a/c can't keep up in the heat of the day (Mart: fit in, new home)

[oldtoiletsmkgdflrpots]

Originally Posted by janejanejanejanejane

Did you notice a difference in your electric bill when you switched units?

Yes, it was lower.

[CptnRn]

Originally Posted by oldtoiletsmkgdflrpots

What do people turn their thermostats to at night? Ideally I'd like it to be about 60 some or colder but I don't run the air that long. At night it is set at 72. Anything above that is toooooo hot. Love the air conditioner we have now. (probably about three years old now)

74 at night with ceiling fan on low. 77-78 during the day, with a fan blowing.

[janineg]

76 day and night, with ceiling fans on, but I'll get it up to 78 once we're more acclimated. 76 is very comfortable.

[CptnRn]

Originally Posted by janejanejanejanejane

Air vents blow 65/66...this time of day (4pm-6pm) a/c can't get below 78/79. Have high ceilings in almost every room. I am comfortable under a fan, comfortable in general, so that's why I am frustrated. Unit is 11 years old, but our other newer unit can't get much lower either, maybe 77 in heat of day.
I just called my a/c guy and asked if it should be serviced to make it cool better and he said that won't really help that and that 65/66 out of vent is ok this time of day. I dunno...

I just thought of another possibility. Have your HVAC guy check the coils to make sure they are clean. If you do not use a very high quality air filter and change it regularly, lint, hairs and dust can build up on the coils restricting the airflow through the coils. I discovered this in the first house we owned, after 15 years or so when we had arranged to have the HVAC system replaced, there was a 1/8" +/- mat of lint, hair and dust covering the coils. After that I always used high quality air filters and changed them regularly. I have an event on my computer calendar which reminds me to change the filters regularly.

[janejanejanejanejane]

I change them regularly. Did you not change your cheaper filter regularly? I have been told a few times to use the thinner, cheaper filters because otherwise it makes the a/c work harder. I also have a reminder to change ours every few months.

[10scoachrick]

Originally Posted by janejanejanejanejane

I change them regularly. Did you not change your cheaper filter regularly? I have been told a few times to use the thinner, cheaper filters because otherwise it makes the a/c work harder. I also have a reminder to change ours every few months.

Can't go too cheap with the filters...the really bad ones don't actually filter anything except hunks of stuff. An inexpensive pleated filter that has a bit of 'fluff' instead of just a thin single layer is likely the way to go for cheaper filters. IF the system is capable enough, the more restrictive filters don't hurt a thing...in fact, they should do what they are designed to do...filter smaller particulates. A blower system that is already struggling is going to be hurt by a more restrictive filter(s).

The renewal cycle is based more on hours used vs calendar time. I go once a month or so during heavy-use season like June-Sept and less often during months that don't require the use of the system for A/C OR heat. That also changes if you use your fan only setting for circulation...the more air that moves through the system, the more often the filters need to be changed.

[DashRiprock]

I've had to replace three A/C units in my lifetime, and every time I've gone either 1/2 or 1 ton more than the "load test" recommended. I don't think the engineers who design those things understand Texas heat.

The units I replaced all did the same as yours - they would work but could never get the house below 77/78 (on a good day, sometimes it wouldn't budge below 80) no matter how long it ran, even after cleaning the coils, replacing freon, sealing ducts, etc. I know my insulation wasn't the best, but insulation never is. When it came time to replace, I had them upsize the whole unit and it made a world of difference. It's like maintaining the right air pressure on your tires - yeah, you need to do that to get the optimum performance, but if all you've got is a 75 HP engine, you're still going to struggle to get over that hill.

Bottom line is that Texas is hot, for long stretches of time, and engineers in Syracuse don't understand that.

[CptnRn]

Originally Posted by janejanejanejanejane

I change them regularly. Did you not change your cheaper filter regularly? I have been told a few times to use the thinner, cheaper filters because otherwise it makes the a/c work harder. I also have a reminder to change ours every few months.

Yes I replaced them regularly, but the thin cheap filters proved inadequate. The last two times when I replaced the HVAC units (2 different houses) I asked the installer to size the unit adequately for high efficiency filters. That helps allergens from the air also, very important around Austin.

[Trainwreck20]

Originally Posted by DashRiprock

I've had to replace three A/C units in my lifetime, and every time I've gone either 1/2 or 1 ton more than the "load test" recommended.

My neighbor recently (3 months ago?) had her AC unit replaced. The guy who did the replacement recommended reducing the size of the unit from a 5 ton to a 4 ton. He explained that the over-sized units can actually cool a house down too quickly w/o circulating enough air and it results in the humidity not being lowered enough and the unit not running enough. It is hard to compare before and after, since she increased the SEER (the old unit was 15 years old), but the new unit is operating fabulously. The AC man explained that some developers ended up only putting in one (or two) size units for all their homes in a project and don't fit properly on a house-by-house basis.

[10scoachrick]

Originally Posted by Trainwreck20

My neighbor recently (3 months ago?) had her AC unit replaced. The guy who did the replacement recommended reducing the size of the unit from a 5 ton to a 4 ton. He explained that the over-sized units can actually cool a house down too quickly w/o circulating enough air and it results in the humidity not being lowered enough and the unit not running enough. It is hard to compare before and after, since she increased the SEER (the old unit was 15 years old), but the new unit is operating fabulously. The AC man explained that some developers ended up only putting in one (or two) size units for all their homes in a project and don't fit properly on a house-by-house basis.

Ain't THAT the truth! Our townhouse complex ranges in size from 1600sq ft to 2300 and all were spec'd with the same unit(fine for the smaller townhomes, not so fine for the two larger sizes)