my house is too hot...new AC or more insulation

[mcveigh]

my duplex is way too hot, it's like 79 degrees F during the day with the AC set at 74.
size: a little over 900 sqft
compressor: 1.5 tons, 9 yrs old, leaks freon
airhandler: 1.5 tons, original in house (20+ yrs old), dirty and drain pan is rusted

I have cleaned the airhandler as best I can, but it's still pretty dirty.
everyone has said that 1.5 tons is too small for the size and that I should get a 2 ton compressor and airhandler.

the temp difference between the air intake and furthest vent is 18degrees on avg. that is supposed to be good I guess, then what improvements would I see w/ new equipment? more airflow?

should I invest money in new windows and better insulation in the attic?
the insulation is currently just that paper cellulose junk.
I live in Florida BTW.

 

[NokiaDude]

Go get a 5 ton unit. My grandpa has one for his monster old spanish style house and it barely keeps it below 74F on hot days. Just think of what it can do for your duplex!

 

[cavemanmoron]

do you own or rent?

duplex,is that like a 1/2 of a house?

if you Own,insulate,and new windows,unless you live in florida,and then get hurricane insurance,and wait.

 

[Gyrene]

If you feel like waiting until 10 AM for an answer, I can run a Trace 700 Load for you, and tell you exactly what to do. But if you want a quick answer, get a new unit. The U-value of your roof won't change much with just insulation, and I'm guessing the majority of the heat is coming from latent load, since your unit pretty much sucks.

Using a general HVAC rule of thumb (300 cfm per ton) and doing a quick calc with your squarefootage, you're running about 2 cfm/sq ft. Which is fine for an executive office or a library at a school, but is not nearly enough for a home environment with TVs, computers, kitchen appliances. You definately need a new unit. 3 ton should do it. 5 ton might be a bit of an overkill, depending on how your system is zoned.

 

[mcveigh]

Originally posted by: dtyn
If you feel like waiting until 10 AM for an answer, I can run a Trace 700 Load for you, and tell you exactly what to do. But if you want a quick answer, get a new unit. The U-value of your roof won't change much with just insulation, and I'm guessing the majority of the heat is coming from latent load, since your unit pretty much sucks.

Using a general HVAC rule of thumb (300 cfm per ton) and doing a quick calc with your squarefootage, you're running about 2 cfm/sq ft. Which is fine for an executive office or a library at a school, but is not nearly enough for a home environment with TVs, computers, kitchen appliances. You definately need a new unit. 3 ton should do it. 5 ton might be a bit of an overkill, depending on how your system is zoned.

could you translate that into laymens terms

 

[Gyrene]

Let me see if I can say this in the correct way....j00r unit = teh sux0r, j00 n33d 4 n3w 0n3.

Talk to some local AC people about getting a new unit. From the limited information I have, I would recommend a 3 ton, but get that confirmed. (if you're near orlando, give Lee Company a call, they're a wonderful company, very helpful to the consumer) <--- shameless plug for my company

EDIT: Plus, leaking some R11 freon (I assume that's what you have) is a great way to get the enviro-nazis on your ass. I don't even want to talk about the anal-retentive people that design-build companies have to deal with.

 

[mcveigh]

i've gotten 3 different estimates, it's just I want to understand what improvements I will see before shelling out 3000.

 

[dman]

Originally posted by: mcveigh
i've gotten 3 different estimates, it's just I want to understand what improvements I will see before shelling out 3000.

Not an A/C person, but, I did some research for my previous home before we moved (ended up selling as-is and informing buyer it needed a new a/c):

You'll save a small amount on your electric bill while cooling the house more effectively and efficiently than before (that 15-20y/o unit is a ways behind the new stuff).

Will the savings in electricity pay for the new A/C? No, not really, but it will help offset some of the cost... over a LONG period of time... so long that really by the time you start to see some benefits you are about due for a new unit. IS it worth it to go to higher efficiency:

From howstuffworks:

"It is important to get a unit as close to the correct capacity as possible. Too small a unit may not be able to cool the room on a hot day. Too large a unit will cost more to operate. It may also cool the room too quickly and leave excessive moisture in the air"

 

[HomeBrewerDude]

Note that the calculations cited above assume stable energy prices. That is not likely to happen.

 

[Hayabusa Rider]

Originally posted by: mcveigh

Originally posted by: dtyn
If you feel like waiting until 10 AM for an answer, I can run a Trace 700 Load for you, and tell you exactly what to do. But if you want a quick answer, get a new unit. The U-value of your roof won't change much with just insulation, and I'm guessing the majority of the heat is coming from latent load, since your unit pretty much sucks.

Using a general HVAC rule of thumb (300 cfm per ton) and doing a quick calc with your squarefootage, you're running about 2 cfm/sq ft. Which is fine for an executive office or a library at a school, but is not nearly enough for a home environment with TVs, computers, kitchen appliances. You definately need a new unit. 3 ton should do it. 5 ton might be a bit of an overkill, depending on how your system is zoned.

could you translate that into laymens terms

Adding more insulation to your roof wont help much, which is where a lot of heat comes from. Perfectly insulated, your home still generates heat through appliances etc, which your unit just compensates for, but not much else. If you were cooling an empty room, devoid of anything which produces heat, you might be ok, but you are not. Get a unit twice the size of the current one.


Better?