How so, there is a significant drop in the temperature that the water
evaporates requiring even more Btu/lb to evaporate?That won't happen
and you always round down to 1000 anyways. You must have meant to say
that your scheme is less penalized on the make up air sensible heat
gain at night?
It could even drop down to below 80 at night, but because you are
dealing with an average temperature, this already is covered in your
24/7 water rate that must be used. If your system was designed for the
peak outside temperature, you could shut it off at night. Or you could
try running it steady all night to maximize the stored coolth taking
advantage of the free make up air. Just have a sonic sensor listen for
the splashing as someone tries to go down the hall to the bathroom in
the middle of the night and shut of the water. :)
A swamp cooler designed for the peak load could have the pump shut off
and then just run the fan to keep up with the small internal gain in
the middle of the night if the temp dropped a couple below 80.
Well, what can I say, if a swamp cooler would have beat your system
under the microscopic load, I would have been the first to tell you.
You just might have to use a chart for that one, or maybe keep your
plus and minus signs straight and keep the wet bulb temperature
Before you had 10,000 Btu/hr on a 2,000 square foot slab. That was
idealistic at best. Then you went down to 5700, now 3485 Btu/hr gain on
a 2,000 sq ft house. Try 15,500 Btu/hr on 1225 sq ft. air temp 106, 7%
You will not be able to shut it off, your design is for the average
outdoor temperature. You are below that temperature at night so you
have to keep running the system, store what ever the hell you can, so
that when the outdoor temp rises up above that average in the
afternoon, you will limit how much you exceed the comfort condition by.
If you had some system designed for a peak load, then like I have
already conceded, you can try and see exactly how cool you could get
that slab. But with a system designed to make comfort during an
average, it has to run all the time, to keep it 'comfortable' for at
least a few hours each day. You can over cool at night, but you will
still be outside of the comfort zone each afternoon. Sq Lit's link of
this past June's weather data showed a lot of triple digit days.
Accepted, I will just keep the insults to humourous now and not
degrading. Queen's English, don't start counting 'u's
I can see why you base it on temperature only, because it allows you to
attempt to rationalize cooling loads of 3485 Btu/hr so that your scheme
can be shown to theoretically work.
The sun is a big part of the picture. The slab is wet, you neglect the
sun so it's dark and you spread a lot of bullshit, so I say you are all
set to grow mushrooms in Arizona. :)
You overcool at night, for a while in the day you hold your condition,
late afternoon the "comfort zone" is history.
You want the capability of being able to store some useful 'coolth' to
save on something in the heat of the day, then design a system for the
peak temperature and load. Just that when the ambient gets into triple
digits, you are stuck with the spiral of make up air sensible heat and
the extra water meaning more exhaust. It is the big flaw in your
scheme. A swamp cooler does not face this problem as it directly deals
with the outside air.
No, a swamp cooler can actually work. They are out there providing
cooling during triple digit ambients in homes with a poorer insulation
and less external shading than I am trying to get you to apply your
Your scheme will theoretically work, but will use more water, need to
move more air, plus the issue of having a wet floor and mold. You are
going to have to use ceiling fans to blast the air down though. I
looked at some winter heating losses from Canada, and the portion
through a slab 4 ft below grade was pretty minor and the soil is a lot
colder than 80 :)
I have been jesting with this latest side track of yours. You can hook
a swamp cooler up to an HRV, some one has something like this already.
You could also run swamp cooler at more than 80% effective and blow
pretty damp air through the block cores as well. Cleaning out the block
cores is yet another problem along with all the critters that will move
in there. Plus it is a cold floor, poor idea to begin with.
I looked at an old heating load from Canada, -24F ambient, 72 indoor
temp, basement slab about 4 ft below grade, R12 insulated walls,
uninsulated slab, soil temp about 42 F.
Lower level below grade about 1600 sq ft, upper level 1600 sq ft - well
insulated R22 walls, R40 ceiling, triple pane low e windows with argon,
Total heat load 45,894 Btu/hr. Sensible cooling load for 86F ambient,
48 N lattitude, blinds drawn on windows --15,321 Btu/hr.
Heat loss through floor in winter 3,197 Btu/hr . 2 Btu/hr/sq ft. So
let's forget a cold floor cooling system in Arizona, with 3485 Btu/hr
The idea of radiant floor heat is great. You get radiant transfer of
heat, and some natural convection, the air does not stratify too bad
and it is sure nice to walk on with bare feet.
I also mentioned before, radiant ceiling panels that will provide some
sensible cooling in summer and they have natural convection working
with them and some heat will directly transfer from you to the ceiling.
I did not read about these panels, they yanked me from my nice
comfortable desk and made me rebuild and improve the machine that makes
But relying on a cool slab, only really seems to work for miniscule
cooling loads. It is unhealthy, it works against natural convection,
your feet are going to be wet, and you will be miserable.
So why on earth do you want to keep trying to plead your case? This
scheme was a dog at best and I will concede that you have have proven
it can work for a dog house.
A real house, a real load, a swamp cooler is the lesser of two evils.
Sure, just like a swamp cooler. Storing coolth at night and turning the
water off during the hottest part of the day uses less daily water than
running it all day. The slab can store coolth. Might as well use that, vs
pretending it isn't there and keeping its temperature constant all day.
As simple seekers of truth, I suggest we call this "an indoor scheme," vs
"your scheme," so we can discuss it more objectively, with more respect
and fewer male egos, personal attacks, ridicule, and so on.
That would use more daily water.
That's a more efficient direction. Davis Energy Systems has an evaporative
system that switches from swamp cooling to dry ventilation at night, at
http://www.carb-swa.com/PDF%20files/CNNovember05.pdf , but a damp slab can
lose more heat to room air than a dry slab, at the same air temp, with less
airflow, since its effective air film conductance is a lot higher.
Exactly the same, vs "beat," but it appears you still disagree with that.
And I suggest we drop this idea of a "microscopic load," for now. The load
can be large or small, depending on the house size, the amount of insulation,
and so on. For simplicity of discussion, I picked a house with 425 Btu/h-F
of conductance to outdoor air (quite buildable, though maybe atypical in
the southwest) so the cooling load increases with the outdoor air temp. If
you like, you can imagine the load isn't entirely conductive, with sun on
walls, air leakage, internal heat gain, and so on. We can talk about larger
loads later, if you like, once we sort out the performance in this case.
No thanks. It's OK to say "I don't know," but better to answer the question.
Q = 3485x6h = 20.9K Btu. C = 2000x4/12x25 = 16.7K Btu/F... dT = Q/C = 1.25 F,
ignoring the soil's heat capacitance.
I disagree. That's easy to do, with a little precooling.
I disagree. Wide comfort ranges are possible here.
Or just eliminate them. A comment like "You're crazy if you believe that"
doesn't explain how a system performs or fails to perform as described.
Arrogance aside, the first step is to determine whether it works on paper.
If we turn these words into numbers, I believe we will find the contrary,
that any kind of evaporative cooler will have less daily water consumption
if it runs harder at night and shuts off during the hot part of the day,
because of the lower makeup air penalty at night that you mentioned.
And who is to say internal evaporation cannot? :-)
I disagree. It can equal or better swamp cooler performance.
That's plan b), with 2 watt ceiling fans. Again, let's forget that for now.
It's OK to say "I don't know," but better to answer the question...
Why clean the block cores? Your pet Gila monster might take care of
critters. Ernie the Ermine takes care of Rich Komp's solar hypocaust
hollow block floor in Maine.
No thanks. I'm not clear on your logic here. Arizona isn't 24 below, and
dry soil is a great insulator, with helpful thermal mass.
I disagree. We might discuss larger loads later.
I disagree. You might say it's ungodly as well. In rhetoric, an assertion
demands no more than a counterassertion. Numbers are more useful... :-)
Yes and it will at least maintain the condition. Your scheme cannot
maintain the condition.
Or you just open the windows at night.
No Nick, not the same amount of water.
Try a real load and a real temperature then. It is a microscopic laod,
that barely covers the heat from a refrigerator and a deep freezer.
Show me a house with such a microscopic cooling load.
Nick, I jumped through a hoop for you and showed how much water air has
to be moved with the flooded floor scheme vs a swamp cooler and it
shows that under a real load and a real design temperature your system
is flawed. So you keep countering with smaller loads on bigger houses.
Disagree all you want, your system can only keep up when it is at an
It works on paper for a microscopic load and when it the ambient
temperature is 12 degrees or more cooler than what a system should
properly be designed for.
Because it indirectly deals with the outside air and adds this hot air
directly to the space it is inherently flawed and will need more water
and a higher exchange of air than a swamp cooler will. Try it at 106F,
7%RH, sensible heat gain of 15,500 btu/hr on a 1225 sq ft home.
I am getting bored of asking you to do this. You want to shut me up,
put your numbers up against this test. Plain a simple, else go start
another thread on bunnies.
You will find that there is an upward spiral- sensible heat of make up
needs more water to cool it off, more water means more exhaust, more
exhaust means more make up air.
Hey I already through down the gauntlet 10 posts ago, but in case you
forgot, scroll up a few lines.
No, no comparisons at all, A slab in contact with 42 degree soil
collects so much heat from the space, but a wet slab on 80 degree soil
will cool a house in Arizona.
Nick, I gave you some numbers to try, put up or shut up. Its that
Yes, it can, if you want to use more water over a day's time, but
turning it off in the hottest part of the day can save water with
no loss in comfort.
That requires a lot more slab and insulation and airflow.
No Abby, exactly the same, or less.
That is incorrect.
I disagree. An assertion demands no more than a counterassertion :-)
Collects or loses? Who cares, in the southwest?
I suggest you open your mind and examine the numbers.
Article 759892 of alt.home.repair:
Subject: Cool tower alternatives
Date: 29 Oct 2005 16:23:08 -0400
Organization: Villanova University
Nader Chalfoun and Christopher Trumble had an interesting Tucson cool tower
story in the Spring 2005 U Oregon "Connector" architecture newsletter.
It's nice to avoid the energy of a swamp cooler blower. Can we also avoid
the large structure (sacrificing architectural drama) and use less water,
based on weather conditions, with constant comfort and better controls?
How about testing an alternative? Evaporate water inside a house and
also run a small exhaust fan as needed to remove water vapor from
the house. The most efficient corner for evaporative cooling in the
ASHRAE 55-2004 comfort zone is at 80 F and w = 0.012, approximately.
We (not me, with recent flooding in PA :-) might turn on a small indoor
swamp cooler with a thermostat when the indoor temp rises to 80 F and
turn on an exhaust fan with a humidistat when the indoor RH rises to
54% (w = 0.012 at 80 F.)
With enough green plants in a house, the cooler might seldom turn on.
With enough air leaks, the exhaust fan might seldom turn on.
Or run a soaker hose with pressurized water from a solenoid valve (which
might come from a dead washing machine) over a floorslab in an existing
house or under a floorslab with a vapor barrier under the hose in a new
house. The slab's thermal mass might store coolth for more efficient
cooling with cooler night air below the comfort temp near the floor.
During the day, a slow ceiling fan with a room temp thermostat and an
occupancy sensor could provide efficient cooling as needed. The fan could
provide comfort cooling and raise the acceptable RH all the way to 100% at
81 F with v = 0.5 m/s, according to ASHRAE-55's BASIC program, altho that
might cause mold, on a continuous basis. The slab could also lower the
mean radiant temp. A low-e ceiling and walls could radiate less to the slab
when nobody's home, conserving stored coolth.
NREL says Tucson has an average humidity ratio wo = 0.0054 in June, with
a 67.9/99.6 F daily min/max. An 80 F house with a 400 Btu/h-F thermal
conductance and 4K Btu/h of internal gain might need (99.6-80)400+4K
= 8240 Btu/h of cooling at 3 PM.
Evaporating P lb/h of water makes 1000P Btu/h, and cooling C cfm from 99.6
to 80 F to make up for required exhaust air takes about (99.6-80)C Btu/h,
and 1000P = 8240+(99.6-80)C with 0.075 lb/ft^3 air and P = 60C0.075(wi-0.0054)
and wi = 0.0120 makes P = 0.0297C and 29.7C = 8240 + 19.6C, so C = 816 cfm
and P = 24.2 lb/h of water, with a net cooling of 8240/24.2 = 340 Btu/lb.
How many pounds of water per hour would a cool tower need to achieve
the same 80 F at 54% RH inside this house?
Ps = e^(17.863-9621/(460+80)) = 1.047 "Hg at 80 F and 100% RH, so A ft^2
of 80 F damp floorslab in 80 F air at 54% RH might evaporate 0.1APs(1-0.54)
= 0.048A lb/h of water, (mis)using an ASHRAE swimming pool formula, ie
502 ft^2 of slab might evaporate 24.2 lb/h.
At 81 F and 100% RH indoors, 1000P = (99.6-81)400+(99.6-81)C and wi = 0.0233
and P = 0.0808C, so 80.8C = 7440 + 18.6C, so C = 120 cfm and P = 9.7 lb/h
with 7440/9.7 = 770 Btu/lb of net cooling. This could work even in August,
when conventional swamp cooling wouldn't, with wo = 0.0117 and Tdp = 61 F.
It might precool a slab faster and more efficiently than simple AC.
An 80 F slab under 67.9 F air with wo = 0.0054 and Pa = 29.921/(0.62198/wo+1)
= 0.257 "Hg might evaporate 0.1A(Ps-Pa) = 0.0789A lb/h and lose (80-67.9)1.5A
= 18.2A Btu/h of sensible heat, for a total of 97.1A Btu/h. With enough air,
a 1000 ft^2 slab might lose 24hx8240Btu/h = 198K Btu in 198K/97100 = 2 hours
on a June night, with 198K/158 = 1255 Btu/lb of net cooling.
See you have to go back to using an average temperature again. :)
5,700 Btu/hr covers the internal gain of the space with not much else
to spare. A completely unrealistic load under with an unrealistic
outdoor ambient. I will play along with your numbers for the sake of
You do not have the license to round off numbers like your friend, but
in this case you are conservative.
I get 9.77 lb/hr 339 CFM of exhaust with your scheme based on water
evaporating at 68F. This neglects the extra heat and water needed
because of the slab.
You are running ceiling fans or not?
Under this completely impractical load your scheme does work out to
less air and water than a swamp cooler. A swamp cooler would be 500
CFM, 12.2 pounds/hr which ignores fan heat which would be minimal under
this low flow. The floor would be dry though.
With a REAL load and using a REAL ambient condition, not the average
temperature, you will find the upward spiral of exhaust rate and water
consumption as I have demonstrated with PREVIOUS calculations.
Yes the scheme works when it is cool outside, but let's avoid the
science fiction here.
Your scheme is all based on an 'average temperature', therefore the
'cooler outdoor air' is already factored in. You cannot use this for a
'credit' and then ignore the triple digit heat.
Your average scheme would have to run 24/7 in an average day. You have
to try and cool the home down below 80F at night, in order to limit
how many degrees above 80 the space rises to in late afternoon and
early evening. You are trying to maintain the extreme warm/humid edge
of the comfort zone as an 'average' so it sounds like cool and clammy
when everyone wakes up, not bad from late morning to early afternoon,
hot and humid from late after noon till about midnight, and Goldilocks
would find it just right (80F) when she could finally fall asleep.
That floor is going to always be WET in June, it is an average
condition design. The floor will only have a chance to dry when is
cooler than average out. Maybe it is cooler than average when it is
raining. Spores only need a wet food source and they are off to the
Chapter Two of the Pine Chronicles, still science fiction. Like saying
"My 10W PV panel cannot run a stove element, but if I charge a bank of
batteries for two weeks, I can fry some eggs."
The system cannot keep up during the hottest part of the day,so you are
saying 'simply shut it off and it will'. You have to run 24/7 as you
are designing around an average temperature. If it was designed for a
peak, it would not run 24/7.
Ah you editted yourself here and added 'Twb' to the left of the equal
sign, anything else you want to change? Sure there are no typos still?
No subscript error perhaps? No decimal point in the wrong place?Is it
wet bulb temp to the left of the equal sign? Is it wet bulb temp that
you are taking the natural log of? One of those temps supposed to be a
dewpoint? Is 56.66 a constant or a temperature or a multiple of the
I do not see how you can approximate the wet bulb temperature from that
equation as written.
Bowen did not like Willis?
Under a real load and a design temperature, a swamp cooler can work.
Under the same set of REALISTIC circumstances your scheme needs a
higher airflow rate than a swamp cooler and uses more water than a
Your scheme has to run 24/7 on an average day so it willl grow mold and
the hot make up air will make the occupants uncomfortable. On an
'average day' the condition you maintain will average out to the
extreme temperature/humidity combination that is classified as
comfortable. In maintaining this average, you will also have to keep
the place cool and clammy at night and then allow it to be hot and
humid in late afternoon. When it is hotter than an average day,as in a
typical air conditioning design situation, your system it is doomed to
create the comfort level typical of an indoor swimming pool.
When you factor in the heat gain of the slab, a swamp cooler will
maintain a lower temperature with less air and water. Your exhaust rate
will be high and triple digit make up will feel like a sirocco.
I have shown this based on a design ambient temperature and a LOW but
REALISTIC cooling load on a small house. A house with better insulation
and more external shading than is typical in the SW. I mentioned the
flux plot before, that may help you work things out.
Fourth and final chance to take a stab at my numbers.
proven unhealthy, ignoring that , a dripping wet ceiling would work
better than a flooded floor. At least natural convection would work
> bathtub experiments say a lot about house cooling,
Yes they do, in particular with what you were proposing
Yes and hopefully now, you now understand evaporative cooling. You
clearly did not before yet you smuggly tell us 'hvac crimianls' how
superior your intellect and understanding of physics is. Too funny.
heat gain by sun is significant and matters in a realistic situation.
Some species may find it comfortable. Its pushing the edge, scroll down
and see further comments on this, keep an eye open for the keywords
'underwear' and 'rubber boots'
fan speed is relative to blade geometry and the amount of air being
moved. You have taken this out of context as you have no clue as to the
magnitude of air that you would have to drive down from the ceiling to
air moving parallel to the slab, is not making contact with a slab.
Consider a DX cooling coil, air either makes contact with the coil and
loses heat (sensible & latent), or it sails through the fins and tubes
without making contact and leaves at the same condition it entered.
Mixture of the air that makes contact with that which avoids making
contact, is the leaving air condition.
The majority of the air being driven down by the ceiling fan does not
contact the slab, therefore a high flow is needed to get the cooling.
The flooded floor humidifies the air, it adds latent heat without
directly taking using sensible heat from the air. A portion of the heat
that evaporates water will come from the soil and ultimately the
ambient air and sun.
I suggested you try to use a flux plot several times to work out the
heat flow into the slab but this was ignored.
Maybe you gain a Btu/hr per square foot of slab from the soil.
Convection and radiation can be of similar magnitude
You used a formula based on mean radiant temperature.
out of context rhetoric, however a lower mean temperature would
indicate a more comfortable room
yes heat that will evaporate water from the flooded floor will come
from outside of the house in addition to heat inside the house. The
flooded floor increases heat flow into the house from the outside.
Concrete has thermal mass, heat will flow into it,. You like to call it
'coolth' and blindly use the concept to plug holes in your schemes. You
like numbers but arbitrarily write off the important details.
Vapor barriers are not a significant insulator, as you were implying.
At best it prevents your scheme from losing water to the earth. You
were calling it an insulator but most likely you meant it was keeping
water from the slab from dampening the soil beneath, and increasing the
conductivity of the soil . By stopping water leaving the slab to the
soil, it also reduced the amount of water the flooded floor wastes.
Heat will conduct through the soil to the slab. Maybe you meant lose
Attract was a poor choice of words, like saying a vacuum cleaner sucks
in air. Water is driven towards the slab, atmospheric pressure pushes
air into the vacuum cleaner.
I made no mention of deep artesian wells, again out of context
Not directly treating the outside air is an inherent flaw. You were
also trying to use a non-realistic load and a low average ambinet
temperature before. The effect of the make up air was not properly
accounted for in that the flow rate and the temperature of the make up
air were being kept artifically low.
An indoor swamp cooler does require a high air flow, a lot higher air
flow than what a swamp cooler directly treating outside air will
require. If you were to actually address the airflow needed to cause
the room air to convect heat to the slab below you would have realized
the 'high airflow' needed for the sensible cooling portion of your
The air flow of the ceiling fans, to get the sensible cooling process
of your scheme to work will be orders of magnitude higher than what an
evaporative cooler would require. The problem is you were evaporating
water to cool a slab, you were not proposing an AIR PROCESS known as
You were cooling a concrete slab and humidifying room air, then trying
to get a mixture of room air and make up air to stabalize in the
extreme corner of temperature/humidity that some people walking around
in their underwear and wearing rubber boots may find comfortable
A missaplication of concepts you read about did not pan out this time.
You want respect and professional discussion? Then give some. Quit
crossposting stuff to rile up us 'HVAC Criminals" in an attempt to
boost your ego and show us 'how smart you are'. At least this round you
did not have to demonstrate how to derive pi not intrinsic to GW Basic.
I am gloating now but what were your words? Was it, 'obtuse',
'arrogant' ? Just look at the man in the mirror.
I am more confused now then when I started reading the thread. But I did
the discussion and have done a little reading because of your debate. Well
effort and knowledge gained is never a bad thing. Just started watching this
as I always figured it was to much theory for me. Thanks,
Well the numbers show the problem with running room air through an
evaporative cooler, the inherent flaw. It shows that you never
considered how it ideally works on hot air with low dewpoint. You did
not consider this when you proposed the flooded floor.
If you could have dis-proved what the numbers say, you would have done
so already. All you have is denial, rhetoric and funny poems left.
How about a poem or a song then?
Nick's Physics in F Minor
I'm a solar geek but that's okay
I invent my own physics every day
I often joust with the HVAC Criminals
But they only scoff and get subliminal
Maybe it's a hint or a simple clue
As to why my schemes only work in a zoo
Every time they are right I just say they are wrong
I dream up bullshit numbers after a hit from my bong
Coolth and Grainger are my two best friends
I use them every time so my drivel never ends
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