Home A/C help.

[classy]

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.

Rolled insulation is better for r-value. And blown insulation has a tendency to shrink and settle over time faster than rolled insulation. Blown insulation is cheaper and easier to install. And as I said you can install it anywhere, unlike rolled.

http://www.atticadvice.com/best-attic-insulation.html

The R-factor is slightly better in the case of batts. While the batts have an R-value of 3.1 to 4.2 per inch (in the case of fiberglass), the blown in fiberglass has an R factor of 2.3 to 2.8 per inch. While batts will provide you with a stable, known R-value, the blown-in insulation’s R-value can vary due to the variation in thickness. So what will it be? Only you know, but make sure that you base your decision on the aforementioned factors.

 

[Vette73]

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.

No they don't. Cellouse has a higher R value per inch then fiberglass. Let alone blown in fills in much more area then the rolls do.

Cellulose manufacturers are required by federal law to provide the "settled thickness" on their bags. Some even provide the "installed thickness." So the whole "it will settle..." is BS as they already give those numbers.


http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11650

 

[Vette73]

Rolled insulation is better for r-value. And blown insulation has a tendency to shrink and settle over time faster than rolled insulation. Blown insulation is cheaper and easier to install. And as I said you can install it anywhere, unlike rolled.

http://www.atticadvice.com/best-attic-insulation.html

The R-factor is slightly better in the case of batts. While the batts have an R-value of 3.1 to 4.2 per inch (in the case of fiberglass), the blown in fiberglass has an R factor of 2.3 to 2.8 per inch. While batts will provide you with a stable, known R-value, the blown-in insulation’s R-value can vary due to the variation in thickness. So what will it be? Only you know, but make sure that you base your decision on the aforementioned factors.

not sure why you think that site is any good, it looks like shit.

The gov rates fiberglass Rolls at R2.9-3.8 per inch. Cellouse is R3.2-3.8. And again that does not take into account cellouse performs better at wild temp swing and fills in a lot of gaps rolls will never get to.

http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm?mytopic=11510

 

[BarkingGhostar]

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?

If the system was working then it wasn't broke. Hence, no fix needed. Have you considered that the unit might be under-sized, or that the correctly sized system isn't designed to cool when it is that hot out?

When my under-sized unit finally failed, I replaced it with one a little over-sized and it does the job. Of course, its not cresting 100ºF (let along 105-110ºF), and I wouldn't expect the system to take on that challenge at its current cooling capacity.

 

[classy]

not sure why you think that site is any good, it looks like shit.

The gov rates fiberglass Rolls at R2.9-3.8 per inch. Cellouse is R3.2-3.8. And again that does not take into account cellouse performs better at wild temp swing and fills in a lot of gaps rolls will never get to.

http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm?mytopic=11510

I just quoted that site, but many many are just like. Cellulose will lose its R value faster and it also is prone to mold. They both have the pros and cons. But overall, rolled insulation, is slightly better. And so many home owners pack their homes air tight from the attic top down, then have black mold growing out of control.

And ultimately insulation properly installed will trump type of insulation used.

 

[Imp]

Glad I just finished 3 grad courses on buildings science and HVAC. Bla bla bla, not professional advice below.

Your cooling load is affected my heat transmittance through the envelope, solar gain through windows, and air leakage in or out (did I miss one?). This is the total amount of heat energy getting into your house. The A/C unit's job is to take care of this load. It has a finite capacity.

You can address heat transmittance through insulation of the entire envelope. Solar gain can be taken care of with better (expensive) windows, curtains, and trees (plant some cacti?). Does anything grow that can provide some shade 24/7, without you having to remember to close the curtain? Air leakage is a bitch. Good luck sealing all the cracks.

On the other end of the equation you have your A/C. If you have an air-tight, super insulated house, you won't need a big A/C. It sounds like your A/C just isn't big enough for the job if it's cooling the house by 30F, but stuck there.

 

[Josh123]

So with the home owners insurance, I probably wouldn't be able to get it replaced with a larger unit if it's blowing cool air would I?

 

[dabuddha]

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.

What about laying down the rolls on top of the blowed in stuff?

 

[Red Squirrel]

How many square feet and how many tons is the AC? Very basic rule of thumb is 1 Ton per 500squarefeet, though for texas, I'd probably say more like 2 tons. Of course there is tons of other factors which only a heat gain calculation could tell.

I'd be thinking the problem is insulation and/or vapor barrier issues. You can have over R60 in the attic, but if there is a big hole somewhere in the vapor barrier, you are either loosing cold air, or gaining hot air (probably both, it would do a convection effect).

Things to check for is chimney chases and other wall cavities that go from the basement to the attic. Since it's probably super hot in the attic, and heat rises, chances are it would be drawing in cool air through this hole if it's not properly sealed, which causes a vacuum in the house which means hot air is entering somewhere.

You'd almost have to get an airtight test done on your house to find any leaks, and go from there.

 

[highland145]

So with the home owners insurance, I probably wouldn't be able to get it replaced with a larger unit if it's blowing cool air would I?

That would be a no. Don't think it's the unit. Think it's the lack of insulation. Update on the insulation?

The added space doesn't have an access? Might have to make one if you want to know if it's insulated or not.

 

[Imp]

So with the home owners insurance, I probably wouldn't be able to get it replaced with a larger unit if it's blowing cool air would I?

Technically it is working (get an HVAC guy to actually verify that for you). However, if it really is undersized and you didn't change anything (cut any trees down, rip out any insulation, screw with the windows?), then the designer/builder screwed up and put in an inadequate system (unless your temperatures are really outside the average or what they used in their design).

How old/new is your house?

If electricity is dirt cheap, you can add a window unit (band-aid). These things to work together. Long-term, taking care of the insulation would probably save you quite a bit. Depends on hwo long you plan on hanging around.

 

[classy]

What about laying down the rolls on top of the blowed in stuff?

I don't know. I know the one contractor who has done this for about 30 years, said he thinks a person should stick with whatever is in the attic to begin with.

 

[Imp]

You say you have a home "warranty". Is that from the original builder?

 

[Vette73]

What about laying down the rolls on top of the blowed in stuff?

I would not do that as fiberglass is not as good as cellouse in that term. I like fiberglass batts when framing but blow in cellouse over that to add to the final R and also fill in all the gaps. Rolls don't do that.

That and buy 20 or more packages and Lowes/HD will let you use the machine for free.

 

[squirrel dog]

what size is your house,in sq ft. What size is your ac,in tons? My 2400 sq ft house has a 5 ton rudd unit that works great in S.Louisiana.

 

[Josh123]

I'm not quite sure what the sq ft of the house is off the top of my head but I can find out tonight. I'm not sure about the ac unit either.

 

[piasabird]

What about vapor barier. This is one thing they are always talking about on the home builder shows. Also they are all using the insulation that is foam like that is sprayed on and it expands. Roof vents sometimes help also.

I had an issue with my heater/air unit in the winter and sometimes if you use the wrong kind of air filter is slows down the air pressure. Hepa filters sometimes can slow down the blower till the heater shuts off from the Air Limit Switch. Hepa Filters can lower your air pressure pushing out toward your vents.

 

[bruceb]

Since your unit is very old, you may consider a replacement. Also, have a qualified tech do an air leakage test. You would be surprised at how much of the air CFM never makes it to all the duct outlets. Also, the unit may need just a few more ounces of freon to make it cool better. Generally, if there is a long line set between the outside unit and the inside evaporator, you add extra to compensate for the line length. Also, the condenser or evaporator coil fins may be plugged with years of dirt and as such will not properly cool. And check your systems air filter.

 

[BoomerD]

What about windows?

Single pane windows, or cheap, crappy double pane windows are a major source of heat intrusion.
Our house was built in 1997, but the contractor used cheap aluminum-framed double-pane windows. Within a few years, many of them had lost the "seal" between the panes, and were not much better than single pane windows.
We replaced all the windows in the house with Simonton vinyl windows and the comfort level in the house improved dramatically.

Before, if you stood in front of a window in the summer, it was like standing in front of a blast furnace with the doors open...in the winter, like standing in front of one of the big freezer cases in the grocery store...
Now, no noticeable difference in temperature in front of the windows...plus, they have a mild tint, so it's like having sun glasses on the house...
While I'll probably never recoup the cost of the windows in energy savings, the added comfort is worth it to us.

A nice side-benefit is that the house is now MUCH quieter. I don't hear nearly as much outside noise as before. GOOD windows are also good insulation.

 

[Josh123]

What about windows?

Single pane windows, or cheap, crappy double pane windows are a major source of heat intrusion.
Our house was built in 1997, but the contractor used cheap aluminum-framed double-pane windows. Within a few years, many of them had lost the "seal" between the panes, and were not much better than single pane windows.
We replaced all the windows in the house with Simonton vinyl windows and the comfort level in the house improved dramatically.

Before, if you stood in front of a window in the summer, it was like standing in front of a blast furnace with the doors open...in the winter, like standing in front of one of the big freezer cases in the grocery store...
Now, no noticeable difference in temperature in front of the windows...plus, they have a mild tint, so it's like having sun glasses on the house...
While I'll probably never recoup the cost of the windows in energy savings, the added comfort is worth it to us.

A nice side-benefit is that the house is now MUCH quieter. I don't hear nearly as much outside noise as before. GOOD windows are also good insulation.

I would like to totally redo all of our windows since they are crappy double pane ones. I know how expensive a project like that can be so it won't be anytime soon I'm afraid.

 

[BoomerD]

I would like to totally redo all of our windows since they are crappy double pane ones. I know how expensive a project like that can be so it won't be anytime soon I'm afraid.

Ours ran us about $10K. Nowadays, the local utility companies offer decent rebates...and the tax credits for new windows has been MUCH better than when we put ours in the house.