Posted by amdx on June 24, 2010, 10:40 pm
--
MikeK
> wrote:
>>
>>> Ya! The initial purpose is to keep 12 chest freezers running.
>>
>>Zowie! Think about getting a walk-in freezer, dude! Twelve
>>chest freezers has a lot of surface area to insulate, one big
>>unit would be lower maintenance and less power usage.
> Well, let's do a little math based on actual data. I've logged all
> the power consumptions of all the appliances in my house and in my
> restaurant.
> Initial cost.
> An 8' square walk-in costs about $,000 installed. A large chest
> freezer is around $00 at Sam's Club. 12 freezers is $600. The win
> on initial cost goes to the chest freezer.
> Capacity: No contest - 12 large chest freezers hold far more than a
> walk-in because, well, one must leave room to walk around in the
> walk-in.
> Operating cost.
> The large chest freezer that I have in my home consumes $.41 a month
> in electricity. Multiply that by 12 and $2.92. My approx 10' X 6'
> walk-in freezer consumed $4.92/month measured during the summer
> months. Again, the win goes to the chest freezers. All measurements
> were done with calibrated revenue meters.
> http://www.neon-john.com/Misc/Energy_Audit.htm
> Reliability
> The walk-in has several single point failure vunerabilities. The
> condensing unit. The liquid solenoid valve. The defrost timer. The
> defrost heater. Etc. All failed during the 12 year life of that
> walk-in. Unfortunately the compressor failed during our vacation
> closing and all was lost. Insurance paid out about $000 for that
> one. If a chest freezer fails, he might lose those contents but the
> other 11 are still running. Win goes to the chest freezers.
> The one major area where the walk-in wins is cool-down. The chest
> freezers are so economical to operate because their refrigeration
> systems are just barely large enough to keep already-cold contents
> cold. Cool-down is very slow. The walk-in, OTOH, with its 3HP
> compressor and high velocity evaporator fans would freeze a steam
> table pan of boiling hot stew in about an hour.
> So based on the numbers, the correct advice is "keep the chest
> freezers, dude!"
Way cool man!
We actually have a walk in, 9' x 6' x 6' we ran it for a short time as
needed.
But haven't used it for 5 or 6 years, it seems to be good as a storage
locker at
this point. I plug it in occasionally just as maintenance.
My wife's gut feeling is that it uses a lot of electricity. She is quite
aware of where
the pennies go, so I didn't argue.
I like to have real numbers, thanks for the study you made.
As far as cool down, when we get shrimp to load in the freezers it is
already frozen.
If it wasn't, it would probably go bad before it froze! We usually put
about 600 lbs
in one freezer.
Mike
Posted by whit3rd on June 25, 2010, 9:12 am
> wrote:
> >> Ya! The initial purpose is to keep 12 chest freezers running.
> >Zowie! Think about getting a walk-in freezer, dude! Twelve
> >chest freezers has a lot of surface area to insulate, one big
> >unit would be lower maintenance and less power usage.
> Initial cost.
> An 8' square walk-in costs about $,000 installed. A large chest
> freezer is around $00 at Sam's Club. 12 freezers is $600. The win
> on initial cost goes to the chest freezer.
Not fair. The walk-in takes 64 sq feet of floor area, the
twelve chests take over twice that. What's the cost of
a building nowadays, $0 per square foot?
> Capacity: No contest - 12 large chest freezers hold far more than a
> walk-in because, well, one must leave room to walk around in the
> walk-in.
Again, unfair. Choose the right size of walk-in and redo that
argument.
> The large chest freezer that I have in my home consumes $.41 a month
> in electricity. Multiply that by 12 and $2.92. My approx 10' X 6'
> walk-in freezer consumed $4.92/month measured during the summer
> months. Again, the win goes to the chest freezers.
This sounds odd to me; firstly, a freezer indoors costs you twice,
once
in freezer electricity and (in summer) again in airconditioning cost.
Secondly, walk-in freezers ought to have the same efficiency as
a chest freezer, and should need less cooling because they have
similar insulation but lower external surface area.
> Reliability
> The walk-in has several single point failure vunerabilities. The
> condensing unit. The liquid solenoid valve. The defrost timer. The
> defrost heater. Etc. All failed during the 12 year life of that
> walk-in. Unfortunately the compressor failed during our vacation
> closing and all was lost. Insurance paid out about $000 for that
> one. If a chest freezer fails, he might lose those contents but the
> other 11 are still running. Win goes to the chest freezers.
Your 'spare' for the walk-in is gonna be a phone call to get
a refrigerated container delivered. Any trucking company can
do this for you. I'm dubious that you plan to lose all of
the contents of a chest if/when one fails, either. And with
twelve chest freezers, they're gonna fail twelve times as
often. Either way, your contingency plans should cover faults.
Posted by amdx on June 25, 2010, 12:06 pm
--
MikeK
> wrote:
> >> Ya! The initial purpose is to keep 12 chest freezers running.
> >Zowie! Think about getting a walk-in freezer, dude! Twelve
> >chest freezers has a lot of surface area to insulate, one big
> >unit would be lower maintenance and less power usage.
>> Initial cost.
>> An 8' square walk-in costs about $,000 installed. A large chest
>> freezer is around $00 at Sam's Club. 12 freezers is $600. The win
> on initial cost goes to the chest freezer.
>Not fair. The walk-in takes 64 sq feet of floor area, the
>twelve chests take over twice that. What's the cost of
>a building nowadays, $0 per square foot?
It is cubic feet, not floor area that counts. The walkin is at least
2 times the height of the feezers.
>> Capacity: No contest - 12 large chest freezers hold far more than a
>> walk-in because, well, one must leave room to walk around in the
>> walk-in.
>Again, unfair. Choose the right size of walk-in and redo that
argument.
Refer to previous answer, a larger walkin will cost even more.
>> The large chest freezer that I have in my home consumes $.41 a month
>> in electricity. Multiply that by 12 and $2.92. My approx 10' X 6'
>> walk-in freezer consumed $4.92/month measured during the summer
>> months. Again, the win goes to the chest freezers.
This sounds odd to me; firstly, a freezer indoors costs you twice,
>once
.in freezer electricity and (in summer) again in airconditioning cost.
>Secondly, walk-in freezers ought to have the same efficiency as
>a chest freezer, and should need less cooling because they have
>similar insulation but lower external surface area.
My freezers are outdoors in a screened porch.
I agree on your lower external surface area, same efficiency
staement.
> Reliability
> The walk-in has several single point failure vunerabilities. The
> condensing unit. The liquid solenoid valve. The defrost timer. The
> defrost heater. Etc. All failed during the 12 year life of that
> walk-in. Unfortunately the compressor failed during our vacation
> closing and all was lost. Insurance paid out about $000 for that
> one. If a chest freezer fails, he might lose those contents but the
> other 11 are still running. Win goes to the chest freezers.
>Your 'spare' for the walk-in is gonna be a phone call to get
>a refrigerated container delivered. Any trucking company can
>do this for you. I'm dubious that you plan to lose all of
>the contents of a chest if/when one fails, either.
I never said I would lose all the contents of a chest freezer.
That's why my alarms are set at -5F, so I get an early warning.
And we always keep an empty one.
>And with
>twelve chest freezers, they're gonna fail twelve times as
>often. Either way, your contingency plans should cover faults.
Maybe, but chest freezers seem to have long lives, 10 to 20 years.
Posted by vaughn on June 25, 2010, 4:42 pm
>...a freezer indoors costs you twice,once
>in freezer electricity and (in summer) again in airconditioning cost.
Actually, the situation is not nearly so simple. In terms of the BTU's of heat
that are pumped out of the freezer into the room, they are the *very same* heat
BTUs that leaked from the room into the freezer. So that turns out to be a
wash. Further, the freezers would operate a bit more efficiently in the cooled
space because 1) There would be less delta-T across the insulation, so less heat
loss + less compressor operation, and 2) the condenser would operate a bit
more efficiently in the cooled room because it would see a larger delta-T. On
the other side of the equation, all of the waste heat (I squared R loss + core
loss) from the compressor motors and (if any) fan motors would appear as heat
load to the AC.
Vaughn
Posted by GregS on June 25, 2010, 7:19 pm
>>...a freezer indoors costs you twice,once
>>in freezer electricity and (in summer) again in airconditioning cost.
>Actually, the situation is not nearly so simple. In terms of the BTU's of heat
>
>that are pumped out of the freezer into the room, they are the *very same* heat
>
>BTUs that leaked from the room into the freezer. So that turns out to be a
>wash. Further, the freezers would operate a bit more efficiently in the cooled
>
>space because 1) There would be less delta-T across the insulation, so less
> heat
>loss + less compressor operation, and 2) the condenser would operate a bit
>more efficiently in the cooled room because it would see a larger delta-T. On
>the other side of the equation, all of the waste heat (I squared R loss + core
>loss) from the compressor motors and (if any) fan motors would appear as heat
>load to the AC.
>Vaughn
With surround coils imbedded under the sheetmetal, the differential
is more constant. How thick the insulation is more important.
greg
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>>
>>> Ya! The initial purpose is to keep 12 chest freezers running.
>>
>>Zowie! Think about getting a walk-in freezer, dude! Twelve
>>chest freezers has a lot of surface area to insulate, one big
>>unit would be lower maintenance and less power usage.
> Well, let's do a little math based on actual data. I've logged all
> the power consumptions of all the appliances in my house and in my
> restaurant.
> Initial cost.
> An 8' square walk-in costs about $,000 installed. A large chest
> freezer is around $00 at Sam's Club. 12 freezers is $600. The win
> on initial cost goes to the chest freezer.
> Capacity: No contest - 12 large chest freezers hold far more than a
> walk-in because, well, one must leave room to walk around in the
> walk-in.
> Operating cost.
> The large chest freezer that I have in my home consumes $.41 a month
> in electricity. Multiply that by 12 and $2.92. My approx 10' X 6'
> walk-in freezer consumed $4.92/month measured during the summer
> months. Again, the win goes to the chest freezers. All measurements
> were done with calibrated revenue meters.
> http://www.neon-john.com/Misc/Energy_Audit.htm
> Reliability
> The walk-in has several single point failure vunerabilities. The
> condensing unit. The liquid solenoid valve. The defrost timer. The
> defrost heater. Etc. All failed during the 12 year life of that
> walk-in. Unfortunately the compressor failed during our vacation
> closing and all was lost. Insurance paid out about $000 for that
> one. If a chest freezer fails, he might lose those contents but the
> other 11 are still running. Win goes to the chest freezers.
> The one major area where the walk-in wins is cool-down. The chest
> freezers are so economical to operate because their refrigeration
> systems are just barely large enough to keep already-cold contents
> cold. Cool-down is very slow. The walk-in, OTOH, with its 3HP
> compressor and high velocity evaporator fans would freeze a steam
> table pan of boiling hot stew in about an hour.
> So based on the numbers, the correct advice is "keep the chest
> freezers, dude!"