I am using some of those stainless steel types I got from
ebay. They were originally purchased for soil temperature in
a greenhouse but I am now using them for exterior air
temperature. After a year in service they are doing well.

Allen

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-
> bounces@mit.edu] On Behalf Of James Holland
> Sent: Wednesday, October 28, 2015 12:14 PM
> To: piclist@mit.edu
> Subject: RE: [EE] Soil temperature sensing methods,
> thermodynamics
>=20
> > From: James Cameron <quozl@laptop.org>
> > Subject: [
> > To: piclist@mit.edu
> > Message-ID: <20151028021328.GB2367@us.netrek.org>
> > Content-Type: text/plain; charset=3Diso-8859-1
> >
> > I'm curious as to the thermal resource beneath me.
> >
> > I've dug a 500mm deep hole and inserted a tube, 1m long
> 33mm diameter
> > 2.16mm wall thickness, with caps at both ends.  The tube
is
> straight
> > plastic pressure piping for water reticulation.  I've
set it
> vertical
> > using a spirit level before backfilling the hole.
> >
> > I'm planning a 600mm long tube over the exposed half for
> blocking
> > sunlight, with air vents.
> >
> > How to restrict the thermally induced air flow within
the
> tube?
> >
> > Is there any value in sensors at different heights?
> >
> > I'm most familiar with DS1820 series sensors.  Are there
any
> sensors
> > more suited to this application?
> >
> > p.s. ground here has not frozen in living memory, winter
> frosts only
> > affect grassed areas, and only for a few hours.  Surface
can
> be 65?C
> > to 75?C on a calm day in summer.
> >
> > --
> > James Cameron
> > http://quozl.linux.org.au/
>=20
> You can get the 18B20 sensor potted in a stainless steel
> housing, maybe you could just bury one or two of those in
the
> ground. There are plenty of vendors, I just picked this
one at
> random as an example:
> http://www.ebay.co.uk/itm/2x-DS18B20-1M-Waterproof-
> Sensor-Digital-thermometer-Thermal-Probe-Arduino-
> UK/331626763281?_trksid=3Dp2141725.c100338.m3726&_trkpar
> ms=3Daid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%
> 3D20150313114020%26meid%3Deccc7aeef0274a3e9e751d44
> c7ae2bd9%26pid%3D100338%26rk%3D6%26rkt%3D9%26sd%3
> D190784248550
> James
>=20
> --
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