The Housechick Blog

First in our series of the Top Ten Things to Know about Tucson Real Estate:

There are two major home cooling systems that we find in Tucson Homes: Central Air Conditioning and Evaporative Coolers, or Swamp Coolers, as they are affectionately known.

If you haven’t heard by now, Tucson can be hot.  We are in the Sonoran Desert, after all.

Newcomers to the area are often concerned about how they will stay cool in our summer months.  Swimming pools and central air are typically high on their list of “must-haves” for a Tucson home.

Well, not every home in the Tucson area has central air conditioning, or A/C.  We have two major cooling systems: the A/C and the Evaporative Cooler.

The A/C is what most people know and understand.  I’m not going to explain how an A/C works here, there’s an excellent description on this site.

There’s also a wall A/C, which is a small unit typically installed in a window or wall space.  Also, a widely known and understood item.

Let’s talk about the evaporative cooler, or the swamp cooler, as most people call it.

The swamp cooler is really a fairly simple device.  It looks like a big vented box, has ductwork attaching it to the house, and will typically sit either on the roof or is attached to the side of a house. 

Couple ways to identify the swamp cooler:

• There is no return air duct.  Air only goes one way: into the house.
• There is a water source running into the cooler, usually a small copper tube that runs across the roof.
• In older styles, all sides of the exterior are vented.
• And the big tip-off: a big mineral deposit stain on the downward slope of the roof below the cooler.

Swamp coolers work by pulling hot outside air through a wet pad, which cools the air.  The cooled air is then pumped into the house with a fan.  That’s evaporation at work.  I can’t explain the science, but here’s a good analogy: lick your hand, then blow on it.  Hand feels cooler, doesn’t it?  That’s evaporation.

The cooled air is pumped into the house, which basically pressurizes the house.  Home owners open doors and crack windows to give the air pressure in the house a “release valve” which also directs cooled air towards those places, making them cooler.  Got it?  If you want the air to flow through the bedroom, slightly open a window in the bedroom so air is drawn through that room.

On the plus side, the swamp cooler is dirt cheap to run, is also cheap and simple to maintain, and works really well when it is dry and not humid.

On the negative side, the swamp cooler needs frequent maintenance, doesn’t have any air filtration for dust or pollen particles, and doesn’t work when it is humid outside.  We’re talking Monsoon Season Sweats here, when it is 90% humidity and 100 degrees outside.  Go find a pool, your swamp cooler will do you no good.

Here’s how it works.  There is a water reservoir at the bottom of the box, and a pump sits in that reservoir.  The water pump, similar to that of a fountain, pulls water from the reservoir and pumps it through plastic tubing, called the “snake”, which drips water onto all of the pads.  The pads line the inside of the box where ever the box is vented, and are made of some kind of absorbent material that looks like hay wrapped in a big hair net.  A fan, sometimes called a “squirrel cage”, pulls air through the wet pads and pushes it into the house.  Voila!  Cool air.

When a homeowner wants to turn on their swamp cooler, first they turn on the pump for a couple minutes, to let the pads soak full of water, and then the fan can be turned on.  These controls are usually inside the house, and can be a little rotary switch or a collection of regular switches.

At the end of the warm season, coolers are “winterized.”  This means all the water is drained, the pads are discarded, joints are greased, and everything including the water pump and tubing needs to be cleaned and de-mineralized.  There’s also something called a “cookie sheet” that is placed between the house and the cooler, into the duct work, that keeps cold air from entering your house during winter through the cooler.  After a good cleaning, a smart home owner will put a special tarp over the unit to keep it clean and in good condition for the next year.

At the start of the warm season, tarps come off, water supplies are reconnected, pads are installed, cookie sheets are pulled out, and the cooling season begins.  Coolers may need monthly maintenance as well: replacing the pads, throwing in a special mosquito repellant dunk to keep them from breeding in your reservoir, cleaning out clogged spider tubes, that sort of thing.  A good calcium and lime cleaner and a ladder are the swamp cooler owner’s best friend in the summer months!

Since swamp coolers are a concentration of water on the roof, it is imperative to keep them in good working order so that water does not constantly run onto the roof, which could degrade the roof and cause leaks.  It’s a pretty common source of water damage in the interior of houses, especially in our older 1950’s homes.  I guarantee you, if there has been a swamp cooler on the roof for the last 60 years, then there has been a leak at some point.  It’s okay, you might see some stains or warping inside.  It happens, and we can deal with it.

So there you have it.  Swamp coolers and Air Conditioners.  One of the mysteries of Tucson Real Estate explained.

Photo from Flickr, Courtesy of Kingdafy