> 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
>=20
> I'm curious as to the thermal resource beneath me.
>=20
> 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.
>=20
> I'm planning a 600mm long tube over the exposed half for blocking
> sunlight, with air vents.
>=20
> How to restrict the thermally induced air flow within the tube?
>=20
> Is there any value in sensors at different heights?
>=20
> I'm most familiar with DS1820 series sensors.  Are there any sensors
> more suited to this application?
>=20
> 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.
>=20
> --=20
> James Cameron
> http://quozl.linux.org.au/

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 ven=
dors, I just picked this one at random as an example:
http://www.ebay.co.uk/itm/2x-DS18B20-1M-Waterproof-Sensor-Digital-thermomet=
er-Thermal-Probe-Arduino-UK/331626763281?_trksid=3Dp2141725.c100338.m3726&_=
trkparms=3Daid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26=
meid%3Deccc7aeef0274a3e9e751d44c7ae2bd9%26pid%3D100338%26rk%3D6%26rkt%3D9%2=
6sd%3D190784248550
James
 		 	   		 =20
--=20
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