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Posted: 6/13/2002 4:00:32 PM EDT
for the first time in my life I have an A/C equipped home. right now at 4:45 pst seattle it's 95 degrees outside.It reads 81 in my home.i have it set at 74 degrees.The question is how much temp difference between outside temp and inside temp is normal??If outside is 94 degrees what are my chances of bringing it dowm to 74.

Link Posted: 6/13/2002 4:32:41 PM EDT
No flame, but, Dude have you been in a coma?
Link Posted: 6/13/2002 4:36:44 PM EDT
My AC will easily bring a room down to 70 degrees regardless of what temp is outside, and I have lived thru 110 degree weather.


PS Welcome to the 21st century[;)]
Link Posted: 6/13/2002 4:40:25 PM EDT
There are a lot of variables like how well your home is insulated, humidity level, how long the AC has been running (duh), etc. But if 81 is the best it can do, either the system is too weak for the size of the home or it's in disrepair.
Link Posted: 6/13/2002 4:40:57 PM EDT
Depends alot on humidity,and size of unit, 50-60% humidity on a 90 degree day should show a 20-30 degree drop (measured at vent) this doesn't take into account this size of room nor size of unit. Good luck
Link Posted: 6/13/2002 4:59:56 PM EDT
I have split central AC. Two high efficiency, 12seer, York 2 tonne units. The units are sized correctly for my house. The contractor talked me out of getting 2 1/2 tonne units, saying they weren't necessary.(wish I hadn't listened) If it was 110 degrees outside, there is no way they would bring the temp down to 70 degrees, like sgtar15's do. But my house is old and the insulation is poor.
Years ago, when I first had central AC, I put the thermostat at 70 or 71, during a particular brutal hot spell. (different brand of AC - Magic Chef, I believe) When the monthly ComEd bills of $400 started coming, I quickly learned to set the thermostat at a more sensible level.
Link Posted: 6/13/2002 5:13:38 PM EDT
Whine, whine, whine!  Just open the window!
Link Posted: 6/13/2002 5:21:23 PM EDT
There's a lot of variables here---
How good is your house insulated?
How airtight is your house?
Is the unit sized correctly?
etc etc

Here's a quick AC101

1.The large copper line should be cool to the touch.It may be sweating also where it's not insulated.The smaller copper line should be warm to the touch.

2.A basic rule of thumb in the south is 1 ton of cooling for every 5-600 sq. ft. of house.A 2000 sq ft house would have a 3 1/2 to 4 ton unit.

3. Standard temp drop across the Air Handler(inside unit)is 20 degrees.Some of the newer high efficiency units with a variable speed fan might have a 30 degree diff between entering and leaving air.

The two most important things you can do for your unit are
1.Change your filters regularly.Don't use those cheap .50 cent filters,save your money.These are the ones that are made of strands of fiberglass and you can see through them.If you can see through it,how much dirt is that going to catch?

Use either a Hepa filter or a washable filter.The Hepa filter will look like it has pleats or look like an accordian.The washable is usually made of foam.When it gets dirty,wash with water hose,dry and slap it back in.

2.Clean your indoor and outdoor coils at least once a year.Since you probably don't have access to coil cleaner just take your water hose to it.The outdoor coil may need it 2 or 3 times a year if it's in a dirty/sandy location.

I officialy certify you as an Air Conditioning Mechanic now!!  

Link Posted: 6/13/2002 5:21:52 PM EDT
25 year old home.Rambler style 2100 SF.3 year old 4 ton unit.temp measured at vent is 58 degrees.been running for 5 hours

thanks for any advice/info

Btw i wish I was in a coma.Too damn hot outside[8D][:D]
Link Posted: 6/13/2002 5:25:44 PM EDT
Sounds like you're getting a good split across the coil.If it's been running for 5 hrs I'd look at the insulation and how airtight the house is.
Link Posted: 6/13/2002 5:43:56 PM EDT
Wash-Ar15, check the freon (or whatever the PC newspeak is for it this week) level.  I've found that most of the time when the compressor doesn't cycle, the freon is low.  That's one wild-guess.  Is there enough air flow coming from the vents?

The contractor talked me out of getting 2 1/2 tonne units...
View Quote

Buy the bigger unit is my usual advise.  I've never understood why air- conditioner "professionals" always recommend undersized units.  I used to do programming for environmental control systems, and the biggest problem we always found was that the AC couldn't keep the buildings a comfortable temperature when the humidity was high, we had several hot days in a row, or there was a lot of traffic in/out the doors.  We worked on one Blockbuster Video after another that had inadequate cooling, and the "professionals" still insisted on using the same size units, that didn't work elsewhere.  Yes, the table in your textbook might say a particular tonnage is enough, but when you know from experience it isn't, why keep recommending it to your customers?  The managers blamed us for the buildings being too hot and losing customers, but we were often running the AC as much as we could.  We even turned-off zones of lighting near the windows to reduce the heat, and that still wasn't enough.z
Link Posted: 6/14/2002 12:26:01 AM EDT
The house I rented in Oklahoma City had one old two ton Coleman unit for an 1800 square foot house.
It took it a while to cool down the house, but after it had cooled down it cycled on for about 40 minutes out of the hour for those 100% humidity and 115f degree days.

Best temp was 64 degrees inside (in the room with the main outlet duct) when it was 112 outside at high noon.

Electric bills were in the $225 range.

Had it been my house I would have broken the house into two zones, installed two units and plumbed in AC for the garage.

If all your AC can get is 81 on a 95 degree day there are problems.

Today in Oak Harbor I opened all the windows and ran a couple of fans for today, I was nice and cool.
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