
Whole House Fan and Evaporative Cooler - luu
https://www.jefftk.com/p/whole-house-fan-evaporative-cooler
======
mchannon
As the owner of a whole house fan + evaporative cooler, and someone who lives
in a city where hundreds of thousands of people own and operate them, I invite
Mr. Kaufman to visit Albuquerque, to watch them in everyday operation, where
we've been swamping it up for over 50 years. It's a bit bizarre to read about
it as if it's a brand new theory.

Let me clear up a few misconceptions: You put the fan on the inlet next to the
"pad" where the water soaks in (nowadays usually located at a central point on
the roof). This works a lot better than a single outlet point for a number of
reasons, not least of which the source of air can be made to have reduced
dust. (Imagine a leaf blower or old diesel next to a window on a structure
with negative pressure).

There are never circumstances where a whole-house fan is made less effective
with humidification. It may be no more effective, but for those 100% humid
nights where it's cool enough to cool down the house, the swamp still runs. In
humid environments, it may warm up the house at night (due to temperatures,
not humidity), which is why swamps don't get used in most places.

~~~
schiffern
> _There are never circumstances where a whole-house fan is made less
> effective with humidification. It may be no more effective, but for those
> 100% humid nights where it 's cool enough to cool down the house, the swamp
> still runs._

This. Put simply, the wet bulb temperature is _always_ colder than the dry
bulb temperature.

[https://en.wikipedia.org/wiki/Wet-
bulb_temperature](https://en.wikipedia.org/wiki/Wet-bulb_temperature)

------
Sharlin
This idea is older than one might realize. Ancient Persians and other Middle
Eastern civilizations knew how to combine a windcatcher, or _bâdgir_ , with a
_qanat_ , an underground channel, to create an effective evaporative cooler.

[https://en.wikipedia.org/wiki/Windcatcher](https://en.wikipedia.org/wiki/Windcatcher)

[https://en.wikipedia.org/wiki/Qanat](https://en.wikipedia.org/wiki/Qanat)

~~~
saiya-jin
Many people don't understand how effective Qanats are, but they were/are used
to store freakin' ice in the middle of freakin' Iranian scorching desert -
seen one near Yazd.

Big respect to the builders/engineers. It's 2400 years old

~~~
matt4077
Just FYI: You seem to have been shadowbanned for quite a while. I vouched for
this comment to let you know, because I didn't see anything obviously
deserving such treatment.

~~~
gabriel34
He was banned and notified of it:
[https://news.ycombinator.com/item?id=13606809](https://news.ycombinator.com/item?id=13606809)

------
vanderZwan
A while ago a Low-Tech Magazine article discussing compressed air as energy
storage got a lot of traction here[0][1]. One of the more promising approaches
it included was _combining_ the compressed air energy storage with heating and
cooling solutions. This integrated approach should result in much higher
energy efficiencies, since problems with one technology basically become
solutions for another. Evaporative cooling could be yet another low-tech tool
in the toolbox here.

Aside: that LTM article made me think of a complaint of a friend of mine on
that the solar panels on his house are almost never at optimal efficiency due
to temperature. At which point I asked him if active cooling of solar panels
using heat transport + a heat buffer underneath the house + re-using said heat
in winter might be a win-win solution for that - he thought it was a good idea
but also too ambitious a project for him to undertake.

Shared all HN links with the author, hope he joins in on the discussion here.

[0] _" Ditch the Batteries: Off-Grid Compressed Air Energy Storage"_,
[http://www.lowtechmagazine.com/2018/05/ditch-the-
batteries-o...](http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-
off-the-grid-compressed-air-energy-storage.html)

[1]
[https://news.ycombinator.com/item?id=17143163](https://news.ycombinator.com/item?id=17143163)

~~~
wallace_f
These ideas are very cool, but I don't believe they will see succeed in the
mainstream marketplace without price signals.

I also don't trust government bureaucrats to figure this all out, either.

A carbon tax basically would just reward good ideas in the market, and punish
the bad ones.

However, almost no one supports it. You get some big figures like Musk and the
economist, Mankiw; but both the left and the right of mainstream politics
don't want it. The right doesn't want new taxes nor to particularly combat
global warming; the left is ideologically opposed to market-based solutions
and instead supports big government/power-grab solutions--specifically cap and
trade.

TL;DR consider supporting a carbon tax if you like these ideas and want to
combat global warming

~~~
vidarh
The left is by no means a monolithic block in these respects. A lot of the
left - perhaps not so visible in the US - are ideologically opposed to big
government. Libertarianism started with an anarchist, after all (Joseph
Dejacques; who criticised Proudhon - the "founder" of anarchism - for being a
"mere moderate anarchist, liberal but not libertarian").

Lots of left-wing ideologies favour using market mechanisms this way, and I
wish more would - you can want to use market-mechanisms this way whether or
not you're for free-market competition in terms of valuation and trade of
company shares.

~~~
jessaustin
Among the USA war media's most important tasks is the maintenance of the false
binary. They've done yeoman's work recently: how else could one explain that
mainstream progressive thought is now to constantly foment nuclear war with
Russia? (I'll quote Chancellor Merkel here: "I think it must once again become
normal for Russian and American presidents to meet.") Alternatively, how is it
that the party of Lincoln is now prominently associated with Nazis? (Go ahead,
tell me _one_ of these observations is wrong...)

In reality, the two "choices" imposed upon us are Coke and Pepsi, two noxious
compounds that require extended chemical analysis to differentiate. They both
want more war, all the time, in every case, for whatever reason. The real
reason, of course, is so that they may skim some of those sweet armaments
manufacturing profits. No it's not a conspiracy. Important influencers know
which side of their toast is buttered, but they are a small minority and they
don't need to coordinate in secret. Everyone who _doesn 't_ revolve from
bureaucratic post to public office to lobbyist to executive board to think-
tank sinecure, is a mere useful idiot. If 10-20% of American voters ever learn
about horseshoe theory, they'll be screwed. Therefore the media mentions that
about as often as they mention e.g. Libya or Yemen.

So, it's little surprise that we Americans have no clue about leftist thought.

~~~
WaxProlix
I was mostly with you until the "horseshoe theory" stuff, which seems out of
place. If anything, "horseshoe theory" is a recent fabrication to reinforce
the notion that the space outside of our false-binary choices are all invalid,
and equally so. Social Democrats, Anarchists, and Nazis all get sort of lumped
into the don't-even-think-about-it box together.

~~~
jessaustin
I'm sure it has been used that way! I'm thinking more about the areas of
agreement that exist among people with different politics. Maybe we don't
agree on the exact right destination for e.g. some $2T chunk of money, but we
agree that it shouldn't be used to kill random people overseas. That ain't
centrist! I occasionally lurk over at Caitlin Johnstone's site and I get a
kick out of the "cross-ideological collaboration" she's doing.

------
bsmith
As the cofounder of a heavily HVAC-related tech company, I can echo that this
is indeed nowhere near a new idea.

Many large commercial buildings already do something similar, but instead of
blowing cool, humid air through the structure, they use evaporation to cool
the water itself in a condenser loop (with large cooling towers moving outside
air across the water as it cascades down within the towers). The condenser
water then enters a heat exchanger where it cools another loop of water that
flows to the cooling coils in blower units throughout the building (you don't
want dirty water that's been in contact with outside air going through cooling
coils, so they are isolated loops).

Bear in mind, as others have mentioned, this approach is humidity-limited and
is therefore rarely seen outside of arid regions. And also note that humidity
levels tend to be highest at night when the air is the coolest, which further
limits the effectiveness of evaporative cooling at night. Once relative
humidity reaches 100%, you get absolutely no cooling from evaporation.

~~~
gm-conspiracy
The domain in your profile is not currently active.

~~~
bsmith
Yikes! Thanks...I need to fix that.

------
dlhavema
My family lived in Phoenix, AZ since i was 6, and he had an Evap Cool and a
traditional AC. Early in the summer the Evap works great and is way cheaper.
Once it gets too hot or too humid, you switch over to the AC. The fun part
was, my Dad would hold off switching as long as he could, and kind of compete
with a friend nearby to see who could "stand it with the evap" as long as
possible.

The hardest part i couldn't ever keep straight, was with the Evap you need
doors open and with the AC you close them. i would get it straight by the time
he'd switch over to the other system..

------
cjenkins
Evaporative cooler owner here. Thought I would add a few data points in case
people were curious. We live in Denver, CO (arid climate, typically mid 90Fs
in the summer but can reach over 100F. We tied the all time record of 105 in
June FYI).

We inherited a MasterCool evaporative cooler (think big metal box where the
evaporative pads are made of aspen fibers) when we bought our house. It wasn't
very well sealed so we were only able to drive the temperature down ~10-15
degrees F so it would get pretty uncomfortable once it got above 90.

Replaced recently with a Breezair unit and it's been way better. The air it
draws in seems to all be going through the evaporation media so we've been
able to maintain 72-75 degrees in our old drafty house throughout the summer
so far. I mostly don't mind the added humidity as I get fairly dry skin but we
have a few doors which swell and stick due to absorbing the additional
moisture.

I really wanted to get a Coolerado unit but they only seem to be readily
available for commercial applications. The difference with this unit is that
it is an indirect evaporative cooler so the air it blows into the cooled space
has no added humidity (and it claims to be able to achieve > 100% wet bulb
temperature due to its design [1]).

[1]
[http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTI...](http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTIC.pdf)

~~~
gm-conspiracy
The Coolerado looks like a self-contained evaporative cooler with a heat-
exchanger.

What are the costs and specs on such equipment?

~~~
cjenkins
The specs seem fairly detailed (at least to a non-HVAC person) on their
website [IE: 1].

Cost on the other hand doesn't seem to be readily available (my guess is
expensive since they seem to be targeting businesses vs consumers).

[1] [http://www.coolerado.com/m50-energy-efficient-air-
conditione...](http://www.coolerado.com/m50-energy-efficient-air-conditioner/)
(Downloads tab)

------
weaksauce
If you have a smallish house and a centrally located fan, a whole house fan is
amazing. The rooms get cooler and the attic gets cooler too. You can shut
doors to make a specific room cool in minutes. Seriously one of the best
things you can do to a house imo.

~~~
athorax
The attic getting cooler is one of the most important aspects of a house fan.
The thermometer in my attic regularly reads 20° F above the outside
temperature. Blowing that huge pocket of hot air out makes a huge difference.

~~~
blacksmith_tb
My last house had a hot attic with a window at each end - I always intended to
set up four fans on relays, two in each window, so it could blow cool air in
from either end, to take into account which side was cool and shady (and night
they could just switch off to to reduce wear).

~~~
JoblessWonder
In case this ever comes up again... they have attic fans that are activated
via temperature so that would your overnight issue and I'd imagine the gains
by rotating which side is pulling in air is negligible compared to the effort
to control it.

------
skate22
House fans are pretty cool, but as someone who has had one before: be cautious
of the airflow blowing out the flame on your gas stove / pilot light of
various appliances.

It has only happened to me once or twice, and is a non issue if you choose
which window(s) to open carefully.

That being said, we love our total home fan, and it's also great for clearing
out various odors

Edit: if people are having campfires near your house you'll want to shut it
off asap

~~~
MrBuddyCasino
Isn't there a temperature sensor that will shut down gas supply if heat stops?

~~~
azernik
This is true for gas heaters (actually it's usually a physical valve that
opens on thermal expansion, not a sensor). This prevents a blown pilot from
being a safety concern, but it's a pain to manually relight them.

I know of no gas stove that has such a feature, though.

~~~
ams6110
Gas water heaters have this, as do older gas furnaces (any newer furnaces will
have electronic ignition not a standing pilot).

For kitchen stoves, most have electronic ignition as well. For an older stove,
the amount of gas released from an unlit pilot is not significant enough to
pose a danger.

~~~
azernik
The issue isn't pilot lights for the oven itself; it's the stovetop. Most of
the ones I've seen have individual electric lighters for each burner, which
must be semi-manually activated (by turning the knob past "maximum" to a
"light" setting until it catches). If you turn it to on without lighting it,
or turn it off enough to put out the fire but not enough to completely cut off
gas flow, you'll get a constant gas leak.

------
schiffern
> _Another option would be to use the wall, ceiling, or floor as an
> evaporative surface._

This proposal may seem over-complicated at first, but low-tech cob walls
naturally exploit this effect by "breathing" humidity.

"these results show that earth buildings in diverse climates have significant
potential to cool themselves evaporatively through sorption of moisture from
humid night air and evaporation during the following day’s heat."

~~ _Intrinsic Evaporative Cooling by Hygroscopic Earth Materials_ ,
[http://www.mdpi.com/2076-3263/6/3/38/htm](http://www.mdpi.com/2076-3263/6/3/38/htm)

------
rietta
My parents have a whole house fan in their Atlanta, Georgia, home and its not
been intentionally used in 30 years. Growing up I remember accidentally
turning it on a few times and it was incredibly loud. Given the high summer
heat and high humidity I don't understand why the builders included it.

~~~
powvans
I grew up in North Georgia, near Athens. My grandparents had a whole home fan
like what you’re describing. Extremely loud, terrifying as a child. The house
is well shaded by trees and has a full basement. The basement provides a
reservoir of cool air and the fan pulls that air up from the basement into the
main area of the house.

This solution wasn’t very effective in July and August. My grandmother had A/C
installed not long after my grandfather died. Apparently he just refused to
accept it as a necessity.

It’s interesting though. The principles have been around for a long time. I’ve
been told that it’s the reason for very high ceilings in Victorian homes. The
idea is that the hot air in the room rises and draws cooler air from beneath
the house. In my experience, even with A/C it can be hard to stay comfortable
in a house like that during the summer.

~~~
watersb
The whole-house fan was useful in swampy Waycross, GA, but we never had a
house with such a fan in Athens.

Our house in Clearwater Florida, on the Gulf coast, desperately needed a
whole-house exhaust fan; the compressor on the air conditioner would routinely
trip a current-limiting circuit breaker, and the house would be 15 degrees F
hotter than the outdoor temperatures.

Our whole-house swamp cooler in southern New Mexico worked really really well.

------
anotheramala
There is a somewhat new company out of India which has an improved approach.
As others mentioned, swamp coolers have been around for a long time,
especially in India. They are not popular anymore but AC's are expensive.

Their approach is use the refrigerative compressor to chill water for an
cooler instead of chilling the air.

The efficiency is greatly improved and they claim 10% of running costs.

[https://www.thebetterindia.com/52984/vaayu-hybrid-
chillers-c...](https://www.thebetterindia.com/52984/vaayu-hybrid-chillers-
cooler-air-conditioner-indore/)

[http://www.vaayuindia.com/](http://www.vaayuindia.com/)

~~~
brudgers
Large buildings commonly use chilled water HVAC systems. The scale at which
these systems make sense is larger than a single family residence.

[http://www.york.com/for-your-workplace/chilled-water-
systems](http://www.york.com/for-your-workplace/chilled-water-systems)

~~~
anotheramala
Yes I edited my comment. Looks like the approach of vaayu is to directly do
evaporative cooling. So a chilled water swamp cooler. The commercial systems
use the chilled water in closed coils.

------
peterwwillis
A home built in the 1860s uses the principle of the whole house fan, but
without the fan: you just open the windows at night and close 'em during the
day, and you can regulate more with an attic trap door. It works well _most of
the time_ , but sometimes there's problems.

Namely, if humidity gets trapped in the house, when you shut the house during
the day, it can smell like mildew. It can be near-impossible to remove the
humidity from the house without an air conditioner of some sort, or a
dehumidifier. An evaporative cooler at night would make this worse because
you're adding humidity.

Another problem is multiple storeys. The top floor will always be hotter, and
it can build during hot days and leech the cool air from below. You need a
powerful attic fan to remove excess heat and humidity or the top floor will
become a swamp.

If you live in a big city, the average ambient temperature during the summer
is probably going to be high enough that a whole house fan will not replace
air conditioning, but could supplement it.

------
froindt
My parents have had a whole house fan for around 10 years and love it. They
can probably get through about 75% of the summer without turning on the air
conditioner, leading to significant cost savings. They also have a very well
insulated house, so once the cool air is inside, the house is really good at
staying cool.

~~~
dsr_
This would be a more valuable comment if we knew where your parents lived,
approximately. The solutions for Maine are not necessarily the solutions for
Minnesota or New Mexico.

~~~
froindt
Late on the reply, but Iowa.

------
perlpimp
I thought you need pretty dry air to cool air via evaporation. The most
unbearable kind of heat is a humid one wonder how well evaporative cooling
would work in tropics for that.

~~~
TheSpiceIsLife
Six of one, half a dozen of the other.

48 degrees dry heat is pretty unbearable.[1] Bagdad can get hot too, hot and
dry, 51.1 record high.[2]

1\.
[https://en.wikipedia.org/wiki/Port_Augusta#Climate](https://en.wikipedia.org/wiki/Port_Augusta#Climate)

2\.
[https://en.wikipedia.org/wiki/Baghdad#Climate](https://en.wikipedia.org/wiki/Baghdad#Climate)

------
samatman
Since warm air can carry quite a bit more moisture than cool, this specific
idea is likely to result in condensation as the cool outside air joins the
moistened warm house air.

If the roof insulation is less than perfect, simply wetting the roof
periodically will go a long way toward drawing heat out of the house.

If the roof insulation is good enough that this wouldn't work, you very likely
don't have a problem to begin with.

~~~
killjoywashere
In the Southwest it is common to use roof-top heat exchangers to warm backyard
pools, but the same houses have A\C and may have solar as well (which
incidentally shades a section of the roof), so I suspect “watering your roof”
would not be terribly effective. Worth a try though.

~~~
ams6110
Watering the roof should be quite effective, but rather wasteful if you are
using utility/drinking water. If you have a way to collect rainwater, and
recapture what runs off of the roof, it could be effective, but evaporative
losses will be large.

------
naushniki
[https://www.youtube.com/watch?v=Mo3psiMZjGc](https://www.youtube.com/watch?v=Mo3psiMZjGc)

------
martin1b
My concert with swamp coolers is the increase of humidity along with warm
temperatures. Creates a breeding ground for mold growth. The idea is great but
application depends on your structure.

------
fakename
My condo has a whole house fan, which is rigged up to a wireless remote that
the former owner couldn't find. I need to spend twenty minutes setting up a
new remote wiring setup, but it's only punishingly hot 2-3 days a year in
Oakland, and on those 2-3 days, I know that even if I prime it, the heat will
be over by the time the remote arrives, so I never pull the trigger.

Tldr, this is why we need same day voter registration.

