On 12/28/2015 9:59 PM, Snuffy "Hub Cap" McKinney wrote:
"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.

Yet you notice I saw a 20 degree rise in the course of a couple of minutes
by moving mine from the "sheltered porch" to the "open yard" 12 feet away?
I could actually *watch* the indicator move every few seconds!

20 degrees is not a trivial error!