I just posted this in the SA bored but thought I would post it here to get some of you experts involved.

Have any of you guys had trouble with your AC not being able to keep up in this hot weather? For example, I went to the coast this weekend, and when I left I set the AC to 83. I just got back about an hour and 10 minutes ago and turned it down to 77. Well after an hour and 10 minutes, the thermostat says it has only gone down 1 degree in here to 82.

I think something is wrong. The AC blows cold air, it just takes FOREVER to cool the house off. It will eventually get down to temperature, but usually not till the middle of the night when it cools down outside.

I had a friend of the family who works at an AC company come out and look at it and he said everything is fine. My first thought was the freon, but he said that the charge was good. He measured the temperature of the air where it comes out of the vent, and where it gets sucked into the return air and said everything was good. But it still takes forever for the house to cool off.

Are any of you experiencing the same thing? Do you think I should get a second opinion? Honest AC guy recommendations (San Antonio)? Any help would be great. TIA

[This message has been edited by lotsofhp (edited 6/13/2011 3:49p).]

Second opinion is needed.

If its not 15-20 degrees cooler coming out of the vents than it is at the air return, something is wrong.

I would imagine that after an hour, you should easily be at 77 degrees.

[This message has been edited by jed1154 (edited 6/13/2011 4:13p).]

When was the house built? Is it pretty energy inefficient? How did the unit perform last summer?

House was build in 2006, but I didn't move into it till March 2010. The house sat vacant till I bought it.

I would say the house is pretty efficient. I remember last summer thinking that the house really stayed cool for a long time. So this does make me think something has happened.

Honest question: Is there any insulation in the attic?

I work for a SA insulation company and have had to go out to several houses where the builder either forgot to call in the blown, or the builder ran out of town before finishing and the blown got overlooked. You should have between 10-12" of insulation to meet the R-30 code.

Could be lots of things. If it sat for a while and got the ambient inside temp up in the eighties and it was hot when you got home (did not look at the time of the post), it could take it a while to get all of the heat out of the house.

That 15 - 20 degree difference in supply and return is a decent guideline. It is important, because the AC will only "cool" so much. So how cold the supply air come out is directly related to how hot the return air is. If the house sat for a while at 83, there may be a fair amount of heat to remove.

Did it get better over night? You can pick up a handheld IR point thermometer for $50 or so. Not a bad idea to have one and have a general idea of what your normal supply temps are. Then you can compare occasionally to decide if it is working right.

I came home a week or so ago and noticed the unit was running but it did not feel cool in the house. Looked real fast with my IR camera and saw a higher than normal temp. Started to freak out till I realized that it had come on like 5 or 10 minutes and the ambient temps was high in the house and the outside temp was high. Took it a little while to get ahead of things.



Kevin Weiss


[This message has been edited by TexAgs staff (edited 6/15/2011 2:16p).]

Since you'd been gone for a while the house had a pretty good bit of time to soak up a fair amount of heat. Concrete can hold a good deal of heat, and your walls/insulation had soaked up a good bit as well. It can take a while to get all of that heat out. I'd keep an eye on it during a "normal" week for you, and then compare your utility bills to last summer.

You can also get up in the attic one evening and crawl around looking for cool spots that could indicate a leak in a duct. Excessive dust/dirt around doors and windows can also be indicators of a leak in the attic. Your system is losing air from the living space into the attic. The house then has to pull air from outside to make up the pressure difference.

size of house?
One or two stories?
size of unit(s) ?

These all matter since you were gone for awhile.

Thought I would piggy back on this thread since I'm having similar issues.

3 year old house and unit (3 ton)
2 story, 2100 sf, zoned AC

I was having problems keeping temp when it was getting up at 100 degrees. Air coming out of the vents was 63 at 76 in the room. I replaced the filters and checked the outside unit which looked ok at first glance. After reading another thread on here, I took a closer look since a poster mentioned dog hair and sure enough, the back sides were filthy from my dog laying between there and the house. Gave it a good cleaning and within an hour the air was coming out less than 60 so I thought I solved my problem.

Next day, air coming out at about 63 again. It was keeping temp at 76-77 but was running constantly to do it until later in the evening when outside temps dropped. What else is easy to check before I call the AC guy out? Would it be unusual for the freon levels to be low after only 3 years?

TIA

[This message has been edited by aggielax48 (edited 6/22/2011 11:56a).]

If you can hold 76 in over 100 degree weather.... Set it..... And forget it! You're achieving better results than alot of ppl

At times it doesn't though. It would get to 78-79, and one time 80 upstairs. The approximately 13 degree delta makes me think something isn't right, and since the past three summers it could hold 72 without running all day, something has changed.

I think your last sentence summed it up. It's time to call the pros man.

I added freon the other day due to a leak and writing the check hurt. Atleast the house is cooler....

aggielax, we're in the same boat at my house. it used to be able to keep up just fine, but it's running constantly this summer and not keeping up.

i changed the filters already as well with no improvement.

I will second the IR temp gun idea. Not only handy for this, but great for cooking when you want your pan at a certain temp.
I use mine to get my cast iron griddle to 400, and get perfect pancakes every time!

Just to follow up, I had another guy come give me a second oppinion and it turns out the freon was low. I have r10a and I guess maybe the first guy who said the freon was fine thought I was running r22. Aparently r10a runs at a highe pressure. Took 4 more lbs. House is cool again.

A 410 system is charged via liquid line temp and charging chart inside inside electrical access panel. R22 and 410 are two different animals, when you charge them.

The more important question is where is your leak.

I have a 2300 sq ft home in Texas brand new just built 1 year ago
it has a 3 ton unit and runs constantly it doesn't matter what is the ambient temp
i got with the builder and they said that's the right size of unit for that house

I had them spray more insulation in attic it is a 2 story house

I set t stat at 70 unit just runs and runs it takes hours before it makes temp
I think unit is to small

any thoughts


ADS

ADS said:

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I have a 2300 sq ft home in Texas brand new just built 1 year ago
it has a 3 ton unit and runs constantly it doesn't matter what is the ambient temp
i got with the builder and they said that's the right size of unit for that house

I had them spray more insulation in attic it is a 2 story house

I set t stat at 70 unit just runs and runs it takes hours before it makes temp
I think unit is to small

any thoughts


ADS

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I own a 2100 sf home with a 4 ton unit. It previously had a 3 ton and would never cool so we upsized it when it was replaced.

We also own a 2450sf home with a 5 ton.

Just my 2 cents.

ADS said:

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I have a 2300 sq ft home in Texas brand new just built 1 year ago
it has a 3 ton unit and runs constantly it doesn't matter what is the ambient temp
i got with the builder and they said that's the right size of unit for that house

I had them spray more insulation in attic it is a 2 story house

I set t stat at 70 unit just runs and runs it takes hours before it makes temp
I think unit is to small

any thoughts


ADS

---

When you say sprayed more insulation ?

Foam ?
Or traditional ?

ADS said:

---

I have a 2300 sq ft home in Texas brand new just built 1 year ago
it has a 3 ton unit and runs constantly it doesn't matter what is the ambient temp
i got with the builder and they said that's the right size of unit for that house

I had them spray more insulation in attic it is a 2 story house

I set t stat at 70 unit just runs and runs it takes hours before it makes temp
I think unit is to small

any thoughts

ADS

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I'd talk with the AC contractor vs just the builder. Make sure the builder knows what he's saying. Have tonage calculation done or have them show you their calculation for your house. Have an AC tech check for freon pressure, stuck valve, etc.. if not satisfied with the builder's contractor, get a second opinion from a non vested technician.