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#1
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Garage heater kit for fridge?
Frigidaire sells a $29 5303918301 laminated "garage heater kit," with
2 wires that wraps around the cold control of a fridge to allow it to work in to work in a cooler room, down to about 40 F. It apparently heats the thermostat to fool the compressor into turning on, even if the fridge compartment is cool enough (eg 40 F in a 40 F room. Without this kit, the compressor does not run often enough to keep ice cream from melting. How does this work, exactly? Is the heater always on? Is it just adding enough heat to the fridge compartment to make the compressor run long enough to keep the freezer compartment frozen? If so, why is it wrapped around the cold control, vs somewhere else in the fridge box? I just bought an 18.2 CF Hotpoint fridge. I'd like to cover the outside with 2" foamboard and run it in a cool kitchen to reduce the energy used from 480 kWh/year to 240 or so, but Hotpoints don't come with these kits. Would leaving the light on all the time in the fridge compartment do the same thing? Is there a more energy-efficient way to do this? Warming the whole fridge box takes more power than just warming the thermostat. Nick |
#2
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Garage heater kit for fridge?
wrote in message I just bought an 18.2 CF Hotpoint fridge. I'd like to cover the outside with 2" foamboard and run it in a cool kitchen to reduce the energy used from 480 kWh/year to 240 or so, but Hotpoints don't come with these kits. Would leaving the light on all the time in the fridge compartment do the same thing? Is there a more energy-efficient way to do this? Warming the whole fridge box takes more power than just warming the thermostat. Nick Warming the fridge box is dumb too, as the food will be getting warm along with the thermostat. |
#3
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Garage heater kit for fridge?
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#4
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Garage heater kit for fridge?
Edwin Pawlowski wrote:
wrote in message I just bought an 18.2 CF Hotpoint fridge. I'd like to cover the outside with 2" foamboard and run it in a cool kitchen to reduce the energy used from 480 kWh/year to 240 or so, but Hotpoints don't come with these kits. Would leaving the light on all the time in the fridge compartment do the same thing? Is there a more energy-efficient way to do this? Warming the whole fridge box takes more power than just warming the thermostat. Warming the fridge box is dumb too, as the food will be getting warm along with the thermostat. The thermostat would still control the fridge temp. The Hotpoint manual says don't run it in a room cooler than 60 F... 2" of extra foamboard would lower the fridge box conductance to about 2 Btu/h-F and the freezer conductance to about 1, so the freezer would need about 40 Btu/h of cooling at 0 F in a 40 F room, which might come from a 15 watt bulb in a 40 F fridge box that runs whenever the room is less than 60 F. If the light uses 15 watts and the fridge uses 5, on average, that's 20x24h = 480 Wh/day, ie 175 kWh/year if the room were always 40 F or 26x24h = 624 Wh/day if the room were always 70 F. It would be nice to get this down to 100 Wh, like the Mt. Best chest freezer fridge modification. With better controls, it might only need 5x23h = 120 Wh/day. Nick |
#5
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Garage heater kit for fridge?
On Sep 27, 3:46*am, wrote:
Frigidaire sells a $29 5303918301 laminated "garage heater kit," with 2 wires that wraps around the cold control of a fridge to allow it to work in to work in a cooler room, down to about 40 F. It apparently heats the thermostat to fool the compressor into turning on, even if the fridge compartment is cool enough (eg 40 F in a 40 F room. Without this kit, the compressor does not run often enough to keep ice cream from melting. How does this work, exactly? Is the heater always on? Is it just adding enough heat to the fridge compartment to make the compressor run long enough to keep the freezer compartment frozen? If so, why is it wrapped around the cold control, vs somewhere else in the fridge box? I just bought an 18.2 CF Hotpoint fridge. I'd like to cover the outside with 2" foamboard and run it in a cool kitchen to reduce the energy used from 480 kWh/year to 240 or so, but Hotpoints don't come with these kits. Would leaving the light on all the time in the fridge compartment do the same thing? Is there a more energy-efficient way to do this? Warming the whole fridge box takes more power than just warming the thermostat. Nick I would not jump into this without research, my home ac condensor has a heater for the compressor , there are low temp ratings for all compressor equipment I have. My low temp warning is about 50-55f for my sears energy star frige. I would worry about ruining the unit, leaving a light on will just waste energy like opening the door 24hrs a day. |
#6
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Garage heater kit for fridge?
Uncle Monster wrote:
... something I read indicates that the heater is for adding heat to the "control compartment" to fool the thermostat into making the compressor run for a longer period of time. Is the heater always on? Maybe it turns off when the compressor runs? Why heat the control compartment instead of the box? If the control is heated, the thermostat could still work, but the fridge box would be colder than without the heater, given the same thermostat setting. Putting a bulb in the box would just increase the run time without affecting the box temp. This could be more efficient with 2 fans and 2 thermostats and no heater. Disabling the door heater and auto-defrost could also help. Nick |
#7
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Garage heater kit for fridge?
wrote in message If the light uses 15 watts and the fridge uses 5, on average, that's 20x24h = 480 Wh/day, ie 175 kWh/year if the room were always 40 F or 26x24h = 624 Wh/day if the room were always 70 F. It would be nice to get this down to 100 Wh, like the Mt. Best chest freezer fridge modification. With better controls, it might only need 5x23h = 120 Wh/day. Nick The thermostat unit heats just that tiny portion of the unit to make the freezer be colder. To warm the entire refrigerator box with a 40W bulb is wasteful and will warm the contents a bit. Saving energy at the expense of potential food deterioration or spoilage does not make sense. |
#8
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Garage heater kit for fridge?
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#9
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Garage heater kit for fridge?
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#10
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Garage heater kit for fridge?
Edwin Pawlowski wrote:
wrote in message If the light uses 15 watts and the fridge uses 5, on average, that's 20x24h = 480 Wh/day, ie 175 kWh/year if the room were always 40 F or 26x24h = 624 Wh/day if the room were always 70 F. It would be nice to get this down to 100 Wh, like the Mt. Best chest freezer fridge modification. With better controls, it might only need 5x23h = 120 Wh/day. Or 24h(40F-10F)1Btu/h-F/3.41Btu/h/W/3COP = 70 Wh/day, ie 26 kWh/year worth $2.60 per year at 10 cents/kWh, with a 10 F freezer compartment and a 40 F fridge compartment in a 40 F room. The thermostat unit heats just that tiny portion of the unit to make the freezer be colder. But the thermostat's in the fridge compartment, no? The fridge wants to be about 34 F... To warm the entire refrigerator box with a 40W bulb is wasteful and will warm the contents a bit. Who mentioned 40 watts? A bulb in the box would not change the box temp. Nick |
#11
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Garage heater kit for fridge?
Uncle Monster wrote:
... The heat is just enough to trick the thermostat, not to warm the refrigerator compartment. How would that accomplish the goal? Nick |
#12
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Garage heater kit for fridge?
wrote in message To warm the entire refrigerator box with a 40W bulb is wasteful and will warm the contents a bit. Who mentioned 40 watts? A bulb in the box would not change the box temp. Nick If it does not change the box temperature, it is not going to make the thermostat do its thing. 40 watts burning adds heat and while it is mostly overcome by the operation of the compressor, it still has to raise the temperature a bit. How much depends on the differential of the thermostat. |
#13
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Garage heater kit for fridge?
On Sat 27 Sep 2008 01:46:53a, told us...
Frigidaire sells a $29 5303918301 laminated "garage heater kit," with 2 wires that wraps around the cold control of a fridge to allow it to work in to work in a cooler room, down to about 40 F. It apparently heats the thermostat to fool the compressor into turning on, even if the fridge compartment is cool enough (eg 40 F in a 40 F room. Without this kit, the compressor does not run often enough to keep ice cream from melting. How does this work, exactly? Is the heater always on? Is it just adding enough heat to the fridge compartment to make the compressor run long enough to keep the freezer compartment frozen? If so, why is it wrapped around the cold control, vs somewhere else in the fridge box? I just bought an 18.2 CF Hotpoint fridge. Maybe you should have bought the Frigidaire. Problem solved. I'd like to cover the outside with 2" foamboard and run it in a cool kitchen to reduce the energy used from 480 kWh/year to 240 or so, but Hotpoints don't come with these kits. Would leaving the light on all the time in the fridge compartment do the same thing? Is there a more energy-efficient way to do this? Warming the whole fridge box takes more power than just warming the thermostat. How cold do you plan on keeping the kitchen? Most refrigerators perform perfectly well down to around 60°F. Unless you're always dressed for winter, anything lower could hardly be considered comfortable. I must say, a refrigerator encased in 2" foamboard sounds really "attractive". Not! Why on earth would you really want to do this? I don't think you'll be saving a thing and you need a different project. :-) -- Wayne Boatwright ******************************************* Date: Saturday, 09(IX)/27(XXVII)/08(MMVIII) ******************************************* Countdown till Veteran's Day 6wks 2dys 8hrs 27mins ******************************************* Bring me my blue soap box. I want to make a speech. ******************************************* |
#14
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Garage heater kit for fridge?
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#15
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Garage heater kit for fridge?
Edwin Pawlowski wrote:
wrote in message To warm the entire refrigerator box with a 40W bulb is wasteful and will warm the contents a bit. Who mentioned 40 watts? A bulb in the box would not change the box temp. If it does not change the box temperature, it is not going to make the thermostat do its thing. The box temp change would be minimal. ... 40 watts burning adds heat Who mentioned 40 watts? Nick |
#16
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Garage heater kit for fridge?
Wayne Boatwright wrote:
How cold do you plan on keeping the kitchen? I kept it 36 F one year. Nick |
#17
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Garage heater kit for fridge?
Uncle Monster wrote:
... The heat is just enough to trick the thermostat, not to warm the refrigerator compartment. How would that accomplish the goal? The slight heat produced by the heater is enough to raise the temperature around the thermostat to trick it into running the compressor for a longer period of time. It's not necessary to increase the temperature of the whole refrigerated box, just the temperature around the thermostat. That doesn't make sense to me... Nick |
#18
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Garage heater kit for fridge?
On Sat 27 Sep 2008 05:18:08p, told us...
Wayne Boatwright wrote: How cold do you plan on keeping the kitchen? I kept it 36 F one year. Nick That's beyond my comprehension. At that temperature, you don't even need a refrigerator, just a freezer. -- Wayne Boatwright ******************************************* Date: Saturday, 09(IX)/27(XXVII)/08(MMVIII) ******************************************* Countdown till Veteran's Day 6wks 2dys 6hrs 6mins ******************************************* When you're arguing with a fool, make sure he isn't doing the same thing. ******************************************* |
#19
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Garage heater kit for fridge?
wrote in message Who mentioned 40 watts? Nick Typical appliance bulb wattage |
#21
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Garage heater kit for fridge?
larry wrote:
wrote: Uncle Monster wrote: ... The heat is just enough to trick the thermostat, not to warm the refrigerator compartment. How would that accomplish the goal? The slight heat produced by the heater is enough to raise the temperature around the thermostat to trick it into running the compressor for a longer period of time. It's not necessary to increase the temperature of the whole refrigerated box, just the temperature around the thermostat. That doesn't make sense to me... It's like the timer with a 10K resistor clipped under a regular wall thermostat to do an over-night "setback". Thermostat thinks it's getting warmer and turns off the furnace when the room isn't warmer. But that makes the room colder at night. How do we keep the fridge a constant 40 F and the freezer frozen in a 40 F room? If the freezer stays 0 F in a 60 F room while the 40 F fridge box is gaining Q Btu/h from the room, cooling the room to 50 will reduce the fridge gain to Q/2, so the compressor will run half the time. But the required freezer run time will only go down by 50/60, so we need to add enough heat to the fridge box (vs the thermostat box) to raise the run time back up to 50/60 of the 60 F room run time, no? The fridge box won't absorb any heat at all from a 40 F room, but the freezer still needs 40/60 of the 60 F room run time to stay 0 F. Nick |
#22
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Garage heater kit for fridge?
Wayne Boatwright wrote:
How cold do you plan on keeping the kitchen? I kept it 36 F one year. That's beyond my comprehension. It's easy to do with the kitchen off the back of my house. With 2' stone walls (C ~ 50 Btu/F-ft^2) inside R10 insulation and RC = 500 hours, the kitchen temp changes slowly. Starting at 36 F, it would cool to 30+(36-30)e^-(24h/500h) = 35.7 over an average 30 F January day. Leaving the kitchen door to the rest of the house open for a few minutes a day makes up for that cooling. At that temperature, you don't even need a refrigerator, just a freezer. Right, but then spring happens. Maybe the freezer needs a thermostat that turns on a 15 watt bulb in the fridge box when the freezer temp rises to 10 F. Where can I find one of those? Nick |
#23
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Garage heater kit for fridge?
... Maybe the freezer needs a thermostat that turns on a 15 watt bulb
in the fridge box when the freezer temp rises to 15 F. Where can I find one of those? Aha. Danfoss 015-0283, for $23.95... http://www.rparts.com/Catalog/Major_.../015-0283r.htm Nick |
#25
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Garage heater kit for fridge?
larry wrote:
wrote: larry wrote: wrote: Uncle Monster wrote: ... The heat is just enough to trick the thermostat, not to warm the refrigerator compartment. How would that accomplish the goal? The slight heat produced by the heater is enough to raise the temperature around the thermostat to trick it into running the compressor for a longer period of time. It's not necessary to increase the temperature of the whole refrigerated box, just the temperature around the thermostat. That doesn't make sense to me... It's like the timer with a 10K resistor clipped under a regular wall thermostat to do an over-night "setback". Thermostat thinks it's getting warmer and turns off the furnace when the room isn't warmer. But that makes the room colder at night. How do we keep the fridge a constant 40 F and the freezer frozen in a 40 F room? If the freezer stays 0 F in a 60 F room while the 40 F fridge box is gaining Q Btu/h from the room, cooling the room to 50 will reduce the fridge gain to Q/2, so the compressor will run half the time. But the required freezer run time will only go down by 50/60, so we need to add enough heat to the fridge box (vs the thermostat box) to raise the run time back up to 50/60 of the 60 F room run time, no? The fridge box won't absorb any heat at all from a 40 F room, but the freezer still needs 40/60 of the 60 F room run time to stay 0 F. Nick The way the closed loop control works on modern frig's is working against you. You need a little redesign. Given: 1. the freezer, goal=0F, always needs cool in your ambient temp range, 40F to 80?F. 2. the coldbox (frig - i hate these terms), goal=36F, needs cool on hot days and maybe none on cold days. Plan: 1. freezer, meet the demand first, put the thermostat for the freezer IN THE FREEZER, where the coils are to begin with. Closed the loop on the freezer, it will take care of itself. 2. Coldbox. Block the existing air path between the freezer and the coldbox below. Control that airflow with a moving vane and and fan connected to a thermostat in the coldbox to cool the coldbox with cold air from the freezer to the target temp 40F. Cheap way of doing the coldbox control is a bimetalic strip in the coldbox that pushes the vane open as the temperature exceeds 40F. A small microswitch could switch on the fan as long as it detects the vane is open. Just about everything you need is already in the frig. Take up the baseplate in the freezer, you will see the cooling coils, the air path, with vane, to the coldbox, and a fan near the back, that circulates cool in the freezer and coldbox. Plus a big heater to thaw the coils. There is a schematic in an envelop near the compressor or defrost tray. I don't know how this will affect defrost cycle. second thought, close off the kitchen and roll the frig to the living room... You can't be married... ;-) -- larry/dallas It's all about cost. The commercial refrigeration systems I install/build/repair usually work well regardless of the ambient temperature. I'm about to move two walk in coolers and reinstall them where the condensing units will be in a back room rather than two stories up on a roof. The units will work without a problem because of their more sophisticated control system than a home refrigerator. The control systems use not only thermostats but pressure and fan controls to maintain the temperature. I've worked on Sub-Zero brand refrigerators made for home use that were built like commercial coolers with semi-hermetic compressors and commercial controls but GOLLY! those damn things are expensive. They will work in just about any ambient temperature but the cost is out of my range. I could always take a standard home refrigerator and modify it for a lot less money. [8~{} Uncle Monster |
#26
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Garage heater kit for fridge?
On Sun 28 Sep 2008 01:22:57a, told us...
Wayne Boatwright wrote: How cold do you plan on keeping the kitchen? I kept it 36 F one year. That's beyond my comprehension. It's easy to do with the kitchen off the back of my house. With 2' stone walls (C ~ 50 Btu/F-ft^2) inside R10 insulation and RC = 500 hours, the kitchen temp changes slowly. Starting at 36 F, it would cool to 30+(36-30)e^-(24h/500h) = 35.7 over an average 30 F January day. Leaving the kitchen door to the rest of the house open for a few minutes a day makes up for that cooling. Being able to do it is not beyond my comprehension. Why anyone would really want to do it is beyond my comprehension. I want every room in my house to be at a comfortable temperature at all times. I would find it inconvenient and uncomfortable to have to wait for it to warm up enough for the kitchen to be useful. You are not saving siginficant energy, since to be able to use the kitchen you're robbing other parts of the house of its heat which has to be compensated for each time you do it. At that temperature, you don't even need a refrigerator, just a freezer. Right, but then spring happens. Maybe the freezer needs a thermostat that turns on a 15 watt bulb in the fridge box when the freezer temp rises to 10 F. Where can I find one of those? Well, yes, spring happens. As to where to find what you're looking for, I have no idea. -- Wayne Boatwright ******************************************* Date: Monday, 09(IX)/29(XXIX)/08(MMVIII) ******************************************* Countdown till Veteran's Day 6wks 19hrs 36mins ******************************************* I is knot dain bramaged! ******************************************* |
#27
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Garage heater kit for fridge?
In article ,
wrote: Uncle Monster wrote: ... The heat is just enough to trick the thermostat, not to warm the refrigerator compartment. How would that accomplish the goal? ...explanastion snipped... That doesn't make sense to me... Nick The darn thing works, does it need to make any more sense than that? -- Better to be stuck up in a tree than tied to one. Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar.org |
#28
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Garage heater kit for fridge?
Wayne Boatwright wrote:
How cold do you plan on keeping the kitchen? I kept it 36 F one year. That's beyond my comprehension. It's easy to do with the kitchen off the back of my house. With 2' stone walls (C ~ 50 Btu/F-ft^2) inside R10 insulation and RC = 500 hours, the kitchen temp changes slowly. Starting at 36 F, it would cool to 30+(36-30)e^-(24h/500h) = 35.7 over an average 30 F January day. Leaving the kitchen door to the rest of the house open for a few minutes a day makes up for that cooling. With the door to the rest of the house closed, it would cool from 36 to 32 in -500ln((32-30)/(36-30)) = 549 hours, ie 23 days. Being able to do it is not beyond my comprehension. Why anyone would really want to do it is beyond my comprehension. Pity. You are not saving siginficant energy, since to be able to use the kitchen you're robbing other parts of the house of its heat which has to be compensated for each time you do it. Au contraire, the fridge uses less energy in a cool room, and the room itself needs less heat if it's cooler on average. As to where to find what you're looking for, I have no idea. Danfoss sells $24 freezer stats... Nick |
#29
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Garage heater kit for fridge?
On Tue 30 Sep 2008 09:17:47a, told us...
Wayne Boatwright wrote: How cold do you plan on keeping the kitchen? I kept it 36 F one year. That's beyond my comprehension. It's easy to do with the kitchen off the back of my house. With 2' stone walls (C ~ 50 Btu/F-ft^2) inside R10 insulation and RC = 500 hours, the kitchen temp changes slowly. Starting at 36 F, it would cool to 30+(36-30)e^-(24h/500h) = 35.7 over an average 30 F January day. Leaving the kitchen door to the rest of the house open for a few minutes a day makes up for that cooling. With the door to the rest of the house closed, it would cool from 36 to 32 in -500ln((32-30)/(36-30)) = 549 hours, ie 23 days. Being able to do it is not beyond my comprehension. Why anyone would really want to do it is beyond my comprehension. Pity. I can't imagine anyone else in the civilized world wanting to do this. Most would probably find this a very uncomfortable situation at best. You are not saving siginficant energy, since to be able to use the kitchen you're robbing other parts of the house of its heat which has to be compensated for each time you do it. Au contraire, the fridge uses less energy in a cool room, and the room itself needs less heat if it's cooler on average. Are you doing this to save money or as just a weird experiment? As to where to find what you're looking for, I have no idea. Danfoss sells $24 freezer stats... Then you've found your answer. -- Wayne Boatwright ******************************************* Date: Tuesday, 09(IX)/30(XXX)/08(MMVIII) ******************************************* Countdown till Veteran's Day 5wks 6dys 6hrs 4mins ******************************************* I have no idea what that meant. - Dot Warner ******************************************* |
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