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abu
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welcome

Post by abu » Tue Dec 11, 2001 5:16 am

Good to see BB back up again.
Here is my query since last one got erased.
Is it possible to modify freezers to operate as air conditioners without too much modifications? I am thinking of third world use where air cons are ridiculously expensive?<p>Abu

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Joseph
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Re: welcome

Post by Joseph » Tue Dec 11, 2001 5:32 am

I have been thinking about the idea too, but mainly for heat output. For airconditioning, one way would be to remove the door and to build it into a wall with the hot side outside. Remember that many refrigerators are not designed to run continuously though. The compressors can tend to overheat.<p>The way I was thinking, as a geothermal heat pump would circulate water from the freezer unit into the ground where it would be warmed back up. One advantage here over trying to convert an airconditioner is that the set-up would be simpler and quieter, but the output would not quite be half as much as a standard 5000 BTU airconditioner

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Chris Smith
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Re: welcome

Post by Chris Smith » Tue Dec 11, 2001 2:07 pm

There is no major difference between a freezer and a air conditioning unit, except the efficiency and the degree of temperature that is trying to be achieved. My modified freezer was made from a large air conditioner unit modified in reverse to what you are trying to do because the air conditioner by comparison was a large unit of many BTU's, 240 volt, and very efficient at removing large quantities of heat. It would freeze about 3 cubic feet of water in just minutes. Modifying a small freezer to make a air conditioner will be impracticable because it is designed to remove small amounts of heat, from a well insulated and sealed box. Air conditioners on the other hand are designed to remove large amounts of heat from a room size box that isn't usually insulated. Comparing a 10 cubic foot freezer to a room size medium unit doesn't add up. It can be done but a larger evaporator should be used, and more fluid should also be added as well as a large cooling fan added to the heat exchanger, something that almost all small freezers lack. Most home freezers use about 4 ounces or less of Freon, while the AC unit I used took almost one pound of Freon making it very efficient. Your starting small and trying to achieve too much from a unit that wasn't designed to work that hard. Some fridges and freezers are only a couple of hundred BTU's by comparison to AC units that start off at 1500 and go up to many thousands of BTU's. If you want a AC unit to work from the average size Freezer, you'll need to place your self and it into a small cardboard box the size of a wash machine or fridge shipping box, insulate it well, and then you might succeed? If you have a commercial freezer on the other hand, one with a several horse motor and commercial pump, containing several gallons of coolant, then you can cool down a whole house easily. Its all about BTUs, and the removing of as many as possible, equal to the ambient heat around you, and the heat loss acording to insulation, as well as efficiency.

unknown_entity
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Re: welcome

Post by unknown_entity » Tue Dec 11, 2001 5:22 pm

well a 240v is going to be more efficient than a 120v model,and 3 phase is even more efficient than 240v. But I have never heard of a 3 phase fridge. Other than that i don't know much about freezers.

BIG K
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Re: welcome

Post by BIG K » Wed Dec 12, 2001 12:34 am

They do make 3 phase commercial units because of what you said...efficency. And they use less electricity in the process. But I don't recall seeing any home units for 3 phase power.....

Dean Huster
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Re: welcome

Post by Dean Huster » Wed Dec 12, 2001 5:58 am

I wouldn't concern myself with a 3-phase design for a residence anyway. Most power companies will only drop 3-phase service to industrial concerns, irrigation pumps, oil wells or large buildings that can justify the expense of their installing three transformers. And if there isn't a 3-phase line already running by your property, you can forget it in most cases.<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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Chris Smith
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Re: welcome

Post by Chris Smith » Wed Dec 12, 2001 12:07 pm

Where did "Three phase" come from? That only relates to motors, not AC?

unknown_entity
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Re: welcome

Post by unknown_entity » Thu Dec 13, 2001 8:05 pm

Well i was just saying which type of power would be more efficient. I didn't even think there was such a thing as a 3 phase fridge. i just used it to compare different types of power.<p>[ December 13, 2001: Message edited by: unknown_entity ]</p>

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Chris Smith
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Re: welcome

Post by Chris Smith » Thu Dec 13, 2001 10:18 pm

Three phase is always more efficient, but I couldnt see where the term "got introduced"? Did I miss somthing, was why I remarked? Single phase, or any other, in the motor that drives a compressor, is secondary to the Cooling unit in terms of the workings of that unit? We were into the BTU's and how and why the compressor works best, etc.

onagnan
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Re: welcome

Post by onagnan » Fri Dec 28, 2001 11:28 am

Sorry Will never work. Ref Compressor will have about 800 BTU and any AC will be at least 4000+ BTU. A persol alone produces more than that. Not A good way . If you would like a better solution sen over more details and I may be able to come up with something. I work with Ref and AC for A life time. Hope this helps Good Luck

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