Home built fan aspirated radiation shield

[Bashy]

Hi peeps

After three days its finished (apart from the fan, will be added when it arrives)



I still think that when the fan arrives and i start to fit it, i may need to add another
saucer due to the height of my sensor, I also had to lay the sensor on its side due
to fitting issues but its in there with plenty of space around it. (WMR928NX sensor)

Also as the bottoms of my saucers are concaved and water would sit in there, i had
to find a quick way to fill it (i wanted to get it finished today) I used candle wax, I
heated it up in a tin on the gas hob, once melted to a consistency like water i just
poured it on the saucer bottom and let it cool, then finished off the paint that i had
left.

Ok granted it dont look the best but i thought that after 2 days of trying to fill the lips
i had best do something about the lid lol
As for the bracket its strong but thin, so the RS sways a little in a good wind, I may
stabilize it when i get round to actually sorting a more permanent spot for siting the
sensors.

An important note for anyone wishing to give this a go

Good preparation will improve the fitting of the parts and the end product.
I thought i did a good job on the preparation but when it came to painting i was so wrong.
Make sure you use a flexible filler, Sand (no less than 800 grit) all the saucers to a smooth
finish, I would highly recommend a flexi bond as the base coat, this helps the adhesion of
the primer (i forgot and when i caught 1 of the saucers it peeled a little)

I may even do it again next year and try to get it a little tidier next time lol

Thanks Breitling for idea and walk through that made it all possible

[Breitling]

Nice looking Bashy. Now time to check your temp data. Let us know.

[Bashy]

Sorry for the late reply, i wanted to get an idea of what it was like...

Without the Fan (should be here Wednesday) it is reading about 3^oc above
what it actually should be (this is only when the sun is out)....

I bought one of them garden thermometers, the one where it has a 2, a min and a max
with internal sliders (from wilkos). When the sun was gone yesterday evening i compared
readings and there was about 1^oc on my OS, in other words the manual gauge
was reading 1^oc below my unit. I dont know if this is out or my unit is out.

I have an ornament from Fuerteventura with a thermometer on it, i will take that out now
and see what they all say in an hour or so....

I will be back.....

[Clanger]

I bought one of them garden thermometers, the one where it has a 2, a min and a max
with internal sliders (from wilkos). When the sun was gone yesterday evening i compared
readings and there was about 1^oc on my OS, in other words the manual gauge
was reading 1^oc below my unit. I dont know if this is out or my unit is out.

Hi,
Don't think you can compare a thermometer from Wilkos with your OS one.
Have you thought about getting an additional OS thermometer sensor?
That's probably the best way to test. 

[Bashy]

Hi Clanger

I have 4 temp gauges out there at present, all in the shade away from any heat source.
I think the temp is pretty steady now, readings are:

Electrisave: 23.0^oc Humidity 52%
OS internal: 21.7^oc humidity 58%
Dolphin: 20.0.0^oc
Wilkos: 19.0^oc

Main sensor in the Radiation shield (without fan) no sun is 19.3^oc humidity 58%

So the closest sensor is the Wilkos 1 lol

[Bashy]

Ok, with no sun for the last hour or so, the OS is showing 18.7 and the Wilkos is showing 18.0
There at opposite sides of the garden, the wilkos is in total shade on the (brick) shed wall so
due to the wind dir at present its also pretty calm on the wilks as well

Hopefully i will get another sensor shortly so that i can do a more accurate comparison...

[Bashy]

Ok, The fan came today, So its now fitted and working

Please take a look at the image and let me know if you think thats enough of the
solar sensor covered please? You can see greater detail if you click the View
Original Size



It looks like i might need to add some more wax to the top one as well, when it was
tightened up before it cracked the wax around the spacer and when i removed it to
fit the fan some of the wax came away

I might just have a good look around for a new top saucer that is not concaved
If anyone finds any, please let me know?

[Breitling]

Please take a look at the image and let me know if you think thats enough of the
solar sensor covered please?

Why do you cover part of the cell?  Let it work in its whole surface. What you have to seal is the junction between the black case and the clear cover (a bit silicone should be enough). Seal the back electrical terminals as well with grease, wax or silicone....

[Bashy]

Hi, Someone said on here somewhere to cover part of the cells so that the fan is not getting too much power!

[Breitling]

No, the fan is weak enough. If you cover part of the cell, the effect is the motor not always running. Measurement may vary a bit if the motor is or isn't running. On a cloudy day you will have intermitent working periods, so intermitent changes in measurement. Keep the cell clear to let the motor run all day, from the first light to the dawn. Your data will be smoother.

[Bashy]

Sorry for the late reply, i formatted the comp and started again due to WD crashing every so often....

Ok, great, I have removed the tape now thanks,
Will now see how it goes

Although, its supposed to be 18^oC and mine is saying 20.9^oC
So firefox says pmsl (now is 18c and today supposed to be 20c) oh well....
Hopefully when the sensors come i will be able to take some proper readings

Thanks for your help and advice and i will report back at a later stage

No, the fan is weak enough. If you cover part of the cell, the effect is the motor not always running. Measurement may vary a bit if the motor is or isn't running. On a cloudy day you will have intermitent working periods, so intermitent changes in measurement. Keep the cell clear to let the motor run all day, from the first light to the dawn. Your data will be smoother.

[administrator]

Although, its supposed to be 18^oC and mine is saying 20.9^oC

Welcome to the world of forecasting. Forecasts aren't guaranteed to be right, so don't use them to check the accuracy of your sensors! The only way to check that your sensor is reading correctly is to check the temperature with another (accurate) device, e.g. a thermometer next to the sensor and see if they agree. You might also find that your sensor is reading the temperature fairly accurately, but you local temperature may vary from other local stations due to differences in your environment.

[Bashy]

Yeah, cheers for that Chris, this i do understand and will have to wait for the
sensors to turn up before i can get a more accurate reading, I know the internal
unit BTHR918918N is supposed to be for inside only, should i try this for now
whilst its dry and warm, or should i just wait?

Welcome to the world of forecasting. Forecasts aren't guaranteed to be right, so don't use them to check the accuracy of your sensors! The only way to check that your sensor is reading correctly is to check the temperature with another (accurate) device, e.g. a thermometer next to the sensor and see if they agree. You might also find that your sensor is reading the temperature fairly accurately, but you local temperature may vary from other local stations due to differences in your environment.

[niko]

Also note that most common thermometers are not very accurate, they may display to a tenth of a degree, but are only correct to within 1 or 2 degrees. Precision thermometers are expensive 

[Bashy]

Are you referring to the OS thermometers?

As for a better comparison...

FARS (OS Sensor)   20.7^oC in direct sunlight
Probe (OS Sensor) 20.6^oC in shade on cold concrete floor

So that looks near as damn it to me

Also note that most common thermometers are not very accurate, they may display to a tenth of a degree, but are only correct to within 1 or 2 degrees. Precision thermometers are expensive