stevenson screen / temperature guage positioning

[Solorize]

Hi,

Currently I have my temperature sensor inside a fan asperated homemade stevenson screen
which is fixed to a shed ,which is in the most shaded position in my garden.

I think I may be getting higher temperatures when the shed heats up,
but I have no where else that gets that amount of shade, as my garden is
south facing.

Therefore is it best to leave the stevenson screen where it is currently
sited, or move it to the front of my lawn, to the right of the steps which lead
up from a patio to the lawn, which would mean that it would get sun on it 90% of the day,
but would allow more air to pass around it and it would not get heated upby the shed.

From the below link you can see where it is currently sited.
The main photo (viewing south) shoes the extent of my garden.

http://www.wokinghamweather.co.uk/weatherstation.html

[beteljuice]

Bottom right of the picture there appears to be another shed or large bunker ?
That would be north facing, could you not extend your cables to that ?

If not, could you extend the temp sensor to say 300mm or more from the shed ?
Your aspirator unit looks reasonably effecient, so I wouldn't expect more than 1C high in strong sun, which is actually quite good !

[RayProudfoot]

I'd move it to the right of the steps but no too far away from the open part of your lawn. That will be an excellent placement for the sensor. Doesn't matter it being in full sun. That's where the Stevenson Screen does its job.

What does concern me is the height of your anemometer. It's very sheltered at its current height. Best position is on a pole lashed to the chimney around 33ft up. Is that possible?

[Solorize]

Thanks for both of your replies.

I may try beteljuice's idea of extending the position of the stevenson screen out
further from my shed. I have some aluminium angle profiles that I can
attached to the existing brackets and then mount the screen near the end.
So I should be able to get it about 200-300mm away from the shed.

If I still get high readings then I will have to see about moving it to
near the steps. And come up with a way to mount it on a couple of
poles or similar.

Ray, I have another pole that I have been thinking of attaching to my
existing pole which should get it up twice as high. Which I was going to
do at the same time as moving the screen, as I would have to attach
a longer cable (which I have) anyway.

So I will need to get a few more cable ties and a couple of jubilee clips,
and if I get time do it this weekend.

I would prefer to extend the pole in it's current location as I don't
fancy siting it on my roof especially 1. as I am not good with heights
and 2. I don't have a chimney

[RayProudfoot]

Thanks for both of your replies.

I may try beteljuice's idea of extending the position of the stevenson screen out
further from my shed. I have some aluminium angle profiles that I can
attached to the existing brackets and then mount the screen near the end.
So I should be able to get it about 200-300mm away from the shed.

If I still get high readings then I will have to see about moving it to
near the steps. And come up with a way to mount it on a couple of
poles or similar.

Solarize, the ideal location for a thermometer is in a stevenson screen 4ft above a grassed area well away from concrete and other areas of potential heat. Few can achieve that but you're pretty close. Ideally place the SS in the middle of your lawn or as near as is practical.

Ray, I have another pole that I have been thinking of attaching to my
existing pole which should get it up twice as high. Which I was going to
do at the same time as moving the screen, as I would have to attach
a longer cable (which I have) anyway.

So I will need to get a few more cable ties and a couple of jubilee clips,
and if I get time do it this weekend.

I would prefer to extend the pole in it's current location as I don't
fancy siting it on my roof especially 1. as I am not good with heights
and 2. I don't have a chimney

Higher positiioning will certainly help and I understand your reluctance to go onto a roof even if it was an option. If you have a gable end that would be a good alternative if you're okay up ladders. Otherwise as high as you can manage.

I thought long and hard before positioning my anemometer on the chimney but good readings are important to me. Fortunately I haven't needed to call the aerial installer back for over 2 years. That day will come of course.

[Solorize]

Ok after a quick nip down to Homebase, to pick up
a few bits. I have added another pole to my existing
one which has considerably extended the height of
my anemometer.

The photo is a bit deceiving, but the anemometer
is just below the height of the tv aerial on the house
on the left.

It does seem to wave about in the wind a bit, but I made
sure that the poles are fixed together securely so hopefully
it won't be a problem

I have made some extended angles to reposition my Stevenson screen
but I need to work out a way to get the transmitter moved out
to the new postion as it is currently screwed to the shed using
the original mounting arm. So I will have to see if I can make a cross
bracing piece that has a way of mounting the transmitter into it.

[beteljuice]

You are going to need some stays / guys at that length of mast

[Solorize]

hmmm, slight problem... I don't have anywhere to
put guys to, plus the other half will do her nut if
I have cables coming of it LOL.

Do you think it will be ok to leave as is without
any additional support?

It seems to wave about a little bit more than the house
tv aerials in the current wind conditions which are approx
20mph gusts. But I am not too sure how it would behave
in "really" windy conditions.

I guess I could just monitor it and if it looks too dangerous
then I could put it back down to 1 pole high.

Also do you think with it swaying about will it have adverce effects
on the readings?

I am just trying to upload a video I took of it on my mobile phone
to youtube and will post the link so you can see, if it ever uploads

ok I finally managed to get the video to upload, but when it plays
it keeps on stopping and starting If you wait for it to get through
the stopping and starting you will be able to see it moving the most
at about 1m:05s onwards in the video.

Link to video below (to see it best please view in full screen mode):
http://www.youtube.com/watch?v=RJq9i44-OH0

[beteljuice]

It's looks as though it is still in the 'shade' of nearby trees ?

Imagine what an 80mph gust will do - I think it might rip the side out of your shed unless it's extremely well constructed

When the beteljuice 30 feet mast (one and half inch dia aluminium) was up, it was guyed at approx. 18 feet and 27 feet.
I tried just one set of guys, but frightend myself and the neighbours conservatory when a shackle came loose

[Solorize]

There is one large oak tree at the end of a neighbors garden,
but there is not much I can do about that, except sneek over
there with a chain saw and cut it down

So I have to live with that maybe affecting the readings a bit.

The position it's in, is the least sheltered position in my garden,
unless I mount it on the side of my house at eave level and
have it extend up over roof height. But as i've mentioned before
I am not that good with heights. So will probably leave it situate
where it currently is.

I think I will monitor how much it sways when we have more
powerfull winds and if it looks dangerous I will move the
thinner pole section down lower on the main thicker mast
to reduce the overall height.

I have it secured via two aerial mounting brackets which
are bolted through into a plywood pattress to clamp
it to the shed wall. When I checked yesterday the pole was
only moving from the top down to the top most bracket
position and not below, So it may be ok and not damage
the shed.

My only concern is the pole waving about soo much that it
bends the main pole at the top bracket position, but am
unsure how much force and lateral movement would need
to be applied by the wind for this to happen.