Ventus W831 Weather Station. First impressions.

The lack of direct reading of wind speed and direction prompted the arrival of a Ventus W831 weather station as a present for my birthday.

The overall impression is one of high quality plastic casting and the complexity of available readings on the display unit.

The 28½ pages of English language instructions are competently written but sometimes rather complex to take in on first reading. They also lack some important details. Perhaps more importantly, they are sometimes, simply incorrect. For example, they talk about releasing latches for hatches on battery compartments. When in reality all the batteries are hidden behind moulded plastic plates with sealing rubber gaskets. All of which require quite a small screwdriver to remove and replace several tiny screws in each case. I found a jewellers screwdriver with a straight blade worked best on the cross-head screws.

Only the indoor display unit has easily accessible batteries. Working on the remote units out of doors would introduce a very high risk off loss of these tiny screws. It is strongly suggested that the batteries are changed with the units brought down and resting on a lipped tray to catch any escaping screws! This may seriously affect where the units can be sited to allow easy removal.

As can be seen in these images I have added the combined, all-plastic anemometer and wind vane unit to my wind surfing mast. Simple stainless steel bar clamps and 2"/50mm long screws are provided and allowed easy fixing of the wind instrument base to my mast. Though the screws were only just long enough for my use, most owners would probably use a smaller diameter pipe.

The all white, Ventus wind vane is rather easier to see against the background trees than my original black yachting arrow. Though seen against a bright sky it can appear quite dark in silhouette.

I originally bought this lightweight, fibreglass mast very cheaply from a flea market to support a simple plastic wind vane borrowed from a yachting application. The GRP mast is very light but stiff and provides perfect support for lightweight instruments such as these. Though it does flex slightly in strong winds it has the advantage of raising the wind reading units some 5 metres off the ground without the risk of it causing damage or injury. Which might well occur if a heavier metal or wooden mast fell in a storm.

Ideally the mast ought to be 10 metres high to comply with meteorological standards. Even higher for situations with obstructions like trees and buildings. Only an open field would really allow the minimum height of 10m for truly accurate wind measurements. I decided that 5 meters was ample for my situation but then I am not expecting professional standards. Adding an aluminium extension pole to the mast only added more flexibility to the mast itself.

At least my wind measuring instruments are erected in the open and not slung under the eaves of a bungalow or carport surrounded in dense shrubbery. Which is quite a common sight in many cases as I cycle the lanes of Denmark. Weather stations are remarkably popular decorations for Danish homes. Though very few owners seem to grasp the need for height and clear exposure to obtain accurate wind readings. No doubt some of these devices are also connected to the Internet. They feed this glaringly incorrect information out to a wider audience as if it contributed to the sum of all knowledge. The Ventus W831 does not offer such a live Internet connection. Only an application which allows weather data to be saved on one's home computer.

I mounted the Ventus wind apparatus just below the original wind vane to ensure there was no physical interference. The extension arm was arranged to point south to provide the "cleanest" air from the prevailing wind directions. SW and SE are the norm for my location. Though, interestingly, the wind was coming from the north on the day I set everything up. Thankfully both vanes are following each other very closely. So I can be sure there are no interference problems despite the very unusual wind direction meeting the mast first after filtering through tall but open trees. The Ventus is much more sensitive to changes in direction of light winds thanks to small, stainless steel, journal, ball bearings. So shaft friction is at a [very low] minimum.

In this image I have dimensioned the case and rather small screen of the display unit. The screen is actually slightly smaller than my Imperial dimensions suggest. A difficult photographic subject whether the screen is lit or not. The protective plastic screen cover is rather shiny and readily reflects well lit backgrounds. I have adjusted the image brightness to better match the actual view. The screen is actually quite dark but legible in both cases of lit and unlit. The displayed text, graphs and symbols appear slightly sharper than these images suggest. Since the screen relies on reflection in the unlit mode it helps to have it placed in a good light but not directly reflecting a window. Reading it by artificial light will probably require that the screen is lit after dusk.

The buttons along the bottom of the screen make an irritating electronic squeal from inside the display case when released. Nor do they always have the desired effect! Particular problems exist around the wind speed settings and labels. The Set button steps through changes which should really be changed by the arrow keys. Wind chill is fixed in the Centigrade scale as far as I can discover. Which hardly makes sense when Fahrenheit temperature scales are chosen for display.

Here the screen is lit with the compact [plug in] 7.5V power supply. The display unit takes four internal AA batteries but they would drain if the screen was lit constantly. There are useful options for control of screen illumination but the PS is essential for a constantly lit screen. 

Lacking batteries and switching off the power supply caused the screen to return to default settings on start-up next day! I had to reset the display to m/s wind speed and Fahrenheit temperature scales. The location had also changed from Copenhagen to Berlin.

Once a city is entered I can't see how any finer location setting is possible. The adjustable scales are shown on the bundled software screen but they are greyed out. Rather strangely, there is no option to allow fine adjustment of location. No batteries are supplied with the Ventus W8311. An omission which caught us out as no fewer than eight  'AA' size batteries are required. Four in the display unit and two each in the wind, hygro-thermo and rainfall units respectively. Harvesting used batteries from various clocks and thermometers around the house provided enough for the wind and hygro-thermo units to be tested. The display head and rainfall would have to wait until I had reached the shops.

Low wind speed reading is really remarkably sensitive. With readings down to 1/10th of one meter/second! Far more sensitive than my large, all brass, copper and bronze vintage Casella anemometer. However, there is quite a lag between movement of the Ventus rotor and screen updates appearing indoors. The same goes for the wind vane. With very long pauses between changes to angles of pointing after I have watched the vane turn. I placed the mast outside so that I could easily watch the wind mast over the top of my computer monitor while sitting in front of a window. I shall have to time the separation between updates to confirm exactly how long they are. [About 35 seconds assuming a change in pointing or wind speed]

See W831 First impressions Pt 2 for more.

Click on any image for an enlargement.

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