[ARCHIVED THREAD] - BOL Chest Freezer Conversion, Solar Panels, Evaluation WORKING GREAT! (Page 2 of 3)
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This is all very cool ! The time delay feature is gold, in my opinion, aught to built into *every* compressor driven appliance. It's a sickening sound when the lights flicker and you hear 2 refrigerators, AC and freezer all straining against locked rotor amps until the cheesey thermal overload kicks out. Meantime the windings have had a couple thousand watts of heat being dumped into them as the motor strains. DA, thanks for the suggestion on the Johnson control. It's working out well and I'm actually thinking about putting one on the freezer to keep it above -5F to about 10F to save energy. You are aware of the control's 'setback" function? |
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Still too lazy to have ordered a kill-a-watt meter. Got my electric bill for when I added in 2 window ac units and my chest freezer being used as a fridge. Went up a whopping 30 bucks to 63 bucks. I think it actually only went up 28 bucks. One ac unit is a 5k but the other one is a larger unit but I don't recall its rating. Chest fridge is still cruising along happily and as I do better at making proper use of its space it is doing fine at keeping things cool. I decided to just put the beer on the bottom and let it get cold and I put my temp sensor a bit higher up with the more sensitive foods that I don't want to get close to frozen. I run mine cool enough that some condensation will freeze now and then but you can't put a water bottle in the bottom and get it to freeze or even get slushy. I kind of figured the window ac units would cost a lot more since I was expecting the chest fridge to cost me what my little dorm size fridge used to cost me to run, so I am darn happy with how things are working out right now. The window ac units run all the time and are cooling the whole first floor of the house down but the back room does not stay all that cool compared to the rest of the place. I use an oscillating fan to help the big ac unit cool several rooms which the ac instructions say not to do but I never did care much about actually following instructions even though I sometimes am bored enough to read them. I will eventually get a kill a watt meter but right now I have enough on my plate I don't need anything else showing up on the doorstep for me to have to mess with yet. By next month I should have a lot more wrapped up and actually want to measure stuff and figure out the electric bill a bit better. |
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So far the chest freezer and the chest refrigerator have been working great. SO loves them -and my meals have been getting much better, we don't have to lug around ice anymore and this trip up here last night, I've got some beers in the frig -I think WooHoo! One a week!
Had a problem with one of the Xantrexes tripping out in the middle of the night but after finding a poor connection to a fuse at the Solar Star battery connection, haven't had that problem in a while. I monitor the status of the units via IP cameras anywhere there's an Inet conx. I'll be adding more IP cams to look at the Outback and Xantrex panels to monitor voltage etc, and soon I'll show here a way to remotely turn on and off equipment and reset the Xantrexes and even disconnect loads on cloudy days.. Also, one of the chest freezers shows a poor power factor reading on the KilOWatz meter and I may have to exchange. That reading is about .65 while the other frezer/frig reads very close to 1. I don't understand 'power factor' well... Why would one show a good PF and the other show a 'bad' PF? |
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Ski, is that chart referring to the temp differential between the inside of the chest and ambient? No, that's just the change in ambient temperatures, assuming the inside temperature of the fridge remains constant. For example, if the room temperature changed from 70 to 80 degrees, that would be a 10 degree increase, and could be expected to result in roughly a 45 percent increase in fridge power consumption (or compressor run-time). |
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Ski, is that chart referring to the temp differential between the inside of the chest and ambient? No, that's just the change in ambient temperatures, assuming the inside temperature of the fridge remains constant. For example, if the room temperature changed from 70 to 80 degrees, that would be a 10 degree increase, and could be expected to result in roughly a 45 percent increase in fridge power consumption (or compressor run-time). Interesting. Thank you! I've seen some variation with temp but didn't expect it to be this great. Now I'll have to make more detailed measurements. How about the power factor issue I mention a few posts up? |
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Not sure what to make of the difference in PF between your two units...
Perhaps it has something to do with the difference in operating temperatures? Maybe the compressor's PF changes when it's working harder (i.e., maintaining a bigger difference between the chest and ambient temperatures)? Some electric motors have a similar behavior - The PF changes quite a bit depending on how hard to motor is being worked. In order to find out, you might try setting both units for identical interior temperatures, and then compare their PF's after they've had a chance to stabilize at this new temperature. |
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Not sure what to make of the difference in PF between your two units... Perhaps it has something to do with the difference in operating temperatures? Maybe the compressor's PF changes when it's working harder (i.e., maintaining a bigger difference between the chest and ambient temperatures)? Some electric motors have a similar behavior - The PF changes quite a bit depending on how hard to motor is being worked. In order to find out, you might try setting both units for identical interior temperatures, and then compare their PF's after they've had a chance to stabilize at this new temperature. What I was thinking, but that's going to be tough. My SO has both 1/2 full now. So I may have to pick up another to test with and return one if it doesn't match. |
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So I may have to pick up another to test with and return one if it doesn't match. Good luck explaining why you want to return it, especially if it still does an adequate job of keeping things frozen... "You said you wanted to return it because the 'power WHAT' isn't working properly?"
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Not sure what to make of the difference in PF between your two units... Perhaps it has something to do with the difference in operating temperatures? Maybe the compressor's PF changes when it's working harder (i.e., maintaining a bigger difference between the chest and ambient temperatures)? Some electric motors have a similar behavior - The PF changes quite a bit depending on how hard to motor is being worked. In order to find out, you might try setting both units for identical interior temperatures, and then compare their PF's after they've had a chance to stabilize at this new temperature. Yesterday I got my SO to take stuff that couldn't be frozen out of the chest fridge and unplugged the temp control and let it cool down to the same temp as the freezer with the poor power factor [of .65]. The PF on the fridge was still nearly 1, so I swapped the power sources [Xantrex 1800 watt ProSines] and nothing changed. Also swapped the KilOWatz meters, no change. The model numbers on the two freezers are slightly different and the service sheet shows that the model with the better power factor consumes about 5 watts more in the "last 1/3 of the cooling cycle". So I'm stumped, do I have a problem from the lower PF or not? Does a higher power factor equate to lower efficiency when driven by my solar system? |
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Does a higher power factor equate to lower efficiency when driven by my solar system? Probably depends on how well your Xantrex inverter handles the low PF. If the inverter consumes roughly the same amount of battery current when powering your "problem" fridge as it does when powering your "normal" fridge*, then you aren't experiencing any loss of efficiency. *Assuming both fridges are set to the same interior temperature - If one fridge is set to a much colder temperature than the other, the greater temperature differential will cause its compressor to draw more current. Do you have a DC clamp-on ammeter, or some other way of measuring the inverter's DC input current? |
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Does a higher power factor equate to lower efficiency when driven by my solar system? Probably depends on how well your Xantrex inverter handles the low PF. If the inverter consumes roughly the same amount of battery current when powering your "problem" fridge as it does when powering your "normal" fridge*, then you aren't experiencing any loss of efficiency. *Assuming both fridges are set to the same interior temperature - If one fridge is set to a much colder temperature than the other, the greater temperature differential will cause its compressor to draw more current. Do you have a DC clamp-on ammeter, or some other way of measuring the inverter's DC input current? Yep, understand that [service AC equip sometimes...] Temps were equalized in the test. Have a Fluke DC etc clamp on... However, the Xantrex ProSines have a readout. What do you suggest? The actual freezer "watts" according to the KilOWatz were the same IIRC, will verify when I go to the 'barn'. |
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The Fluke will probably give a more accurate reading. Unlike using the Kill-A-Watt, measuring DC battery current will tell you if the inverter is actually less efficient with low PF loads. Took some careful measurements just now. Parasitic load from each Xantrex is ~ 23 watts. Freezer run 'watts' is ~88 watts and corresponds to the Fluke measured draw by Xantrex minus parasitics and corresponds to DC draw minus parasitics within 7 watts on average or better. . Fridg run watts is about 130 watts [! it has better PF] and corresponds to DC draw minus parasitics within 6 watts on average or better. [measured at actual voltage and current at same time and multiplied for watts] So, the PF disparagy doesn't seem to be an issue. It is surprising the wattage range specs difference between GE models: FCM7DUCWW [Freezer] rating @ 90F OR 70F ambient, 90-105 watts last third of cycle and FCM7DUDWW [Frig] rating @ 90F OR 70F ambient, 100 - 115 watts last third of cycle It looks like my Fridg is a 'DUD' pun intended |
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Only concerned about PF in order to maximize efficiency. Apparently the inverters are able to 'reuse' the 'reflected' power, in a sense.
Ah, the type of motor! Good point! I never looked at the wiring diagrams. The one in the mod'ed fridge is an LG and the one in the unmod'ed freezer is an ZLT. Now I guess it boils down to which compressor is most efficient with respect to 'cooling power'. I'll have to unload them, let them warm up and use the KilOWattz to measure that. This will be interesting to talk the SO into... |
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Just to add some information to this thread: I have an Engel MT45 and ran a few test using a Doc Watson DC meter. When kept closed with the insulator zipped up it used 275 watt hours a day. This was with ambient air temps of 90's. However, I thought that was unrealistic test because if TSHTF it will be opened a closed quite a bit. So every twelve hours I put 2 gallons of room temp water in the unit to make it work. The energy usage jumped to 660 watt hours per day. I guess I need to size my system to that load to ensure that I have enough solar to run. From what I'm reading it's not significantly more efficient than Expy's setup, and was a quite a bit more expensive. That difference in cost could have gone towards the solar panels required to run it.
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Just to add some information to this thread: I have an Engel MT45 and ran a few test using a Doc Watson DC meter. When kept closed with the insulator zipped up it used 275 watt hours a day. This was with ambient air temps of 90's. However, I thought that was unrealistic test because if TSHTF it will be opened a closed quite a bit. So every twelve hours I put 2 gallons of room temp water in the unit to make it work. The energy usage jumped to 660 watt hours per day. I guess I need to size my system to that load to ensure that I have enough solar to run. From what I'm reading it's not significantly more efficient than Expy's setup, and was a quite a bit more expensive. That difference in cost could have gone towards the solar panels required to run it. Good observations Cfcw. The energy required to cool or freeze 2 gallons of water will be roughly the same for any fridge, regardless of brand or marketing hype. Also, I think being able to purchase a decent quality chest freezer for less than $200 in amazing. Your Engel has the advantage of being more portable of course and for some applications that freature is critical.. |
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Am I the only one that loves these threads, but feels like an idiot after reading them? Great stuff! I love these posts, but often feel like I've been watching a French movie without sub-titles! Electricity and all it does is still black magic to me! I am working on it.
stasiman |
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it's not significantly more efficient than Expy's setup As another point of comparison, Sun Frost makes a line of super-efficient (and super-expensive!) 12 volt fridges and freezers - Energy consumption data is published here. |
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it's not significantly more efficient than Expy's setup As another point of comparison, Sun Frost makes a line of super-efficient (and super-expensive!) 12 volt fridges and freezers - Energy consumption data is published here. I looked a display model of the GE's I've got and the one on store display has a Danfoss compressor, very famous quality brand. What folks are buying aren't Danfoss compressor equiped units, the model number has an A in it for those and the carton leaves off the important digits to tell w/out opening it up... |
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Seems to me that one of the biggest drawbacks with using a chest freezer as a fridge is that it leaves you without the ability to keep frozen food. I'm real big on frozen TV dinners, so that's a serious problem for me... So, I'm wondering - If you put frozen food inside a small ice chest, and then kept the ice chest inside your chest fridge, how long would the food inside stay frozen? Seems like it would last for quite a while, since the ice chest would only have a 20-40 degree temperature difference between the inside and outside of it. Unfortunately, all of the "7 day" coolers are too big to fit inside the average chest freezer, so you'd probably have to settle on using a smaller, less-insulated ice chest instead. |
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I am halfway talked into getting another 5.5 cubic foot chest freezer so I can have a freezer. If winter would get here and be decent I might have a freezer for free but down here it is hard to trust that. With a little electric fan running the temp is spread evenly in the chest freezer. Without the fan you can have the lower parts freezing stuff barely while the upper areas don't come close to freezing stuff but are still darn cold. About a 5 to 7 degree temp spread maybe. Hard to measure since I don't have 2 temp sensors to put to use. Looks like I am going to get away from 3rd shift and overtime and having a freezer to use will be nice so I am probably going to pick another one up and put it to use to save on food costs and what not. |
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I am halfway talked into getting another 5.5 cubic foot chest freezer so I can have a freezer. If winter would get here and be decent I might have a freezer for free but down here it is hard to trust that. With a little electric fan running the temp is spread evenly in the chest freezer. Without the fan you can have the lower parts freezing stuff barely while the upper areas don't come close to freezing stuff but are still darn cold. About a 5 to 7 degree temp spread maybe. Hard to measure since I don't have 2 temp sensors to put to use. Looks like I am going to get away from 3rd shift and overtime and having a freezer to use will be nice so I am probably going to pick another one up and put it to use to save on food costs and what not. If you are going to freeze stuff, it's got to be hard frozen, like minus 10. Keeping items at a couple of degrees within 32 is just asking for stale squishy food. |
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Seems to me that one of the biggest drawbacks with using a chest freezer as a fridge is that it leaves you without the ability to keep frozen food. I'm real big on frozen TV dinners, so that's a serious problem for me... So, I'm wondering - If you put frozen food inside a small ice chest, and then kept the ice chest inside your chest fridge, how long would the food inside stay frozen? Seems like it would last for quite a while, since the ice chest would only have a 20-40 degree temperature difference between the inside and outside of it. Unfortunately, all of the "7 day" coolers are too big to fit inside the average chest freezer, so you'd probably have to settle on using a smaller, less-insulated ice chest instead. Skibane, that's why we went with two chest freezers, one conv to a fridge. Sitting here right now in the container finishing supper after working all day on a drainage system, and I must say my SO is able to fix much better and healthier meals now w/out having to go down every couple days for ice and food. After the past 246 hrs, the freezer was at 42 watts/hr and the fridge at surprisingly, 14 watts/hr, and ambient is cooler now. The fancy coolers are about $80 about half the cost of a complete freezer. Amazing. |
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I am halfway talked into getting another 5.5 cubic foot chest freezer so I can have a freezer. If winter would get here and be decent I might have a freezer for free but down here it is hard to trust that. With a little electric fan running the temp is spread evenly in the chest freezer. Without the fan you can have the lower parts freezing stuff barely while the upper areas don't come close to freezing stuff but are still darn cold. About a 5 to 7 degree temp spread maybe. Hard to measure since I don't have 2 temp sensors to put to use. Looks like I am going to get away from 3rd shift and overtime and having a freezer to use will be nice so I am probably going to pick another one up and put it to use to save on food costs and what not. Biere, the hardware store has freezer and fridge thermometers for about $3. Seem to be accurate. |
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Quoted: Biere, the hardware store has freezer and fridge thermometers for about $3. Seem to be accurate. I never remember to buy the thermometer only things, I generally buy one of the temp sensors that has a sensor for outside temps and the outside temp sensor can go live in the fridge or freezer. Make it easy to watch temps without opening the door all the time. And about the comment on keeping things hard frozen, I agree that you want a larger temp difference I just mentioned the difference without a fan in case someone did want to mess with a cooler and what not in one of these. There are better places to put the cooler than others if trying to do that. I figure I will just buy a freezer once I get back to 2nd shift and can actually have a schedule that involves more than sleeping and going to work. The more I mess with my chest fridge the more I realize that organizing it is a bit of an art. You want to keep it full so it cycles less but with a chest of any sort it is easy to pack stuff in and then have problems getting to what is in the bottom. Those fridge packs of beer or pop wind up on their end in a chest fridge and you just reach into it for a beer or pop. The basket sees a lot of use for stuff in use, like packs of sammich meat and cheese and sliced onions and what not. Overall I am darn happy with my setup as long as it will live for a few years. |
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The more I mess with my chest fridge the more I realize that organizing it is a bit of an art. You want to keep it full so it cycles less How about using styrofoam blocks to temporarily take up any unused space? They don't contain any mass per se, so the compressor shouldn't have to work much to bring them down to interior temperature - and they'll effectively reduce the chest's interior volume. Less volume to cool = less compressor run-time. |
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27 watts to run a chest freezer? Are you sure of this? I guess I haven't owned a freezer in years, I'm used to huge energy bills from them. Can anyone that has one confirm energy usage? I am interested too. Many years ago, I tried to run a small freezer on a boat from 2 powerful solar panels. Insulation was 6" thick, top opening and despite that, it didn't work. This was in the tropics, around 82F ambient temp. In full sun, properly oriented, the solar panels produced only 50% average of the nominal output for about 8 hours, If I did not turn them towards the sun, it went down to 35%. I abandoned the project and got a kerosene freezer, it worked well. I am interested in your set up. (Thank you for posting BTW). Are you absolutely certain that you use only 27W/hr average? What is the ambient temp. around the freezer? |
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Just came to the barn and saw the question...
Looked at the Killowatts meter and after 310 hours of fridge operation, it's used 3760 watt-hrs. That's less than 13 watts/hr. It's been cooler recently, maybe high 75 to 80's and 50 to 60 at night. F. Freezer is still running about 40 watts/hr. |
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The more I mess with my chest fridge the more I realize that organizing it is a bit of an art. You want to keep it full so it cycles less How about using styrofoam blocks to temporarily take up any unused space? They don't contain any mass per se, so the compressor shouldn't have to work much to bring them down to interior temperature - and they'll effectively reduce the chest's interior volume. Less volume to cool = less compressor run-time. If I'm considering the empty/full freezer issue correctly, whether you have it full or nearly empty, [the thermal losses thru the insulation being the same], the energy used to maintain an internal temp constant once the freezer is in equilibrium, should be about the same. It just doesn't make any difference. |
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If I'm considering the empty/full freezer issue correctly, whether you have it full or nearly empty, [the thermal losses thru the insulation being the same], the energy used to maintain an internal temp constant once the freezer is in equilibrium, should be about the same. It just doesn't make any difference. The difference comes from the fact that empty parts of the compartment contain air. Air can move around, transferring heat - particularly when you open the compartment door. Conversely, the "air" in styrofoam is immobile, and thus isn't capable of transferring much heat (or of being displaced by warmer air when the door is open). |
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27 watts to run a chest freezer? Are you sure of this? I guess I haven't owned a freezer in years, I'm used to huge energy bills from them. Can anyone that has one confirm energy usage? I am interested too. Many years ago, I tried to run a small freezer on a boat from 2 powerful solar panels. Insulation was 6" thick, top opening and despite that, it didn't work. This was in the tropics, around 82F ambient temp. In full sun, properly oriented, the solar panels produced only 50% average of the nominal output for about 8 hours, If I did not turn them towards the sun, it went down to 35%. I abandoned the project and got a kerosene freezer, it worked well. I am interested in your set up. (Thank you for posting BTW). Are you absolutely certain that you use only 27W/hr average? What is the ambient temp. around the freezer? Yep. These are pretty spot on numbers for a chest freezer of modern design. I have a 15 cubic foot chest freezer, Energy Star compliant, and it averages about 35 watts an hour. I keep it at a cold -10 F. Now, by comparison, the old top & bottom frost free fridge for beer and overflow from upstairs, in the basement uses about 125 watts an hour –– it's 20 years old. The frost free function is an energy hog...get the box cold, then warm it back up, just to suck all the heat back out...and repeat. My basement is about 70 F. Just for comparison, I had to replace the 15 year old chest freezer a year or two back. Same size at 15 cubic feet, and that old Kenmore used about 90 watts an hour. Almost triple the energy to keep stuff at -10. The only green I am interested in is $$$ So a simple chiller made from a chest freezer of modern design would very easily use only 10 watts an hour. |
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Quoted: Quoted: Quoted: Biere, the hardware store has freezer and fridge thermometers for about $3. Seem to be accurate. <snip> "I never remember to buy the thermometer only things, I generally buy one of the temp sensors that has a sensor for outside temps and the outside temp sensor can go live in the fridge or freezer." Biere, the problem with my wireless remote thermometers is they stop working at below 10F after awhile. [See pix below, temp was at -6F then it failed later. Work great in the fridge but fail in the freezer. I think moisture condenses and freezes on the ckt bd. The $2.95 thermometers you hang on a basket work great but I can't monitor them on a network cam. Here's a pix of my wireless thermometers monitoring lots of things. A network camera is focused on them so I can read temps anywhere in the world! http://tickerforum.org/akcs-www?getimagenr=75978 Pick up a can of conformal coating spray, do a little surgery and cover the circuit board...might be able to make 'em last on the cheap (though the spray won't be "inexpensive"). |
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My board name came off the side of a busweiser bottle. If there is empty space I toss a case of beer in it. If I go grocery shopping and need to make room friends from work always seem to be dropping by to help test each beer can to make sure the beer inside meets the acceptable expectations of the consumption date someone stuck on the side of the can. Never had a can get close to its consume by date. Styrofoam sounds ok but I am kind of thinking about the 12 volt computer fan but since these chest fridges don't get rid of moisture anything in there can wind up with moisture on it. Warm groceries will get damp and add moisture if the conditions are right. However, I have never had some of my shredded cheese last so long and I don't know if it because of the chest fridge or if I am doing something different and don't realize it. I don't really keep much in a fridge. I went a month or 3 with no fridge and no cooler. I do like cold beer so there is beer in the fridge. I like milk so there is milk in the fridge. I like sammich stuff so there is mayo and mustard and meat and cheese in the fridge. I have some butter and other odds and ends in the fridge as well but for the most part I don't really need a 5.5 cubic ft fridge but I am too cheap to buy one of the tiny engel fridges yet. A fan will circulate air better and a washcloth or towel in the bottom will absorb moisture and you can change it out now and then. |
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Thanks for the replies.
I live in Florida and the only spot for such a freezer would be in the garage. That means ambient temperature is often 120F in the summer. I wanted to buy an insulated garage door anyway, that will make a difference and then maybe surround the freezer itself with a blue foam box. I have the solar panels and stuff and may try that soon. |
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then maybe surround the freezer itself with a blue foam box.
Likely that'll be counter productive...*unless* the freezer has separate hot-side coils that are fan cooled, like a bar beer chiller, a typical home style chest freezer uses the four walls of the chest as the hot side and just gravity convection drags ambient air across the outside and gets rid of the heat that way. The floor and the lid don't have any coils and those could be extra insulated, but not walls. |
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I have a 5.5 cubic foot holiday brand chest fridge and the front of it gets warm to the touch when it is running. If the power was out I would cover it when it was not running and control when it runs so that it would not kick on and put off heat while I had it all covered up. Some extra comfortors or insulation works fine for covering it up. |
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I have a 5.5 cubic foot holiday brand chest fridge and the front of it gets warm to the touch when it is running. If the power was out I would cover it when it was not running and control when it runs so that it would not kick on and put off heat while I had it all covered up. Some extra comfortors or insulation works fine for covering it up. Perfect ! That would be the exactly correct application of extra insullation. |
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Am I the only one that loves these threads, but feels like an idiot after reading them? Great stuff! I love these posts, but often feel like I've been watching a French movie without sub-titles! Electricity and all it does is still black magic to me! I am working on it.
stasiman Me 3!LOL!!! I'd love to try solar and stuff like this, but I'd likely burn the house down!
Thanks for sharing all of the good info though guys. |
