View Full Version : Evaporative Cooler and AC
05-17-2007, 04:56 PM
My home has a swamp cooler and roof-mounted central air. This week, is the first week the swamp cooler hasnt kept the house at the a temp cooler than 75 degrees. Which means, the AC has been turned on each day at around 2:00PM.
My questions are centered around, whether it is or isnt recommended to run both swamp and AC at the same time. I've heard opinions on both sides.
I figured I would take it to the pro's to tell me the real story.
Thoughts or opinions?
05-17-2007, 07:43 PM
A refrigerant based a/c conditioner's job is to remove moisture from the air...A swamp cooler puts moisture into the air....if you are constantly putting more moisture in the air, the a/c has to work that much harder to remove the moisture before it can adequatley comfort you. Much like if you were to live in a humid area and open your windows at night letting in the cool night air and moisture and the a/c has to work all day to get it back out. A waste of electricity IMO. I tell my customers to keep their windows closed 24/7 and set the stat to what they want their house to be and leave it alone.
05-17-2007, 08:48 PM
So, If I run the Swamp cooler in the morning, the AC has to work harder if I need to turn it on at like 3:00 in the afternoon when the temp spikes high enough that the swamp cooler cant cool enough to keep the temperature below 80.
With the dry air here in the desert, I'm curious how long it takes for the AC unit to remove the moisture and become more effective.
I know running the swamp cooler uses about 1/4 or less of the energy of the AC unit. Seen it on the bills last year, Swamp thru May, then bills went up almost 3 times the amount in June.
05-17-2007, 08:52 PM
If you run just one at a time, with a couple hours in between, they won't be fighting each other.
05-18-2007, 11:41 AM
I run my evap all day long and than shut it off and flip the a/c on about an hour before we go to bed. Even on a hot muggy day when I shut off the evap, the a/c will have the house feeling dry and cool in about 30 minutes. Which brings me to another question. Last year our old unit would pretty much start dripping out of the condensation line not long after I shut off the evap. Now our new 13 seer unit takes several hours before anything will drip from the line. I have heard others talk on this site about newer efficient units not removing as much moisture, why is that?? Or am I just immagining it?
Note the Original Poster is located in Las Vegas. I submit in that city removing humidity may be an unwanted by-product of mechanical AC, far from an essential wanted function. Therefore I have trouble seeing how the evaporative cooler is adding to a problem. People comfort is supposed to require 35-45% humidity, am I right?
I am a homeowner near Houston TX where much is opposite. Humidity removal is an equally big job as cooling the air, so I may be missing something about the Las Vegas question.
Would not this and other questions be a lot easier to understand and answer, if people would get a humidity meter and have that info available for the question? A cheap one at Walmart costs less than most restaurant meals.
Hope this helps -- Pstu
05-18-2007, 01:35 PM
This time of year, I'm having trouble figuring out how your evap isn't working better than that! If I were in your shoes, I'd be runnin' the evap full blast all night long, trying to load cold into the house. If your walls, foundation, furniture, etc are all at say 55-60ºF at 6am, I'd think your house would stay quite cool. With the swamper running all morning to help maintain that cool, it seems like your house should be in good shape with just the swampbox, given the recent temps at ~100ºF.
So I'm wondering if your had your swamp serviced recently. If your pad(s) aren't thoroughly saturated - top to bottom and edge to edge - then hot uncooled air is being mixed in with your moist cooled air and making your evap. less efficient.
That said, I'd sure run the evap at night this time of year and shut it down in the morning. When the house began to get uncomfortable, I'd flip on the A/C. I can't imagine you'd be losing any money doing it this way. However, I'd never run both at the same time (tho you probably can't even do that with your piggyback configuration).
05-18-2007, 06:12 PM
My master cool is keeping my house 69 degrees everyday right now. I have the 12 inch celdek pad in mine which is claimed to be about 92 percent efficient. Alot of people I see at Lowes and Home Depot are buying those cruddy blue foam pads or the green paper pads which are no where near as efficient. If I happen to be in there and see someone buying them, I will at least suggest that they buy the old fashion aspen pads. A little messy, but they work great. Right now our humidity in vegas is running about 7 percent, temps around 98 degrees.
05-19-2007, 03:37 AM
I just checked the history on my Vantage Pro2 Weather Station and it showed the dew point got up pretty high(55°)in Phoenix on the 17th. If Vegas got the same or close to the same high dew point, that would explain why your swamp didn't work. Since then it has dropped so low, I have to up the stat on my swamp. It got plain chilly with the air being so dry before the 17th and today. Humidity has been in the mid teens with temps around 100°s.
When I'm working in the garage during the monsoon season, I leave the door from my house open and the garage door cracked a few inches and let the air flow thru. When I am done, I close up the house and switch on the AC and in <20 minutes, it is comfortable in the house. Yes, it does run longer at first, but getting air flow thru the garage helps make it bearable when I'm working there. I also have a 1800 CFM swamp on the side of the garage. When the dew point is really high, that thing will spit water, salty water. :mad:
To answer the OPs question, don't run them both at once.
05-19-2007, 01:03 PM
Our water in vegas is terrible. I have a dump system on the house cooler and the garage cooler. My cooler is piggybacked, something the previous owner did many years ago. I did however add a switch that you have to flip so the a/c and evap cannot run at the same time.
05-19-2007, 08:55 PM
You should also have a baffle or barametric dampner to prevent the AC from blowing out the cooler.
05-20-2007, 10:05 PM
the previous owner had one in the cooler but not in the a/c unit. When I changed the unit out a couple of months ago, I added one in the new transition between the unit and the elbow on the roof.
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