Home A/C help.

[Josh123]

So I live in Texas and the temp is usually anywhere from 98-110 outside. My A/C unit can't keep my house cooler than 81-84 in the middle of the day and I'm not sure what to do. I have a home warrenty on the house and put in a service ticket a week or two ago and had a guy come out and look at it. He changed a blower setting or something and it does seem to blow more cool air but it hasn't made an impact on the temperature.

I put in another service request but what should I say when they send another guy out? Should I have to pay another $60 service fee since they didn't fix the job the first time?

 

[highland145]

Enough insulation in the attic?

 

[Demo24]

A combination of two things you need to look at: correct amount of insulation and a properly sized/working unit. Also if you have a number of windows, especially if they are older, helps to find ways to shield them.


We've been working on this issue with our house. Our old unit just wasn't cutting it anymore, old, leaking freon, etc. So it was replaced to a significantly larger and more efficient unit, plus a good bit more insulation was pumped into the attic, and in the back of the house new windows replaced the old single-pane. Made a massive difference! The front part of the house still gets hot simply because of the number of windows, but manageable.

 

[Analog]

AC is all about ΔT. A properly working AC produces a ΔT between what air temp it brings in and what it puts out. I.e. suppose it brings in air at 85F and puts out air at 65F. Thats a 20 degree ΔT. If its doing that, but your house's insulation is poor, then the air in the house doesn't stay cool, but the AC IS doing its job.

On the other hand, if its bringing in air at 85F and putting air out at 80F, then it probably has a compressor or Freon issue. You should be able to check this yourself with a simple thermometer. Just make sure you measure the air coming out of the unit as close to the discharge as possible (not including vents). HTH.

 

[PottedMeat]

Enough insulation in the attic?

or ventilation - make sure the soffit vents aren't blocked

 

[soulcougher73]

We have the same issue in our house. Its was 100 degees yesterday and our house was 81-84 degrees even though temp was set to be 74 degrees. I was told on super hot days that 15 degrees less than the outside temp was about as good as ACs are good for. No idea if that is true, but ive heard it from 2 people now. Our AC unit is about 15 years old so im sure its due for a replacement with a more efficient one soon.

 

[IndyColtsFan]

Without more details, it is hard to say. Here are some tips:

1. Keep the blower fan running to help circulation. That is probably what the guy adjusted.

2. If you have a two story house, close the vents on the bottom story and only open the vents on the top story that you need. For example, we have a vent in our master closet and we close it year-round.

3. See if the unit is sized properly, as others have mentioned.

4. Think about an attic fan if you don't have one. I think we're going to put one in eventually; unfortunately, there was a really good deal recently and we missed it.

 

[highland145]

We have the same issue in our house. Its was 100 degees yesterday and our house was 81-84 degrees even though temp was set to be 74 degrees. I was told on super hot days that 15 degrees less than the outside temp was about as good as ACs are good for. No idea if that is true, but ive heard it from 2 people now. Our AC unit is about 15 years old so im sure its due for a replacement with a more efficient one soon.

Nope. What Analog said, you should have a 15 to 20 degree drop from the air going into your return compared to the temp coming out of your registers (easiest places to check). We've been 95+ for ever, it feels like, and the house is 74.

Like mentioned, better windows, weather stripping, attic insulation, attic vent. Cheap fixes (except for the windows) if the unit is working right. Our new-ish one is doing well after the pita kinks got worked out. $1500 tax credit, too.

 

[Josh123]

AC is all about ΔT. A properly working AC produces a ΔT between what air temp it brings in and what it puts out. I.e. suppose it brings in air at 85F and puts out air at 65F. Thats a 20 degree ΔT. If its doing that, but your house's insulation is poor, then the air in the house doesn't stay cool, but the AC IS doing its job.

On the other hand, if its bringing in air at 85F and putting air out at 80F, then it probably has a compressor or Freon issue. You should be able to check this yourself with a simple thermometer. Just make sure you measure the air coming out of the unit as close to the discharge as possible (not including vents). HTH.

He did check this and it was bringing in 80 degree air and putting it back out at 60 degree so I guess it's something else. He said the A/C unit is probably around 10-12 years old so I've just been worried it will need replacing so I would rather it be replaced while the home warranty is active.

We usually close off two rooms and shut off the air so I figured it would cool the house. I'll stick my head up in the attic and see how the insulation looks. What exactly should I be looking for though? How think of a layer would be sufficient?

 

[Texashiker]

Consider getting a window unit and put it in a room close to the AC intake.

Is there a window (like a backdoor) in the same room as the AC intake? If so, put something over the window to keep to room cool.

 

[Sluggo]

What exactly should I be looking for though? How think of a layer would be sufficient?

Assuming blown in insulation you are going to want at least 12" more if you can afford it.

 

[mvbighead]

Without more details, it is hard to say. Here are some tips:

1. Keep the blower fan running to help circulation. That is probably what the guy adjusted.

2. If you have a two story house, close the vents on the bottom story and only open the vents on the top story that you need. For example, we have a vent in our master closet and we close it year-round.

3. See if the unit is sized properly, as others have mentioned.

4. Think about an attic fan if you don't have one. I think we're going to put one in eventually; unfortunately, there was a really good deal recently and we missed it.

What he said.

Close vents in rooms that aren't used frequently. Personally, I have closed vents near windows so that I am not cooling what is getting immediately warmed by sunlight. Let the air work through from the darker side of the house so that it gets colder where you want it (main living spaces).

Also, if it is a total pain of a hot day, mildly open a few vents in certain areas where you want the temperature neutral, but close everything else except for the room you will be staying in the most frequently. In my situation, that is my basement living room. It gets nice and cold, while other areas aren't as cold. But, at least you have one room that is comfortable.

 

[mvbighead]

One other thing is curtains. Especially black out curtains. If you don't want permanent ones up, you can find the spring based rods that are held up between the walls of a window opening. If you can reduce the amount of sunlight hitting your walls/carpets/etc., you should be able to reduce the heat build up in the house.

 

[Analog]

He did check this and it was bringing in 80 degree air and putting it back out at 60 degree so I guess it's something else. He said the A/C unit is probably around 10-12 years old so I've just been worried it will need replacing so I would rather it be replaced while the home warranty is active.

We usually close off two rooms and shut off the air so I figured it would cool the house. I'll stick my head up in the attic and see how the insulation looks. What exactly should I be looking for though? How think of a layer would be sufficient?

You've got a good AC unit if its dropping 20 degrees. The problem is something else - poor insulation, not sized appropriately for the volume of house, etc.

 

[highland145]

^^
The heat gun showed 5 degrees less on our white plantation shutters compared to the darker ones.

Do I Have Enough?
No matter what kind of insulation you currently have in your attic, one quick way to determine if you need more is to look across the span of your attic. If your insulation is just level with or below your floor joists (i.e., you can easily see your joists), you should add more. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough and adding more may not be cost-effective. It is important that the insulation be evenly distributed with no low spots; sometimes there is enough insulation in the middle of the attic and very little along the eaves. To see how to add insulation out to the eaves, see Installing Rafter Vents (on Page 4.4). If your attic insulation covers your joists and is distributed evenly, you probably have enough.
How Much Should I Add?
Insulation levels are specified by R-Value. R-Value is a measure of insulation’s ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
3.2 SEALING BASEMENT AIR LEAKS
4.1

http://www.energystar.gov/index.cfm?c=diy.diy_attic_insulation

 

[Vette73]

Also is the duct work soft or rigid?

Had a new AC unit put in one place I was renting and took over a day to drop 10degrees. The flex duct work was old and a lot of the insulation was torn. But the owner did not want to replace so we had to run the AC even more.


Change filter and clean the AC coils as well.

 

[Texashiker]

If all else fails, paint the roof of your house white.

 

[classy]

This can be one issue or multiple.

The most important and cheapest money saver is good curtains. You can add all the insulation up top in the world, but if your windows are still letting a lot of sunlight, the house will still be overly hot. Get insulated ones. Your ac at 10-12 years old is probaly getting a little long in the tooth and its probably single stage. I would invest in top notch curtains first. And for a big surprise, get yourself a big oscilating fan to constantly circulate the air. You'll be shocked at how much your home will cool off in the day and how quickly it will cool at night.
Do you have an attic fan?
And check how much humidity have in the house, big one here.
If you are running 60% or so adding a $150 cheap dehumidifier will also help a lot in cooling your home.
Be very careful about overly making the house tight. Overly tight houses will generate mold more. Contrary to popular belief, a house needs to breathe.

 

[dabuddha]

Is the blown in insulation better than those rolls/sheets?

 

[Josh123]

Also we the previous owners of the house turned the garage into an office of some sort with a laundry room attached to it. This whole part of the house doesn't have any insulation from what I can tell since it doesn't connect with the attic, anything I can do about this? It gets pretty damn hot in there because we usually have two computers going.

 

[classy]

Is the blown in insulation better than those rolls/sheets?

Generally no. But its easier to use and install. It can be put anywhere with realtive ease.

 

[dabuddha]

Generally no. But its easier to use and install. It can be put anywhere with realtive ease.

Ahh good to know. I was going to pickup more insulation for my attic and thought the rolls would be easier to lay down since they're supposed to be cut already to fit between the joists.

 

[Vette73]

Generally no. But its easier to use and install. It can be put anywhere with realtive ease.

I disagree. The paper blown in, most common, does better to sheild heat then fiberglass. That and it fills in gaps that the rolls will never get to.

I rolled in r30 in my addation and blow in another R20-30 on top of that.

I don't like all fiberglass or all blow in. They both have their pros and cons.

 

[OILFIELDTRASH]

It's been 105 in north Tx lately and my ac cools the house to 78f just fine. That's a 27f difference and I have no doubt it would cool it even further if I wanted to. I also have a Trane that's about 8 years old.

I had the same issue as you once. It was low on freon. I'd pay the extra money and have an authorized service provider work on your unit. I called out a generic ac repair place (Comfort Experts) and about a few hundred dollars later my house was still hot and they had done nothing except take my money. I looked on Trane's website and found an authorized service provider and he found it right off the bat. Comfort Experts didn't even have the correct tools to test the unit. I was out $140 and he also repaired some wiring a rabbit had chewed up.

 

[classy]

Ahh good to know. I was going to pickup more insulation for my attic and thought the rolls would be easier to lay down since they're supposed to be cut already to fit between the joists.

I spent two years on learning house energy info. Got a brand system and everything. Rolls provide better r value and don't absorb moisture like blown it, so it retains its r-value longer. Blown in is easier and quicker to install though. But its just as messy IMO.