Thermometers: What's the Problem with Accuracy?
 

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?
--
Pete Cresswell

Thermometers: What's the Problem with Accuracy?
 

On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734

Thermometers: What's the Problem with Accuracy?
 

On 2/4/2018 11:11 AM, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734

Looks nice but no spec's on absolute accuracy so no way to know if are
any better than the run-of-the-mill cheap consumer thermometers Pete's
already tried.

Lee Valley probably can supply data and there's at least a decent chance
they may meet the need, but wouldn't bet too much on it without checking
first before laying out $50.

Of course, highly accurate thermometers/sensors are available from
suppliers for lab/scientific measurements, but one pays for the
precision/accuracy.

I don't know otomh what one could find from Omega these days in the
lower-end price range, but there's one place to look.

--

Thermometers: What's the Problem with Accuracy?
 

On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734


As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.





--
Bod

Thermometers: What's the Problem with Accuracy?
 

In article , lid
says...

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?


The best way to get a thermometer that should be correct is to look at
all of them in the store and see how many are showing the same
temperature.

If possiable you should take one and place it in a solution of ice and
water. It should show 32 deg F or 0 deg C. While this will only give a
one point calibration, it should hold close enough for normal ranges of
food or human comfort.

Thermometers: What's the Problem with Accuracy?
 

On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?

Spending enough money to get one that has a little quality control in
the manufacturing phase?
My Bacharach sling always shows to be the same as the lab grade
thermometer we use to calibrate the instruments we use for state water
samples but they cost $80+
Digital stuff itself is what I call the great lie. They give you a
very precise reading, that is usually wrong. I have an $8000 (MSRP)
digital water tester from the state that we have to calibrate before
and after every use and about 10-15% of the time, they do not pass the
verification calibration after the test on at least one parameter.

Thermometers: What's the Problem with Accuracy?
 

On Sunday, February 4, 2018 at 12:54:53 PM UTC-5, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734


As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.


I'm surprised you're surprised. Given the chauvinism rampant in the U.S.,
it's only to be expected.

Cindy Hamilton

Thermometers: What's the Problem with Accuracy?
 

In alt.home.repair, on Sun, 04 Feb 2018 11:51:08 -0500,
"(PeteCresswell)" wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

That only works if the bulb is exactly the right size and the amount of
alcohol or mercury inside is exactly correct. I don't want to spend
too much just to get accuracy that won't really help me.

- Each reads a different temp from 68 to 74 degrees.

Last time I bought a thermometer, about 40 years ago (not counting a
digital one that claims to measure humidity), a glass one, there were
about 8 on the rack and I looked at each temp and bought one whose
reading was part of the cluster of readings very close to each other.

What more could I do.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

I don't think the card is the problem. Glass thermometers sometimes or
always have a scratch, a file mark, at 32 degrees, on one side of the
tube, I've read. I've never looked closely and I've never seen the
mark, but it makes sense (and it contradicts my first paragraph above,
come to think of it). They'd put all the thermometers in a mixture of
melting ice and water, maybe even in a refrigerated room. Pull them out
one at a time and file the scratch wherever the level happens to be.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?

Cynicism. Hopelessness.

Thermometers: What's the Problem with Accuracy?
 

On 02/04/2018 11:01 AM, wrote:
Digital stuff itself is what I call the great lie. They give you a
very precise reading, that is usually wrong. I have an $8000 (MSRP)
digital water tester from the state that we have to calibrate before
and after every use and about 10-15% of the time, they do not pass the
verification calibration after the test on at least one parameter.

There are a lot of slips betwixt that cup and lip. I worked for a
company that made pH and ion concentration meters. First you start with
the sensor, which was a Ross electrode in this case. They aren't
identical out of the gate and their characteristics change over time.
The output is fed to an AD converter, which introduces sampling errors
depending on how good the converter is and the rate at which you read
the output. There is noise that has to be cleaned up and finally a
number is obtained. That is fed through the algorithm is question to get
a ion concentration or ph. Finally you wind up with the magic 5.376,
which is precisely displayed on the readout.

Thermistors, thermocouples, glass electrodes, LVDTs and so forth are a
pain in the butt to calibrate and keep in calibration.

Philosophically speaking the entire project to convert the real world to
mathematical equations has been a product of human hubris. It's been
handy at times but it isn't real.

Thermometers: What's the Problem with Accuracy?
 

On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:

On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734


As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C

Thermometers: What's the Problem with Accuracy?
 

On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?

Pete,

Maybe check here. I never knew so little until I bought a good unit
for my outdoor meat smokers and instant read (few seconds) units. It
can with a certificate of accuracy +/- .

I very much doubt cheap units can be calibrated.

"... Find info on instrumentation, sensors, measurement and control,
calibration and a variety of commercial applications."

https://www.thermoworks.com/learning-center

Thermometers: What's the Problem with Accuracy?
 

On 2/4/2018 1:52 PM, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:
....

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
....

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C

Precisely...since US doesn't have the culture that guv'mint can enforce
stuff like this universally on the general public, popular usage remains
(similar as to having kept almost exclusively other US/Imperial measures
as well).

I'm a nuclear engineer by BS, MS Physics (Nuclear Science) and spent
over 30 year in the traces and still, while I'm capable of thinking
through roughly what C corresponds to F and vice versa, it's still only
just native F that really resonates; it's just the system that is ingrained.

While in the reactor design world, all the nuclear calculations were in
conventional metric units (scaled for the purpose, for example, nuclear
absorption cross sections are in "barns", a barn being 10E-24 cm^2) but
all the thermo guys were in English units so we consistently used core
inlet/outlet temperatures of 555/605F and had (and still remember many)
values of the steam tables such as that Tsat at 2200 psia is 649.45 F
(although those are like 1977 Table values; they've been updated so
probably a hundredth or few off currently-published numbers).

I'm sure in the now almost 40 years since last actually worked inside a
reactor vendor (spent last 20+ yr consulting for various utilities and
US DOE rather than with vendor) the design protocol will have all moved
to metric just for the consistency. We began the process even while I
was still at the vendor when teaming with German and French partners;
their licensing authorities at the time required it although it never
changed our practices in the US.

The argument has raged forever and while there are valid reasons for
metric in business and industry and inside those fields things have gone
almost universally that way, there's just no overpowering reason that
familiar units must change so the status quo remains and new generations
continue to be reared with no practical day-to-day acquaintance with
them so they also are only innately comfortable with F for temp and the
cycle continues...

--

Thermometers: What's the Problem with Accuracy?
 

On Sunday, February 4, 2018 at 2:52:17 PM UTC-5, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:

On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734


As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C

I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

Cindy Hamilton

Thermometers: What's the Problem with Accuracy?
 

Per :

http://www.leevalley.com/us/garden/P...=2,40733,40734


But the question is: if you put five of those things side-by-side, how many
of them will read the same temperature - and will it be the correct
temperature.
--
Pete Cresswell

Thermometers: What's the Problem with Accuracy?
 

On Sun, 4 Feb 2018 13:29:51 -0800 (PST), Cindy Hamilton
wrote:

I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

Cindy Hamilton

Think of it as "close enough for government work."

Trust me I'm from the government, I'm here to help.

....or as Bubba says, "it looks good from my house!"

Thermometers: What's the Problem with Accuracy?
 

On 2/4/2018 3:32 PM, (PeteCresswell) wrote:
Per :

http://www.leevalley.com/us/garden/P...=2,40733,40734


But the question is: if you put five of those things side-by-side, how many
of them will read the same temperature - and will it be the correct
temperature.

Ask Lee Valley for spec's and see if they are anything but fancied up
Chinese imports or no...I'd guess probably not, but ya' never know 'til
you ask. :)

--

Thermometers: What's the Problem with Accuracy?
 

On Sunday, February 4, 2018 at 2:52:17 PM UTC-5, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:

On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734


As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C
Exactly.

Unlike the metric system for mass, length, volume, etc., there is no calculation advantage to using C over F.

They are both 100 point scales invented by Europeans. The C scale is 100 degrees between freezing and boiling, the F scale is 100 degrees between how cold and how hot it normally got outside in Europe.

Thermometers: What's the Problem with Accuracy?
 

http://www.leevalley.com/us/garden/P...=2,40733,40734


But the question is: if you put five of those things side-by-side, how many
of them will read the same temperature - and will it be the correct
temperature.


They are accurate.
Buy a more expensive one if you want ...
http://tinyurl.com/y89uxh4j

+ / - 1 degree
http://tinyurl.com/y9cc7re6

John T.

Thermometers: What's the Problem with Accuracy?
 

On Sun, 04 Feb 2018 17:21:58 -0500, wrote:


http://www.leevalley.com/us/garden/P...=2,40733,40734


But the question is: if you put five of those things side-by-side, how many
of them will read the same temperature - and will it be the correct
temperature.


They are accurate.
Buy a more expensive one if you want ...
http://tinyurl.com/y89uxh4j
+ / - 1 degree $ 100. ..
http://tinyurl.com/y9cc7re6
John T.


+ / - 2 degrees for $ 10.

http://tinyurl.com/y7bgvwrr

John T.

Thermometers: What's the Problem with Accuracy?
 

Per Cindy Hamilton:
I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

My take is that when you're out in it a couple degrees, or even 1 degree F
can be significant and it seems easier to say "Fifty-One: than
"Ten-point-six".

Or do people who use Celsius just drop the decimal and say "Ten-six"?


--
Pete Cresswell

Thermometers: What's the Problem with Accuracy?
 

On 2/4/2018 10:51 AM, (PeteCresswell) wrote:
I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.
....


Isotech TTI-22 True Temperature Indicator
Thermometer with 0.001°C accuracy and 0.0001°C resolution

And, it's a bargain at _only_ $6,073.00!!!

But, you get:

Includes
FREE Ground Shipping
FREE Lifetime Tech Support

:)

Omega has a line of low-cost glass lab thermometers but don't specify
accuracy on them, either; they have others of lab quality that are $10+
or so each instead of $5-6.

They used to have an ambient-air monitor that was pretty good that we
used to use to monitor air temp around the boilers but it doesn't seem
to be available any longer and the one other I looked at from another
vendor was also listed as discontinued. That's all the time I had...

The problem with inexpensive bulb thermometers is that the capillary
dimension has to be exceedingly precise in order to control both the
linearity and scaling and doing that drives the price up -- actually,
like matching v-belts; to get precise ones they would just select from
the run those that matched given calibration but as somebody else noted,
the ordinary Walmart/drugstore/etc., ones will not have gone through
much if any screening at all; what you get is a measure of the
manufacturing process variability by doing the comparisons you've done.

But, the time/effort required to do screening adds up so even moderately
accurate ones get to be fairly pricey pretty quickly.

If a bulb thermometer serves the purpose, probably one of the
secondary-school lab suppliers or the like will be the best bet.

--

Thermometers: What's the Problem with Accuracy?
 

On 2/4/2018 3:29 PM, Cindy Hamilton wrote:
....

I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.
....

Well, there's the same question around 212, too, from that standpoint... :)

I ran into a minor instance here just recently -- fixed up a monitoring
system in the well house to alert me if the temperature drops that
indicates I need to go relight the gas heater (occasionally the high KS
wind will manage to blow out the pilot). I used a cute little $6
digital thermostat module in "heat" mode to turn on an LED in the window
I can see if temp drops below setpoint.

I just stuck the RTD sensor inside the small project box I mounted the
controller in and velcro-ed it to the wall near the power outlet on the
plywood backer board for the electrical panel, etc. Since the block
building walls aren't insulated, it gets pretty cool right on the wall
surface so wasn't sure where would need to set the setpoint to not false
alarm on really cold days even though the little heater keeps the bulk
air temperature around 50F. Started at 5C -- 41F and we had some
bitter nights shortly thereafter and it triggered. So, not wanting to
try to cut it too close, 1F is ~0.5F so lowered it to 4.5F and added
3/4" of foam packing between the solid wood board mount and the unit.

So far, it's not triggered again but it's not been below zero again
since, either; we'll just "hide and watch" and see how it goes.

But, long-winded that got me wondering; are European
thermostats/thermometers registering tenths or are they using 1C
setpoint tolerances? I can tell difference in our house between a 69F
where we normally keep for winter and 70F setpoint; there's a
significant run-time difference as well so if it were 20C or 21C that
were the choices, the 20C -- 68F is notably chilly and so 70F would be
next best granularity could get and that would, over time, be observable
in heating bills.

Not huge, but "yes, I think it can make a difference" in ordinary things...

--

Thermometers: What's the Problem with Accuracy?
 

On Sun, 4 Feb 2018 13:29:51 -0800 (PST), Cindy Hamilton
wrote:


I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

Cindy Hamilton

Yep. Pretty easy to tell if the milk is cold or the ice cream is melting.
Out of curiosity I checked the 3 thermometers in my house.
They are an "alcohol" wall thermo, digital thermostat, and digital meat thermo.
All of them read 70F.
Maybe those measuring cold are inaccurate.

Thermometers: What's the Problem with Accuracy?
 

On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.
--
Bod


Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^

[8~{} Uncle Temperate Monster

Thermometers: What's the Problem with Accuracy?
 

On 02/04/2018 03:33 PM, (PeteCresswell) wrote:
Per Cindy Hamilton:
I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

My take is that when you're out in it a couple degrees, or even 1 degree F
can be significant and it seems easier to say "Fifty-One: than
"Ten-point-six".

Or do people who use Celsius just drop the decimal and say "Ten-six"?



From what I've seen as far as weather goes fractional values aren't
used. It's -2 in Berlin at 0500 and will hit a high of 2 with -6
overnight on Tuesday

Thermometers: What's the Problem with Accuracy?
 

On Sunday, February 4, 2018 at 3:29:56 PM UTC-6, Cindy Hamilton wrote:
On Sunday, February 4, 2018 at 2:52:17 PM UTC-5, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:

On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands)..
Canada retains it as a supplementary scale that can be used alongside
Celsius.

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C

I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

Cindy Hamilton


As far as human comfort goes, it's the humidity that counts. 72°F at 50% humidity is more comfortable 72°F at 90% humidity. I serviced and installed HVAC systems back when I was doing service work for businesses. I like 2 stage AC systems because they control humidity much better. The newest more advanced(more expensive) HVAC systems are variable giving a more precise control of humidity. ^_^

[8~{} Uncle Chilly Monster
[8~{} Uncle Humid Monster

Thermometers: What's the Problem with Accuracy?
 

Bod wrote: "- show quoted text -
As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use/"

The scale used has nothing to do
with the accuracy(or inaccuracy) of
the thermometers Pete tested.

Thermometers: What's the Problem with Accuracy?
 

On 04/02/2018 19:52, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:

On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.



http://www.leevalley.com/us/garden/P...=2,40733,40734


As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C

Understood, but C has become the universal standard.

--
Bod

Thermometers: What's the Problem with Accuracy?
 

On 04/02/2018 20:49, dpb wrote:
On 2/4/2018 1:52 PM, wrote:
On Sun, 4 Feb 2018 17:54:48 +0000, Bod wrote:
...

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
...

We use what we are used to. OTOH Fahrenheit gives you about twice the
precision without resorting to decimals. I am comfortable with both
since my science friends are all C

Precisely...since US doesn't have the culture that guv'mint can enforce
stuff like this universally on the general public, popular usage remains
(similar as to having kept almost exclusively other US/Imperial measures
as well).

I'm a nuclear engineer by BS, MS Physics (Nuclear Science) and spent
over 30 year in the traces and still, while I'm capable of thinking
through roughly what C corresponds to F and vice versa, it's still only
just native F that really resonates; it's just the system that is
ingrained.

While in the reactor design world, all the nuclear calculations were in
conventional metric units (scaled for the purpose, for example, nuclear
absorption cross sections are in "barns", a barn being 10E-24 cm^2) but
all the thermo guys were in English units so we consistently used core
inlet/outlet temperatures of 555/605F and had (and still remember many)
values of the steam tables such as that Tsat at 2200 psia is 649.45 F
(although those are like 1977 Table values; they've been updated so
probably a hundredth or few off currently-published numbers).

I'm sure in the now almost 40 years since last actually worked inside a
reactor vendor (spent last 20+ yr consulting for various utilities and
US DOE rather than with vendor) the design protocol will have all moved
to metric just for the consistency.Â* We began the process even while I
was still at the vendor when teaming with German and French partners;
their licensing authorities at the time required it although it never
changed our practices in the US.

The argument has raged forever and while there are valid reasons for
metric in business and industry and inside those fields things have gone
almost universally that way, there's just no overpowering reason that
familiar units must change so the status quo remains and new generations
continue to be reared with no practical day-to-day acquaintance with
them so they also are only innately comfortable with F for temp and the
cycle continues...

--

I was brought up on Fahrenheit, but soon adapted to C which is so
straightforward for everyday use once you get used to it and you soon
get used to it. It's so much more logical with 0 being freezing and a
100 for boiling, IMO.
--
Bod

Thermometers: What's the Problem with Accuracy?
 

On 05/02/2018 00:34, Uncle Monster wrote:
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.
--
Bod


Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^

[8~{} Uncle Temperate Monster

I grew up on Fahrenheit and the change to Centigrade was virtually
seamless, you quickly adapt. So now I'm comfortable reading both scales,
but C is so much more practical for everday use, plus it is the
universal standard.
Why stubbornly stick to last century thermal measurements!

--
Bod

Thermometers: What's the Problem with Accuracy?
 

On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote in

- Each reads a different temp from 68 to 74 degrees.

For cheap thermometers, that's not bad. Just take the average of the
four and then calculate the difference between the average and each of
the four and use that as a correction factor for each of the four.
That will probably bring you to a 99.9% accuracy for each of the four.

--
Web based forums are like subscribing to 10 different newspapers
and having to visit 10 different news stands to pickup each one.
Email list-server groups and USENET are like having all of those
newspapers delivered to your door every morning.

Thermometers: What's the Problem with Accuracy?
 

On 05/02/2018 01:58, wrote:
Bod wrote: "- show quoted text -
As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use/"

The scale used has nothing to do
with the accuracy(or inaccuracy) of
the thermometers Pete tested.

Indeed, that's why I said "as an aside".

--
Bod

Thermometers: What's the Problem with Accuracy?
 

On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote:
On 05/02/2018 00:34, Uncle Monster wrote:
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands)..
Canada retains it as a supplementary scale that can be used alongside
Celsius.
--
Bod

Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^

[8~{} Uncle Temperate Monster

I grew up on Fahrenheit and the change to Centigrade was virtually
seamless, you quickly adapt. So now I'm comfortable reading both scales,
but C is so much more practical for everday use, plus it is the
universal standard.
Why stubbornly stick to last century thermal measurements!
--
Bod


We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^

[8~{} Uncle Ornery Monster

Thermometers: What's the Problem with Accuracy?
 

On 05/02/2018 07:37, Uncle Monster wrote:
On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote:
On 05/02/2018 00:34, Uncle Monster wrote:
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.
--
Bod

Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^

[8~{} Uncle Temperate Monster

I grew up on Fahrenheit and the change to Centigrade was virtually
seamless, you quickly adapt. So now I'm comfortable reading both scales,
but C is so much more practical for everday use, plus it is the
universal standard.
Why stubbornly stick to last century thermal measurements!
--
Bod


We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^

[8~{} Uncle Ornery Monster

I've noticed, plus:

Of all the countries in the world, only three still use the archaic
Imperial system of weights and measures:

Liberia.
Myanmar (a.k.a. €œthe country formerly known as Burma€�)
United States of America.

--
Bod

Thermometers: What's the Problem with Accuracy?
 

"(PeteCresswell)" wrote:
I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?

Best way of testing bulb thermometers is insert in water beaker with
stirring mechanism for rapid low. Add ice should be hear 32 degrees. Air
currents can be tricky and scales can slip. +- 1 degree typical variance.
My two outside units are at least 3 degrees off. Can't find easy way to
cal. Some resistors probably need tweaked.

Greg

Thermometers: What's the Problem with Accuracy?
 

On Sunday, February 4, 2018 at 5:33:30 PM UTC-5, (PeteCresswell) wrote:
Per Cindy Hamilton:
I've never understood the "precision" argument. Does it matter whether
it's 70, 71, or 72 F ? I suppose 31, 32, and 33 F are more significant.

My take is that when you're out in it a couple degrees, or even 1 degree F
can be significant and it seems easier to say "Fifty-One: than
"Ten-point-six".

Or do people who use Celsius just drop the decimal and say "Ten-six"?

They would just say 10. At http://www.cbc.ca/windsor/weather/s0000646.html,
the current temperature is -14 and today's high is expected to be -5.
That's for Windsor, which is a short drive from where I am.

Cindy Hamilton

Thermometers: What's the Problem with Accuracy?
 

On Monday, February 5, 2018 at 2:52:26 AM UTC-5, Bod wrote:
On 05/02/2018 07:37, Uncle Monster wrote:
On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote:
On 05/02/2018 00:34, Uncle Monster wrote:
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.
--
Bod

Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^

[8~{} Uncle Temperate Monster

I grew up on Fahrenheit and the change to Centigrade was virtually
seamless, you quickly adapt. So now I'm comfortable reading both scales,
but C is so much more practical for everday use, plus it is the
universal standard.
Why stubbornly stick to last century thermal measurements!
--
Bod


We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^

[8~{} Uncle Ornery Monster

I've noticed, plus:

Of all the countries in the world, only three still use the archaic
Imperial system of weights and measures:

Liberia.
Myanmar (a.k.a. €œthe country formerly known as Burma€�)
United States of America.

It's surprising how much "secret" adoption of SI has gone on here.
Two-liter bottles of Coke. 750-ml bottles of wine. My husband
has both metric and English tools in his workshop. And of course
we use the same second as the rest of the world.

Cindy Hamilton

Thermometers: What's the Problem with Accuracy?
 

On 2/4/2018 11:51 AM, (PeteCresswell) wrote:
I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

For Instance:

- 4 thermometers of same make/model, hanging on the same rack.

- Alcohol bulb/glass tube - you'd think basic physics...

- Each reads a different temp from 68 to 74 degrees.

Only thing I can think of is that the card behind the glass thingie is
misaligned, but looking at these things, there does not seem to be enough
physical room for those kinds of errors.

Also, at home I have a couple of digital indoor/outdoor thermometers.

Bring the outdoor sensor inside and put it right next to the master part, and
they're a couple degrees different.

Is there any hope at all of finding four thermometers which:

- All read the same temp when placed side-by-side
- Read the correct temp.

What am I missing?



You have a refrigerator/freezer reading in the high 60s to low 70s. You
have bigger problems than an inaccurate thermometer.

Thermometers: What's the Problem with Accuracy?
 

On 05/02/2018 11:42, Cindy Hamilton wrote:
On Monday, February 5, 2018 at 2:52:26 AM UTC-5, Bod wrote:
On 05/02/2018 07:37, Uncle Monster wrote:
On Monday, February 5, 2018 at 12:33:16 AM UTC-6, Bod wrote:
On 05/02/2018 00:34, Uncle Monster wrote:
On Sunday, February 4, 2018 at 11:54:53 AM UTC-6, Bod wrote:
On 04/02/2018 17:11, wrote:
On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote:

I've been trying to buy four refrigerator/freezer thermometers and it's
frustrating how inaccurate/inconsistent they are.

http://www.leevalley.com/us/garden/P...=2,40733,40734

As an aside, I'm surprised that the US is still using Fahrenheit instead
of the universal Centigrade.
There's only about 8 countries that still use F.

Fahrenheit remains the official scale for the following countries:

The Bahamas, Belize, the Cayman Islands, Palau and the United States and
associated territories (Puerto Rico, Guam and the U.S. Virgin Islands).
Canada retains it as a supplementary scale that can be used alongside
Celsius.
--
Bod

Bulb type thermometers here in The U.S. have both scales printed on them and digital thermometers can switch from one to the other. It's whatever you grew up with that determines your point of view. Of course, someone working in the field of chemistry or physics is probably going to prefer the Centigrade scale. ^_^

[8~{} Uncle Temperate Monster

I grew up on Fahrenheit and the change to Centigrade was virtually
seamless, you quickly adapt. So now I'm comfortable reading both scales,
but C is so much more practical for everday use, plus it is the
universal standard.
Why stubbornly stick to last century thermal measurements!
--
Bod


We Americans are more ornery and resistant to changing our habits than other people of the world. ^_^

[8~{} Uncle Ornery Monster

I've noticed, plus:

Of all the countries in the world, only three still use the archaic
Imperial system of weights and measures:

Liberia.
Myanmar (a.k.a. €œthe country formerly known as Burma€�)
United States of America.

It's surprising how much "secret" adoption of SI has gone on here.
Two-liter bottles of Coke. 750-ml bottles of wine. My husband
has both metric and English tools in his workshop. And of course
we use the same second as the rest of the world.

Cindy Hamilton

I see.

--
Bod

Thermometers: What's the Problem with Accuracy?
 

It's surprising how much "secret" adoption of SI has gone on here.
Two-liter bottles of Coke. 750-ml bottles of wine.
And we use the same second as the rest of the world.


.... it just seems much longer - since the Scary Clown :-)