"Don Y" wrote in message ...
On 12/27/2015 10:49 AM, Vic Smith wrote:
On Sun, 27 Dec 2015 07:49:30 -0700, Don Y

I'm not interested in personal comfort as much
as having "real data" for the HVAC system and
to know whether the citrus trees are in jeopardy.

E.g., Mandarins get upset at 32 (not 30 or 34)
but Navels will tolerate 28 (but not 26). The
mechanisms used to protect them usually only afford
a couple (3 or 4?) degrees of added protection -- but,
only when you *know* they need to be used.

In that case you need the sensors at the trees.

Trees are within 10-20 feet of the house. So, there's
likely no difference in temperatures there vs here
IN THE ABSENCE OF MAN-MADE INFLUENCES.

Locating them at/in the trees would expose them to the
daytime sun.

For example, I was outside a few minutes ago checking the
fruit. I moved a thermometer (not a wired sensor) from
it's location on the porch out into the yard -- 12 feet
away. In the time it took for me to walk to three of
the trees and back, the registered temperature had
climbed from 51F to 72F. (I'm *sure* the air temperature
hadn't changed that much! : )

Nearby weather reporting sites range from ~47F to ~57F.
The closest to my location (unsure of its relative elevation)
reports 50F -- which is in line with my 51.

[My 51 is usually high due to its location in a "heat trap"]

I was interested in the temp difference at various roof vents once when installing an attic fan. Went to the dollar store and picked out 12 that were reading the same in the store and set them outside of the vents so I could read them from the ground. Then checked them with binoculars ever couple of hours. This was on a hot summer day and all were in the shade of the eaves. I didn't see more than a couple of degrees difference between the sunny & shady sides of the house.