We are building a new home, 4200 sq ft (family of 9) and A/C is the standard option. We are in the mohave desert about an hour and a half from las vegas, Elevation is about 3600 ft. Super dry here. Not as hot as Phoenix or even Vegas. It seems to me that a swamp cooler would work better here than anywhere. Any thoughts on evaporative coolers?
Swamp coolers work well here in AZ. The newer, more expensive ones, are pretty efficient and use less water. With a regular swamp cooler, what you see is what you get. Spend the extra couple of bucks on the nice cedar pads, if you get one. Use filtered water, if possible.
You might consider a subterranean cooling system as well. You can build it to move air in and out of your home, cooling it in the summer and heating it in the winter. A thermostat can be attached to a fan to regulate the temps. I can't recall how many linear feet you need per cubic foot of space, but you will have to run quite a bit of tubing to make it effective. Perhaps it would be best to isolate some room systems too?
While you can spend a lot on a high-tech version, it's really not necessary. You can do it yourself with PVC. Some applications use french drain tubing, because it'll let the moisture leave the pipe more readily, which can be a problem as the air cools and causes condensation. If you're on a hill, this can also be addressed through a downslope vent using gravity. It'll take a little research to discover your best options.
The important data for making this choice is the summer dew point. If it's below 55F, then you can be comfortable with a swamp cooler. I've lived with them in Palm Springs, Phoenix, and Albuquerque and I was comfortable. Not so much in Carlsbad, NM, where the dew point hangs in the low 60s for good stretches during the summer. It's those stretches that make you want to go out and get some A/C.
We had a swamp cooler in SLC for over 20 years. It worked great...until the temps were over 95-100. Then it could barely keep up. It didn't work so well during monsoonal heat either, not so sure that applies to the Mohave area. That cooler was aged in 1993 and we never did need to replace it. I'll defer to others who say they've improved in the last decades.
What did work great was taking advantage of the extreme swings in dawn to afternoon temperature. Salt Lake mornings are rarely above 70 degrees. I'd run that swamp cooler (fan only) as hard as I could in the mornings with all the windows open, then shut the whole house tight until late afternoon, trying to bank the coolness through the heat of the day. And that was in a marginally sealed and insulated 1920s house. With modern construction, I would install two fans: house to attic and attic to outside. I'd run the attic to outside on a thermostat to keep the an overheated attic from radiating back into the living space, and I'd use the house-to-attic to draw cool outside morning air through the house more efficiently than running the swamp cooler fan.
Make sure your builder installs a low window on the north side of the house, away from the swamp cooler, so you can draw the coolest air throughout the house. Being able to keep the windows open is another advantage of the swamp cooler IMO.
And +1 on the cedar pads, much nicer than the manufactured material ones they push.
Location: Southern Colorado 6200 ft elevation, 20" annual precip, zone 6a/5b
posted 4 years ago
I've used swamp coolers for about twenty years and I live in a dry climate perhaps not to different than yours. We currently use two window mount units in our home and have a roof mount unit on our office.
Installation and operation costs of evap coolers is almost certainly much lower than AC. This is especially true if you use evap window units.
I don't like roof mount evap units. You have to cover them tightly in the winter to keep cold from blowing down the ducts. We also cover roof unit indoor openings in winter, also to slow drafts. As someone already noted, if you have a roof mount unit someone will have to go up there at least twice a year to service the unit and all adjustment, cleaning, etc. has to be done on the roof.
We use one evap cooler in our kitchen window during the warm part of the year. It adequately cools the main living area almost all the time: it lags at certain times, such as when we have a thunderstorm with rain and the sun pops out hot immediately afterward. That makes the air temporarily to moist for the cooler to cool. The other time when I wish for more cooling is when I'm canning food in late summer! Pressure cookers put out a lot of heat! Our daytime temps rarely go over 95*
We also have a cooler that cools the second floor where our bedrooms are. It is smaller and we don't run it during the day. Our summer nights are usually about 60* so it doesn't take much to cool during the night.
In hot summer we put the coolers on timers. We set these timers to shut off the cooler about dawn or soon after. If we close up windows and blinds in the morning the house will stay cool for many hours with no additional cooling. If your home will contain lots of mass, such as concrete floors, this will work very well. For a passive solar home our place has a sort of medium amount of mass and it still works fine.
In a dry climate the addition of water to the indoor air is usually a benefit. Your house plants and your skin will love the moisture! AC tens to lower indoor air humidity while evap adds to it.
We remove our primary evap unit in the fall and re-install it in the spring. Yes, there is more annual labor with evap coolers and you you will occasionally need to replace the pads. If you have hard water you may wind up with what looks almost like fungus eating your cooler: it's some combination of minerals from your water coating the cooler's pads. This can be scrubbed off, but it's a hassle. Where I live we have city water that comes from a lake, so it doesn't have much mineral content. My friend who's cooler runs on well water has to clean the cooler and replace the pads every fall.
IMO, shredded wood pads work better than synthetic pads. Here the pads a made of aspen most usually.
AC units tend to reuse captive house air while evap units push air in from outside. Our family thinks the fresh air is far preferable.
Cheap evap units now are made in such a way that the motor can't be replaced. This sucks! Spend more money and talk to a reputable HVAC store/contractor who can steer you to a quality unit. It's bad when big things like a cooler are made so they can't be fixed! I hate it! Ok, just little rant on the side.
I've seen three types of evap units. Most common is the type that has fixed side panels of fiber pads and a pump which pushes the water into troughs which dribble it down the pad. I've also seen one with the pads on a round frame which rotated the pad through the water and didn't work well. There's another type, once sold by Sears, which has a sort of loop of pad which runs on rollers to keep the pad wet. The typical fixed pad type remains more reliable, IMO. In the standard type, if a pump quits they are readily available and easy to replace.
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