Weather like this,,

[norgeway]

Proves my point about air conditioning in a house, Nowdays everyone wants to size a c units just big enough under ideal conditions to run nearly all the time to maintain a set temperature, Well and good if its 80, but let it get over 90 and a hundred for several days and you wont be able to keep your house cool, likewise, if you cook a big meal, as i sometimes do, You can forget the air keeping up, My theory is, If I set that sucker to 60, then it dang well better get my house to 60 and shut off, and it sure as hell better keep it at 60 if i run the oven all day, And when I replace the 2 ton unit that is in this house, 4 tons are going in, No one will ever prove to me a unit running all the time will use less energy than a unit that actually is big enough to cycle now and then, People say , well it needs to run to dehumidify properly, what good is dry air if it wont get as cool as you want it!!

 

[maytag85]

The Bryant central system I have works well on moderately warm days but struggles on hot days and since it’s monsoon season in the southwest I’ll be running it earlier in the morning to when I go to bed to keep it cooled and dehumidified inside. Going to have to start using my Kenmore window air conditioner I have to help keep my room cooled off since it’s the hottest and stuffiest room in my whole house and the rest of the house will be a comfortable 70 or 72 F while my room is 78 to 80 degrees.

 

[qsd-dan]

Oversizing an A/C unit in a humid area is almost guaranteed to cause mold issues. Not worth the risk.

 

[tomturbomatic]

With the increasing heat we are seeing each year, I would imagine that AC engineers are going to have to build a bit of reserve into their calculations for sizing air conditioning systems so that they will be able to cope with the increasing summer temperatures. I have never been totally at ease with just one air conditioning system. I always like to have back up because for many years our central system would break down and we had no back up. Once we installed the Westinghouse window unit in the breakfast room, we at least had part of the house cool if the central system broke.

With my window units, I am not bothered by barking dogs and other neighborhood noises and I only cool the parts of the house I use. I have solar screens on the windows and plantings to shade the house and those things help lessen the cooling load, too.

 

[retro-man]

I over sized my central ac. 3 tons was recommended I went with 4 tons. It works great on these hottest days. I can use the stove all day and it keeps up with it and cycles off regularly. Humidity is removed greatly. The amount of water coming out of the discharge pipe is like a faucet running on low stream. Humidity stays 38 to 41 percent while it is 101 degrees outside humidity at 100% and dew point at 73. No mold no mildew, just cool comfortable air in my house. I don't believe that a 3 ton unit would have worked as well. Mine does not run for more that 20 minutes at a time, so I believe that this uses less energy not running for hours at a time with a smaller unit. When it goes down in the 80's outside it works just as well. Usually keep inside at 74 degrees during the day and 71 degrees at night.

Jon

 

[chachp]

Mold issues

 

<span style="font-family: helvetica;">Why does over sizing an A/C unit cause mold?  I would think the opposite.  </span>

 

<span style="font-family: helvetica;">My Ex's husband worked (he's retired now) for Carrier for years.  Years ago he told us it's more energy efficient to keep your fan on constant all the time and let the A/C and furnace cycle on and off as needed.  He said it helps maintain a more consistent temp in the house.  He said the fans on modern furnaces are designed to run constantly and don't use more than the power a 60 watt light bulb would use.</span>

 

<span style="font-family: helvetica;">I've never tried to figure out if I would save a considerable amount of money by letting the fan cycle on and off but I do know I don't get those hot spots in my house when the fan runs all the time.  We are in the high 90s right now with very high humidity and our unit keeps up just fine.  We have a well insulated all brick home.  It's about 2400 sq ft. and we have a 4 ton Trane unit that was put in last summer.  It replaced a 20 year old American Standard zoned unit that was working fine until there was a leak in the condenser coil (I think I said that right).  We decided to replace it all vs. piece meal.  There didn't seem to be much sense in pairing a high efficiency A/C unit with a 20 year old furnace so we bit the bullet and did it all.</span>

 

[retro-man]

The thing I find with the blower running constantly during cooling season is that once the compressor shuts off the coiling coil warms up and all the moisture that is on the coil gets released back into the air of the house. Brings the humidity up fast. I just run the fan on auto during the summer. I don't have hot or cold spots so no need to run it during the winter. When my house was built and they installed the system we had someone come out and balance all the vents in the house so everything it even through out. Temps are consistent in all rooms.

Jon

 

[chachp]

Balance the vents

 

<span style="font-family: helvetica;">We had that done too when they put in the new system.  I haven't even tried letting the fan cycle since we put in the new system because I've run it like this for so long.  I suppose I should try that.</span>

 

<span style="font-family: helvetica;">When we had the new system put in I asked the techs what they recommend and he said in our climate they recommend running the fan all the time.  I should add that our system has a variable speed fan. So when the system is not calling for the compressor or the furnace it's running really low.  We don't even hear it.  When it calls for cool or heat the speed ramps up.  It's a very quiet system so we barely hear it even at high speed.</span>

 

[petek]

Don't all the new central units today, the word escapes me, adjust their Btu output to match the heat load required as does my mini split? I think my 24,000 btu can go down to about 6,000 btu.

 

[tomturbomatic]

Are you talking about an inverter allowing a constantly variable speed direct current compressor or the benefits of an electronic expansion valve or both?

 

[yogitunes]

like it or not, Hans is correct...

when I got my house back in 1993, the sizing required 18,000BTU window A/C....which ran a lot to get the place cool, but as mentioned, if you lit up the oven/stove top, you killed off your conditioned air, and took a while for it to recover...not to mention elevated electric bills.....always set to AUTO, but ran for a greater portion of the day...

3 years later I switched to 30,000BTU's....this unit is set at number 3, and fan speed to LOW, runs for about 15 minutes each hour, if even that...and chills the heck out of this place...if I have a house full of guest, like a wash-in, or firing up the oven...a simple adjustment of the fan speed to High, you dont have to wait for the heat to trigger it, it will chill back down in no time....

a little overkill is never a bad thing.....you can't make a small unit bigger, but you can adjust a bigger unit to a lower setting....

never had an issue of excess humidity.....too much humidity is just as bad as no humidity....as it can suck the moisture out of plants and aquariums...

most important on this size unit, my electric bill has dropped drastically!....had this unit all these years, and wont consider anything smaller, EVER!...

 

[vacerator]

I think every

unit struggles in extreme heat. I keep out T-stat 10 degres warmer than the outdoor temp. If it's 90f outside, set any cooler than 78 it doesn't even cycle off.
We have a 2.5 ton high efficiency (in the early 90's) unit, and a Lenox variable speed furnace, which also ramps down for a minute once the unit shuts off to push ll the cool air from the ductwork.

 

[rp2813]

I have a situation where the front of the house is west facing with no shade, and it heats up fast.  The back of the house where the bedrooms are is east facing and is much cooler.  I run the fan continuously while the AC is operating in order to help even things out.   Add to this that if I leave the fan set to "auto" it will cut out while the evaporator is still cool enough to be beneficial, so that's another reason to leave the fan running continuously.

 

Since it's typical for temps to drop to comfortable levels at night here, once the outdoor temperature evens out with the indoor temp, I throw open the windows and switch to box fans.  We've had more hot days so far this year than usual, so switching to fans helps to keep my electric bill lower.  The central fan is really loud and there's no speed setting for it, so that's another reason I shut it off once things equalize.

 

[circlew]

My Aunt Doris that lived in Mississippi would keep her houses downright cold - even when it was nearly 100 out. Their Camelia Dr., Jackson house that they lived in between '63 and '90 had the original Chrysler Airtemp HVAC system the entire time they lived there. It never had any problem regardless of how hot it got. I think the next house in Brandon had Bryant equipment, and it made cold air, too. I will say that every place I remember them living in had heavy lined drapes on most windows, and they were kept closed all day. That helped keep a lot of heat out.

 

[askolover]

We have a 2 ton gas package unit Amana (Goodman, made in Fayetteville TN) that just turned 20 years old.  It cools this 1956 house down ok but I think it could have been a little larger to account for the insulation in the walls.  When I get my new windows and siding installed it will probably be just right.  I still have window units in the bedrooms so I don't have to cool the whole house down while I sleep.  An 8k Haier in the main bedroom and a 6k in my dark room.  My sleep room should have been fine with a 5k unit but it struggled for 20 years and this year the switch started getting wonky so I just replaced it and went with a 6k.  I have a heated waterbed in that room and it puts out enough heat to compete with the old 5k unit.  This new 6k unit works great....except that the interior of it is white styrofoam which lets in a LOT of light and I need it DARK to sleep in the daytime.  I took black paint and painted the inside of it black as far as I could reach and that helped a lot.  It's tolerable now.

 

[kevin313]

Seems to me the world is getting hotter, but I've been thinking if we are going to be able air-condition ourselves out of this situation. Many parts of the developing world, which a generation ago had little available air conditioning options, are now installing massive amounts of a/c.

Where is all this energy coming from? The power needs of the world increase every year, yet the generation of much of that power is creating an atmosphere that fosters higher temperatures. Do I have this all wrong? Please let me know if I'm not thinking right about this.

I have central a/c in my two homes (Carrier and Amana) and they both do a good job in keeping the house at 72 degrees, which is where I like it. I know some people have health issues or preferences that require colder temperatures, but I grew up at a time when we didn't have a/c in the house, so we went down to the basement to cool off, or went to our local movie theatre or department store to enjoy their nice "cooled by refrigeration" air! Somehow we survived the hot, muggy Michigan summers.

 

[vacerator]

Yes, and

my basement is a few degres cooler than the main floor. I'm down here a lot with my model railroad. The back of our house faces west with no shade. Kitchen back there too, so you can bet I BBQ a lot in summer. I draw the blinds in the afternoon from May to September. Once the afternoon sun heats up the brick, roof and attic, the walls retain heat even though insulated. The one with the T-stat is on the center of the house wall. The walls are naturally warmer from half way off the floors. That makes the air run more.

 

[twintubdexter]

Don't see anything unusual...

<span style="font-size: 14pt; color: #339966;">I don't understand what people are talking about. What heat?</span>

 

[circlew]

One thing I remember about the South is that many of the houses had white or very light colored roofs, so as to reflect the sun. This helped keep the attic cooler. One of my cousins in Hattiesburg put a black shingle roof on his house, and was soon sorry.