Outdoor thermometer placement

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On 12/27/2015 4:40 PM, Don Y wrote:

I've not been to grandparents' old place in TX Valley in years to know what they now use (of course, it's two-three generations removed from grandparents now) but for temp measurement I'd think you'd get by pretty nicely with just a covered box near where you really need the detail info; as you point out if you're really after that local micro-difference to protect individual tree(s) it may not be enough unless you go for it in an all or nothing fashion whenever you do get an indication (likely the most reasonable alternative). But, as another I think noted, I've got a Davis Instruments weather station that seems to be quite accurate simply with the sun shielding they come with "out of the box" -- it sits out in the midday sun in SW KS at 100+ F w/o measuring ridiculously high temps that occur from directly-exposed thermometers.
The standard thermometer on the north side of the house at the top of the porch also has always seemed pretty good -- it's 8' or so, roughly from actual outside wall of the house so the heating effects don't seem very influential as far as can tell...
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On 12/28/2015 8:32 AM, dpb wrote:

Radiate heat from the (masonry) house isn't the problem, IMO. Rather, it is the heat trapped under the roofline that elevates the temperature registered by the thermometer/sensor.
I would like to come up with a "solution" that others can recreate (as I assume others will be interested in much of the technology that I've developed -- and I'm not interested in going into manufacturing! :> )
COTS "weather stations", IME, are just "curiosities". They give the user/owner a sense of what the weather is like -- without having to be precise (note "precise" and "accurate" have different technical meanings).
E.g., an indoor thermometer doesn't have to be accurate at all! Do you *really* know if it is 68F in the house? 71? What's the temperature at the other end of the hallway? In the kitchen? etc.
All you want from the "thermostat" is to keep the temperature AT a particular point -- and, some way of referring to that point (we could call it "foogle" just as easily as "68") as well as points ABOVE and BELOW ("elgar" is just below "foogle" and "gismatch" is just above! :> )
OTOH, if you know that a particular fruit is hardy to 32F (or 28F), then you don't want to play guessing games wondering if 32 is "elgar", "foogle" or "gismatch"!
You also want to know the *actual* relationship between these so you can perform reliable mathematical operations on them: "How much energy do I have to expend to create a local "foogle" microclimate when the outdoor temperature is "elgar"? Or, "dingbrill"? At which point will I no longer be able to influence the microclimate based on these calculations??
[Someone with the sort of interest I'm concerned about will be willing to sort out *proper* placement of a sensor instead of just relying on what's convenient]
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On 12/28/2015 11:54 AM, Don Y wrote: ...

Well, if you're really thinking you're going to get into it in that depth, then there's a _ton_ of research already done and a large fraction of it illustrates that simply knowing air temperature (no matter how accurately) ain't _nearly_ enough to reliably predict damage.
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On 12/28/2015 11:41 AM, dpb wrote:

Correct. That's why I also note wind speed/direction, barometric pressure, solar radiation along with azimuth/elevation, dew point, etc. I'm not looking for a "toy" that just throws numbers at a casual user/hobbyist but, rather, a genuine control system! :> The extent of control depending on how much the user is willing to "invest" in instrumentation.
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On 12/28/2015 12:52 PM, Don Y wrote:

Much more expense will be involved in the mitigating devices than the measurement, probably by orders of magnitude. What, specifically, do you think you can physically control?
While done most specifically for CA, it has much general bearing --
<biomet.ucdavis.edu/frostprotection/Principles%20of%20Frost%20Protection/PFPlong/PFPlong.pdf> As noted, all this will have been well developed in FL as well; you're trying to reinvent the wheel it seems.
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On 12/28/2015 12:44 PM, dpb wrote:

I use environmental monitoring to bias the HVAC control algorithms (compensating for losses/gains from exterior events; intelligently determining whether to use evaporative cooling vs. refrigeration; *anticipating* required control actions to achieve desired results), to determine irrigation needs (transpirational losses); as well as deciding when/if any local controls can benefit the vegetation (fruit being *my* concern but others might be more interested in their orchid collections, etc.).
Wrt the fruit trees, I can control air flow through the individual trees, some local heat sources and "misting" (coating the trees with a fine layer of ice).
I can also know when "all is lost" and not attempt further action ("wood" will be damaged).

How many folks do you know who can do that IN THEIR BACK YARD?
Which paragraph discusses impact of solar radiation on heat gain in a residence? Or, "comfort factor" compensation for air infiltration?
Where does it tell me the economic tradeoff of using evaporative cooling on a particular day vs. refrigeration? Or, the penalty of using refrigeration *after* evaporative cooling?
Where does it tell me about the (affordable) COTS control system that I can PURCHASE to do these things?
I'd *really* not like to have to "reinvent the wheel" so would greatly appreciate those pointers! :>
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On Mon, 28 Dec 2015 10:54:56 -0700, Don Y

You get a chimey effect that moves the sir through the pipe when the sun shines - negating any radiant heat absoption, you get full time shade, and no heat entrapment. Put it on a pole out close to the trees. It will be about the most accurate temperature record you can get, across all variables. Mount the temp sensor in the middle of the pipe. 2 or 3 feet long is adequate - longer won't hurt
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On 12/28/2015 1:24 PM, snipped-for-privacy@snyder.on.ca wrote:

The point is that there is no single-point measurement location that suffices; it depends on the type of event (advection vis a vis radiation, eg) , whether there is and how heavy an inversion later exists, and a zillion other details.
It's been studied extensively by all the research organizations in the citrus-producing areas, both public and private if he'd just make use of that body of knowledge instead of seemingly thinking he's the first to have thought of it. :(
In general, a 6-ft measurement, another at tree-top height and about 40' if higher than the canopy is generally what is typically done in commercial groves. How much other detail they use for actual leaf and bark temperatures and such is mostly dependent upon how valuable the crop is.
For a hobbyist or noncommercial it likely isn't practical anyway owing to the cost of the mitigating effects required to do anything effective, anyway, other than if can cover a few small trees or do a minimal amount of sprinkling or the like. It's hardly likely the fuel bill for heaters will make it cost-effective for a homeowner with a few trees unless they've just got resources to burn (so to speak).
The cost for monitoring these days is pretty much peanuts; it's the downstream costs that are the killer for anybody except the commercial grower.
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On 12/28/2015 12:58 PM, dpb wrote:

Sheer arrogance and ignorance on your part! As I said elsewhere:
How many folks do you know who can do that IN THEIR BACK YARD?
Which paragraph discusses impact of solar radiation on heat gain in a residence? Or, "comfort factor" compensation for air infiltration?
Where does it tell me the economic tradeoff of using evaporative cooling on a particular day vs. refrigeration? Or, the penalty of using refrigeration *after* evaporative cooling?
Where does it tell me about the (affordable) COTS control system that I can PURCHASE to do these things?
I'd *really* not like to have to "reinvent the wheel" so would greatly appreciate those pointers! :>
So, please tell me -- and the rest of those reading -- exactly *who* has "thought of it" before?!
I guess *your* problem is failing to understand that not all problems *have* been "thought of before". Or, having too narrow a concept of what you can actually *do* with "data" once you have it! It's a relatively common problem: people who can't see past their own experience...
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On 12/28/2015 2:09 PM, Don Y wrote:

No, simply stating fact...and, as said, have quite a bit of family experience in the citrus/truck farming "bidness" from the '30s and on w/ mother's side of the family in the TX valley...

Not many which is why I said it generally ain't agonna' be practical...

Well, that's a completely different kettle o' fish than citrus grove freeze protection which is all I had addressed...

I spent some 40 yr of engineering consulting doing data collection and usage so I've a pretty good idea of what can be done w/ data...from online coal ash and elemental analyzers to pulverized coal flow w/ acoustic noise inference via nonlinear processing of the chaotic (as opposed to stationary stochastic) flow patterns to more conventional vibration and such including online heat-rate performance monitoring for fossil plants (much more related to your HVAC question albeit on a much larger scale and with temperatures and pressures a little higher! :)
In the specific areas you've mentioned here I don't know offhand who's done what; granted, but that wasn't what I thought you were interested in as noted above.
While it's a reasonable conjecture, I'd venture 90% of homeowners will get far more "bang for the buck" simply by adding insulation or the other routine energy-efficiency changes than what could gain by dynamic control such as you posit above.
Similar to the questions re: who can do serious control of freeze mitigation in their backyard, how many houses have both evaporative _and_ refrigerating cooling systems?
I'd still guess there's quite a bit of useful work having been done and for your purposes worrying about a degree or two of error in that external temperature is also a case of misplaced concern since as you mention it isn't that critical to a precise degree what an internal temperature is if it's somewhere in the mid-range of the comfort zone most folks will be happy enough...
<https://www.ashrae.org/resources--publications/bookstore/thermal-comfort-tool?utm_source=promotion&utm_medium=landingpage&utm_campaign 179&utm_term179&utm_content179> As for the predictions you're talking about, application of the load calculations manual would basically provide all the information required to evaluate alternatives as far as input costs, etc., if applied to a specific structure and installed systems as opposed to the sizing calculation itself. But, all the basic heat loss/input computations are outlined to do it...
I'm sure there are optimizing controls already for commercial buildings altho not my area of direct expertise but again I doubt it'll be found to be cost-beneficial to this degree for single-family residential applications. Beyond the thermostat runback at night and converting old, low-efficiency furnaces/boilers to higher-efficiency units and the aforementioned closing up of other heat/cooling loss venues, the remainder is, in my estimation, likely to be found to be in the noise level of actual cost/benefit.
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On 12/28/2015 2:13 PM, dpb wrote:

Knowing what to do and having <something> that will actually *do* it are entirely different things! You can wire an on/off switch to your furnace and keep the interior of your home at a comfortable temperature... by flipping it on and off throughout the course of the day!
Not many people would opt for that form of control, though! So, <someone> makes an AFFORDABLE device that does this FOR you and suddenly it's commonplace!

And *no one* commercially addresses all of the areas that I've mentioned with an integrated, affordable controller. Because the "citrus growers" don't give a rat's ass about interior HVAC controls; and the HVAC control developers don't give a rats ass about citrus protection, cactus protection, orchid protection, etc. The folks who designed the controller for our evaporative cooler cared nothing about the controls for the furnace (i.e., added their own indoor temperature sensor despite the fact that the air conditioner *and* furnace already have this!).
No one deals with anything outside their own little microcosm of experience.
So, you'd end up with N different systems (assuming you could find COTS systems to do these things!)

I notice you didn't mention anything about HVAC despite my reference to it early in the thread: 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.

Actually, you get a lot of benefit (energy saving and comfort) by putting smarts into a home thermostat. SWMBO opts for an open window despite the fact that the outdoor temperature is 30-ish at night. Neither of us wants the house warm while sleeping. OTOH, if I'm up late working, I don't want it *cold*. Both of us want it warm *before* we wake up -- yet having it warm too soon before rising would be wasteful of energy.
Adding insulation to a building after it's been built isn't always possible. E.g., our walls are cement block. Adding insulation would require adding a layer of styrofoam outside the block and reapplying the stucco to that surface. Or, framing *in* the interior walls to create additional space for fiberglass bats or blown in.
Adding ceiling in the ceiling is essentially impossible as the roof is 9" above the ceiling -- and can't be "filled solid" or it won't be able to breathe. So, unless I wanted to incur serious expenses to remodel the house, *smart* control of the HVAC is a far easier way to save money. *And*, can be applied to my neighbor's house (and HIS neighbor's house, etc.) just as easily/econmically as here!
I.e., the solution SCALES well!
Likewise, a solution to addressing the citrus problems we encounter in our little microclimate would benefit everyone in the neighborhood with citrus trees or other "frost tender" plants. E.g., the Saguaros also don't like the cold; and, with a 75 year investment in a plant (if it has "arms", it's 75 years old or more), you don't want to lose it just because of a weather event.

Here? Probably 30%. There has been some talk of banning evapporative coolers as water is precious but the cost of refrigeration makes that as the EXCLUSIVE form of cooling impractical for folks with limited means.
(recall my comment re: seeing past their own experience?)

It's not just "perception". Take the leftmost two digits of your income and figure out your effective hourly wage. How happy would you be if your employer compensated you based on that? On average, you'd be cheated out of $500 for every 2000 hours (1 year) worked.
Hence precision is more important than accuracy.
OTOH, precision without accuracy doesn't help for things that have actual physical limits: plants die at fixed temperatures regardless of how *precise* the temperature measurement.
A precise but inaccurate temperature measurement will be reflected in additional inaccuracy for any other measurements/calculations on which it is relied.

Exactly. The *controls* are too expensive. But, the algorithms and instrumentation are not.
A simple test to see if it's rained recently makes a big difference in the amount of water used by an otherwise dumb/naive irrigation system! (why water if it rained yesterday? Or, if it is RAINING TODAY??)
An irrigation controller that considers evaporative and transpirational losses wouldn't foolishly water during the hot part of the day as ~40% of the water is lost!
These sorts of things are reasonably well known -- yet frequently ignored by the folks charged with setting the "dumb" controllers.

What do you do when the house is empty but it's daytime? Keep it nice and warm -- in case someone comes home from work, early? Do you connect the HVAC to your telephone/internet and REQUIRE the homeowner to "phone home" prior to arriving and "turn up the heat" so its warm (cool) when they walk in the door? Should *they* look at the current weather conditions and make the decision as to WHEN they should tweek the temperature setpoint? Perhaps query the house to see what the actual indoor temperature is, the outdoor temperature, wind speed, etc. and make a "gut feel" calculation? Or, maybe just wait until they get home and manually make the change at that time? Perhaps opting not to let the house deviate too far from that desired temperature because they don't want to have to wait a long time for it to return to their "comfort zone"?
What if they have forced air vs. hot water heat at their new residence? Should they relearn these "gut feel" calculations to reflect the different control actions of their new HVAC plant? How soon before retiring/arising should they adjust the AC/furnace/heatpump in the bedroom area as opposed to the living areas? (multizone control)
Don't look at *your* experience(s) and extrapolate from that unless you're aware of what other folks' experiences are!
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On 12/28/2015 12:24 PM, snipped-for-privacy@snyder.on.ca wrote:

I don't think that would be a viable option for most folks. It's one thing to have to make an effort to "put it in the right place"; another thing entirely to have to locate something that is that physically large and visually unappealing! Likewise, I need to come up with a smaller "rain detector"... one that isn't as visually obtrusive (and, ideally, requires less maintenance).
[People don't want to make "careers" out of this sort of thing! When was the last time you calibrated your household thermostat?]
I'm going to investigate radiation shields and see if I can come up with an approach that is easily reproduced that affords greater flexibility in siting. I can make a bunch of sensors, calibrate them (to each other) and set them in different shields located in the same general area. Take data, then relocate the group to other locations and see how they perform compared to each other, etc.
I'll talk to someone at the university and see what they say about setting up a "control" against which to measure them. That way, just let a machine do all the data collection in a more repeatable fashion instead of playing wack-a-mole with different sensors, placements, etc.
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On 12/27/2015 8:24 AM, Don Y wrote:

We have 2 of them. One on the front porch and one outside the back of the house by a window. The temps are pretty close even though the shade hits both of them during the day at some point. We also have a thermometer on our vehicles in the driveway, too. It's usually only a couple of degrees difference in temp from the porch to the driveway.
--
Maggie

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On Sun, 27 Dec 2015 07:24:12 -0700, Don Y

feet off the ground and open at both ends. Mount the thermometer in the center of the pipe. Of course this only works for remote reading thermometers.
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wrote:

I have a tree about 6ft. from a house window. I put a thermometer on the tree. During rain, water ran down the tree trunk and would get inside the thermometer. I finally drilled a hole in the bottom of the plastic front of it to let the water drain out, but eventually it ruined the thermometer. Now I have a new one, but I mounted it on a board, put a piece of tin at the top of the board to hang over the thermometer and divert the water away from it. Then I screwed the whole board to the tree. I hope this works better.
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Anywhere on the north side of a building that has a wall that is reasonably insulated and that has air flow should be satisfactory. Don't make a 6-day project out of a five minute task!!!
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Stevenson Screen.
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i had the same problem, especially when i lived in Las Vegas
life is [so] hard, isn't it?
you might try Multiple outdoor sensor locations
marc
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