I've just moved to the central valley of California and will be here for at most 2-3 more years.. I'm wondering if it's worthwhile to invest in a portable swamp cooler even though my apartment already comes with a window a/c (albeit an inefficient one!) I'm thinking of taking advantage of the relatively dry climate here in reducing my cooling costs (and saving the AC only for those rare hot and muggy days.)
Sure. Turn it on with a thermostat when the room temp reaches 80, and turn on a window exhaust fan with a humidistat when the RH reaches 65%.
Herbach and Rademan (800) 848-8001
Nick
Too muggy, and too complex. If you're going to go for that kind of complexity, get a window mount/outside air only unit. The best cooler design of them all, the Essick RotoBelt, no longer comes in a window unit, though. It's essential for effective adiabatic cooling to maintain positive static pressure, maintain a good inside air velocity and assure quick air exchange. Otherwise, the place feels like Indiana in August...NOT pleasant.
80° dry bulb at 65% RH is "sweat time" for most people. Also, she lives in the San Joaquin Valley, which can be pretty muggy in summer. She sounds like she's not from here, so "muggy" can be relative. To me, a 90° day at anything above 25% RH is "muggy." I refuse to venture to any southern or midwestern state in summer...period...been there, done that! No WONDER Texans are nuts...it's that awful climate! Here, the average RH at peak daytime temperature runs between 3 to 10%. I love to watch southerners try to move here; they dry up and blow away! On a 100°F/5% RH day, my swampie puts out 4500 CFM of air at 68°/65% RH. Once the heat load of the building, contents and occupants warms it up, it's usually 75° @ between 44-55% RH...perfect! Overall power savings using adiabatic versus mechanical refrigeration is around 65-70%, because refrigeration will cycle on all but the hottest/muggiest days if properly sized. If both were to run continuously, the savings is more in the order of 85%.IF she's in a dry enough location to effectively use adiabatic cooling, which would be in the Sierra foothills or up north of Sacramento, which would mean the RH of the outside air would have to be below 20-25% at daytime temperatures at a maximum, it can save a TON on her PG&E bill. I'm south of her, in Edison country, and even though the rates are somewhat lower, using evaporative vis à vis refrigeration puts me in a "conservation" usage bracket. That lowers my overall power costs to around 7¢/KWh. The pigs next door are easily paying 12-16¢/KWh or more due to wasteful use of refrigeration and other electric appliances, and they just sit there and bitch while they shove more barbeque into their mouths. Good...they're die sooner.
dB
Well, the ASHRAE 55-2004 comfort standard says 80 F with w = 0.012 is comfortable, and 80 F at 100% RH makes Pw = 1.033 "Hg, and w = 0.012 makes Pa = 0.566 "Hg, and Pa/Pw = 0.55, so I shoulda said 55%. IMO, a thermostat and a humidistat and a small exhaust fan are not "too complex." For "less complex," with no portable swampie, we might evaporate P = 0.1A(Pw-Pa) lb/h of water from an A ft^2 floorslab automatically dampened with a solenoid valve scrounged from an old washing machine and a thermostat to make 1000P Btu/h of cooling.
This is more efficiently done at night, storing coolth in the slab, with a 58.1 F average daily min and a 93.2 F average daily max in Sacramento in July, then stirring cool air up into the room with a ceiling fan to keep the room air 80 F when it is occupied during the day, with no external ventilation. We can store 100K Btu of coolth in a 10K Btu/F
4" x 1200 ft^2 slab with a 10 F temp swing.
I disagree.
V = 0.5 vs 0.1 m/s can raise the comfort zone to 82.9 F with w = 0.0121.
Removing the water vapor takes C cfm of exhaust air, where P = 60C0.075(Wc-Wa) = 4.5C(0.012-0.0087) = 0.01485C, ie C = 67.3P on an average 75.7 F July day in Sacramento.
With a 66.9 F average night temp, moving 100 cfm of outdoor air through a 70 F house would provide about 100(70-66.9) = 310 Btu/h of cooling.
Evaporating 0.01485x100 = 1.485 lb/h of water would provide another
1485 Btu/h, for a total of 1795 Btu/h, with A = 10x1.485/(1.033-0.0566) = 32 ft^2 of floorslab, approximately. A 90 watt $55 Lasko 2155A 16" 2470 cfm window box fan could provide 44.3K Btu/h (3.7 tons) of cooling with 36.7 pounds of water per hour evaporating from a 700 ft^2 slab.Nick
IMO Coolers work fine until the dew point reaches 45 degrees. The weather man says 40 but that is way to clammy for me.
Down sides are Need to exchange the air constantly. Older homes in Phoenix always had a window or door open. Now that is a burgerlers dream. Then came up ducts.
Since they are using outside air all of the dirt and crap in the air is flushed in to the pan. Cooler homes are dustier.
As for the portable models. As long as you are exchanging the air they work. Put one in a garage in the back corner and turn it on. It will start re cycling the humid air and then it gets uncomfortable in a hurry,,,, for me at least.
Nice theorhetical, but putting into practice in a wood frame apartment's a little difficult.
Again, the numbers work on that, but adapting it to exising households?
Ah, here's were experience takes precidence. If you use the already-named Essick RotoBelt with a polyplastic endless belt of filter media, the filtration efficiency (assuming both pad gearmotors are operating, e.g., max cooling mode) exceeds ASHRAE 30% filter specifications. Old-time Excelsior pads provided filtration from low flying birds and scant little else, and added the enjoyment of mold and mildow, something a belt type media has no problem with. Added benefit is that the pads are continuously cleaned each trip through the sump...but I digress.
If you want ASHRAE 30% filtration and want maximum air flow, you must have some positive static pressure in the conditioned space.
Trust me, having worked in Sacramento more than a few times...swampies do NOT work effectively there on a typical delta summer's day! You cite the average, but the peak is what is of concern. Also, the average moisture statistics for that area are misleading; relative humidity in that area makes wide swings during the day.
Nice theorheticals, but it won't work in practice. Neither will a portable swampie. If she's up toward Auburn, or up further north, say, Tehama or Williams, she's got a chance with adiabatic. If she's in downtown Sac, or going west toward Davis the Carquinez Straits, it's refrigeration all the way, most of the time, until you get as far west as, say, Martinez.
Theorhetical numbers are cute. Experience and metrics are better.
dB
You're going the wrong way. Swampies work better the lower the dew point. Out here, where subfreezing dew points are the norm, they work better than mechanical refrigeration.
Up ducts, more properly barometric exhaust vents, hinder exhausting air too much and maintain too high a static pressure to provide good free air flow. The open window works better, and you can regulate each room's temperature that way. If you live off of Van Buren, you're screwed anyway; they'll just bust the door down.
No longer true. With synthetic pads, things have much improved with cleanliness. The RotoBelt I mentioned earlier approachs 30% ASHRAE rated pleated filter media in efficiency. The old dusty, stinky "swampie house" should be a thing of the past, unless one uses an old, traditional louvered box cooler.
Exactly. You cannot, in practice, use reciruclated air in an adiabatic cooling system. With very low moisture content, you can get away with it for awhile, but in most real life situations, it's only good for a SHORT while. Other downside to that: anything ferrous rusts...like it's in Georgia.
For reference: at my location, 75° dry bulb with 45-55% RH is the norm during the hottest parts of the a 95° day with the dew point at or below 35°. This is with a RotoBelt 4500 CFM model with the fan on the low speed, approximately 1/6 HP. When the dry bulb rises above about 95°, then I go to a full 4500 CFM, and it stays around 75° all the way up to around 105°. After that, inside dry bulb increases linearly with increase in outside dry bulb, and w begins to rise. I just tough it out for an hour, and after sunset, it drops rapidly, house is purged, all is chilly cool again.
I'll never go back to refrigeration in a desert area again. The old timers had it right all along; abiabatic's the way to go. Side benefit: I don't have that "desert rat" skin you see on people who move up from LA and Orange County that only know how to use their AC. I've seen the RH in such homes as low as 15%, which is almost dangerous at those low temps.
dB
Yeah, they are here too.
Dunno about that, but they are certainly much better power consumption wise.
Thats trivially fixable, just put a decent security grill over the open whatever.
Nope, completely trivial to make it so they cant bust it down.
You only have to do that well enough so that its too much trouble and they loot the neighbour's place instead.
And you can blow them away from behind the grille anyway.
Mine gets dusty because I turn it off and open all the patio doors up when its cool enough outside.
I usually turn it off in the early evening because its too cool for me.
But then I like it warmer than most and dont turn it on until the inside temp is about 88F
I might add it, but just for winter heating and the very ocassional high humidity days.
No it isnt.
No. Here's where you change the subject :-)
We doan need no steenkeeng polyplastic.
No thanks.
They work a lot better at night, with 58.1 vs 93.2 F air. If 1000(0.012-0.0087) = 0.24(T-80), T = 93.75. Not much margin.
The peak requires AC or coolth storage, eg a slab.
I disagree.
Nick
swamp coolers are ONLY a viable option if you live in arizona, southern nevada or southern new mexico
anywhere else and you will be truly miserable
even in those locales they are way too muggy for me
I was a kid we had one in Western Kansas. I thought it was great then.
Tried one south of OKC in Oklahoma, definitely too humid there.
j.
I disagree.
Nick
Untrue. They work well in many areas of inland California, specifically the high desert areas.
you are correct, I had forgotten about the death valley desert area of california
any place that is around 10% humidity might be viable
Apparently you know less about California than you think you do.
"The Frezz" is uncomfortably humid to me in summer, as is most of the San Joaquin...and Bakersfield still stinks!
dB
They worked pretty well for the 23 yrs I lived in Northern Utah. They quit being very effective at about 30% - 40% RH though. When the RH went up in the evenings I'd just turn the pump off and use the cooler fan only to draw in the cool night air.
DJ
Bzzzzzzzt ... Wrong!
Seek medical attention.
Wow! You think 10 percent humidity is too muggy?? Where the heck do you live? Swamp coolers are used all over New Mexico; it's not a high humidity state.
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