New Dishwasher and Rinse Aid

I'd been expecting my 1999 Kenmore dishwasher to fail any day now since about 2006.  It was then that Debby, a nice lady at work, told me about Lemi-Shine Machine Cleaner.  Thanks to Lemi-Shine machine cleaner, my Kenmore dishwasher kept running for 25 years.  Whenever it was getting super noisy, I'd run a cleaning cycle and it would be back to normal.

I had also bought some of the Lemi-Shine Power Booster (which can also be used as machine cleaner) and I was using that up (the combination of Power Booster and Cascade was leaving crud on my glasses even after one cleaning cycle, so I'm not going to do that again).

Perhaps it was coincidence, but on about the 3rd day in a row I used Power Booster, the motor was sounding as quiet as brand new...but it started leaking.  Water ran down the kitchen floor towards the sliding glass door (because it slopes slightly that way).  I mopped it up right way with towels, this could have wrecked my 30 year old kitchen run under the kitchen table.  (I can see why dishwasher leaking is such a big concern now.)

Researching dishwashers, I decided to get a Bosch 800, is among the most highly rated at Consumer Reports and Elsewhere.  Actually CR rates the Bosch Benchmark series the highest, then lists the Bosch 500 series because it is cheaper even though it doesn't have the rated drying performance of the 800 (that's the key difference, because the 800 has CrystalDry) and it's not better in any other way either.  So basically, if you want the best (and don't care much that you could save a couple hundred bucks) it's between the 800 and Benchmark models.

The benchmark models are a lot more expensive.  That gives you quieter (probably just more insulation), the "on" light reflected on the floor shows the time remaining (which you could also read on top), a

lighted interior, and one actual performance feature: water softener.

Strangely the addition of the water softener made no difference in the CR rated washing or drying performance of the Benchmark vs 800 models.  Sometimes water softening agents (salts) are included in cleaning pods, might be included in rinse aids, and rinse aids already virtually eliminate spotting.

What I see is a lot greater complexity here, with potential downside risks.  Always mixing in salt (which might be redundant anyway given your rinse aid) would not be good, I would think, for all the metal parts (even if stainless).  I suppose we're not talking about 10 years, but what about 25 years?

I even worry that the reduced sound level might be achieved while trapping greater heat in the motor, causing it not to last 25 years either.

Now these sorts of estimates could always be wrong.  Sometimes the most deluxe models are not just the same stuff with a bit added on, but better basic parts, or perhaps built on a different line where more care is taken.  The cheaper models may include the parts that didn't make the grade for the top.  Etc.  One never knows.

But I decided I could do without the extra Benchmark features and costs.  Also, there was an 800 model that was temporarily imported from Europe because US production was lagging demand.  That model takes longer to get from any source.  I don't recall seeing them listed at Lowes at all but at Best Buy,

and the soonest delivery was almost a month away.  You had to really dig to find the info on that model.

One unquestionable advantage of the imported 800 was that it also included the "water softener" (which is basically just a dispenser that dispenses salt in the water).   I would have to pay slightly more and wait a month longer for a feature I have concerns about and don't really need.

Lowes also had an "exclusive" model of the 800, which didn't seem to have any different features at

all, simply a lower price.  I wanted to go with the standard 800 as rated in Consumer Reports.

Along with all this, I did notice in another Consumer Reports article that Miele is the brand most highly rated for reliability of all (though this was for all products, not just dishwashers).  But Miele didn't actually rate very well in CR's tests, and they didn't get good ratings from Lowes customers either--who often complained about installation issues.  It seems to me if you're getting a superpremium luxury product like Miele, you should get it from an elevated dealer, like Ferguson for example, and have it installed by certified plumbers.  And not even buy such a product if your city doesn't have Miele service (which San Antonio does).  This is probably going to add $500 to the cost, but if you're buying Miele you shouldn't be fretting about that.  (Yes, the Miele does have a water softening system too.)

There's a general principle and that's to stick with the main line.  The further off the main line you go, the greater issues and risks.  At Lowes, the Bosch 800 is the upper part of the main line, but still the main line.  They stock as many (or nearly so) as all the other models.  They were shown as having 68 in stock.  Miele is nearly a special order for Lowes, not something every installer is necessarily going to be familiar with.

But all this about dishwashers and water softeners got me thinking about rinse aids.  I haven't been 100% in keeping my rinse aid dispenser full, more like 5% maybe, but I think it does help a lot.

For the fancy energy saving dry (I've always used no-heat dry as I think it saves wear on the machine) the rinse aid is more important than ever.

Bosch is known for recommending Finish rinse aid, which may well be the one I've usually bought.

By many accounts, Bosch recommends that brand not because others would be harmful, but because Finish pays them for that endorsement.

Anyway, now that I'm paying more attention to ingredients, and based on reviews, availability, and cost I've purchased Ecover rinse aid.   It's in the "better" group that has excellent performance as well as not having toxic ingredients.  The "best" group has the safest ingredients of all, but doesn't work as well and pricey/hard to find.

The actual dishwasher detergent stuff is rinsed off.  But the rinse aid is part of the rinse water, and some eventually dries on your dishes (even though the whole point of rinse aid is that as little dries on your dishes as possible).

Sliding glass door "lubrication" with pure dimethicone

In October 2023 I shattered the stationary part of my sliding glass door by trying to drill out the pin hole larger.  Apparently this drilling hit the glass envelope (so that's why the pin was so hard to get in) and shattered it.

I had to seal up the back with plastic sheeting until I could get repaired, which I did pretty quickly.  I also complained about the sliding part dragging and advanced that I needed new rollers (and so they also replaced them).  The rollers were the originals, now 40 years old.  (I wasn't sure afterwards if that was really necessary, perhaps cleaning and lubrication would have been sufficient, the original rollers looked like they might have been better made.)

The door worked great for awhile, and I am convinced now that the pin locking method, combined with some house settling, forced the wheels down into a lower position where they started dragging.  So possibly you should not use pin locks for windows with rollers, and especially not where there is known house shifting.

But without regular cleaning (and "lubrication" ?) a year later the door was getting increasingly difficult.  I tried vaccuming and olive oil (which oxidized right away) and then I tried adjusting to make it better.  I tried to adjust the opening gap as you are supposed to, but it was hard to get there.  Then for awhile I was simply cleaning the track with isopropyl alcohol, which seemingly needed doing each time.  Finally, after a last bit of adjusting, the door completely froze up.  I called the sliding door company again.  For nearly a week I couldn't use the back door at all, which meant I didn't go to the backyard or to Lyndhurst.  I didn't refill the birdbath.  Oh, sure I could use the side gate, but I'd have to get dressed and bring my Zap cane in case of dogs (there have been dogs on the street and walking by my house these past few months).

The sliding glass door company came out and fixed it for free (apparently there was a warranty of some kind for a year or so, I didn't even know).  Two strong guys lifted the door out of the track (it was not easy and I don't think I could do it myself as I had been planning to before) and found that one of the rollers had been adjusted too far so it came out of it's thread and was now just dragging.  They adjusted the opening (but in the end, I think they simply had to adjust the back up all the way and the opening wasn't really any better than before).  I did some more track cleaning while they were busy.  It wasn't clear if they used some kind of lubricant (but I'm thinking they did on the door wheels axles themselves, which is where it really counts).

They told me I should keep the track clean and lubricated with Silicone Spray.  My friend Noelia is always telling me I should "just use Vaseline and that will fix it).  Some experts say track lubrication isn't really necessary, it's the wheels that need lubrication and the track is supposed to stick just a little so the wheels turn--and that was my go-to opinion until now.

I continue to believe now my biggest failing was not keeping the track clean.  When I started working on the door, and prematurely adjusting the wheels first, I found the rack was full of cat hair and dirt which took multiple cleanings to get off.

But I decided to research the lubrication question.  Silicone Spray is indeed what most manufacturers and installers recommend.  Some recommend graphite.  Just a few recommend Vaseline or oils, but Vaseline and oils are more often criticized for attracting dirt.

I began to wonder, "What if I could do the cleaning and lubrication in one go, that would make sense."  And indeed there is a product just like that, recommended by more than Vaseline.  You may have heard of it.  Pledge.

Now some picky furniture people say to NEVER use Pledge and the stuff should be taken off the market.  It seems some fancy wood finishes (and not bog standard Urethane) are made cloudy by repeated use of Pledge.  (Actually, many commercial polishes also contain a bit of silicone too, for a smoother finish.)

But on Urethane coated wood, which is essentially sealed in plastic, you can use anything, even water (if there are no gaps...).  So Pledge should be fine with that, Pledge will make it nice and slick.

It turns out (and I knew this before) that the old fashioned Pledge formulations contain silicone!  That's what gives the smoothness and shine--silicone in the form of Dimethicone.  This is the same stuff that's in silicone spray.

Now you should never use standard WD-40 for any lubricating purpose (it's a protectant and water displacer) but the same company, under the label "WD-40 Professional" makes a Silicone Spray which is "perfect" for sliding glass doors.  If you go to Lowes looking for a Silicone Spray, that's what you will find.

Now that's what the installer might recommend (and maybe what they used on the wheels, but I didn't see them use anything) but I got to thinking Pledge would be better, as I could do the cleaning and "lubricating" in one go, every week or so.

If you ask google AI, it will tell you Pledge is a fine way to lubricate your sliding door track, but there are other options.  (In a long thread I read, some manufacturer recommends Endust, which has no silicone but another kind of polishing ingredient.)

I had a new liquid pledge on hand but it turns out it's a "cleaner" only with no silicone (Everyday Clean Multisurface PH Balanced cleaner).  SC Johnson has now bifurcated the Pledge products into two kinds, the cleaners and the polishes, and only the polishes contain Dimethicone, so that way you can easily avoid it (though I see no reason to).

Then I started looking at the ingredients in these products.  I quickly came to the conclusion that the Dimethicone (which is used in many personal care products and cosmetics) may well be the safest ingredient there.  Dimethicone is used in drugs too, and it's the core ingredient in stomach gas relief products.

It's the other stuff in the Pledge products I have more concerns about.  In future, I see no reason not to use HEB Field & Future cleaner, which seems to have the safest list of ingredients of all, be non-acidic, available without fragrances or dies (why can't we get those out of everything!).  The Pledge multipurpose cleaner is better than many previous generations of cleaners, just not quite as good as as Field & Future in terms of ingredients, in my judgement.  But no reason not to use it up either.

Then I looked at the WD-40 Professional Silicone Spray, but it's worse.  Sure the Dimethicone is there and it's safe, but the rest of the stuff is a pile of awful petroleum based propellants.

I then decided on an all new approach (still not tried as I've been sick for a few weeks and haven't actually cleaned the sliding door track weekly as hoped or even monthly yet--it's just about a month since the repair and the door still slides like glass).  First I'll do the cleaning, with any cleaner safe on aluminum and steel (even that Pledge multisurface cleaner, or the HEB "Field & Future" brand household cleaner (which, btw, is excellent and about the safest cleaner you can get, even safer than the Lemishine cleaner I used to get because the latter contained a chemical now banned in EU).  Then, after the cleaning, I'll lubricate by rubbing in a few drops of dimethicone spaced along the track.

It turns out you can simply buy pure "Cosmetic Grade" Dimethicone in a bottle, and I also got a dropper for it.

Bathroom Vanities

Why isn't my bathroom vanity at the same height as my kitchen countertops, I was thinking years ago.  That height is 36 inches.

In fact, that's exactly what Ferguson recommends for a master bathroom vanity.

(Both of my vanities are at 29.5 inches high.  That must have been the builder's default or cheapest option.  30 inches is the recommended height for a kid's vanity.)

At the 29.5 inch high bathroom vanity I always have to bend down.  It's terrible for my back.

But I've got so many other unfunded priorities now:

1) New oven

2) Carport

3) New Patio and cover

4) Additional foundation piers around (existing) patio

5) Complete the garage conversion (after Carport)...currently 1/2 of the garage is converted to a bonus room.

And big things may need to be replaced soon:

1) Car (!!!)

2) Dishwasher (still going after 24 years)

3) Refrigerator (still going after 14 years)

4) Central Air Conditioner (3 years left on 10 year warranty)

Wet Bulb alone is not sufficient

The latest widely cited paper on human limits does NOT endorse the wet bulb temperature as accurately mapping human limits.

Quite the opposite.

A lowered wet bulb threshold of around 30C (86F) is suitable for assessing high wet bulb temperatures that are mostly from high humidity below dry bulb temperatures of 40C.  Above 40C (104F), the wet bulb temperature does not adequately assess the stress from dry heat alone.  At 50C (122F) the critical wet bulb temperature has fallen by 4C to 26C.

It still looks like the wet bulb temperature limits, with these caveats, are good to 50C dry bulb, and predict these limits better than other measures.

Meanwhile, I'm continuing to make no sense of the heat index in these regards.  The heat index can also be calculated by temperature and humidity, but the result does not highlight the danger of very high humidity at relatively low temperatures in the same way that wet bulb temperature does.  Comparing a few calculations, it appears to me the heat index underplays humidity at low temperatures, and overplays relatively high temperature and low humidities, as compared to the wet bulb temperature, and probably human limits as well.  

For example, the Heat Index of the now accepted threshold for wet bulb temperature in humid environments (30C at 100% humidity) is merely 112F.  Holding the wet bulb temperature constant but raising the dry bulb temperature to 40C where wet bulb is still a useful measure (40C at 46% humidity) yields a heat index of 126F.  Adaptability is about the same but the Heat Index has shot up by 14F.  The heat index at the formerly believed wet bulb threshold temperature (35C at 100% humidity) has a staggering Heat Index of 161F.

The heat index is only useful because it more intuitively maps higher than average humidity levels into elevated temperatures.  Without a full explanation, and possibly some un-learning, people lacking scientific backgrounds may find it hard to fully understand the wet bulb temperature criterion (I myself have had great frustration trying to explain it to people with more verbal than quantitative backgrounds) because the threshold numbers just seem too low.  But you can't just add 20C to the wet bulb temperature to get the heat index, they are based on different functions.

Wet Bulb and Heat Index

 One of the things I learned from living one week without central air conditioning during a heat wave in Texas is the critical importance of humidity.  

While we often talk only about temperature, humidity is just as important as temperature in determining comfort and safety.  They really need to be combined in one index for that purpose.   The two most common ones are Wet Bulb Temperature and Heat Index.  Those are two different ways of combining temperature and humidity into one number.

 (There are endless other similar indexes you can find at Wikipedia, sometimes adding in more information like sunlight and wind speed, of these the WBGT is most commonly specified for occupational safety...but rarely measured directly).

The Wet Bulb temperature is the temperature that would be read from a "wet bulb" covered in saturated wet cloth that is evaporating water.  At low humidities, evaporation is increased and the wet bulb is far cooler than the normal ("dry bulb")  Only at 100% humidity is the wet bulb temperature the same as the dry bulb temperature  Once you grasp the basic idea, it is a very powerful tool, because it is easy to understand that when the temperature and humidity are high enough, your body can get no cooling effect from perspiration, and you cannot survive that situation for very long.  And this relates to our body temperature of 97-99F.  To carry off the heat our body produces at rest, the Wet Bulb temperature has to be 95F or less for even the most healthy people.  Recent studies show a better number is 86F for most people including young and elderly.  These are often referred to in Celsius: 35C for very healthy people, and 30C for most people.  These maximums assume you are in the shade and getting as much air cooling as possible (possibly with a powered fan helping, and light if any clothing).

Using this information, and a Wet Bulb calculator it is easy to calculate the maximum safe humidity at any temperature (which the highest point where the Wet Bulb temperature is still below 86F).

Below 86F....all humidities are "safe" with sufficient air cooling and shade

86F        99%

90F        84%

95F        66%

100F      54%

105F      43%

110F      35%

115F      28%

120F      22%

Above 122F is dangerous regardless of humidity or air movement

Because the outside humidity virtually always drops as the temperature rises, dangerous Wet Bulb temperatures are very rare in areas that humans inhabit.  However, this is changing because of global heating and dangerous outside Wet Bulb temperatures are beginning to appear more often.  Inside there may be trapped humidity combined with solar heating, leading to more dangerous and uncomfortable wet bulb temperatures than outside unless you have air conditioning.

The Heat Index expresses the combination of temperature and humidity more intuitively for most people, as it relates everything to a typical and comfortable temperature/humidity combination, rather than the 100% humidity extreme case which is rarely observed.  So the heat index goes higher than the dry bulb temperature when the humidity is notionally "high" and therefore matching our intuition that high humidity is making it "hotter." So, to show how this works, look at the Heat Index for 100F:

Temp    Humidity    Heat Index    Wet Bulb Temp

100F    30%              102                76F

100F    35%              106                78F

100F    40%              109                80F

100F    45%              113                82F

100F    50%              118                84F

100F    54%              123                85.7F

Here is a calculator for Heat Index.

Here is an article on it.

Plan B now proven

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.

Barely Tolerable

"Don't Try This At Home (except in emergency)"

My 7 year old (then and still perhaps state of the art) central air conditioner failed on early Sunday morning, around 4am.  I had fallen asleep and left the back door open from midnight to 3am.  It was "cool" outside after midnight, about the same temperature as indoor air, but way more humidity.  That pushed my blower motor over the edge as it was probably doing a lot of low speed dehumidification.  Due to an installation mistake, my system may have a smaller blower motor than would be called for.  I hope the repair fixes that.  Now I'm waiting for I hope will be warranty repair at no cost to me, with my full parts and labor contract.  Any kind of "emergency" service by anyone else (especially me) might invalidate my warranty.

Waiting for about one week, in daily temperatures that reached as high as 105 by my measurements, or possibly higher.

Outdoors, note peak (right sidebar) high temp of 104.7F with 21% Humidity

Now I realize one must always have a backup plan.  Last time my (previous) air conditioning went out (not counting the many times I flushed the drain and fixed drain faults) it was only a mild May, with highs around 90, and I just opened the windows in the evenings until morning, and it was tolerable.

That would probably not be a workable solution under current temperatures, though I haven't tried, and the 15 hours without any backup wasn't bad, but as the day wore on I became aware that I was heating up inside thermal mass, and the next day would be must much harder to take, and then the next one harder still, as the interior floor, foundations, and walls heated up to a new level and were no longer helping to keep me cool.  (My sense is that it would take about 3 days to fully reach the new higher equilibrium temperature...which would be near deadly).

Instead, within 14 hours, my best friend lent me her spare portable air conditioner, which they quit using after they went entirely to window units throughout their home and cabin shed on a permanent basis with no central air.

BTW, Consumer Reports says window units are far more effective than "portable air conditioners," and they can't recommend a single portable air conditioner.  You should generally follow their advice unless you are adventurous and at least somewhat knowledgeable about math and engineering stuff like me.

But I'm not trying to cool one room on a regular basis.  I'm trying to cool my entire 1250 square foot living space, with an emphasis on the bedroom (which I don't want to disturb with a window unit) and the kitchen (which has no window except a sliding glass window).  Just enough to make it through the repairing of my central unit.  Just enough to be tolerable and survivable.  Not necessarily comfortable.

Peak kitchen temp on Thursday Night, 90F at 35% Humidity, "Tolerable"

The only two rooms which have conveniently accessible windows are the very rooms I care least about cooling.

The gym in particular, which is the converted half of the originally 2 car (now 1 car barely) garage.  It has one very accessible window, near the doorway to the rest of the house.  It made perfect sense to me to put a portable air conditioner right in the doorway to the gym, blowing out cold and dehumidified air into the hallways to the bedroom and to the living room.  I have fans assisting those two flows on the ground (where they should be, to blow the coldest air) and also thence from the living room into the kitchen.

Since I set up all the flows like this I'm getting tolerable but barely tolerable conditions in both the kitchen and the master bedroom (at the other end of the hallway from which all other doors are now closed).  The two rooms I care about, with more attention rightfully given to the master bedroom.  And the rest of the house is about the same too. Before the last fan re-positioning, the kitchen was intolerable from 3-9PM.

Also I've decided it's necessary to close the electric kitchen vent after 1pm or whenever the temperature reaches 100F (or perhaps as much as possible).  At lower temps, despite higher wet bulb temperature outside, it sometimes feels better to have the vent open.  My temporary portable AC system is doing a much better job of controlling humidity, actually, than temperature.  It's not doing very good at temperature at all, but the low humidity levels it is producing may actually be more important than doing a mediocre job at temperature with no control over humidity.

All this with an "ineffective" 8000 BTU (old) 6000 BTU (DOE new) portable air conditioner, set to 60F (lowest temperature).

It's an LG dual inverter type which is quieter than my fans and never cycles on/off either.  I presume it may not always be running at 100% depending on many variables, the difference between set point and average temperature, the humidity and how much needs to be removed, and so on.

I was worried whether I could move a portable to the doorway and use it like I am, because of the limited length of some of the flexible ducts they come with (and they always advise you never to add more).

But the LG has a very good length duct, it looks like it could expand to 10 feet or more.  I'm worried that other units, in particular dual duct units, couldn't do that.

I'm also worried that dual duct units might suck stuff in, like freak rainfall.  With the exhaust port constantly blowing out, that risk seems minimal.

But if you are contemplating more ordinary usage, window mount makes the most sense followed by dual duct.

However I don't know if any dual duct type units have the highly desirable Dual Inverter that LG has (in only some models, I've found out the hard way, the white ones in particular, and not the black ones they sell at Home Depot).  

Without the Dual Inverter, even if you do like most people do (and not Consumer Reports) and simply set the temperature to the very minimum, like 60F, to squeeze the last bit of power out of it...even if you do all that, the unit WILL STILL be cycling on and off as it deters itself from freezing up via that means too.

The Dual Inverter can simply back down to just below the frost point...and keep it there...with no cycling whatsoever.  I've been in hotel rooms with those noisily cycling machines which often mean you can't easily get to sleep (though I usually do, it still feels nightmarish).

And that's the joy and beauty of Dual Inverter.  I simply leave it to 60F running all day long (as well as the fans and various baffles I am using) and squeeze the last bit of cooling power to keep an emergency situation from getting worse, until my main unit gets repaired.  AND cool my entire house with one "ineffective" portable unit.  At least to some level that's barely tolerable.

But that's also why the Dual Inverters may not always seem to be blowing colder (they can blow 100% of the time if needed) because they must optimize the compressor level to deal with the frost point without shutting down.

So I (mistakenly) bought the largest black LG portable at Home Depot but fortunately figured out that it was not a Dual Inverter unit like I had borrowed before starting the very challenging job of unloading the 80 pound box from my car.

Now I've ordered the largest white LG portable from Lowes (who had an even better price than Amazon, and I've traditionally had the best handling from Lowes as well).  It's rated about 60% more capacity, 14000 BTU by the old standard and 10000 BTU by the new standard, than the one I am using now.  But before it arrives I will have to endure a few more days with the smaller unit, and after it arrives, I hope my central AC will work

Other than the weight, it should be possible to use it just as effectively as I'm using the smaller loaned unit, but with hopefully some better comfort (though still unlikely to be perfect) and to survive even hotter temperatures (which could occur in August or September).  Should once again my central AC fail.  I need to be more prepared.

And a personal AC failure is far more likely than an extended grid failure, despite frequent feelings to the reverse.  But having a portable generator which could also power a refrigerator and a large portable AC could be a lifesaver too, I am thinking now.

Meanwhile, with my emergency AC system forcing me to, I'm learning a lot more about where the limits of comfort and survival actually are.  The beginning of this learning starts with understand wet bulb temperature, and also how humidity constantly (and hugely!) varies with temperature on a typical day.

Most people have this sense that "all the bad stuff happens at once (or just to me)" even though in many cases this isn't true.  Most often it's one thing, or the other, and that's also sort of how it works with temperature and humidity.

And so, over the past 24 hours outside there was a high temperature of 104.7F (which I'll round to 105) at which time the humidity was 21%.  Then, in the evening, there was a more comfortable (very comfortable outside in fact, thanks to slight breezes) low of 79 at 82% humidity.  That's what my meter shows (though an untutored person might surmise that the high of 105F went with the 82% humidity instead, from looking at the inside display of my outside thermometer) and applying the usual "all the bad stuff happens at once (or just to me)" filter.

We would expect those two readings of 105F/21% and 79F/82% to represent more or less the same actual moisture in the air, which doesn't change much, but under different heating conditions (heated by the intense sunlight, or not).

That greater consistency is somewhat reflected by the wet bulb temperature, which is the temperature of a bulb covered in damp cloth which is evaporating water.  But what the wet bulb temperature is really useful for is determining how much evaporative cooling can help.

Our bodies are partly if not largely cooled by water evaporation.  (Other sources will imply our bodies are entirely cooled by water evaporation, but clearly there is also a certain degree of regular convection as well.)  So it is precisely the wet bulb temperature which informs us how well we can cool ourselves, or not.

The wet bulb temperature would be identical to the regular "dry bulb" temperature under the condition of 100% humidity.  So with anything less than 100% humidity, the wet bulb temperature will be lower than the dry bulb temperature, and at 0% humidity it will be as low as it can get relative to the dry bulb temperature.

35 C (equivalent to 95F) is the theoretical 'maximum' wet bulb temperature under which our bodies can still cool themselves.   Above that is quickly fatal for even very healthy people who are just relaxing.  But for people with less than optimal health and vigor, lower thresholds have been proposed, including 30C and 31C.

Here are some temperature/humidity combinations which yield the usually fatal 35C:

95F, 100%  (obviously)

100F, 82%

105F, 68%

110F, 55%

115F, 45%

120F, 37%

122F, 35%

These conditions are rarely seen in even the hottest cities, because as the dry bulb temperature shoots up way past 95F, usually the relative humidity drops to the floor at exactly the same time.  For example, the condition I measured here a few days ago, 104F with 21% humidity has a wet bulb temperature of only 73.5F, quite far away from 35C.

What you cannot do is simply combine the humidity you may have heard reported last night (such as the 79% I measured last night) and apply it to the dry bulb temperature you measure today.  Computing the wet bulb temperature requires that both temperature and humidity be measured at exactly the same time.

This relationship is not just cause-and-effect, it is definitional because the "relative humidity" itself is a measure of home much moisture is in the air compared to how much moisture the air can possibly hold--at that temperature.  As the temperature rises, the air can possibly hold more moisture, so given the same amount of moisture at a higher temperature the relative humidity will go down.  You will observe exactly the same effect of declining relative humidity even in a greenhouse or locked car in the sunlight, except under conditions where the moisture is being added to (such as from the breath and perspiration of the person or dog in that locked car, and by the way, never leave a person or dog in a locked car).

Now while the wet bulb temperature is a good measurement to make to determine how safe the temperature/humidity is for humans or similar animals, it is not necessarily equivalent to a comfort index.  It appears to me anyway that we can also sense the dry bulb temperature to some degree independently of humidity.  If we have trained ourselves to recognize hotness based entirely on the dry bulb temperature sensation, the effect of high humidity can creep up on us like a sledgehammer.  (This happened to me, born and raised in the relatively dry environments of Southern California, on a summer trip to Indianapolis, where the temperature was only mid 80's--something I was very used to, but the relatively high relative humidity was a knockout which almost made me sick.)

Speaking of which, air conditioning was mostly something I only lusted for in my 36 years of living in Southern California.  It mostly wasn't needed at all during my 14 years in San Diego.  But growing up in the San Fernando Valley, with temperatures reaching above 110F, it would have been nice.

Instead, it seems, we took long summer vacations...  And our cars were (mostly) air conditioned (at least after 1963 or so).

We had been sold a swamp cooler, and it seemed it never worked.  (Now I realize it may have simply not been properly maintained.  Coming from Minnesota, and being traditionally female, my mother did not know anything about keeping mechanical things working.  Nor did I at the age of 11 when my father passed away, despite my sense that I knew everything.  Somewhere along the line we did call for 'service' but probably to the wrong kind of agency.  They simply told us that "swamp coolers are not effective in the San Fernando valley."  That could have been mostly wrong.  It might have simply needed better--or at least some--maintenance.)

So I sat in my tiny 9x10 bedroom looking out the window at our fancy pool and covered patio, with both the indoor and outdoor temperatures above 100F.  Real air conditioning cost thousands of dollars.  Our entire home had only cost $20,000 in 1960 (and before all of my mother's ambitious improvements, which included everything except air conditioning).  So air conditioning seemed like a significant portion of what an entire house cost.  Most people on my street and most people I knew did not have air conditioning, until after 1970 or so.  After winning some wrongful injury lawsuit related to a car accident, a best friend's family splurged on air conditioning.  That was the kind of money you needed, and which my strapped family didn't have, especially given my mother's later ambition to build a second summer home in Mexico on the beach.  Well, that was her air conditioning.

Well even though central air was plenty expensive in the 1960's (and, we were told, would require all new duct work in our house because the 'heat' ducts were too small for air conditioning) it seemed that room air conditioners were already pretty affordable.  So for a few years just before I left the valley to go to college, I wondered what I could do with a room unit.  And, in my imagination, I wouldn't just be cooling my tiny bedroom (where I rarely spent much time anyway, it seemed).  But the entire house.  I figured it would be better than nothing.

But somewhere along the line, somebody disabused me of this notion.  They said that a tiny air conditioner would have basically zero effect on a large house.  They even implied it would make it worse.  I recall someone (possibly my chemistry teacher) told me that a small air conditioner would be "running all the time" and as a result it would reduce humidity*, but it would not lower the temperature by much.  At the time (and not realizing yet how important humidity was), this did not sound like a win.

(*The dehumidification is determined mostly by how much and for how long air is in contact with the evaporator coils.  So 'running all the time' gets you to maximum dehumidification, but not necessarily the coldest dry bulb temperature.)

But here I am today, with vastly more knowledge generally and also 32 years of experience actually using (and maintaining) an air conditioning system of which some kind is virtually required to live where I do now, San Antonio Texas, and I'm doing the experiment I wanted to try as a kid.  I'm cooling (or actually, mostly just dehumidifying) my entire house using a small air conditioner with no more capacity (and possibly less) than an old window unit.

And just as I expected, it's better than nothing.  It may even be a life saver.  And a kind of backup I'm going to always need.  Also a small air conditioner is about the only thing I could imagine powering with a generator or backup electrical system of some kind, except for a very big backup electrical system that can power 220V.

It's not "comfort" but it works.

I have not conducted (and am not even capable of conducting) a proper experiment, but it seems like I may have improved the wet bulb temperature as much as 7F, moving twice as far away from any point which would have been unsafe.

90F, 35% -> 70F web bulb (21C)

Guesstimated w/o emergency portable air conditioning

96F, 40% -> 77 wet bulb (25C)

So, "8000 BTU" works for the whole house, well enough to keep me safe, but I won't call it comfort.

*****

Today (Friday) in the morning I was planning to leave the kitchen vent open, having convinced myself that was ok and even good to do at night (because fostering a kind of heat transfer through the metal itself as well as the very slight air movement I finally felt there).  But instead, I did the opposite experiment.  I pressed the "Bedtime" button on my home control system (which I'd been planning on avoiding) and that closed the vent, as it's long been programmed to do.

At least partly as a result, that morning I saw the lowest morning kitchen temperature I've seen since the first 24 hours of the AC failure.  It was a mere 84F at 43% humidity, pretty nice.

Then, the high temperature during the reluctantly peaked at 91F after holding 90F most of the afternoon.  BTW, the peaking generally occurs right at sundown when the solar heating has stopped, around 9PM.  The continued climb of the temperature even after the outside has started cooling down is no doubt due to the thermal mass of the house, AND it's being warmed by direct solar radiation, for which more is more..

Yesterday, I was wrong in saying it peaked at 91F.  Actually, it peaked at 93F with 33% humidity.  But I'd adjust the other side of the comparison with a guesstimated no AC condition to around 98F, still yielding a guestimated improvement of about 4C in the wet bulb temperature, which is somewhat less than half the way to the 30C temperature advised as the near fatal temperature for the youngest and elderly (instead of 35C).  In short, the weak AC is near doubling the margin from the wet bulb temperatures to be most avoided for the young and elderly, that's my guess.  As a result of AC, that margin is over 10F.

So the lower morning low and evening high are evidence on the side of keeping the kitchen vent closed at all hours to keep the dry and wet bulb temperatures lower (I suppose unless it's needed for some reason, I still think it might be good when running the dryer at night, when the back vent represents an easily preferred airflow source, in contrast to the likely next: the attic.

With all the fans now running, the current 91F (I was going to write 90F, but it may have just now been boosted by the 5 minutes or so I needed to get the newly arrived 10,000 DOE BTU air conditioner inside the house) and 33% is beginning to seem quite fine and normal.  I'm sure I've endured many hotter inside hours in my 36 years of non air conditioned living in Southern California, for example.

And the lower-than-otherwise 33% humidity is a very big part of that, though I'm still don't believe "wet bulb temperature" is the entire story.  Even if the humidity is super low, hot like 122F (50C) is just plain too hot for most life.  That's probably why my wet bulb calculator refuses to go above 122F.

The human body absorbs radiated energy from all sources (which might partly be blocked by clothing, which tends to convert it into infrared energy) and also itself radiates energy slightly, enough to be detected by IR cameras for example.

The shell of a home absorbs much (without white metal roof it is most) of the energy which falls upon it, and after some delay it radiates some of that energy inside to the occupants.  People used to obsess about that but now they tend to obsess more about air leaks, which are generally a bigger issue, but then houses need some ventilation too anyway.

To a limited degree, houses tend to trap moisture inside when it's hot, and they tend to trap dryness inside when it's cold.  The moisture comes from water appliances, people, even the furnishings that expel water as they're heated up.

So I suspect the 'moisture content of air' is generally higher inside during summer unless you have some kind of air conditioner or dehumidifier.  My current vastly undersized air conditioner is serving as much as a dehumidifier as anything else, since it's not dropping the temperature near enough to be fully 'comfortable.'  But in these ranges, the humidity is super important too, and I'm in no great discomfort at all.

The actual moisture content of air is as hard to calculate as anything from the temperature and humidity.

Without low enough humidity, fans are useless.  That's where the 30/35C criteria kick in.  Even with fans, perspiration won't do any good if the wet bulb is above 30C (elderly) or 35C (youthful healthy adults).  With fans, you can push it right to those limits.  So doubling the margin to these temperatures is important.  So, undersized AC is useful for emergency use if not wonderful, and the concurrent approach of keeping home sealed and AC running seems to work best.

Along with obvious tweaks, like shutting down (and not running) big audio and video equipment (just keeping the computer equipment going, at least if dry bulb doesn't exceed 100F) and basically as much as possible, except fans to both distribute the colder air and keep  air blowing past people.

Also not cooking but getting by with prepared meals that can be merely microwaved.  Running stove and oven are going to be impossible for tiny AC to keep up with.

Running dishwasher very late, long after bedtime.