Least AC electric usage options?


  #1  
Old 07-15-13, 03:51 PM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
Least AC electric usage options?

I am being told different things concerning electrical usage when running a window AC. One source says best to cool down the room and then run a fan for an hour and keep repeating this, that this would be better for electrical usage than running the AC continuosly. Another source is saying the opposite, that when you initially turn on an AC it pulls a LOT of current so frequent restarting will use more electricity than leaving it on. Another source is saying if you have 2 adjoining rooms, best to run the AC in one room and leave the door open to the other room so it will cool that room too an use less current.

Can anyone confirm which of the three options above will be best to consume the least amount of electricity please?
 
  #2  
Old 07-15-13, 04:19 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,642
Received 79 Upvotes on 69 Posts
While it's true that there is a significant startup current (when starting an A/C compressor), it only lasts for a second or two and isn't going to make a significant difference in your electric bill. As for the three scenarios you listed, here's my take on them:

#1- This scenario will use the least electricity, however it can give a large temperature swing (depending upon how quickly the room heats up when the A/C is turned off). The fan will make you feel cooler when sitting in front of it, however it isn't actually cooling the room.

#2- This scenario will give the most consistent temperature, since the A/C will turn on as needed to maintain the temperature selected (within a reasonable range). It will use more power, but probably not a lot more power than the first scenario, since it won't have to run for long periods of time once the room is at the desired temperature, since it only needs to maintain the temperature.

#3- While it's possible that an A/C unit in one room could possibly cool 2 rooms (depending upon the size of the rooms), the room that the A/C unit is in will likely be significantly cooler than the adjoining room. If you can tolerate that much variation between the rooms, it's a viable alternative to running 2 A/C units (one in each room).
 
  #3  
Old 07-15-13, 04:39 PM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
What I think you've done for me is "equalized" the first two options , the third option I had tried but the 2nd room did not get any kind of decent cooling so was a waste I think, exactly as you called it but I like the way you've explained everything, I will go with the firs option. Thank you very much!
 
  #4  
Old 07-15-13, 04:45 PM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
Wait a minute, I forgot to complicates even more, if you won't mind? Last issue please, Coned recommends running an AC at 78 degrees if running continuously, would this be better than option one you think?
 
  #5  
Old 07-15-13, 04:56 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,642
Received 79 Upvotes on 69 Posts
You didn't mention what temperature you wanted to maintain in your original post, so I don't know how different it is from 78 degrees. The larger the temperature differential between the inside & outside temperature, the faster the heat transfer will occur. In other words, the larger the temperature differential, the more cooling (or heating in the winter) that will be required to maintain the temperature.

How high a temperature you can tolerate is largely dependent upon the humidity level. Air conditioning removes moisture from the air, thus drying it. If you live in a relatively hot, dry climate such as Arizona, you can probably get by with the temperature at 78-80 since it's relatively dry and little dehumidification is required. On the other hand, in Western NY (where I am), we have had many days recently where the relative humidity has been over 90%. I have my thermostat set to 74. If I set it much higher, it doesn't run enough to dry the air sufficiently, and it feels "sticky" in the house, which is uncomfortable.
 
  #6  
Old 07-15-13, 05:02 PM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
I'm in Queens NY so you know what we will be dealing with for the rest of this week which is why I am looking into my best options to keep the electric bill down as much as I can since we run 4-5 window units here at the same time. Problems are we have 2 older units which doesn't have a temp screen, the other 2 units with temp screens we run at 78 and that works for us by keeping the room just cool enough if you don't move around too much. So now I am wondering if it may be better to run the 2 units at 78 continuosly or go with option 1 even when compared to running at 78?
 
  #7  
Old 07-15-13, 05:11 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,642
Received 79 Upvotes on 69 Posts
Personally, I hate the heat & humidity. I would run both A/C units at 78 (or whatever you can tolerate) and leave it at that. I don't think it's going to cost you that much more, and you have to consider that your comfort is worth something. Running a fan part of the time will let the temperature & humidity level rise even higher than if you run the A/C continuously. I hope you realize that when a window A/C unit is running continuously, the only thing that runs continuously is the circulation fan. The compressor, which is the heavy power consumer, cycles on & off as required. So, it's not drawing full power all the time, only when the thermostat calls for cooling.
 
  #8  
Old 07-15-13, 05:18 PM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
Strange though, when running at at say 72 or so I would hear whenever the compressor turns off and on but when running at 78, it's either I never hear it or never paid attention to it but I would beleive I never hear it turning off and on?
 
  #9  
Old 07-15-13, 05:32 PM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,642
Received 79 Upvotes on 69 Posts
The only thing I can assume is that when set to 78, the compressor turns on so infrequently that you're not aware of it cycling on/off. I would check the actual room temperature with a portable digital thermometer. You may find that when set to 78, the room temperature is actually below the thermostat setting, thus the compressor never runs since the thermostat isn't calling for cooling. If this is the case, you may as well just use a window fan (assuming that you're comfortable with it set to 78). A window fan will be more energy efficient than using a window A/C unit just for the fan. I assume that you realize that if you have the A/C unit set to "fresh air" versus recirculate, it will be pulling in air from outside. If it's warmer outside than inside, it will warm the room. If set to recirculate, it shouldn't heat the room, but it won't cool it either (just the fan). If you want to use just a fan and don't want to pull in outside air, just use a "stand fan" to circulate air inside the room.
 
  #10  
Old 07-15-13, 05:48 PM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
I use a window fan most of the times but on days like today, only hot air you get from that. 78 works good as mentioned if you don't move around too much. I think the only other thing I can do is to put some sort of misting system inside this house.
 
  #11  
Old 07-15-13, 06:31 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 38 Upvotes on 30 Posts
I think the only other thing I can do is to put some sort of misting system inside this house.
If you already have high humidity then a misting system is the LAST thing you want to use. Misting ONLY works when the humidity is low.
 
  #12  
Old 07-16-13, 02:57 AM
M
Member
Thread Starter
Join Date: Jan 2006
Location: NYC
Posts: 693
Received 6 Upvotes on 6 Posts
Hmnn, everything I've ever read about misting suggests that the temp around you drops by at about 25 degrees?
 
  #13  
Old 07-16-13, 03:55 AM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,642
Received 79 Upvotes on 69 Posts
That's true if the humidity is low. This kind of cooling is commonly used in the Southwest where it is hot & dry. This type of cooling (often referred to as "swamp coolers") blows air over a pan of water, adding humidity to the air, which cools the air. However, in the Northeast where we are, the humidity is high, and as Furd stated, adding additional humidity to the room will make it feel even more uncomfortable.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: