How long does a chest freezer last?

chocotaco · Apr 11, 2013

Today's amazing weather (in Southern California) makes it clear that summer is approaching. And I would like to be able to keep brewing ales instead of relegating myself to funky Saisons. Which means I am looking at building a fermentation chamber.

A lot of people use something like a chest freezer or mini fridge, connected to a temperature controller that cuts power to the cooler when the target temperature is reached, and restores power when it gets too warm.

To me, this seems like it would be bad for the lifespan of the freezer or fridge. For about the same price as buying a freezer, I could build an insulated box of about the same size which uses a large thermoelectric heat pump and PID controller to keep the box at a specified temperature. Because it has no moving parts except fans, and low thermal stress due to the PID controller, I think this box would last for the better part of a decade if not longer (probably with swapping out the fans every couple of years).

Obviously I would like to avoid going through the hassle of building this thing, and the nice thing about the chest freezer solution is that it's all of-the-shelf. But first I want to tap into the experiences of the community: Do you have the chest freezer (or fridge) solution for fermentation control? Have you found that the cooler does not like to have its power cycled on and off? Have you had it last a while, or have you had it die after some time?

Chest Freezer:
Pros:

Off the shelf
Easy build
Can later be converted to a keezer/kegerator if I start kegging

Cons:

Life span?
Temp control not as precise

Custom TED/PID chamber:
Pros:

Precise temp control
Long life span/easily repairable

Cons:

Probably could not get cold enough to be a kegerator without consuming massive amounts of power
Probably less power efficient (depending how well the fridge responds to having its power cycled)
Initial build is a PITA

TheDecline · Apr 11, 2013

I would stick with the chest freezer or mini fridge. A mini fridge will last longer at normal ale temps but a chest freezer will still last a long time and with something like a Johnson Controls A419 you get temp accuracy to 1 degree which is more than adequate.

Peltier units are power hungry, especially some where hot like socal. Also, they don't really have the capacity. Cooling a 4 cubic foot box is one thing. Cooling 5 gallons of room temperature liquid in a 4 cubic foot box is another. You would need a fair amount of units to get it down in temp over a reasonable amount of time.

luhrks · Apr 11, 2013

Cutting the duty cycle of a freezer will extend it's service life, not shorten.

63belair · Apr 12, 2013

luhrks said:
Cutting the duty cycle of a freezer will extend it's service life, not shorten.

This. Think about it as if you were using air conditioners. Which will last longer, the air conditioner that is used year round, or the one that gets put away after summer for 9 months out of the year? (It isn't exactly an apples to apples comparison, but close enough)

Echoloc8 · Apr 12, 2013

luhrks said:
Cutting the duty cycle of a freezer will extend it's service life, not shorten.

I thought it was cycling the compressor that shortened the life of a fridge/freezer. And it's the temp controller's hysteresis setting (how many degrees warmer or colder than the set point, if I'm misusing the word) that governs how frequently the compressor kicks on and off.

So it's not as simple as how long you're running the thing, if you're cycling the compressor on and off every minute or two to maintain temp within a super-narrow band.

Right?

-Rich

Pratzie · Apr 12, 2013

luhrks said:
Cutting the duty cycle of a freezer will extend it's service life, not shorten.

This. Because even if u are using it all the time, it wouldn't really be much different then using it as its intended. The compressor will kick on and off depending on how good the insulation of the device is. Its not going to have to work real hard when u think about it because the compressor will kick off at say 50 degrees, and kick back on when it gets to say 52 degrees. its not like it will have to work real hard getting it down two more degrees, or even 10 degrees.

I could see going from 70 to freezing and then kicking back on when it gets to 70 but the temp swings will be fairly mild once it hits ur desired temp.

luhrks · Apr 13, 2013

With my keezer outside in the summer, it would come on for about 5 minutes every hour to maintain fiftyish degrees.

logdrum · Apr 13, 2013

Get a STC-1000 controller & set the compressor delay to 10 min.

TheDecline · Apr 13, 2013

Echoloc8 said:
I thought it was cycling the compressor that shortened the life of a fridge/freezer. And it's the temp controller's hysteresis setting (how many degrees warmer or colder than the set point, if I'm misusing the word) that governs how frequently the compressor kicks on and off.

So it's not as simple as how long you're running the thing, if you're cycling the compressor on and off every minute or two to maintain temp within a super-narrow band.

Right?

-Rich

You have to main problems with using a freezer as a cooler. Firstly is short-cycling which is what you are describing. Having a compressor turn on and off too frequently is damaging. However, in my experience, this is not really a problem because insulation factor is quite high and thus your box temp will stay low for long enough for the system to equalize pressures before restarting. The second problem is what is called a hot pull down. This is the situation where a system is cooling a space that is at a higher than designed temperature. The problem is that these types of systems are designed to run at a certain temperature and causing the unit to run out of that range causes the system to run abnormally. High box temperatures leads to higher evap temp which leads to high super heat which leads to ineffective compressor cooling and lowered efficiency. This will kill a compressor over time but again, in my experience, it will still take years. Or use a mini fridge which is meant to run at those temps instead of a chest freezer. Or build a walk-in cooler with proper equipment.

Source: Im a licensed air conditioning and refrigeration mechanic.

Aschecte · Apr 13, 2013

There are definite pros and cons to both and I do have and use both. I also work in the hvac business for a living and am very familiar with compressor failure and run time short cycle effects. So here we go.

Freezer..... They are utilizing a low temp compressor and ideally run best at 30 degrees or below..... By bypassing the internal thermostat with a A-419 control like I do with mine two things happen. You dead the entire unit and in essence are constantly turning the unit on and off with the external thermostat. You do damage to the compressor no two ways about it. Yu can expect to loose appx. 5 years of life with doing this. Now that said the life span of these newer chest freezers are 15-20 years as long as you service them and make sure the refrigerant charge is adequate and that the evaporator is cleaned etc.... So for a investment of $250 or so for a 7.2 cuft chest freezer expect 10-15 years of useable life. If you convert it to a keezer insulate the hell out of the collar as the less the compressor runs the better the lifespan. The biggest pro to the chest freezer is capacity as well as accurate temperature not to mention the ability to turn it into a serving vessel aka a keezer or tower system.

Ok no to the fermentation chamber build #1 it's a lot cheaper I built mine for about $80 dollars and all it takes is some 2" extruded polystyrene and some pl300 adhesive. A fan and basic electrical knowledge to wire it all up. The negatives are you need to constantly change frozen ice jugs and the unit will go trough ice every 24 hours or so. So there is a labor factor to this. Also the unit will break down just by ware and tear moving carboys in an out and changing the jugs. You'll also have pretty accurate temp control as if you use a mechanical thermal switch thermostat wired to the fan you can aalccutately control the ambient air in the chamber but the swings will happen faster than in the freezer. The biggest pro is the cost and relative reliability.

My vote is the ferm chamber as for $80 and if you get a 5 yeas of service and had to build a new one it is still cheaper than your initial investment of chest freezer, controls, and modifications. The chest freezer is great and I love mine for a keezer but the chamber is where I ferment in. Ohhhh I forgot to mention this big point as well...... Try lifting a 6.( gallon Carboy out of a chest freezer I promise you will be holding your breath and praying it doesn't slip and break all inside the freezer..... With the ferm chamber it's already at floor level and only minimal lateral lifting is required that's another big plus for the ferm chamber.

Hope this helps good luck !!!!

Aschecte · Apr 13, 2013

TheDecline said:
You have to main problems with using a freezer as a cooler. Firstly is short-cycling which is what you are describing. Having a compressor turn on and off too frequently is damaging. However, in my experience, this is not really a problem because insulation factor is quite high and thus your box temp will stay low for long enough for the system to equalize pressures before restarting. The second problem is what is called a hot pull down. This is the situation where a system is cooling a space that is at a higher than designed temperature. The problem is that these types of systems are designed to run at a certain temperature and causing the unit to run out of that range causes the system to run abnormally. High box temperatures leads to higher evap temp which leads to high super heat which leads to ineffective compressor cooling and lowered efficiency. This will kill a compressor over time but again, in my experience, it will still take years. Or use a mini fridge which is meant to run at those temps instead of a chest freezer. Or build a walk-in cooler with proper equipment.

Source: Im a licensed air conditioning and refrigeration mechanic.

Agreed +1

Source : also a licensed hvac technician Nate certified and also certified in section 601c refrigerant training,licensing and reclamation I also proctor for mainstream engineering as well as adult education teaching heating and refrigeration. Hey btw where has been Dan Holligjan been ? I haven't seen any new books in hydronic a from him in like a decade..... Have you seen anything new ?

Bobby_M · Apr 13, 2013

The thing that killed my first chest freezer was running in my 40F garage over the winters. Some of them aren't rated for less than 55F ambient due to the oil in the compressor getting too viscous. Mine lasted 3 seasons.

JuanMoore · Apr 13, 2013

Echoloc8 said:
I thought it was cycling the compressor that shortened the life of a fridge/freezer. And it's the temp controller's hysteresis setting (how many degrees warmer or colder than the set point, if I'm misusing the word) that governs how frequently the compressor kicks on and off.

So it's not as simple as how long you're running the thing, if you're cycling the compressor on and off every minute or two to maintain temp within a super-narrow band.

Right?

-Rich

The thermal mass of even 5 gal of beer is pretty huge, and most people have at least that much in their fermentation chamber at any given time. I have ~30 gal in mine right now. Even maintaining a very tight tolerance won't cause it to cycle any more frequently than when being used as a freezer. If you don't have the probe mounted properly and open the lid frequently or run the freezer without anything in it, then short cycling can become an issue. I tape my probe to the fermenter of the most recently brewed beer, and then tape some foam insulation over it. My ferm chamber is an old fridge, but the temp differential is set to 0.5°C, and the compressor never cycles more than once in an hour. I also have the compressor delay setting on my controller maxed out at 10 min, so that it doesn't short cycle while I'm changing the probe to a new fermenter.

Aschecte · Apr 13, 2013

Bobby_M said:
The thing that killed my first chest freezer was running in my 40F garage over the winters. Some of them aren't rated for less than 55F ambient due to the oil in the compressor getting too viscous. Mine lasted 3 seasons.

Yeah that's a very good point too..... You can overcome this with a compressor crank case heater which will keep the oil about 30 degrees higher than ambient. I don't recommend anyone do this though as we are getting into a realm that should not be tackled by the average homebrewer.

Snisup · Apr 13, 2013

Or you can go with an old (read 50's and older) fridge/freezer and it will last forever. Those things are built like trucks. They are nothing but a compressor so cutting power is the same thing as the stock thermo hitting the setpoint. If you are using the temp controller properly (attaching it to the carboy with insulation) your cycle times will be few and far between for normal ale temps even in hot weather.

Source: I have 3 40s/50s GE units that purr like kittens. All were bought for less than $20!

JuanMoore · Apr 13, 2013

Snisup said:
Or you can go with an old (read 50's and older) fridge/freezer and it will last forever. Those things are built like trucks. They are nothing but a compressor so cutting power is the same thing as the stock thermo hitting the setpoint. If you are using the temp controller properly (attaching it to the carboy with insulation) your cycle times will be few and far between for normal ale temps even in hot weather.

Source: I have 3 40s/50s GE units that purr like kittens. All were bought for less than $20!

My first ferm chamber was an early 50's Philco. It was my home fridge for many years, but my wife didn't like how much condensation it had inside, and that you had to make sure you didn't let the food inside touch the back wall or it would get wet. Unfortunately the compressor line got damaged during a move, and I sold it to an antique appliance dealer.

My ferm chamber now is an early 80's GE fridge. I picked it up on craigslist for $15 because it was dirty and missing the crisper drawers and one of the shelves. I made a wood platform and replaced the molded door panel shelves with a flat panel, and now it will hold 6 of my fermenters. I much prefer it over a chest freezer for several reasons. It holds way more fermenters than a chest freezer with the same footprint, it was dirt cheap, and lifting fermenters and kegs in and out is really easy.

Whut · Apr 13, 2013

FWIW, I've two 8.8cf Kenmoore freezers connected to their own JC A419s and have had them in the garage for ~4 years now. Both are set to cycle within 1˚ of the set temp and have had no issues. Both were NIB when purchased and were around $200 on sale. Did I mention they're in the garage?

bigbeergeek · Apr 13, 2013

Bobby_M said:
The thing that killed my first chest freezer was running in my 40F garage over the winters. Some of them aren't rated for less than 55F ambient due to the oil in the compressor getting too viscous. Mine lasted 3 seasons.

Nice to find out what happened to it, Bobby. :mug:

Bobby_M · Apr 13, 2013

Aschecte said:
Yeah that's a very good point too..... You can overcome this with a compressor crank case heater which will keep the oil about 30 degrees higher than ambient. I don't recommend anyone do this though as we are getting into a realm that should not be tackled by the average homebrewer.

When I got my replacement, my plan was to wire in a delay relay so that it would fire up a small heater to blow on the compressor for a couple minutes before the compressor was energized. I never got around to it.

Aschecte · Apr 13, 2013

Whutever said:
FWIW, I've two 8.8cf Kenmoore freezers connected to their own JC A419s and have had them in the garage for ~4 years now. Both are set to cycle within 1˚ of the set temp and have had no issues. Both were NIB when purchased and were around $200 on sale. Did I mention they're in the garage?

Yes, I heard a rumor you keep them in the garage lol

.... You are in Arizona where it tends to be much warmer than where Bobbym is in the north east about an hour away from me. Don't get me wrong my aunt lives in Tubac AZ and she tells me it gets cold but not like in the north east where we go into the negative digits at times during the winter months. My guess is on hot days your freezer turns on much more often than in the winter and would cycle less year round if you kept them indoors in a conditioned space.

chocotaco · Apr 13, 2013

I have been running a few numbers for a peltier-driven fermentation chamber. Please feel free to check my logic and math!

For the purposes, I've calculated based on approximately the same size as a GE 7.0 ft^3 chest freezer: 37"x31"x23" which is 5360 in^2 in surface area or around 3.5 m^2.

If I use 2-inch thick XPS at an R-value of 5 per inch (R-10 total), we are looking at a thermal conductivity of .567826 W/(m^2*K). With a surface area of 3.5 m^2, that's 3.5 W/K.

If the unit will be kept inside my house, I would estimate that the ambient temperature will be between 65F (18.3C) and 85F (29.4C). If the chamber should be at 65F for a nice ale, that is a maximum differential of 11.1C which means the thermal flux of the system would be (3.5 W/K * 11.1K) = around 39 watts.

Ignoring the load of bringing the system down to 65F (which could be accomplished with the help of ice or external refrigeration, if required) then the heat pump would need to be capable of constantly removing at least 39 watts of heat in order to keep the temperature inside constant. The peltier unit I've found (easily available on numerous websites) should be able to accomplish this at approximately 8A and 8VDC (according to the datasheet), a power draw of 64 watts which is quite low (pretty much equivalent to an incandescent light bulb).

Following is my cost estimate:
1. Peltier unit: $40 shipped
2. XPS insulation: around $35 from Home Depot, maybe less depending on layout
3. Framing and sheathing: Around $30 from home depot + scrounged (home improvement leftovers)
4. Big ol' heatsinks for each side of the heat pump: around $32 shipped from heatsinksusa.com and/or scrounged
5. 40mm^2 x 2in Aluminum extension (to penetrate insulation): around $25 from speedymetals.com
6. Power supply: scrounged (I am a computer guy and have a boneyard of stuff like this)
7. PID unit: around $35 shipped
8. Ultra-quiet 120mm fans: scrounged (see above)
9. Thermal epoxy: scrounged
Total: around $200 (let's call it $250 for unforseen materials needed).

Comparable chest freezer system:
1. Freezer: $239 plus any shipping or delivery charges
2. Controller: around $30 shipped
Total: around $270

Obviously I am ignoring my own man-hours ( whose value is debatable

) But it seems like the peltier chamber is not so easily written off. I am not sure what the average power draw of a chest freezer is, but considering how long I believe it will last, the peltier option is not such a power suck as I might have thought (obviously there will be power lost to the power supply as well; let's call it 100W).

Any thoughts? Is there a write-up of this kind of thing on HBT? If not, should I give it a go and do one? Science would dictate that I do both the peltier and the chest freezer and compare the results, but that will have to wait until I hit the lottery (which I plan on doing very soon! :mug:

)

Aschecte · Apr 13, 2013

chocotaco said:
I have been running a few numbers for a peltier-driven fermentation chamber. Please feel free to check my logic and math!

For the purposes, I've calculated based on approximately the same size as a GE 7.0 ft^3 chest freezer: 37"x31"x23" which is 5360 in^2 in surface area or around 3.5 m^2.

If I use 2-inch thick XPS at an R-value of 5 per inch (R-10 total), we are looking at a thermal conductivity of .567826 W/(m^2*K). With a surface area of 3.5 m^2, that's 3.5 W/K.

If the unit will be kept inside my house, I would estimate that the ambient temperature will be between 65F (18.3C) and 85F (29.4C). If the chamber should be at 65F for a nice ale, that is a maximum differential of 11.1C which means the thermal flux of the system would be (3.5 W/K * 11.1K) = around 39 watts.

Ignoring the load of bringing the system down to 65F (which could be accomplished with the help of ice or external refrigeration, if required) then the heat pump would need to be capable of constantly removing at least 39 watts of heat in order to keep the temperature inside constant. The peltier unit I've found (easily available on numerous websites) should be able to accomplish this at approximately 8A and 8VDC (according to the datasheet), a power draw of 64 watts which is quite low (pretty much equivalent to an incandescent light bulb).

Following is my cost estimate:
1. Peltier unit: $40 shipped
2. XPS insulation: around $35 from Home Depot, maybe less depending on layout
3. Framing and sheathing: Around $30 from home depot + scrounged (home improvement leftovers)
4. Big ol' heatsinks for each side of the heat pump: around $32 shipped from heatsinksusa.com and/or scrounged
5. 40mm^2 x 2in Aluminum extension (to penetrate insulation): around $25 from speedymetals.com
6. Power supply: scrounged (I am a computer guy and have a boneyard of stuff like this)
7. PID unit: around $35 shipped
8. Ultra-quiet 120mm fans: scrounged (see above)
9. Thermal epoxy: scrounged
Total: around $200 (let's call it $250 for unforseen materials needed).

Comparable chest freezer system:
1. Freezer: $239 plus any shipping or delivery charges
2. Controller: around $30 shipped
Total: around $270

Obviously I am ignoring my own man-hours ( whose value is debatable ) But it seems like the peltier chamber is not so easily written off. I am not sure what the average power draw of a chest freezer is, but considering how long I believe it will last, the peltier option is not such a power suck as I might have thought (obviously there will be power lost to the power supply as well; let's call it 100W).

Any thoughts? Is there a write-up of this kind of thing on HBT? If not, should I give it a go and do one? Science would dictate that I do both the peltier and the chest freezer and compare the results, but that will have to wait until I hit the lottery (which I plan on doing very soon! )

Could not have said it better myself

Snisup · Apr 13, 2013

chocotaco said:
I have been running a few numbers for a peltier-driven fermentation chamber. Please feel free to check my logic and math!

For the purposes, I've calculated based on approximately the same size as a GE 7.0 ft^3 chest freezer: 37"x31"x23" which is 5360 in^2 in surface area or around 3.5 m^2.

If I use 2-inch thick XPS at an R-value of 5 per inch (R-10 total), we are looking at a thermal conductivity of .567826 W/(m^2*K). With a surface area of 3.5 m^2, that's 3.5 W/K.

If the unit will be kept inside my house, I would estimate that the ambient temperature will be between 65F (18.3C) and 85F (29.4C). If the chamber should be at 65F for a nice ale, that is a maximum differential of 11.1C which means the thermal flux of the system would be (3.5 W/K * 11.1K) = around 39 watts.

Ignoring the load of bringing the system down to 65F (which could be accomplished with the help of ice or external refrigeration, if required) then the heat pump would need to be capable of constantly removing at least 39 watts of heat in order to keep the temperature inside constant. The peltier unit I've found (easily available on numerous websites) should be able to accomplish this at approximately 8A and 8VDC (according to the datasheet), a power draw of 64 watts which is quite low (pretty much equivalent to an incandescent light bulb).

Following is my cost estimate:
1. Peltier unit: $40 shipped
2. XPS insulation: around $35 from Home Depot, maybe less depending on layout
3. Framing and sheathing: Around $30 from home depot + scrounged (home improvement leftovers)
4. Big ol' heatsinks for each side of the heat pump: around $32 shipped from heatsinksusa.com and/or scrounged
5. 40mm^2 x 2in Aluminum extension (to penetrate insulation): around $25 from speedymetals.com
6. Power supply: scrounged (I am a computer guy and have a boneyard of stuff like this)
7. PID unit: around $35 shipped
8. Ultra-quiet 120mm fans: scrounged (see above)
9. Thermal epoxy: scrounged
Total: around $200 (let's call it $250 for unforseen materials needed).

Comparable chest freezer system:
1. Freezer: $239 plus any shipping or delivery charges
2. Controller: around $30 shipped
Total: around $270

Obviously I am ignoring my own man-hours ( whose value is debatable ) But it seems like the peltier chamber is not so easily written off. I am not sure what the average power draw of a chest freezer is, but considering how long I believe it will last, the peltier option is not such a power suck as I might have thought (obviously there will be power lost to the power supply as well; let's call it 100W).

Any thoughts? Is there a write-up of this kind of thing on HBT? If not, should I give it a go and do one? Science would dictate that I do both the peltier and the chest freezer and compare the results, but that will have to wait until I hit the lottery (which I plan on doing very soon! )

All negated by buying a used fridge/freezer. Even if you had to pay to move it, it would be cheaper to buy a $50 unit on Craigslist. Plus A LOT less work. Garage/Estate sales might even get you something cheaper.

Just my 2¢.

chocotaco · Apr 13, 2013

Addendum: let's say I wanted to convert it to a serving-temp beer fridge/kegerator at some point. Is that possible?

Given the worst-case scenario (God, I hope so!) of 85F in my house (29.4C) and serving temp of 40F (4.4C) we are looking at a thermal flux of (29.4C - 4.4C - 25C) * 3.5 W/K = 87.5W. The datasheet says it's possible, but would take more like 18A at around 12VDC for a power draw of around 216 watts. Not terrible, but when you factor in the efficiency of the power supply it would be more like 275 watts. I think I could live with that, though I'm unsure of how much power a real kegerator draws on average.

At that point I could add another layer of insulation to double the R-value. That would require a new aluminum extension piece at the minimum, and probably a whole new heat pump assembly depending on whether I can remove the heatsinks and peltier from the thermal epoxy (which is unlikely). That would cost around $100 all-in, including the new insulation.

chocotaco · Apr 13, 2013

Snisup said:
All negated by buying a used fridge/freezer. Even if you had to pay to move it, it would be cheaper to buy a $50 unit on Craigslist. Plus A LOT less work. Garage/Estate sales might even get you something cheaper.

Just my 2¢.

Agreed, that is a much more practical solution. Trust me, I have my eyes on Craiglist - although I haven't been particularly impressed with any offers I've seen in my area thus far.

Snisup · Apr 13, 2013

chocotaco said:
Agreed, that is a much more practical solution. Trust me, I have my eyes on Craiglist - although I haven't been particularly impressed with any offers I've seen in my area thus far.

Yeah... That's the only problem with CL. It's hit or miss. I've found estate sales to be very reliable for used brewing related things.

day_trippr · Apr 14, 2013

With Craig's List, it's all about patience. Not only time-wise, but dealing with the stream of less-than-brilliant sellers that put stuff up for sale with barely any information.

If you stand dealing with that - and the time thing - you can score some crazy deals. I picked up a 2yo 10cf chest freezer for $100, a never-used 17cf top-freezer fridge for $100, and a 1yo 17cf top-freezer fridge for $125.

It's all about the patience thing...

Cheers!

TheDecline · Apr 14, 2013

chocotaco said:
I have been running a few numbers for a peltier-driven fermentation chamber. Please feel free to check my logic and math!

For the purposes, I've calculated based on approximately the same size as a GE 7.0 ft^3 chest freezer: 37"x31"x23" which is 5360 in^2 in surface area or around 3.5 m^2.

If I use 2-inch thick XPS at an R-value of 5 per inch (R-10 total), we are looking at a thermal conductivity of .567826 W/(m^2*K). With a surface area of 3.5 m^2, that's 3.5 W/K.

If the unit will be kept inside my house, I would estimate that the ambient temperature will be between 65F (18.3C) and 85F (29.4C). If the chamber should be at 65F for a nice ale, that is a maximum differential of 11.1C which means the thermal flux of the system would be (3.5 W/K * 11.1K) = around 39 watts.

Ignoring the load of bringing the system down to 65F (which could be accomplished with the help of ice or external refrigeration, if required) then the heat pump would need to be capable of constantly removing at least 39 watts of heat in order to keep the temperature inside constant. The peltier unit I've found (easily available on numerous websites) should be able to accomplish this at approximately 8A and 8VDC (according to the datasheet), a power draw of 64 watts which is quite low (pretty much equivalent to an incandescent light bulb).

Following is my cost estimate:
1. Peltier unit: $40 shipped
2. XPS insulation: around $35 from Home Depot, maybe less depending on layout
3. Framing and sheathing: Around $30 from home depot + scrounged (home improvement leftovers)
4. Big ol' heatsinks for each side of the heat pump: around $32 shipped from heatsinksusa.com and/or scrounged
5. 40mm^2 x 2in Aluminum extension (to penetrate insulation): around $25 from speedymetals.com
6. Power supply: scrounged (I am a computer guy and have a boneyard of stuff like this)
7. PID unit: around $35 shipped
8. Ultra-quiet 120mm fans: scrounged (see above)
9. Thermal epoxy: scrounged
Total: around $200 (let's call it $250 for unforseen materials needed).

Comparable chest freezer system:
1. Freezer: $239 plus any shipping or delivery charges
2. Controller: around $30 shipped
Total: around $270

Obviously I am ignoring my own man-hours ( whose value is debatable ) But it seems like the peltier chamber is not so easily written off. I am not sure what the average power draw of a chest freezer is, but considering how long I believe it will last, the peltier option is not such a power suck as I might have thought (obviously there will be power lost to the power supply as well; let's call it 100W).

Any thoughts? Is there a write-up of this kind of thing on HBT? If not, should I give it a go and do one? Science would dictate that I do both the peltier and the chest freezer and compare the results, but that will have to wait until I hit the lottery (which I plan on doing very soon! )

The math is sound. The only problem will be initially getting your beer temp down. You need a lot more capacity to change the temp of something as dense as beer than you do to maintain it. 64W is only capable of dropping 25L of water 1.3 degrees C. per hour. PLUS cooling required to absorb ambient heat. You could subsidize the cooling with ice or something but whats the point when a standard refrigeration system is so readily available and capable.

TheDecline · Apr 14, 2013

Aschecte said:
Agreed +1

Source : also a licensed hvac technician Nate certified and also certified in section 601c refrigerant training,licensing and reclamation I also proctor for mainstream engineering as well as adult education teaching heating and refrigeration. Hey btw where has been Dan Holligjan been ? I haven't seen any new books in hydronic a from him in like a decade..... Have you seen anything new ?

Never heard of the guy. Im in Canada so our situation with trades are a bit different. Our reading material we use is provided by the college where we do our training and after the apprenticeship is done, personally, I just go to seminars and classes provided by the manufacturers and wholesalers to keep up-to-date on new tech.

Aschecte · Apr 14, 2013

TheDecline said:
Never heard of the guy. Im in Canada so our situation with trades are a bit different. Our reading material we use is provided by the college where we do our training and after the apprenticeship is done, personally, I just go to seminars and classes provided by the manufacturers and wholesalers to keep up-to-date on new tech.

No problem.... yeah Dan hollighan is a writer kinda a hydronics guru so to speak... I rarely do hydronics anymore but found his books full of great info on primary secondary piping etc as well as steam systems and older gravity fed systems. I recommend his books you may be able to find some on ebay or Amazon if you are interested. cheers !!

How long does a chest freezer last?

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