Reply by Mat Nieuwenhoven●January 4, 20212021-01-04
On Mon, 04 Jan 2021 04:09:06 -0800, Rick C wrote:
> On Monday, January 4, 2021 at 4:03:54 AM UTC-5, Brett wrote:
>> Mat Nieuwenhoven <mni...@zap.a2000.nl> wrote:
>> > Well, I've measured the fridge's energy use for 25 days. Extrapolated
>> > to a year it used 118 kWh, let's say 130 because in summer our
>> > kitchen is warmer.
>> Times 11 cents a kWh in Texas that’s about 14 dollars a year if I have
>> done the math right. Never going to be cost effective to replace.
>>
>> Can I assume no kids at home as that could multiply the result by four.
Indeed no kids at home normally. But the result doesn't get much higher
even then. I saw a minor increase over the festive season when it was
used much more.The cooler door bleeps if is it is open for longer than a
short time (a minute or so).
>> > It ran 38% of the time. If I take freezer and cooler volume together
>> > (330 liter), then it comes out to 0.39 kWh per liter per year.
> This is a very small refrigerator, approx 11 cu ft. But even so, this
> energy usage is very, very low, about 13.5 watts.
You mean on average over the year if it were running continuously? White-
good equipment like a fridge or washing machine in the EU must be
specified in kWh/year based on a prescribed use pattern. Our model is
specified for 167 kWh/year. It was not even the most efficient in the
catalog, there were other considerations too. It is this model without
the no-frost:
https://home.liebherr.com/en/deu/products/household-appliances/floor-
mounted-appliances-for-households/freestanding-fridge-freezers/details/
cnp-4813_89392.html
I guess for most households here this is upper middle class fridge/cooler
with vertically stacked cool/freeze section. About 60 cm wide which is a
standard here for kitchen cabinets. You can buy side-by-side freeze/
coolers, but they are much less efficient and not many people have the
space for it. Those who want a large freezer frequently have a box-type
(lid on top) freezer in the cellar of garden shed. Our kitchen is
250x250cm exactly, and I guess that is about normal for standard houses.
But you don't really need much storage because the supermarkets are
usually close (walking or bicycling distance). I guess if you buy things
once a week for the whole week you'd need more. But if we have a three-
course meal for 9 persons, indeed space is tight.
> When you open the
> door and the light bulb comes on the energy use quadruples.
3.6 W according to my power meter. The light is a bright LED at the top
front shining downwards, which illuminates the cooling section very well.
But even on older fridges we had the bulb was only 5W or so.
> I believe > he already said his unit has no defrost cycle, so that
alone makes it > very different from 99.9% of the units sold in the US.
The cooling section doesn't need one, because it's minimum temperature is
+ 1 centigrade, and like I wrote before, there is no air connection
between freezing and cooling sections. We could get almost the same model
with no-frost in the freezer section, but it used like 50% more energy,
and that's not worth it for us. There's not much ice accumulating there
anyway.
> Even so, I find the numbers to be surprising.
Energy efficiency is very important here. Most people would pay 23
eurocent/kWh . In test of consumer organizations energy use is a major
point for any product. Cheaper models are usually worse on energy use per
liter. I don't think there are double-door models that rely on airflow
from freezing to cooling section.
Mat Nieuwenhoven
Reply by Rick C●January 4, 20212021-01-04
On Monday, January 4, 2021 at 4:03:54 AM UTC-5, Brett wrote:
> Mat Nieuwenhoven <mni...@zap.a2000.nl> wrote:
> > On Sun, 06 Dec 2020 15:04:45 -0800, Rick C wrote:
> >
> >> On Sunday, December 6, 2020 at 11:56:06 AM UTC-5, Mat Nieuwenhoven
> >> wrote:
> >>> On Mon, 30 Nov 2020 07:46:30 -0800 (PST), Rick C wrote:
> >>>
> >>> <snip>
> >>>> You need to learn how to read specs. The first 1.5% applies to the
> >>>> full range I suspect and the total error is the sum of the two or the
> >>>> greater of the two.
> >>> No, it is 1.5% of the reading OR 1.5 C, whatever is greater. Incomplete
> >>> spec, because they don't say if it is for C or F (I suspect C as it is
> >>> an european device), Because it can do F and C, therefore in F 1.5% of
> >>> reading would be more accurate. Below 0 C is it less accurate, 3% or
> >>> degrees.
> >>>> Stop pretending these devices are accurate. Try measuring a dozen
> >>>> different locations in the fridge. You will get a dozen different
> >>>> readings with a ±1°C range. That's just the variation and does not set
> >>>> the accuracy.
> >>> Well, higher in the fridge is is somewhat warmer, as specified in the
> >>> user's manual. Different packages inside the fridge give different
> >>> readings (by several degrees), likeley due to differences in
> >>> emissivity.
> >>>
> >>> I have started to measure the fridge's energy consumption today. While
> >>> running, the fridge takes 55 to 66 W (it really varies) , I wonder if
> >>> it has a multispeed compressor. Assuming 60 W average, then after some
> >>> days, I should be able to determine how much % of the time the fridge
> >>> is on.
> >>
> >> I put my fridge on a timer to not run when the power is expensive, 3
> >> hrs, twice a day it is cut off. I measure about 1 or 2 degree rise in
> >> temperature, but only by looking in small spaces.
> >>
> >> Funny thing about emissivity, if you point your thermometer at a shiny
> >> box of frozen food or a shiny plastic bag the heat from the outside
> >> radiates inward and is reflected back into your thermometer, raising the
> >> reading significantly. So if I just take every temperature I see in
> >> the freezer, after sitting with the door closed for three hours, I will
> >> find up to 10 degree variations which is pure BS. It's the variation in
> >> emissivity and the room warmth reflecting back to the thermometer. The
> >> low readings can't be false however unless the fridge were actually a
> >> heater keeping the food from freezing while in an arctic environment.
> >>
> >> I turned my thermostat up in the fridge and also adjusted the flap away
> >> from the coldest setting. I think the flap was virtually closed cutting
> >> off effective cooling from the fridge and causing the motor to run
> >> constantly. I can see it now cycles and can even see the defrost cycle
> >> where it runs the heater and leaves the compressor off for a while.
> >>
> >> The power variation is from temperature differences. If the returning
> >> gas is warmer it takes more work to compress it. That reminds me, I
> >> need to clean the coils.
> >
> > Well, I've measured the fridge's energy use for 25 days. Extrapolated to
> > a year it used 118 kWh, let's say 130 because in summer our kitchen is
> > warmer.
> Times 11 cents a kWh in Texas that’s about 14 dollars a year if I have done
> the math right. Never going to be cost effective to replace.
>
> Can I assume no kids at home as that could multiply the result by four.
> > It ran 38% of the time. If I take freezer and cooler volume together (330
> > liter), then it comes out to 0.39 kWh per liter per year.
This is a very small refrigerator, approx 11 cu ft. But even so, this energy usage is very, very low, about 13.5 watts. When you open the door and the light bulb comes on the energy use quadruples. I believe he already said his unit has no defrost cycle, so that alone makes it very different from 99.9% of the units sold in the US.
Even so, I find the numbers to be surprising.
--
Rick C.
++- Get 1,000 miles of free Supercharging
++- Tesla referral code - https://ts.la/richard11209
Reply by Don Y●January 4, 20212021-01-04
On 1/3/2021 4:03 AM, Mat Nieuwenhoven wrote:
> Well, I've measured the fridge's energy use for 25 days. Extrapolated to
> a year it used 118 kWh, let's say 130 because in summer our kitchen is
> warmer.
> It ran 38% of the time. If I take freezer and cooler volume together (330
> liter), then it comes out to 0.39 kWh per liter per year.
That would be a tiny refrigerator, here (USA). Ours is ~600L and it's
just "modest" in size (two people).
It's old so not terribly efficient -- ~800KWHr/yr.
OTOH, it doesn't cost us much to run (~$8/month) -- any one of my servers
or workstations (+ monitors) easily consumes more on an annual basis (as
they have considerably higher operating duty cycles).
And, of course, with a 9-10 month cooling season, money spent to cool
FOOD is negligible compared to what it costs to keep PEOPLE cool!
Reply by Brett●January 4, 20212021-01-04
Mat Nieuwenhoven <mnieuw@zap.a2000.nl> wrote:
> On Sun, 06 Dec 2020 15:04:45 -0800, Rick C wrote:
>
>> On Sunday, December 6, 2020 at 11:56:06 AM UTC-5, Mat Nieuwenhoven
>> wrote:
>>> On Mon, 30 Nov 2020 07:46:30 -0800 (PST), Rick C wrote:
>>>
>>> <snip>
>>>> You need to learn how to read specs. The first 1.5% applies to the
>>>> full range I suspect and the total error is the sum of the two or the
>>>> greater of the two.
>>> No, it is 1.5% of the reading OR 1.5 C, whatever is greater. Incomplete
>>> spec, because they don't say if it is for C or F (I suspect C as it is
>>> an european device), Because it can do F and C, therefore in F 1.5% of
>>> reading would be more accurate. Below 0 C is it less accurate, 3% or
>>> degrees.
>>>> Stop pretending these devices are accurate. Try measuring a dozen
>>>> different locations in the fridge. You will get a dozen different
>>>> readings with a ±1°C range. That's just the variation and does not set
>>>> the accuracy.
>>> Well, higher in the fridge is is somewhat warmer, as specified in the
>>> user's manual. Different packages inside the fridge give different
>>> readings (by several degrees), likeley due to differences in
>>> emissivity.
>>>
>>> I have started to measure the fridge's energy consumption today. While
>>> running, the fridge takes 55 to 66 W (it really varies) , I wonder if
>>> it has a multispeed compressor. Assuming 60 W average, then after some
>>> days, I should be able to determine how much % of the time the fridge
>>> is on.
>>
>> I put my fridge on a timer to not run when the power is expensive, 3
>> hrs, twice a day it is cut off. I measure about 1 or 2 degree rise in
>> temperature, but only by looking in small spaces.
>>
>> Funny thing about emissivity, if you point your thermometer at a shiny
>> box of frozen food or a shiny plastic bag the heat from the outside
>> radiates inward and is reflected back into your thermometer, raising the
>> reading significantly. So if I just take every temperature I see in
>> the freezer, after sitting with the door closed for three hours, I will
>> find up to 10 degree variations which is pure BS. It's the variation in
>> emissivity and the room warmth reflecting back to the thermometer. The
>> low readings can't be false however unless the fridge were actually a
>> heater keeping the food from freezing while in an arctic environment.
>>
>> I turned my thermostat up in the fridge and also adjusted the flap away
>> from the coldest setting. I think the flap was virtually closed cutting
>> off effective cooling from the fridge and causing the motor to run
>> constantly. I can see it now cycles and can even see the defrost cycle
>> where it runs the heater and leaves the compressor off for a while.
>>
>> The power variation is from temperature differences. If the returning
>> gas is warmer it takes more work to compress it. That reminds me, I
>> need to clean the coils.
>
> Well, I've measured the fridge's energy use for 25 days. Extrapolated to
> a year it used 118 kWh, let's say 130 because in summer our kitchen is
> warmer.
Times 11 cents a kWh in Texas that’s about 14 dollars a year if I have done
the math right. Never going to be cost effective to replace.
Can I assume no kids at home as that could multiply the result by four.
> It ran 38% of the time. If I take freezer and cooler volume together (330
> liter), then it comes out to 0.39 kWh per liter per year.
>
> Mat Nieuwenhoven
>
Reply by Mat Nieuwenhoven●January 3, 20212021-01-03
On Sun, 06 Dec 2020 15:04:45 -0800, Rick C wrote:
> On Sunday, December 6, 2020 at 11:56:06 AM UTC-5, Mat Nieuwenhoven
> wrote:
>> On Mon, 30 Nov 2020 07:46:30 -0800 (PST), Rick C wrote:
>>
>> <snip>
>> >You need to learn how to read specs. The first 1.5% applies to the
>> >full range I suspect and the total error is the sum of the two or the
>> >greater of the two.
>> No, it is 1.5% of the reading OR 1.5 C, whatever is greater. Incomplete
>> spec, because they don't say if it is for C or F (I suspect C as it is
>> an european device), Because it can do F and C, therefore in F 1.5% of
>> reading would be more accurate. Below 0 C is it less accurate, 3% or
>> degrees.
>> >Stop pretending these devices are accurate. Try measuring a dozen
>> >different locations in the fridge. You will get a dozen different
>> >readings with a ±1°C range. That's just the variation and does not set
>> >the accuracy.
>> Well, higher in the fridge is is somewhat warmer, as specified in the
>> user's manual. Different packages inside the fridge give different
>> readings (by several degrees), likeley due to differences in
>> emissivity.
>>
>> I have started to measure the fridge's energy consumption today. While
>> running, the fridge takes 55 to 66 W (it really varies) , I wonder if
>> it has a multispeed compressor. Assuming 60 W average, then after some
>> days, I should be able to determine how much % of the time the fridge
>> is on.
>
> I put my fridge on a timer to not run when the power is expensive, 3
> hrs, twice a day it is cut off. I measure about 1 or 2 degree rise in
> temperature, but only by looking in small spaces.
>
> Funny thing about emissivity, if you point your thermometer at a shiny
> box of frozen food or a shiny plastic bag the heat from the outside
> radiates inward and is reflected back into your thermometer, raising the
> reading significantly. So if I just take every temperature I see in
> the freezer, after sitting with the door closed for three hours, I will
> find up to 10 degree variations which is pure BS. It's the variation in
> emissivity and the room warmth reflecting back to the thermometer. The
> low readings can't be false however unless the fridge were actually a
> heater keeping the food from freezing while in an arctic environment.
>
> I turned my thermostat up in the fridge and also adjusted the flap away
> from the coldest setting. I think the flap was virtually closed cutting
> off effective cooling from the fridge and causing the motor to run
> constantly. I can see it now cycles and can even see the defrost cycle
> where it runs the heater and leaves the compressor off for a while.
>
> The power variation is from temperature differences. If the returning
> gas is warmer it takes more work to compress it. That reminds me, I
> need to clean the coils.
Well, I've measured the fridge's energy use for 25 days. Extrapolated to
a year it used 118 kWh, let's say 130 because in summer our kitchen is
warmer.
It ran 38% of the time. If I take freezer and cooler volume together (330
liter), then it comes out to 0.39 kWh per liter per year.
Mat Nieuwenhoven
Reply by Rick C●December 6, 20202020-12-06
On Sunday, December 6, 2020 at 11:56:06 AM UTC-5, Mat Nieuwenhoven wrote:
> On Mon, 30 Nov 2020 07:46:30 -0800 (PST), Rick C wrote:
>
> <snip>
> >You need to learn how to read specs. The first 1.5% applies to the full range I suspect and the total error is the sum of the two or the greater of the two.
> No, it is 1.5% of the reading OR 1.5 C, whatever is greater.
> Incomplete spec, because they don't say if it is for C or F (I
> suspect C as it is an european device), Because it can do F and C,
> therefore in F 1.5% of reading would be more accurate. Below 0 C is
> it less accurate, 3% or degrees.
> >Stop pretending these devices are accurate. Try measuring a dozen different locations in the fridge. You will get a dozen different readings with a ±1°C range. That's just the variation and does not set the accuracy.
> Well, higher in the fridge is is somewhat warmer, as specified in the
> user's manual. Different packages inside the fridge give different
> readings (by several degrees), likeley due to differences in
> emissivity.
>
> I have started to measure the fridge's energy consumption today.
> While running, the fridge takes 55 to 66 W (it really varies) , I
> wonder if it has a multispeed compressor. Assuming 60 W average, then
> after some days, I should be able to determine how much % of the time
> the fridge is on.
I put my fridge on a timer to not run when the power is expensive, 3 hrs, twice a day it is cut off. I measure about 1 or 2 degree rise in temperature, but only by looking in small spaces.
Funny thing about emissivity, if you point your thermometer at a shiny box of frozen food or a shiny plastic bag the heat from the outside radiates inward and is reflected back into your thermometer, raising the reading significantly. So if I just take every temperature I see in the freezer, after sitting with the door closed for three hours, I will find up to 10 degree variations which is pure BS. It's the variation in emissivity and the room warmth reflecting back to the thermometer. The low readings can't be false however unless the fridge were actually a heater keeping the food from freezing while in an arctic environment.
I turned my thermostat up in the fridge and also adjusted the flap away from the coldest setting. I think the flap was virtually closed cutting off effective cooling from the fridge and causing the motor to run constantly. I can see it now cycles and can even see the defrost cycle where it runs the heater and leaves the compressor off for a while.
The power variation is from temperature differences. If the returning gas is warmer it takes more work to compress it. That reminds me, I need to clean the coils.
--
Rick C.
+--+ Get 1,000 miles of free Supercharging
+--+ Tesla referral code - https://ts.la/richard11209
Reply by Mat Nieuwenhoven●December 6, 20202020-12-06
On Mon, 30 Nov 2020 07:46:30 -0800 (PST), Rick C wrote:
<snip>
>You need to learn how to read specs. The first 1.5% applies to the full range I suspect and the total error is the sum of the two or the greater of the two.
No, it is 1.5% of the reading OR 1.5 C, whatever is greater.
Incomplete spec, because they don't say if it is for C or F (I
suspect C as it is an european device), Because it can do F and C,
therefore in F 1.5% of reading would be more accurate. Below 0 C is
it less accurate, 3% or degrees.
>Stop pretending these devices are accurate. Try measuring a dozen different locations in the fridge. You will get a dozen different readings with a ±1°C range. That's just the variation and does not set the accuracy.
Well, higher in the fridge is is somewhat warmer, as specified in the
user's manual. Different packages inside the fridge give different
readings (by several degrees), likeley due to differences in
emissivity.
I have started to measure the fridge's energy consumption today.
While running, the fridge takes 55 to 66 W (it really varies) , I
wonder if it has a multispeed compressor. Assuming 60 W average, then
after some days, I should be able to determine how much % of the time
the fridge is on.
Mat Nieuwenhoven
Reply by Rick C●November 30, 20202020-11-30
On Monday, November 30, 2020 at 2:32:54 AM UTC-5, Mat Nieuwenhoven wrote:
> On Sun, 29 Nov 2020 17:57:42 -0800 (PST), Rick C wrote:
>
> >On Sunday, November 29, 2020 at 6:24:28 PM UTC-5, Grant Edwards wrote:
> >> On 2020-11-29, Mat Nieuwenhoven <mni...@zap.a2000.nl> wrote:
> >> > On Sat, 28 Nov 2020 20:53:51 +0000 (UTC), Grant Edwards wrote:
> >>
> >> >>Maybe they had two compressors. I thought most Bosch ones did.
> >> >
> >> > I did not see a second compressor. [...]
> >> >
> >> > I'm not sure that "a lot of european refrigerators" have two
> >> > compressors. Maybe the side-by-side fridges, they consume much more
> >> > energy.
> >> Maybe they just have two evaporator circuits and I've always
> >> misunderstood the brochure descriptions as meaning that there are two
> >> compressors.
> >
> >If they have a single compressor, it would be sized to match the coils... but which one? What happens if one compartment demands cooling while the other is already demanding cooling. Are both coils driven? If not, does one compartment continue to warm up while the other compartment is cooled? If both coils are connected to the single compressor at the same time, is the design optimized for working with both coils or just one?
> I bet boith coils are driven. There is a "super freeze" mode on it
> which you can use to cool down the freeze section quickly if you
> filled it completely with unfrozen food; that times out after 65
> hours. I've never used it on our current fridge, but on the old one
> twice or so, and the cooling section stayed on the temperature as
> set.as
How does that make any sense? If both coils are always driven, that is like having only one coil, the ratio of cooling is fixed. In fact, it is worse because with one coil a damper is used to control how much cooling applies to each compartment, adjustable by the user. With two coils always driven there's no way to change the apportioning.
I have no idea what your super freeze mode might be doing if the two compartments have no air flow between them there is no way for the second coil to help cool the freezer. What are you talking about?
> >Having two evaporators seems like a poor compromise no matter how you look at it. Two compressors is a lot more expensive, but would work most efficiently and effectively which I thought was the point of using two evaporator coils. I don't see anything wrong with using a single compressor circuit with it cooling both the freezer and fridge.
> Two compressors are rare. It must be one compressor with two coils.
> If the freeze section is below the cool section (which is the vast
> majority) , there cannot be air leak (cold doesn't move upwards)
> unless there is a ventilator to move the air around.
I don't know why you say the "vast majority" of units put the freezer in the bottom. Here very few units have the freezer in the bottom... VERY few. They are either freezer in top or side by side with tall skinny doors. A fan is not uncommon. My freezer in top uses a fan to improve heat exchange and it provides adjustable cooling to the lower refrigerator via the damper.
> >I've had mine on a power monitor for a day now and it seems to run most of the time at around 170 watts. I noticed overnight it cut off every couple of hours for about a half hour. I've also seen the power spike significantly, then dip for a half hour or so. I think that's the defrost cycle. It was accidentally turned off for a couple of hours today and the inside temperatures barely changed. Tomorrow the power monitor (which is actually a power timer switch) will cut if off from 6am to 9am. I'll measure the temp at 9am. I don't know if I can download a record of the usage. I should check. It keeps detailed info for a day and daily numbers for a month, then monthly data for a year. No, looks like no downloading possible.
> Seriously, 170 W and running most of the time? That could be 1000 kWh
> per year. Ours runs shortly every few hours, I have not timed it but
> it seems to be off most of the time. I'll see if there's a cheap
> logging power monitor to be had, just to log how often and long it
> runs. The actual energy use I can measure, but that device is in use
> for this week.
Yes, I agree, you have not timed it so you don't know how much it runs. My fridge is over 30 years old and may be having problems. A few months ago when the weather was warmer it was not keeping cold enough. I've been paying closer attention because of this. $156 is what I estimate annually. What I've read is the typical unit runs a third of the time. So I could save around $100 a year.
--
Rick C.
+--- Get 1,000 miles of free Supercharging
+--- Tesla referral code - https://ts.la/richard11209
Reply by Rick C●November 30, 20202020-11-30
On Monday, November 30, 2020 at 2:19:23 AM UTC-5, Mat Nieuwenhoven wrote:
> On Sun, 29 Nov 2020 11:10:59 -0800 (PST), Rick C wrote:
>
> >On Sunday, November 29, 2020 at 11:30:16 AM UTC-5, Mat Nieuwenhoven wrote:
> >> On Sat, 28 Nov 2020 09:05:12 -0800 (PST), Rick C wrote:
> >>
> >> >On Saturday, November 28, 2020 at 11:04:11 AM UTC-5, Mat Nieuwenhoven wrote:
> >> >> On Fri, 27 Nov 2020 06:58:53 -0800 (PST), Rick C wrote:
> >> >>
> >> >> <snip>
> >> >> >
> >> >> >How does your refrigerator control the temperatures of the two compartments when using a single compressor?
> >> >> I have not looked into it, but it does. The previous one (an 20+
> >> >> years old Bosch) did it too. There is no air connection between
> >> >> freeze and cool department. Both the old and new fridge both have a
> >> >> digital display where you set freeze and cool temperatures
> >> >> independently. They must have some valve or other control thing for
> >> >> it. In fact, some fridges have even different temparature zones
> >> >> inside the cooler department.
> >> >
> >> >Being able to set independent temperatures does not mean there are two coils with valves. It is much more likely to have a controlled damper to modulate the amount of cold air from the freezer entering the refrigerator. My refrigerator has a fan, but I can't say for sure where it blows, freezer only or freezer and refrigerator.
> >> Like I wrote above, there is _no_ connection between freeze and cool
> >> compartments. Not on our old and not on our current fridge. Both are
> >> combined freeze/cool fridges with the 3-drawer freeze section at the
> >> bottom. The cooler section has its coil after the back wall of the
> >> compartment, you can feel it getting colder if it's running. I wonder
> >> too if a controlled air movement damper is not more expensive than
> >> two on-off valves for freeze/cool coils, plus less prone to error.
> >> >> >If you set your refrigerator to -3°C, don't things freeze? My fridge would sometimes freeze things in the bottom when the temperature was set below 40°F (5°C).
> >> >> Never, because cool and freeze are completely independent, even
> >> >> though they must share the same motor, at least on my model, a
> >> >> Liebherr CP4813. The energy differences between modern fridges can
> >> >> run in the hundreds of kWhs per year, according to a consumer test
> >> >> here; energy use was a selection criteria for us.
> >> >
> >> >Sorry, I can't follow your reasoning. If you set the refrigerator temperature to -3°C, it should freeze things. Do I misunderstand the Celsius scale? Or does your refrigerator not keep things at the set temperature?
> >> Ah, I missed the minus sign, sorry. Yes it would freeze up, if I
> >> could do that, but the fridge won't allow me. I never tried it on the
> >> old one (also digitally controlled), but the current one allows
> >> selection only from +1 to +9 C for the cooler compartment. The freeze
> >> section is adjustable from -26 to -16 C.
> >>
> >> Control seems to be accurate too. If I measure the white back wall of
> >> the cooler compartment with an infrared thermometer, it is within 0.1
> >> C of the set 4 degrees centigrade. On white painted metal the
> >> measurement should be fairly accurate.
> >
> >The infrared thermometer you are using is likely ±3°C at best. You'll be luck to see ±2°C of consistency in temperatures around the inside of the fridge, so talking about that sort of accuracy is delving into fantasy. I would also point out that white is a poor color for emissivity and will give the worst result. Black gives a more accurate indication of it's own temperature, but the thermometer is calibrated for some value of emissivity and any other value gives additional error.
> You're right of course, the accuracy was unwarranted because of the
> unknown emissivity. The spec of the thermometer says +/- 1.5 % or
> +/- 1.5 % of the measured value (it goes up to 380 C). So in case it
> displays 4.0 C the accuracy is 0.06 C, and the single decimal is
> fully warranted.
> The emissivity is unknown, but I've measured multiple items with
> different colors on the same item, and it does not seem to vary much.
> The only significant deviation so far is on our central heating
> radiators where the thermostat valve is some kind of shiny metal: the
> radiator itself just behind the valve might read 61C, the valve
> itself through which the hot water enters the radiator reads 29C, and
> it is all metal.
You need to learn how to read specs. The first 1.5% applies to the full range I suspect and the total error is the sum of the two or the greater of the two.
Stop pretending these devices are accurate. Try measuring a dozen different locations in the fridge. You will get a dozen different readings with a ±1°C range. That's just the variation and does not set the accuracy.
--
Rick C.
-+++ Get 1,000 miles of free Supercharging
-+++ Tesla referral code - https://ts.la/richard11209
Reply by Chris●November 30, 20202020-11-30
On 11/30/20 07:01, Mat Nieuwenhoven wrote:
> On Sun, 29 Nov 2020 11:00:36 -0800 (PST), Rick C wrote:
>
>> On Sunday, November 29, 2020 at 3:43:55 AM UTC-5, Tauno Voipio wrote:
>>> On 29.11.20 4.07, Rick C wrote:
>>>> On Saturday, November 28, 2020 at 8:57:43 PM UTC-5, Richard Damon wrote:
>>>>> On 11/28/20 6:16 PM, Rick C wrote:
>>>>>> On Saturday, November 28, 2020 at 3:53:57 PM UTC-5, Grant Edwards wrote:
>>>>>>> On 2020-11-28, Mat Nieuwenhoven<mni...@zap.a2000.nl> wrote:
>>>>>>>> On Fri, 27 Nov 2020 06:58:53 -0800 (PST), Rick C wrote:
>>>>>>>>
>>>>>>>> <snip>
>>>>>>>>>
>>>>>>>>> How does your refrigerator control the temperatures of the two
>>>>>>>>> compartments when using a single compressor?
>>>>>>> Well, a lot of european refrigerators do have two compressors. I know
>>>>>>> mine does. There's no air connection between freezer and refrigerator
>>>>>>> and there are two completely separate thermostats.
>>>>>>>> I have not looked into it, but it does. The previous one (an 20+
>>>>>>>> years old Bosch) did it too.
>>>>>>> Maybe they had two compressors. I thought most Bosch ones did.
>>>>>>
>>>>>> That has to be an expensive refrigerator. Two of everything makes for a lot of works. I can't see the need. With the thermostat in the refrigerator and the evaporator around the freezer, the unit will run until the refrigerator is cold and by then the freezer will be adequately cold. That can be adjusted by adjusting the air flow between the two. I can't see adding a second compressor to take the place of an air damper.
>>>>>>
>>>>> You don't actually need a second compressor. You just need a seperate
>>>>> cooler coil to cool the refrigerator compartment, and control valves to
>>>>> select which cooling coils are being feed by the compressor based on the
>>>>> demands.
>>>>
>>>> That's not the issue. The issue is there is added cost with little gain.. Someone mentioned a unit with multiple freezer compartments. It would be a very specialized use to need multiple freezer compartments in a single refrigerator. None of that makes any sense to me.
>>>>
>>> There is the gain: you can keep the fridge slightly above freezing
>>> and the freeze side well frozen if there are two cooling systems.
>>> A single-compressor unit relies on suitable thermal leak out of
>>> the fridge side to keep the temperature difference between the
>>> compartments.
>>
>> Yes, an adjustable leak, although I think you are ignoring that the refrigerator compartment is where the thermostat is typically located. The adjustment process is to set the temperature of the refrigerator and adjust the damper to control the portion of cooling that reaches the refrigerator compartment with the rest remaining to cool the freezer. Adjust the damper to give the desired freezer temperature.
>>
>> The point is unless there is some reason why this won''t work in a particular case, the added cost of the multiple thermal zone is unwarranted.
>
> Well, one case is where you want seperate control in temperature of
> freeze and cool section. I've looked at a brochure, and in almost all
> cases the simpler fridges only let you adjust the temperature of the
> cooling secion. The freeze section is only specified as "3=1 stars"
> or so.
>
> Mat Nieuwenhoven
>
>
We have separate machines for fridge and freezer, which allows a lot
more choice of format and location. Freezer is in another room, with
the fridge under the worktop in the kitchen. If one fails, you don't
lose everything. Less efficient I guess, but more convenient. Both
are well over ten years old, but don't get obsessed over power
consumption...
Chris