Evaporative Cooler Ducting Design

That looks like it would work. The only thing I would change, is not making the inlet come from under the house. That air will be cooler, therefore denser and harder to move. The cooler air will also reduce the evaporative effect.

Good idea about the prototype, just not sure it will hold up very long. Try it and see.

"The cooler air will also reduce the evaporative effect."

...but the cooler air won't need as much evaporation to cool it to the desired temperature.

Hopefully this cooler is on the north or east side of the house so the sun does not heat it in the afternoon. Otherwise, there should be two layers to the duct work, with insulation in between.

My concern is the large flat areas of sheet. The partial vacuum inside will tend to collapse them. Some form of bracing will be required, either inside or outside.

"...but the cooler air won't need as much evaporation to cool it to the desired temperature."

True - up to a point. For the last year, I have had a temperature transmitter reporting the room temperature on a bleach tank facility where I work. Odd thing is: When the sun goes down, the temperature in the room goes up. There is a certain tipping point of differential temperature where evaporation is less effective.

"When the sun goes down, the temperature in the room goes up."

If it's anything like my place, when the sun goes down, the wind also dies out, so heat is not so efficiently carried away.

Are these open tanks of bleach? If not, then what evaporation is occurring in the room? Is the liquid at room temperature?

My guess would be that humidity goes up as the sun goes down, that will reduce efficiency.

Humidity meters are notoriously bad at giving a correct reading......the only good way is the wet/dry thermometer bulb thing you swing about your head!!!

Just a guess.....

I wuz gonna say that, but didn't, and here's why. The following is the graph of temperature and dew point for my house for the last week:

The vertical lines, if you can see them, are centered under the dates and represent midnight. (I'd rather see the date at noon, but I can't change it). Sunset is currently at 7:47PM, but I have hills to the west, so I lose direct sunlight about 2 hours earlier.

I was observing that the dew point stays pretty steady in the evenings, but with a bit more thought, the dew point is a measure of the absolute humidity, so falling temperature and constant AH does indeed lead to falling RH, so I shoulda said it! You are correct.

It would be nice to see a graph of those temperatures and know a little more about the design of the system. I suspect the temperature probably increase all afternoon, not only after sundown. Is that the case?

I agree on the graph. There are undoubtedly other factors as well: perhaps shade to the south, but not to the west, thermal inertia of the various parts of the building, flow into and out of the tanks, etc.

That is curious. My guess is that some other equipment that normally operates only during the day, or requires more significant cooling during they day, stimulates the exchange of warm moist air off of the rooftop.

Maybe without other cooling equipment operating, , warm hot air stagnates.

Perhaps look into nearby rooftop equiment and see if any of it has a schedule that has it turning on or off at times just prior to the jumps.

TE explanation DKWARNER suggests of the cooler being on a timer makes much more sense...I would tend to think someone with access to the temp graphs would also know about any timer and have been forthcoming.

....

....so I'm curious; timer or no?

'.... ...but the cooler air won't need as much evaporation to cool it to the desired temperature....'

.

Okay, so you save a little water but at the cost of adding heat (fan) to air that was already cool and more importantly removing the cool blanket under the house that minimized heat gain through the floor (perhaps even removing heat from the living space) and replacing it with warm outside air buoyantly looking for opportunities to share some heat or infiltrate uncooled.

Sometimes it takes a different pair of glasses to see the problem a different way.

True, the BBQ is the issue and I didn't think about an exhaust hood type of thing but I guess I got stuck on ducting the cooler.

I will look at the BBQ tonight to see if there is a way to downdraft the smoke or possibly make an exhaust hood. It may be cheaper too or maybe not. I will have to see if I have a fan in my supply closet with a high enough CFM to move the smoke.

Thank you for the suggestions. I will let you know what I find.

Here I go again with them negative waves.

If you really do smoke food, as in cook with indirect heat from a fire box, then ducting the cooker is fine.

If, as I suspect, you BBQ as in cooking burgers n brats or steaks you will find that the top is open as much as it is closed.

So, stick with the ducting the cooler.

Go with a cardboard model and measure the output of the cooler, both ways.

Extech AN400 Cup Thermo-Anemometer Air Velocity meter

$14.00

Lyn,

I just purchased an anemometer off of eBay ($14.09 w/free shipping) so I will wait on the prototype until after I video the smoke flow tonight.

The anemometer will arrive in a few days and hopefully before the weekend. It would be nice to get the air flow readings and prototype on Sunday.

Thanks again.

I would have installed a damper on the duct entering the house....when the evap cooler is off the damper is shut....

https://www.indoorcomfortsupply.com/cgi-bin/commerce.exe?preadd=action&key=2091

Lyn, Thank you for the heads up on the anemometer. A very reasonable if not cheap price for it. Yes I cook a lot of burgers and chicken so it only smokes for about 20 minutes on startup and then I oil the grill prior to dropping the meat on it and that smokes for another 5 to 10 minutes. I'm not a fan of smoked meat. My belly does not like it. SolarEagle, The cooler runs 24/7 around here in Las Vegas when the weather is warm and the damper would be great during winter time when it is off. Right now I cover the outlet face with a piece of 1" insulating foam and that keeps the cold winter weather out. I actually installed the E/C in an unconventional way (through the wall) rather than in a window because the available windows were not in a practical air flow pattern in this house. I will be grilling some chicken tomorrow so I will study in more detail how the smoke exits the grill. Thanks

While the damper duct suggested by Solar Eagle would be a good idea, the design of the master cool mcp44 would prevent that type of damper being installed without extensive modifications. Essick air has a cover available for this model that snaps onto the inside cover-vent.

As for the ducting idea, it would work, just make sure you use a 90* with a radius bend(curve), use flexible insulated ducting ( commercial 48" or larger) and draw the supply air from a port on the opposite or 90* wall. You wouldn't want to draw air directly from under the house because that air could contain molds, dirt, mildew, yuck, etc and that would end up clogging the media pads and then you would have to spend about $150.00 to replace them.

If you lived close enough to me, I'd shoot over there just to help you put the thing together.

I have used "Core Flute" for this sort of prototyping.

This is the stuff that is use by shops for Coke signs etc.

It is just like the corrugated cardboard used in cardboard boxes and the shops throw it away as soon as the promotion is over.

The beauty of it is it is waterproof, cheap, light weight, easy to stick with tape, you can bend it and for a sharper corner you just score it with a knife and fold.

Could you use the exhaust from the E/C to provide the induced draft for the Range Hood over your B-B-Q?

BAB

BAB,

Good idea on the material.

There are several exposition service companies in my neighborhood and they tend to throw away a lot of rigid plastic foam core materials that are used for the convention booths.

I did a bit of thinking and maybe a straight downward suction supply would be better so as to not suck up any of the aforementioned "yuck" from under the house.

I'm grilling some chicken tonight so I will do some video recording of the smoke flow from the grill and see if the grill vent is the better way?

Thanks to all for the assistance!

Is moving the barbecue down the bottom of the garden totally out of the question, Mildred?

How about a temperature sensor on the Barbie that as soon as its lit, turns the AC air onto "Re-circ" when Grilling your meat!!!

If no Re-circ, add one.....too expensive? The let it turn off that A/C.

Add good house insulation asap...

I would personally not like air from under the house, possible "Radon" gas?

See here:-

http://www.epa.gov/radon/pubs/citguide.html

Go for it !, the intake air temperature will pretty soon rise to near that of the ambient (due to the high flow) so evaporation won't be an issue, just add 1 defflector to each 90º elbow, it will greatly reduce restrictions in the flow.

I forgot to add a couple more things to my post ( I worked late and and I was sleepy, ya,ya, naturlich)

On some of the MCP 44 motors, the 250 micro farad cap is oval shaped and is attached to the back of the motor with a Philips screw, remove the screw and replace it with a hex head, coat the threads with Teflon paste. On some of the units, the cap is located inside the cavity behind the control module, some of those were in a fixed position, some were not, it may be a cylinder can shaped cap. The ones with the cylinder shapped can cap may have a threaded shaft protruding from the bottom, a hole can be drilled through the cooler wall and the cap can be affixed with a washer and nut + a dab of silicone ( if your worried about moisture intrusion omit this procedure.

Tips on control module: One some units, the control module is held to the front cover with 4 plastic clips, the clips are integral to the cover and have been known to break off easily ( I have had some success with using a small electronics screwdriver / the type used for adjusting variable potentiometers/ gingerly pry up clip and insert a rounded toothpick between cover and module face, if the clips do break off ( poor engineering design / or sales department decided to make more money selling complete cover assemblies) you will need to get the adapter plate.

Remove module, remove 4 Phillips screws, look at circuit board, there are two weak areas, the fuse and the diodes/resistors/. The fuse is low quality and tends to blow easily, the diodes/ resistors are the part of the board that reduces input current to operate the ic's on the micro controller board ( you will see a ribbon cable connected from main board to the micro board, on some units, the diodes and resistors are spaced too close together and convection causes one or both to overheat ( notice lack of heat sink). The board may have letters NOKE, if so, board is made by Shouzhan Senlin in Ghongden China, the motor may have been produced by Ningbo Xusheng. Chinese companies tend to change suppliers frequently so I have to constantly do research to keep track of where or what comes from who.

Tony,

Wrong thread.

Not sure what this has to do with the ducting but you did spark a thought in my head.

• This cooler is controlled by a remote control and doesn't have a way to control it thermostatically. The house was at 51 Deg. F this morning. I froze my you know what off just getting to the remote control.
• The motor / fan has a tendency to rattle with different back pressures and at the different speeds.
• Maybe when this motor dies, I will replace it with a thermostatically controlled VFD or multi-speed high quality motor?
• I haven't done any research yet regarding the possibility of adding a thermostat. I just wish it was an option at the time I purchased it!
• The elements / pads have been cleaned 3 times with muriatic acid and they are starting to show the wear and tear of the Las Vegas water supply. This water calcifies almost immediately even when I use every filter and additive and automatic water purge.

I appreciate your time in giving this some thought.

I'm assuming from your online handle that you live in Hemet?

Assuming it's a single phase motor, a simple thermostat could easily be placed in the airstream just before it enters the house. Just make sure it is protected from that hard water!

I guess I could put a relay in-between the controller and the motor and just switch the motor on and off with the thermostat rather that trying to interface with the remote controlled electronics?

I must confess that I wasn't thinking of the remote! But I presume the remote is a simple on-off system. A thermostat in the main power line going to the motor would presumably be in series with whatever the remote controls, so whenever it was below the setpoint, the remote would not be able to turn it on.

On the other hand, since there is a remote, there must already be a relay of some kind. This means the thermostat could be connected to the input to the relay, instead of controlling the motor itself. If you can find one with the correct setpoint, a simple glass-enclosed thermal reed switch could do that.

Good idea, I will probably service the cooler before I add anything around it so I wouldn't have to install the ducting, remove it to access the motor, then re-install it.

Damn, this ducting idea is snow-balling to a full weekend of fun and games!

Oh well, at least when it's done, it will be the way I really want it, controlled by a thermostat and smoke free!

Its possible nowadays to buy quite small water softeners and use such water for your cooler.

I have a clothes dryer that captures the water, that water is basically distilled (smells really nice!), if you or someone you know has such a dryer.

Even finding a source of distilled water at a low, low price may be possible.....

Even with an avatar/name like yours, make yourself a distillery......maybe if its hot outside, using solar energy to warm the water......

There must be many ways to get hold of distilled water.....come on "MacGyver"!!

Andy,

I thought about a water softener a while back but I just didn't think I could find a small enough unit and the thought evaporated from my head.

I never gave thought to distilled water.

As for the clothes dryer water capture, I have never heard of that! I sincerely doubt anyone I know here in Las Vegas has one of them.

I will look at that and the possibility of searching in depth for a small water softener? I think I found one on Craigslist. Thank you for the idea!

MacGyver,

Would one of these work for a source of distilled water at your location?

Unredundant,

• About how big is that?
• Does it have to be installed on soil?
• Can I install it on my roof? If so I could gravity feed the cooler!
• What is the output? My cooler has a purge pump that runs every 6 hours and dumps a gallon of water!

You may not need to answer these questions as I'm going to look at a used water softener this afternoon!

I'm sorry I don't have any detail. I found it in an Image search for solar water collectors. All I know is they are used in Ethiopia. It looks like it would use the moisture from the sand and the cactus growing inside. It is just a fancy version of the ones shown in survival manuals using a plastic sheet over a hole in the ground, weighted in the center with a container underneath for collection.

Just call me Moriarty.

Always with the negative waves, Moriarty.

Water is "softened" by trading the Ca and Mg for NaCl.
So, evaporative coolers still MAY have a problem with salt build-up. I don't know this for an absolute fact, but.........................................before spending any money...........

A thought. On hot days summer days my AC unit produces over 5 gallons of condensate water that I could catch. Vegas is about like Phoenix, weatherwise. Maybe you could harvest that water, or your neighbor's.

Lyn,

I did some research on using the softener water and what the consensus is that it will still deposit the "salts" however the deposits aren't as "hard" as the calcium and magnesium.

The salts were reported to be more powdery than solid.

It's worth a shot and I got a like new softener for $40.00 last night.

Gotta love Craigslist!

P.S. Don't look for a date on craigslist, it might end up costing you. LITERALLY!

Been married 35 years. No dates for me.

I wasn't sure about what might precipitate out.

Go for it.

I agree with Lyn's original assessment. Water softening (traditional ion exchange) is an expense for minimal theoretical gain.

Check your consumption rates. Perhaps you can find or build a small reverse osmosis system or perhaps chelation might be an option.

A solar still comes in all sorts of sizes. In lifeboats and life rafts they are about the size of a blowup beach-ball, half a metre or 20" for you die hard imperialists.

I was about 5 when Dad taught my brother and I how to make one out of anything available. Like you, we lived in the desert and Dad always said knowledge is no great weight to carry.

http://en.wikipedia.org/wiki/Solar_still

BAB

WOW!!!

I am simply glad to be of help, its what we all do here!

I did think that the dryer version was a long shot for you, but here we have bad weather/winter and the washing must get done and they produce literally gallons of water just from damp washing.....

I still await from you a a simple solar version that supplies continuous distilled water as long as the Sun is out!!!!

As an aside, search out the big tablet salt for regeneration of the water softener, it actually works out far, far cheaper than those relatively small packets of salt sold in shops for say washing up machines.

Also, as the tablets are really big, the actual total amount used (I can explain if its not obvious) is less than the crystal packets of salt, so its also better for the environment....not just your pocket.

I buy a 25 KG (50 + Lbs) bag for our washing up machine and it lasts about 5-7 years.......I actually forget just how long it last, it may even be longer, I am just guessing. I must remember to write the purchase date on the next one....

Have fun!

Maybe you could use all that condensate for a small scale scrubber on your grill?

You could market the water as liquid smoke.

If you open the control module you will see 5 relays, 1 for the pump, 1 for the purge pump( if equipped), and 3 for each motor speed. Water filter, go to home depot online, order General Electric filter # GXRTQR, Go true value and get 2 Lasco adapters # 17-6813, install filter as close to supply valve as possible. Do not use muriatic acid on the media pads, pads are cellulose composition, contact Munds Inc. for cleaning instructions. If the pads get algae on them, go to pool supply store and get a liquid algacide for black algae, dilute for required concentration. Tips were meant to help Mac guyver so he doesn't have to completely rely on duct tape and a Swiss army knife.

tonyhemet,

Thanks for the wiring assist! I will look into that in a bit.

Well,

The anemometer won't be here until next week so I'm putting it off to the next weekend.

I didn't grill last night, Got home too late from the Dr. office.

There is always tonight?

My concern is not only with access and induction of unwanted critters that flourish under houses into and through the cooler but also with the mold and mildew smell.

In such a dry climate, I don't think that would be much of a concern. Perhaps the first few hours, but once there have been a couple of exchanges of outside air, I doubt if you would smell anything.

Every once in a while I get the fishy bio-slime smell, but that is from the element pads and I use a couple of FeBreeze spritz's and all is good!

Very good points! In the long term, I'm sure you are right.

I appreciate all the suggestions everyone has posted here.

It appears that after reading all of the comments, it is a better idea to vent the smoke from the BBQ rather than ducting the cooler.

Many of you brought up concerns regarding the mold, smells, and even the cooler air layer under the house during the summer heat and the air exchange involved. If I can get my iPhone to actually operate correctly, then I will post a photo of the rear of the BBQ and you may see the gap under the BBQ lid?

You see in the background, the cooler and how it's mounted. It's quite clear that a smoke duct on the BBQ is a much better solution. I just need a fan now!

If your chimney is tall enough and without excessive restrictions, you won't need a fan. The hot barbecue exhaust will preferentially move up a decent chimney and can create significant flow through natural circulation.

....if your home is otherwise well sealed, a good chimney on the barbecue exhaust might pull enough air that you could turn off the fan on the evaporative cooler and still get cooling benefit.

"If your chimney is tall enough and without excessive restrictions, you won't need a fan. The hot barbecue exhaust will preferentially move up a decent chimney and can create significant flow through natural circulation."

True, once the flow is established. Getting that flow started may not be trivial. Then, once the flow is established, it may make the BBQ too hot. Now I was thinking of a charcoal or pellet-type barbeque; if it is a gas-fired BBQ, then the added air flow may cool it down, requiring more gas to maintain the temperature.

"....if your home is otherwise well sealed, a good chimney on the barbecue exhaust might pull enough air that you could turn off the fan on the evaporative cooler and still get cooling benefit."

Are you assuming that the supply air for the BBQ comes out of the house? So far, I've never seen an outdoor BBQ with any form of air connection to the house.

It seems to me he needs to add a hood over the BBQ to capture the smoke and a connected chimney to direct it above the evap cooler input. The opening of the hood would be large enough to NOT have a significant influence on the air/smoke flow inside the BBQ.

The BBQ is natural gas fired and it is a Tru-Infrared grill (whatever that means) I just know that it runs very hot, much hotter than I like to grill so I end up turning it down on low to grill.

Truly it only smokes bad enough to choke us out of the house for maybe 30 minutes while I burn off the last grillings and set the temperature for the upcoming grilling.

You may say that turning off the cooler for those 30 minutes is inconsequential, during the hottest part of the summer in Las Vegas, those 30 minutes makes a huge impact on the temperature of the house and also the cooler almost never recovers the inside temperature from the downtime!

I think I have a spare fan somewhere so when I get a free minute (my work schedule just went into overdrive and I'm working 7 days a week 12 hour days. Good for the pocketbook, rough on this old body!

Since the grill is hot, an appropriate hood with something like 10 feet of 6- or 8-inch chimney tubing should catch the hot air and generate natural convection. If necessary, a small table-top fan carefully directed should get it started in a minute or two. Any fan permanently installed in that chimney is going to get gummed up rather quickly.

A fire lighter (burning!) at the base of the chimney will start it drawing if there is a problem with that, maybe even just a part of one will warm the chimney enough to get it going!

A tiny "shelf" for it to sit on may be needed....

Just a thought!

In the longterm, you sound as though you need some extra insulation for your house. Its not as hot here as where you live maybe, but it can get to 38-40°C in a hot summer and to -28°C in a hard winter.

We had our house professionally insulated in 2008, since then we have never ever switched our A/C on, not a single time! I did have the 100mm insulation (60mm was the "norm" at that time.), today its 150mm. The more the merrier!!

Winter and the house stays warm enough for "survival" with no central heating on, just with body heat, TV, cooking, that is around 17-19°C. This means that the central heating does not work anywhere near as hard as it did before, we have cut our gas usage drastically, probably a third of our usage from before, not forgetting the drastic savings in electricity for the A/C we never use!.

It will take probably another 6 or 7 years to reach full payback, but the comfort in both winter and summer simply cannot be measured so easily.....if I could quantify that better, I would say alone from the comfort side, we reached payback about a week after it was installed!!

If you are looking for a 3 year payback, thats probably not ever possible, here at any rate.....but don't forget the comfort factor!! Which might be also not having smoke in the house for example and still remaining cool when the A/C is off!!

One of my best ever decisions, at least twice as good as I had hoped or even dreamed!!!

I am sure that other here have done the same......hopefully with a similar or even better result!

Often your solipsism is truly amazing. The climate conditions of lush Frankfurt, Germany is very different from the sun baked desert of Las Vegas Nevada.

You are correct, BUT, have you had the house fully insulated? If not, you are simply wasting money for A/C for example....

Its really remarkable how it helps. So don't knock it till you have tried it out properly....not cheap, but as I said, the comfort!!

Also, I forgot to mention, we had new windows the same year (same summer!), they seal well and stop drafts. A new front door as well.....

For the sides where the sun gets, there are special films for windows, that can deflect a lot of the sun's energy back outside....Sunglasses for the house so to say.....and quite cheap to install if you do it yourself!! From inside, they are not noticeable in the day I find....

Though we have roller blinds to keep the sun out, which I prefer myself. Each to his own!! Are roller blinds (outside ones) usual where you are? They also allow air through when down, but prevent insect invasions still, Mosquitoes for example......which we get in the summer.

You have said you had 10cm of insulation added, but you haven't said what kind or where it was placed.

We had our house insulated somewhere around 25 years ago. We chose cellulose (ground-up newspaper with fire retardant added). They had to drill a pair of holes between each pair of studs to fill the walls, and added 15cm in the attic. I had removed the 15cm fiberglass bats that I had added earlier, then put them back on top of the cellulose, so I have close to 30 cm total of insulation in the attic. We then had Vinyl siding added, which included another 1/5cm of Styrofoam and a layer of aluminum foil (which makes it very difficult for cellphone and other similar signals to get in or out of the house).

When we first had it done, we found the house stuffy, having been used to so much air filtration. We soon got used to the new closed house, and open windows whenever appropriate. In our location, that means all windows opened every night during the summer.

We also have a thermostatically controlled fan to ventilate the attic whenever the temperature in the attic gets above something like 30°C.

We also replaced the large windows at the same time, although we still have some small ones to replace...

Yet we still need to use the A/C frequently in the summer, and do!

The fact that the home had A/C was one of the principal reasons we selected the home 45 years ago. Fortunately, that original A/C still works just fine!

You think the same way I do, maybe we can convince Original_Macgyver to do something similar!!

Its the only way.......

Original_Macgyver has not yet said anything about his insulation. He may already have good insulation.

Where I live, there are only a few days a year that don't cool down to around 20°C by bedtime, so we can nearly always open the windows at night.

In Las Vegas, the average low temperature is above 20°C for June, July, August, and September. If I lived there, I wouldn't be able to open the windows except on rare occasions during the summer!

Original_Macgyver's obviously concerned about energy, or he would have A/C, as I suspect most people there do, instead of evaporative cooling. Let's give him the benefit of the doubt!

His house heats up very rapidly according to him, that suggests to me a lack of insulation.....but perhaps he can let us know exactly?

I was going to show histories but the Weather Underground currently uses a different format for the German Summaries, So the following are 10-day forecasts:

for Frankfurt, Germany:

for Las Vegas:

and for comparison, my house:

I need to calibrate the barometer ay my house...

Note that the graph range of temperatures for Frankfurt is 40-70°F; for Las Vegas its 60-100°F, although the 100° line is not labelled, and for my place its 50-80°F.

In case I haven't mentioned it before, you can see the weather at my house any time you like. My station is KCAPLACE21 on the Weather Underground.

Relative humidity would really accentuate the difference.

I wonder why barometric pressure in Germany does not seem to follow the daily trend seen in other places? Pretty high pressures too...and still cloudy with a chance of rain.

Its sad that the picture quality here on CR4 is almost useless.....

Red is temperature, black is humidity I believe.

If yes, its easy to see the days where we still have frosts overnight!!

Naturally, Frankfurt is warmer than here out on the land....we even had a frost yesterday morning too!! Frankfurt had dips in humidity, but no frosts as faras I can see.....

I measure the temperature outside the house, front and back, to decide what to wear when I go out with the dog early, its still 3 or 4 degrees warmer than out in the fields.....even in a small village of 100 houses or so.....

Having lived in Singapore for some years in the 60s, with very little A/C, all these examples are quite "humane" in comparison.

Especially as my first work place at 17 was the boiler rooms of an aircraft carrier! Daily temps between 90° and 95°C......

Thanks for the graphs.

Being familiar with Weatherunderground.com I can tell you that the black is barometric pressure, show here in inches of mercury.

Andy, do you have any information or even guesses as to why the pressure does not follow the same daily cyclic trend as seen in the two other examples?

We are talking about barometric air pressure, which (here at least) is a product of the weather that we are living through.

This weather marches (most of the time!) across the Atlantic and it fires lows and highs at us.....daily, weekly, whatever it wants.....as to rhyme or reason, sorry, no idea, even though reading the weather off our weather charts is a mini hobby of mine!!!

See the link below.

I was never under the impression that air pressure can be almost cyclic on a 24 hour basis as it appears to be in Cal., that is new for me personally....

UK Metoffice weather surface pressure charts

Just as there are tides in the ocean, there are tides in the atmosphere. Since the atmosphere is a mixture of gases and other stuff, the changes are not quite so obvious, but generally there are two peaks and two troughs each day.

Just as some places have much greater changes in the height of the ocean, some places have much greater changes in atmospheric pressure.

Here are the barometric pressure graphs for somewhere near your place and at my station. Unfortunately, when I calibrated my station, I used the local airport as a standard, and they turned out to be way too high, so my entire chart should be moved down roughly 0.15 "Hg. One of these days, I'll recalibrate using some better standard... Since WU scales the graphs to fit the available space, I had to double the vertical axis scale on yours to make them comparable. again, Ive darkened the 30.00 and 30.25 inch lines. The greater variation you experience makes it more difficult to see the twice-daily peaks, although they are definitely visible on the scaled graph for April 23rd.

Its sad that the picture quality here on CR4 is almost useless.....

Red is temperature, black is humidity I believe.

If yes, its easy to see the days where we still have frosts overnight!!

Naturally, Frankfurt is warmer than here out on the land....we even had a frost yesterday morning too!! Frankfurt had dips in humidity, but no frosts as faras I can see.....

I measure the temperature outside the house, front and back, to decide what to wear when I go out with the dog early, its still 3 or 4 degrees warmer than out in the fields.....even in a small village of 100 houses or so.....

Having lived in Singapore for some years in the 60s, with very little A/C, all these examples are quite "humane" in comparison.

Especially as my first work place at 17 was the boiler rooms of an aircraft carrier! Daily temps between 90° and 95°C......

Thanks for the graphs.

Curious how that last post got entered twice...

Red is Temperature, but Black is Pressure in the above graphs.

Here, Red is Temperature, and Green is Dew Point. I found out that by specifying a specific station, I could get the same graphs in history. I put the three graphs in CAD, added new heavier lines for 20, 40, 60, and 80°F, and scaled them vertically so they all have the same scale. We had a wonderful rain of 1.8 inches (46mm) during the night and early morning of the 25th, where you can see the T & DP essentially equal.

This is the largest I can make it for CR4...

Oops! I just noticed I didn't change CA to NV for Las Vegas.

Go to the Weather Underground, and pick a weather site closer to your actual location. Let me know its ID, and I'll get a better comparison.

Look at the active charts link I posted 5 minutes ago.....

I do have some other sites I use as well if that is not enough....but for Android software......

Those charts don't show the variation of any one location.

Go to http://www.wunderground.com/personal-weather-station/dashboard?ID=IFRANKFU267#history, then click on a temperature nearest your location. If you are somewhere other than south and west of Frankfurt, the click on the (-) to show a larger area before choosing a location.

My WU station is KCAPLACE21, about a mile NE of downtown Placerville. you can see my Lat-Lon values below my avatar here in CR4, and I think they are also shown in WU.

"... "humane" in comparison.

Especially as my first work place at 17 was the boiler rooms of an aircraft carrier! Daily temps between 90° and 95°C..."

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I think you are teasing those of us who are more accustomed to temperatures in Fahrenheit... seeing if we are paying attention. Well, the attention bill may be a little late, but it is being paid. 95 C is a bit too hot for a work space outside a boiler and yet not hot enough for inside the boiler either. Clever.

The one time I saw an outside air temperature just over of 50° C, I couldn't believe that people actually lived there. Fortunately, I only had to stay outside the air-conditioned car long enough to refuel; a few minutes. At 60° C, I can imagine a few seconds, maybe half a minute, holding my breath. At 90° C, I can imagine my arm for a few seconds only, but not my whole body. I simply can not believe that anyone could actually work under those conditions!

We had a great holiday on a yacht in Turkey, 2008 if I remember correctly. We went ashore (the wife and I) at around 11 am and it was really hot, a nice little Port with the name "Cash" (English spelling!).

We did not have a thermometer onboard.....

We stopped for a coffee and a glass of water at a small outside restaurant. I asked the waiter if he knew how hot it was (my wife hates high temperatures, always complaining, but not a word up to this point!). He said it had just got to 50°C, my wife started complaining, till I mentioned that till she knew how hot it was, she had not said a word!!

We went shopping as the temperature climbed to 53°C that afternoon!!

On the trip back to Anatalya, a few days later, we went through a "hot air" storm, it was as though God had a giant hair dryer.....far hotter than the 50°C, for about 30 minutes. Upturning some boats, taking all the cushions and chairs on others.....We saved 10 people swept away from their ship while swimming......now that was a REALLY HOT wind!!!

But no thermometer onboard......

High temperatures are a state of mind.....since my RN time, they do not bother me in the slightest....

Thats a pretty standard temp in a sauna, sometimes even hotter.....but we worked in it.....I got back to the UK after 2 years, 20 Kg lighter than I am today......

From Wiki on Saunas:-

Under many circumstances, temperatures approaching and exceeding 100 °C (212 °F) would be completely intolerable. Saunas overcome this problem by controlling the humidity. The hottest Finnish saunas have relatively low humidity levels in which steam is generated by pouring water on the hot stones. This allows air temperatures that could boil water to be tolerated and even enjoyed for longer periods of time.

Few people really believe what we worked in, but we did......

After 6 months, I was transferred to the Upper deck Cranes section. I was thinking COOL!!

WRONG!! Inside the cranes in the tropical sunshine, it was just as hot!!! The only difference was i could work in shorts and sandals!!

We sweated tremendously. I remember my DO sticking his head in the door of the crane to talk to me, I was above him about 20 feet, I moved and I "rained" on his face!! UGH!! He did not complain......

When I think of a boiler room on a ship, dry does not come to mind. Steam traps and maybe a little water in the bilge come to mind. High humidity comes to mind.

I understand how in a very dry environment someone can withstand air temps near the boiling point of water for maybe an hour or two. A work shift in 95 C temperature air at typical humidity below deck in engineering spaces seems reliably deadly.

What am I missing here?

That's nothing. When I was a small boy, in the wintertime I had to walk 5 miles to school and back, through three feet of snow, uphill both ways, every day.

Steam driven fans of massive design, either 6 or 8 (I have forgotten how many!), forcing outside air in and pressurizing the atmosphere in the boiler room slightly, as well as cooling it down a bit I would guess!!

I would expect relative humidity to drop in such cases, but what do you think?

This is the air used years ago to pressurize the boiler, via the boiler room itself, but in its previous refit, the boilers were changed from "Open Face" (Dangerous!) to "Closed Face", with "Extra" steam driven fans, for the air for burning the oil (FFO in those days when I worked there).

We had airlocks on the boiler room access.....

What the effect of this air pressure, had on humidity, I haven't a clue, but we all somehow survived!!!

I did get heat stroke once due to not eating enough lemon flavoured salt tablets (a dish was placed on all tables and we were supposed to eat at least 6 tablets per day! They tasted dreadful!).....

Now thats a story on its own!!! Basically nearly dying and 10 minutes later feeling fine again!! DUUHHHHH!! I remember it like yesterday!! Thats something you never, ever forget!!

We were also supposed to take a Paludrine (spelling?) tablet each day, even though Singapore (thanks to the British Raj was a Mosquito free zone! But we used to forget and make an evening visit to Jahore and get bitten to death!! Though I never ever got Malaria.)

Please don't forget that we only had thermometers in the engine and boiler rooms, no humidity meters, though Singapore generally had usually between 90 and 100% humidity if I remember correctly. (I don't think I even understood really what humidity was in those days....No training and no interest maybe?)