Amana portable A/C: shop limitations, inneresting thermodynamics....

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Awl --
A'ight, so I got one of those portable ditties, for le shop, around 10,000 btu, single hose, as opposed to the more efficient dual hose. A few years ago. Now the unit is flooding condensate.
Upon tearing this unit apart, it is clear that these units are *destined* to fail in a shop, from dust. Altho there is a shitty filter on the cold air coil, there is no filter on the condenser coil, which uses shop air to exhaust the heat, and thus can get VERY dirty. And indeed it was was.
It is VERY difficult to clean either of these coils properly, and even doing the 60-75% job I did was no joke. To properly clean the condenser coil would require *complete* disassembly of the unit..... COMPLETE. Which proly would not be so bad the second time around, but the FIRST time around appears to be one helluva learning curve.
I seemed to be able to do a so-so job by blowing the fins *tangentially*, so as not to jam the dirt/dust further into the fin structure. And blew out the clog in the top drip pan.
All in all, a well-made unit, but with numerous fundamental design flaws, such as this cleaning business, and clogging condensate holes, resulting in flooding -- which is what in fact initiated this effort. They really need to be used in clean, dust-free environments.
Two-hose units would present less of the dirty hot coil/condenser problem. But, ultimately, all hot condensers coils seem to be difficult to clean, it's just that it seems they take longer to get dirty -- except, of course, for these single-hose units.
But here's the neat thermodynamic part:
A/C efficiency is ultimately limited by the outside air temperature, for a traditional condenser coil that uses outside air to remove its heat.
However, with these portable units (single hose), it's the INSIDE air that cools the condenser coils, which is in part why their EERs are so miserable. BUT, it would appear that this miserable EER cannot be made any MORE miserable by very high outside temps, since those temps no longer come into contact with any coil of the unit. !!!
I wonder if there are some circumstances where this arrangement could actually be an *advantage*?? Mebbe in 195 F climates?? :)
--
EA




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OK.
Obviously the exhausted air is replaced by outside air. Ultimately this air will be cooled to "room temperature" by mixing with the cooled air from the cooling coil.
One MAJOR loss of efficiency is that the outside air coming is quite humid. The "condenser" coil doesn't care whether is it cooled by humid or dry air (at least it doesn't care very much.) The system makes lemonaide out of lemmons by using the water taken from the room air to cool (by evaporation) the room air used to cool the "hot side" of the basic A/C system. Most window units are set up to do this.
One place where this might be useful would be in an apartment situation. The replacement air would be drawn in from the hallway which is cooled by another system.

One place where this might be useful would be in an apartment situation. The replacement air would be drawn in from the hallway which is cooled by another system.

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Actually, I hadn't thought of this. Indeed, it does create a minor negative pressure in the room! AND it's blowing out the room's cold air! Heh, it just gets worse and worse! Indeed, it has a third motor to "wick" up the condensate to blow over the evaporator coils.
--
EA



Ultimately this
> air will be cooled to "room temperature" by mixing with the cooled air
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wrote:

How about this:
Next time you have an appliance you want to use in your workshop which was not specifically designed to be used there (i.e. it has no integral provisions for REAL filters) perhaps you should examine it and see where shop air will be drawn through it and modify the exterior of said appliance to hold DUST FILTERS on it...
Prevention is worth hours and hours of predictable labor tearing said appliances down to clean and rebuild them when you could have installed supplemental filtering and not had to even consider taking the air conditioner apart at all...
~~ Evan
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wrote:

How about this:
Next time you have an appliance you want to use in your workshop which was not specifically designed to be used there (i.e. it has no integral provisions for REAL filters) perhaps you should examine it and see where shop air will be drawn through it and modify the exterior of said appliance to hold DUST FILTERS on it...
Prevention is worth hours and hours of predictable labor tearing said appliances down to clean and rebuild them when you could have installed supplemental filtering and not had to even consider taking the air conditioner apart at all... ============================================= It actually won't be that hard to do. I will scavenge the innards of a typical frame filter, and just duct-tape it around that big unfiltered opening. Won't be pretty, but it will work. Even an old bed sheet would proly work!
--
EA

~~ Evan



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On Sat, 10 Jul 2010 20:26:12 -0700 (PDT), Evan

I wonder..do applience designers ever figure out that people have cats and dogs inside the house?
Gunner
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Existential Angst wrote:

That's different. Never saw one that uses indoor air to cool the condenser.
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That's because he is full of shit.
One never cools a room, one removes the heat from the room. This is not possible under "his" scenario.
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It was not I, but you, who failed completely to comprehend his original post.
So... do YOU comprehend post (sic) by reading it, or do you simply post a non-sequitor, then wait for vituperous reactions?
Lloyd
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On Jul 11, 8:40pm, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:

He's one of those special douchebags that insist on pointing out there is no such thing as 'cold' only heat and the absence thereof.
Dave
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Dave__67 wrote:

I suppose my science background also makes me a douche bag. Not comparing him to me, but I suppose you would also have called Einstein a douche bag. If you think it's easy to look smart when everyone around you is a douche bag, go for it chief, everyone smarter than you is a douche bag.
It's getting cold in here, I better turn off the AC so it stops removing heat from the house.
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You are defending a cretin like Litus??????
--
EA



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Existential Angst wrote:

No, defending myself.
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I thought Dave was commenting to Lloyd about ole syphlitic Litus.
--
EA



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It was my impression that this was the norm for portable A/Cs, until the two-hose jobbies started being produced.
Picture a window A/C, that has vents along the sides (on the portion outside the window), and the exhaust in the back.
Now imagine moving that A/C further into the room, so that those vents are on the room side, and only the exhaust is outside. You would then have effectively duplicated a portable A/C, losing inside air (cooled) going to the outside through those vents, for the purpose of cooling the condenser coil.
So you are essentially throwing out already-cooled air.
But, in the context of very high outside ambient temps, mebbe this has some advantages.
Note, tho, that a portable unit like this Amana proly has an EER of 6, while high-end mini-splits have EERs in the upper 20s, with others typically in the high teens. Min spec for EERs now is, iirc, 13.
--
EA





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Existential Angst wrote:

OK, I didn't notice the "portable" in the subject line. That also explains what you meant about the one or two hoses. I was picturing a window unit with one or two hoses and ready to ask you WTF? Now I understand the whole post.
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That's okay, I was worse and focused on his closing thoughts, and concluded that the post was complete bullshit.
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In other words, being an asshole, you decided to throw the baby out with the bathwater, eh? And being an apparently scientifically ignerint asshole, you don't realize that you shouldna thrown out the bathwater, either.
--
EA

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On Sat, 10 Jul 2010 12:25:48 -0400, Existential Angst wrote:

I've owned an Amana portable window unit since 1995. Biggest BTU rating without being 230 volt. I think it's around 14 or 15K. I would say without any doubt that is one of the very best units on the market at the time. Have never done anything to it except clean the inside filter which just pulls out and washes in the sink. It has an energy saver feature which shuts the entire unit down when thermostat has been satisfied then turns the fan on low at 5 minute intervals to "sniff" the air to see if cooling is required, if so compressor starts and the fan returns to whatever setting you chose.
Your problem isn't the unit its your stupidity in placing it in such a hostile environment where no window unit would survive long.
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Mebbe you need another drink??
--
EA



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