My new LG 1419IVSM 10000 DOE BTU (14000 BTU by the previous standard before last year) portable air conditioner meets my expectations as a substantial upgrade over the 6000 (8000) BTU LG portable I've been borrowing from a friend, and likely good enough for emergency household use.
The improvement is substantial and significant, in cooling my entire old and leaky 1240 sq ft home for an emergency (waiting for central AC to get repaired, and as murphy's law would have predicted, the AC failed right at the time it was most needed, in a late July heatwave, and when the backlog for repairs was also greatest).
As I explained in earlier post, I don't have accessible windows in any room I want cooled, so it's not easy for me to use window units (and, yes, I know window units are more effective as room air conditioners than portables, just as Consumer Reports says). Instead, I'm using the accessible window in the half converted garage (which I don't even care about cooling) as the output window for the portable, which is seated in the doorway to this (otherwise closed and insulated) room, blowing out to the hallway for the rest of the house, with circulation by small fans all around on the floors. I had to reposition the fans slightly because this unit blows much harder than the previous one, requiring the fans to start a few feet away from it for best effect (and positioning the fans makes about as big an effect as anything, and I probably need a better set of fans too).
Since the air is blowing out at about gut level (I have set it to about as low angle as possible from the floor to still be effective), and I have blocked off the sides of the unit with baffles, the return air comes from the upper part of the rooms, which is not fan forced, which is likely to be the hotter air. The room the portable is sitting in (which I don't care about) is getting all the waste heat, and is warmer than the rest of the house, so it's also fine that it is from there that the portable gets it's second stream for the compressor side.
However, this portable AC is no miracle either. During the peak interior temperature hour (9pm) just as the sun is setting, it shaved a mere 1 degree off of yesterday's performance with the smaller unit (90F vs 91F) at approximately the same humidity or slightly better (31%). That sounds horrible but actually was quite fine with the ceiling fan running on low, largely thanks to the AC lowered humidity (if not so much temperature).
But then, unlike yesterday, when it stayed at 90F until just before midnight (and when I'd already had the larger unit running for over an hour), it pretty quickly fell back to 88F right after 9PM. 88F at 31% humidity is really fine (as I am writing this) with the ceiling fan on low.
Most of the day, it tracked being about two degrees lower than before with the smaller unit.
But I had had my hopes built up even higher during the 12-6 am interval, when it seemed like the new portable might even be doing too well. I had (and continue to have) the temperature set to 60F (the minimum) rather than anything I really need simply to crank out as much from it as possible. But the downside of that approach could be, if the need falls very low, I could wake up freezing.
I was indeed quite worried about that, as the temperature had already fallen to 82F at 4am. At that rate, it might be below 75F at 8am. (It was probably stupid to worry about that...).
So I decided to slow it down by re-opening all the hallway doors to unused rooms. Most were very much like the bedroom but with no cooling fans. This would create wind eddies and such and mean less was flowing to the bedroom, but still cooling off the rest of the thermal mass in the house.
As a result, it never got below 82F in the master bedroom. I should have kept the doors closed to get the bedroom as low as possible, in preparation for the afternoon heating.
It's almost certainly true that to get colder and colder is harder and harder, as the greater the difference from other sides is, the more potential they have to slow it down.
But anyway, in those wee hours, it seemed as though the 10000 BTU unit was doing a fairly decent job of cooling my entire home, as in almost there. I think that's the way it works, the closer the cooling to the need, the more and more well it does, perhaps even more than linearly reaching optimal levels.
The rest of the day, it's more and more tolerable, but not almost there.
The bedroom for example was a very dry 85F most of the afternoon (as compared with an equally dry 87F yesterday) at peak. The peaks were 87/90F respectively, around 8PM.
So it seems this would be a workable emergency solution, which is good, because anything more would require much greater expense (like mini-splits), expensive carpentry (new openings for window units) or extensive lifestyle changes.
It's been reaching 105F peaks recently outside at mid day. Now, theoretically it could be up to 10F hotter still on the hottest day of the hottest year. But this unit is providing well more than 10F margin from the near deadly, for elderly, 30C wet bulb temperature with current temperatures, so it should still be adequate in the extreme case (or, I could focus it just on one room until that need went away).
This larger unit is slightly larger and significantly heavier than the smaller capacity unit, but it has wheels making it actually easier to move around. It has the same super quiet dual inverter compressor system which never kicks on and off but establishes an even keel just at the proper point. I'm glad I returned the LG 1021BSSM I bought at Home Depot (who handled the return graciously) because it has the other kind of compressor, always kicking on and off, and louder to begin with.
THOUGH, it did occur to me that there might be downsides to the dual inverter system. It *is* more complex, so just by that principle might be less reliable. But that also depends on how good the engineering is, the the Dual Compressor system is LG's flagship, which they must have put considerable effort into getting right. The regular compressor model is a market driven thing, might even be made by someone else. I've seen reports about the regular compressor model failing (and didn't look for those in my model generally...though it gets much higher reviews overall).
The other issue was that possible the old style compressor would actually produce a lower temperature. Therefore, it would change the temperature more than just do dehumidification, as the steady state units do. That might be more desireable. But I tend to think it all comes down to the BTU rating if you are talking about the units from one company in the same basic form factor. And actually, LG claims 500 sq ft cooling for the dual inverter model, and only 450 for the cheaper regular (well, it's still a scroll compressor, which is quieter than the piston type) compressor.
Now, yes, I've started to think again about getting an emergency compressor too, though, as I've explained, the failure of one's central AC is probably much higher probability than a lengthy grid failure.
This episode has been an opportunity to learn and think about wet bulb temperatures, which reflect both temperature and humidity and how much water evaporative cooling (like our bodies use) is possible.
It's clear that the survival value of some kind of air conditioner, and especially one that is nominally too small, is in humidity reduction as much as temperature reduction.
Outdoors, as it heats up, the relative humidity drops rapidly as the temperature increases. So outside it very rarely exceeds the fatal-to-vigorous-humans wet bulb of 35C (95F), or even the fatal-to-other-humans 30C) because the relative humidity at that temperature is far lower.
So for example, yesterday it reached a peak of 102F where I live in San Antonio (the coolest day in a week BTW). But meanwhile the humidity had fallen to 21%. That means the wet bulb temperature outside was only 72F (22.3C) leaving a 7.7C margin from the more stringent 30C wet bulb.
But, indoor spaces trap outdoor heat (because they heat up in the sunlight) and humidity from earlier times and other sources. So indoor spaces that are not monitored for both temperature and humidity (or just wet bulb safety) CAN exceed safe wet bulb temperatures even when the outdoors does not.
So it might actually make sense to go to an outdoor shaded area and turn on a fan there during intense heat rather than stay inside under such conditions.
Sometime after yesterday's peak, or around 9PM to be precise, the wet bulb temperature peaked inside the house. At that time, with the new air conditioner having been run for almost 24 hours, the temperature in the kitchen (which has a sliding glass door facing the west, and the refrigerator, so it becomes the warmest room in the house) was 90F, with a relative humidity of 31%. It had only just become a bit uncomfortable. That means the wet bulb temperature was 68.5F (20.2C), giving a 9.8C margin from the 30C wet bulb. Without air conditioning, I'm sure the wet bulb would be worse than outside, probably half as much safety margin than with the air conditioning...and much less comfort as well.
Outside this morning it was 82F both inside the bedroom and outside. But inside the bedroom, the humidity at that time was a mere 40%, whereas outside it was 72%. So the undersized AC had both normalized the temperature to the lowest outside and reduced the humidity. If instead of running undersized AC, I had opened up all the windows and had big fans bring in as much air as possible all night to cool everything down, and then closed windows at sunrise, I would have been stuck with those 30 extra points of humidity all day, combined with the structure absorbed heat during the day, I think it would have been bad.
So I don't think the obvious no-air-conditioning strategy of opening the windows at night works well for the present conditions (though perhaps with vastly better insulation and thermal mass) but might if the outside temperatures only reached into the lower 90's. Instead, running the small air conditioning all the time and especially at night to drive out the humidity.
Meanwhile, an indoors space may capture the outdoor heat, but combine that with trapped humidity, to produce a deadly situation.
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