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Old 06-10-13, 11:32 AM   #21
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Thanks, that was a great answer. How do you plan on going about testing for this sweet spot?

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Old 06-10-13, 02:47 PM   #22
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So what is your overall impression of the chinese temp controller? I mean, other than your desire for total control of all parameters (which may or may not be possible with the off-the-shelf Chinese unit), how does the unit track and/or learn or respond to its environment? I see it strayed or drifted a bit on you. I'm seriously considering using one to control some sort of heat pump monster in the near future. Regular heat pump thermostats are not that much more expensive, and some have lag and swing controls built in also. Probably not as wide-range as the Chinese unit, but then again the temp sensors don't drift either.

Some of your frustration may be built into the deep freeze itself. I'm sure the unit was built for lower ultimate temp, rather than rapid pulldown. With a cap tube setup, this means lower mass flow and suction pressure, regardless of ambient or box temp by design (longer cap tube). It may not be advantageous to try to limit your box temp/evap temp to prevent frost unless there is some kind of airflow inside the chamber.

With the teensy controlling things, you might be able to add more sensors and gain insight into the temps of everything, but with the stratification and lag (due to the lack of airflow) in box temps, I'm not sure it would do so much good. As temps get close to freezing, you may NEED to have frost to transfer enough energy out of the box. I guess it all depends on how short you want the cooling runs to cycle vs the inherent lag.

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Old 06-11-13, 08:51 AM   #23
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Originally Posted by Daox View Post
Thanks, that was a great answer. How do you plan on going about testing for this sweet spot?
First is build the new controller. I already have all the parts, including a water proof 1-wire sensor, and a spare LCD I can use for the readout.

After that it will be closely monitored trial & error.

I was scheming a way to make the Teensy (Arduino) automatically increase & decrease the hysterisis until the unit reached maximum efficiency, but then reality set in and I decided that trial & error would the best approach to a one-shot problem.

-AC
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Old 06-11-13, 09:03 AM   #24
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So what is your overall impression of the chinese temp controller?
It is working pretty well. It has a menu for correcting any gross errors in the sensor, it has buttons for easily setting the set-point temp, and also for the hysteresis.

It doesn't have any kind of 'learning' ability, liked PID controllers. It doesn't have the ability to do a delayed start.

It can be used for cooling or for heating through a menu selection.

Apparently, it was designed for controlling a peltier cooler or heater that needs no consideration as to delayed start. It has a relay output and inductive loads will probably shorten the relay life.

It is simple and cheap and works.

-AC
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Old 07-15-13, 10:39 AM   #25
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How goes the trial and error? Have you been able to reduce the power consumption any further?
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Old 07-15-13, 02:28 PM   #26
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How goes the trial and error? Have you been able to reduce the power consumption any further?
Thanks for asking...

My data logger is now doing duty as a whole house temperature logger, so I'm not sure what is going on with the power consumption. I am sure it is higher than it was when the weather was cooler, but I don't know how much.

But the Freezerator is working well. As I said previously, the humidity inside the box is higher than the typical refrigerator. This is very good for produce, which lasts far longer than in a normal refrigerator. It also presents a challenge. Right now, I'm dealing with it by using a water absorber pad in the bottom of the unit. A better fix would be a drain tube.


This Haier:


...has a drain tube built in and it's un-hacked specs are very attractive, so it would be a better choice for a Freezerator.

I'm considering the possibility of putting a drain tube into mine. If I could use some kind of heated cone-shaped metal and heat-form a dimple in the bottom of the lining material, then a drain would be quite possible.

But I could just sell my present unit on Craig's List and get the Haier, to hack into a much better Freezerator.

& & &

But my focus is now turning to putting in a radiant floor in my back room... I'm right now emptying everything out in preparation for demolition.

I have finally located some high-density insulating material to use under the PEX & aluminum.

More on that later.

Best,

-AC
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Old 07-16-13, 12:18 PM   #27
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This is very impressive because a lot of older frigs I have tested consume around 2kwh to 2.5kwh a day. A lot of people complain that the new energy star fridges don't use much less power than some of the older fridges with the large exposed rear mounted passive condenser.

Energy star my ***.

If you saw my post http://ecorenovator.org/forum/geothe...elsewhere.html
You would know my fridge isn't doing so well these days. It seems like it comes on all the time but that just might be because I notice the bathroom fan every time its on. I think I will put one of my Kill-a-watt meters on it and see how it does.
I do have an up right freezer with the large exposed passive condenser I may end up converting to a fridge.

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Old 07-16-13, 03:29 PM   #28
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This is very impressive because a lot of older frigs I have tested consume around 2kwh to 2.5kwh a day...
Yeah, it is pretty impressive... partly because it is utilizing the better construction of a freezer, and only asking the compressor to hold 37F or so, instead of 0F. It's also because I'm using a small refrigerator. I have found that I can get by just fine with a smaller system. It's curious that so few EcoRenovators seem to go for the smaller = better idea... oh well.

If you decide to go with a Freezerator conversion, It's quite easy, and if you don't like the results, you can easily switch back.

The Chinese thermostat was about $17. Some people use a beer cooler thermostat, better built for about $50.

I think it is fair to estimate that the Freezerator conversion will use approximately 50% as much power as your freezer normally uses.

It would be a great idea to get a Kill-a-Watt first and establish your freezer's current demand, and also measure the demand after the hack.

There's certainly room on this thread for your story...

Best,

-AC
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Old 07-17-13, 03:12 PM   #29
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Brilliant thread.

I came to similar conclusions why freezarators work so well - it is not the horizontal vs vertical orientation so much as just not having a freezer! In a similar vein, smaller is less energy, but again, the bulk of the savings is nixing the freezer.

My Whirlpool averages about 1 kWh a day in our home (rated 1.1 kWh a day by EPA.) It is about 2 parts fridge and 1 part freezer by volume. If I assume fridge temp is 35F (2C) and freezer temp 15F (-10C), and annual ambient about 68F (20C), then all else being equal, the fridge uses 60% of the energy required for the freezer for equal volumes. This means that my 20 c.f fridge/freezer would average 600 Wh a day if it was a 20 c.f. fridge only. If I had only the fridge space of ~ 13.3 c.f., the average daily consumption would be about 400 Wh a day.


I asked my wife if she would be OK with not having a freezer in the house and got shot down. I had to laugh when she said "What about the ice cream ?!" Even she smiled after she thought about her answer, since we make efforts to not gain weight. I'll have to get her used to the idea over time...

About those temperature swings:How about placing some water (in a container to avoid evaporation) in front of the air vent ? Seems to me that you want a solution that will provide buffer and heat capacity. Of course if the cooling device is efficient with short bursts you can just tighten your on and off limits.

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Old 07-17-13, 04:24 PM   #30
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...This means that my 20 c.f fridge/freezer would average 600 Wh a day if it was a 20 c.f. fridge only. If I had only the fridge space of ~ 13.3 c.f., the average daily consumption would be about 400 Wh a day.
All things being equal, a smaller frig will require smaller power. But the relationship is not linear, because area increases at roughly a square function, and volume increases at roughly a cubic function... and heat loss is proportional to area.

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Originally Posted by ELGo View Post
I asked my wife if she would be OK with not having a freezer in the house and got shot down. I had to laugh when she said "What about the ice cream ?!" Even she smiled after she thought about her answer, since we make efforts to not gain weight. I'll have to get her used to the idea over time...
The old fashioned ice & salt hand-crank ice cream freezers are even more effective than self discipline...

Quote:
Originally Posted by ELGo View Post
About those temperature swings:How about placing some water (in a container to avoid evaporation) in front of the air vent ? Seems to me that you want a solution that will provide buffer and heat capacity. Of course if the cooling device is efficient with short bursts you can just tighten your on and off limits.
I do know that there is a startup inefficiency, and that longer runtimes favor efficiency. When I get the time, I'm going to return to an Arduino controller, because I can build in finer tuning increments, and as I said before, I'd like to zero in on the most efficient cycle time/temp swing compromise.

There might also be some efficiency to be gained with a suitable Phase Change Material (olive oil?)... but I have too many projects demanding my attention, to pursue that right now.

But, I really like the Freezerator project because it's simple, the reward is easily measurable, and the pay-off comes quickly. Lastly, if you're not satisfied with your hack, no irreversible change has been made to the freezer.

If you're going to try the Freezerator, it's important to find the most efficient freezer you can, whether it is chest-type or upright, because your final energy use will be about fifty-ish percent of the freezer consumption.

BTW, if you get a hand-crank ice cream maker, I have some killer recipes... but don't expect them to be low calorie.

Best,

-AC

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