this, I tested the communications in the
locations--rooftop to kitchen--right out of the box, so I could return the whole thing if necessary. For me,
they work perfectly--even through the entire house two stories apart. The base station is the indoor
display that receives data wirelessly from the sensor array, and both displays that data and also sends it
by Wifi to your internet router. This arrangement not only makes the data available to internet weather
networks, but also enables you to view the data--including graphs of change over time that the physical
base station cannot display--on your smartphone, from anywhere. (I find the graphs to be one of the most
useful features of this system.)
On New Year’s Eve, the sensor array was up and running at the top of its 17 foot mast, the base station
was lit with data in the kitchen, and we were live on Weather Underground. Only one thing (I hope)
remained. The sensor array hadn’t been adequately leveled.
The sensor array has a bullseye bubble level built in, which the manual says must be used to level the
array to make the rain gauge and solar radiation/UV sensor read properly. What surprised me was the
lack of any mention of the wind vane: the tail fin end is much heavier than the arrow end, so that the tail will
tend to settle at its lowest point (if there is one). During construction, I had tried to get the mast
perpendicular to the base by first leveling the base, and then so adjusting the struts that heavy washers
hung on the pipe hung straight down it. Then my work turned out to be less than perfect, and the roof
wasn’t flat either. Making matters much worse, there is enough play in the mountains brackets on the
sensor array that the array could be way out of level even mounted on a perfectly vertical mast. But after
all the time I’d spent on the project, I decided it was “good enough,” and I would revisit it later. I then
watched the data for weeks, but didn’t notice any tendency for the wind vane to settle in the same direction.
It would not be hard for the manufacturer to balance the wind vane by adding a little weight to the arrow
end, but there you are. I understand why the light sensor should be level, but can’t quite believe the rain
gauge would be much affected.
President’s Day weekend I decided to tackle the leveling more thoroughly. The central problem was
access: even with the mast lowered to its lowest eleven-foot height, I could barely glimpse the bubble level
in the top of the sensor array from my extension ladder, and couldn’t reach it to make adjustments at all.
My stepladder turned out to be to short. I finally decided to tip the entire rig over and take the nesting ten
-foot upper section of mast completely out, put its butt end on the ground (keeping it vertical with long
plumb bobs), and adjust the sensor array level from the flat rooftop. It was a little trickier than I’d expected,
but in the end successful. After returning it to its place, I had only to watch the plumb bobs (which remain
hanging down the upper mast) while shimming the base. This was the work of perhaps ten minutes--on
top of several hours of effort.
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| The mast aligns almost perfectly with the plumb bobs both n-s, and e-w. |
I actually forgot one additional adjustment needed: to register wind direction properly, the sensor array
must be aligned by compass. I decided to turn to a seldom-used app on my phone: a compass that is
part of a collection of outdoor hiking utilities. In the process, I discovered the app isn’t entirely reliable. I
had thought my street runs almost perfectly due north, and so aligned the array with it. The compass
disagreed--until suddenly it didn’t. As it is, the array is too high up to get a precise bead on. I only hope
it’s good enough. The graduations on the wind indicator are some 4.5 degrees apart, so my rough
orientation might be just adequate.
Snow might be an issue if you have snowy winters. I don't care, myself, that the rain gauge will be
inoperable much of the winter. But when heavy snow stopped my wind vane and anemometer, and didn't
melt for several days, I finally brought the array down and cleaned it off. This might get old; we'll see.
