Another Air Conditioning thread - thouoghts/ideas?

[RagingBITCH]

Alright so little background: bought my current house 4.5 years ago. 1500sq ft house. Air compressor unit outside is a 3 ton about 8 years old. Inside, have a gas powered air handler/furnace. Have a Honeywell electric thermostat - installed 3.5 years ago. Air handler was replaced before I bought the house. (Uses 14x25 air filter - those are changed on a regular basis once per month)

I'd say it had never truly cooled as much as I'd like over the 4.5 years, especially in the TX heat. (105-110 is norm last summer) Last year, I could set it at 80 and it would run non-stop - the thermostat (at the hottest point of the day) would show 84-86 just because it wasn't cooling enough. (IE, it didn't matter what temp I set it at, it wouldn't get to that point) It was recharged with freon but that didn't seem to help. I had a guy come out who took the temperature at the return and said freon pressure looked fine and temperature coming back was fine. (He was a friend of a friend - didn't bother looking at the unit outside or the air handler inside)

This year - had blown in insulation installed, up to a R-49 now. (Previously only had a paltry 5", apparently) Also had additional soffit vents installed and the old ones cleaned out. (Have 3 whirlybirds up top) I cleaned/sprayed down the compressor/fins with water and cleaned out any leaves.

So far it's helped some but it's just not cooling/holding temperature. Last weekend was 105 - I had it set at 79 and it was still running non-stop...it was barely holding 79. (At one point thermostat showed 80 degrees inside for about 15 minutes - this was at about 6PM) I'm looking/fixing to call a few AC companies, but wanted ATOT's general opinion/concensus about what the issue is before I go that route.

Wanted to go with an AC tune-up - hoping during the checks that they find whatever the issue is. That being said - anything else I can check before I actually call them? Any no brainer, easy fixes that I'm just completely overlooking in my own stupidity? Thanks 🙂

- Mel

 

[SpatiallyAware]

3 ton should be plenty for 1500sq/ft. Is this a single level? Crawlspace or slab?

Check all of your ductwork for leaks.. use a stick with tissue paper taped to the end to run across seams and reseal with mastic and metal backed duct tape (NOT the grey stuff)


Have you had it recharged? I've found that a recharge is required every 4-5 years even if there isn't a measurable leak in the system.

You might try to find a good a/c guy (through a referral) to come out and take a look.

 

[AMDMaddness]

I find most 3-ton units inadequate in such high heat areas and your sq ft. Get a 5 ton and a bigger air handler and be done with it... throwing money at a problem that will never get better with any amount of tune ups is a waste. In the end you are never going to be happy unless you upgrade your units.

Some three ton units I'm sure could keep up but I think a great deal are overrated and are more like 2-2.5.

 

[alkemyst]

I find most 3-ton units inadequate in such high heat areas and your sq ft. Get a 5 ton and a bigger air handler and be done with it... throwing money at a problem that will never get better with any amount of tune ups is a waste. In the end you are never going to be happy unless you upgrade your units.

Some three ton units I'm sure could keep up but I think a great deal are overrated and are more like 2-2.5.

Too large an a/c is also a problem.

What one wants is a true heat calculation on their home (I forget the trade name for it). It factors in exposure, windows, roof type/material/color, insulation, etc.

 

[AMDMaddness]

Too large an a/c is also a problem.

What one wants is a true heat calculation on their home (I forget the trade name for it). It factors in exposure, windows, roof type/material/color, insulation, etc.

True.. but in Texas and what he describes.... A to large of an HVAC will not run long enough to remove the humidity and cause a cold damp stinky situation. Of course he may have other factors on his house that is causing issues but in the end a larger HVAC system is what may "cure" the problem.

 

[alkemyst]

True.. but in Texas and what he describes.... A to large of an HVAC will not run long enough to remove the humidity and cause a cold damp stinky situation. Of course he may have other factors on his house that is causing issues but in the end a larger HVAC system is what may "cure" the problem.

Not sure what you are trying to say here, most don't want to take a $6000+ gamble.

Get a heat calculation done and you will know what A/C you need.

 

[Kwatt]

When was the last time the condenser and evaporator was cleaned with a cleanser? A good foaming cleanser.
Get 2 good thermometers place one in the return air and one in a vent close the the unit. Temp difference should be ~20 degrees F. Check this several times during a hot day.

If your condenser is dirty it can cause the compresser internal overloads to shutdown the compresser even though everything appears to be running. The inside fan and the outside fan will both still be running. This can also be caused by adding freon to the system because it appears to be low caused by the evap being dirty or blocked, the filter is dirty, or the evap fan is not moving enough air.

If you have closed any doors or vents try opening them your evap may be starved for air.

My house is a 1465 sq. ft. red brick with no shade it can keep 74 degrees F all summer here in GA. Except for the 3-4 weeks in the hottest part of summer. In those 3-4 weeks it can stay about 78F. The compressor will run all day long those weeks and the power bill will be impressive. This is expected to be one of those weeks. 7 days in a row over 100F!



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[RagingBITCH]

Thanks for the replies back! To answer a few questions:

Single story, slab. Ductwork looks fine - was up there a month ago doing a sweep of the ducts and didn't see/feel any issues, although, I didn't check the one corner of the house. Might be something to look at tomorrow to make sure. The home inspection report (upon re-reviewing it this year) did mention redoing a few pieces of the ductwork to reduce the length for better airflow, but it was only a few of the duct pieces.

Recharge - that just refilling the freon, if low? I had that done last year, unless it's a different thing.

For the larger unit - trying to avoid that, as I only plan on being there another year before selling 🙁 True on the points that it might be underrated - the avg/general rule of thumb of course is 1 ton for every 500 sq ft, so in theory it's perfect, but the house does have vaulted ceilings in living/bedroom. (Some low insulation in those areas due to the clearance on the vaulted side on the outer area)

Roof was replaced 7 years ago, dark colored tiles, about half the windows were replaced when I moved in. (Although I doubt it's energy efficient ones)

The AC unit is on the west side of the house though, so the compressor/outside unit gets hit with the sun at the hottest part of the day - will getting the little fenced in type cover (going around the unit but not over it, of course) to reduce direct sun exposure help at all?

 

[SlitheryDee]

Perhaps you could supplement the a/c with a couple of window units. Get one large enough to cool one or two rooms, shut the central air vents off in those rooms and then the central air may be powerful enough to sufficiently cool the rest of the house.

Oh and I love my a/c and house insulation. I can keep it 66 degrees on a 100+ day with the central air cycling on and off regularly. My electric bills are manageable too. I'll never buy an under powered a/c from now on. I have a 5 ton with an oversized blower on it.

 

[RagingBITCH]

When was the last time the condenser and evaporator was cleaned with a cleanser? A good foaming cleanser.
Get 2 good thermometers place one in the return air and one in a vent close the the unit. Temp difference should be ~20 degrees F. Check this several times during a hot day.

If your condenser is dirty it can cause the compresser internal overloads to shutdown the compresser even though everything appears to be running. The inside fan and the outside fan will both still be running. This can also be caused by adding freon to the system because it appears to be low caused by the evap being dirty or blocked, the filter is dirty, or the evap fan is not moving enough air.

If you have closed any doors or vents try opening them your evap may be starved for air.

My house is a 1465 sq. ft. red brick with no shade it can keep 74 degrees F all summer here in GA. Except for the 3-4 weeks in the hottest part of summer. In those 3-4 weeks it can stay about 78F. The compressor will run all day long those weeks and the power bill will be impressive. This is expected to be one of those weeks. 7 days in a row over 100F!

Hey Kwatt - not since I moved in. (The actual cleaning) I've hosed it down with straight water last year and a month ago. I actually went to Home Depot today and bought some cleanser at lunch - will give it a thorough cleaning (or two) tomorrow morning. Everything I had previously read said a water dousing would suffice...the foam cleanser should help?

For closed vents/doors - all are open including the ones in the bathroom. Anything in particular I should check for in the air handler? I'll take 74-78 anyday over, well, 80+ 🙁 Thanks!

 

[mvbighead]

Kind of a simple suggestion, but simple curtains such as black out ones can help a good deal with heat as well.

My guess is you've already taken care of it, but figure if you aren't keeping the sunlight out in general, it's going to be even more difficult to get the temp down.

 

[Kwatt]

Hey Kwatt - not since I moved in. (The actual cleaning) I've hosed it down with straight water last year and a month ago. I actually went to Home Depot today and bought some cleanser at lunch - will give it a thorough cleaning (or two) tomorrow morning. Everything I had previously read said a water dousing would suffice...the foam cleanser should help?

For closed vents/doors - all are open including the ones in the bathroom. Anything in particular I should check for in the air handler? I'll take 74-78 anyday over, well, 80+ 🙁 Thanks!

I don't believe plain water does a good job simply going by the way it looks after using a good cleaner. I have hosed them off before and then used the cleanser and it sure looked cleaner. It will shine after the cleaner.

When I did this work. And went on a call and everything was running it got cleaned before we did anything. We did not even hook up gauges before we cleaned it. If you don't have proper airflow across the condenser and evaporator you can never get an AC working just right.



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[woodie1]

I have to agree with the "3 ton unit isn't big enough" opinions.

I live in South TX where we get 100+ all the time. House is 7 yo 1353 sq. ft. ranch with double pane glass and a 3.5 ton unit. Once the outside reaches over 95F my system begins to run longer (as it should) and is off for fewer minutes. By 4PM it will run continuous for up to an hour and will only be off for 10 minutes before coming on again. I set the thermostat at 79F when it is this hot.

I suggest you consider installing a window unit somewhere to augment your central unit when it cannot keep things cooled properly.

 

[rsutoratosu]

I live in ny and i have a 5 ton for 1300 sq ft , you guys should be getting like 10 ton 🙂 make it feel like north pole

 

[BUTCH1]

As others have mentioned, the evap coil might be due for a good cleaning, Lowes and HD now carry coil cleaner products, I do mine once a year at the start of the season (FL). If you do that and still have problems consider getting a window shaker, around 8K BTU. I know it's not the proper solution (bigger unit) but will get you by in the meantime..

 

[lxskllr]

Plant oak trees to shade the roof. That won't help now, but once the trees are mature, it'll make a huge difference keep the house cool. Also, install ceiling fans.

 

[CPA]

Thanks for the replies back! To answer a few questions:

Single story, slab. Ductwork looks fine - was up there a month ago doing a sweep of the ducts and didn't see/feel any issues, although, I didn't check the one corner of the house. Might be something to look at tomorrow to make sure. The home inspection report (upon re-reviewing it this year) did mention redoing a few pieces of the ductwork to reduce the length for better airflow, but it was only a few of the duct pieces.

Recharge - that just refilling the freon, if low? I had that done last year, unless it's a different thing.

For the larger unit - trying to avoid that, as I only plan on being there another year before selling 🙁 True on the points that it might be underrated - the avg/general rule of thumb of course is 1 ton for every 500 sq ft, so in theory it's perfect, but the house does have vaulted ceilings in living/bedroom. (Some low insulation in those areas due to the clearance on the vaulted side on the outer area)

Roof was replaced 7 years ago, dark colored tiles, about half the windows were replaced when I moved in. (Although I doubt it's energy efficient ones)

The AC unit is on the west side of the house though, so the compressor/outside unit gets hit with the sun at the hottest part of the day - will getting the little fenced in type cover (going around the unit but not over it, of course) to reduce direct sun exposure help at all?

You may have good insulation but do you have good airflow in your attic? If hot air can't escape then it could be effecting the temps in your home.

do some rooms get cooler than others. If so, do you have dampers you could adjust?

Sun exposure on the compressor should have no effect.

I had an AC guy replace my capacitor. He also had to put in about 4 pounds of freon, indicating I have a small leak somewhere. I asked him about the temps in the home and he said basic rule of thumb is that an efficient AC system will get the inside air about 20 degrees cooler than the outside (this is the second AC guy that has told me this, though I'm still skeptical), so it's not out of the realm of possibility that your AC is working like it should but it just can't keep up with the heat.

 

[RagingBITCH]

Thanks for the recommendations guys! Looks like I'll be using condenser cleaner (commercial, foam) on both the inside and outside coils. The inside hasn't been cleaned since the air handler was installed before I bought the house. Will provide some feedback tomorrow - hoping that's the case. Otherwise, I'll have to live with it.

For the guy who asked about the blackout curtains - have those in the living room and one of my other rooms. Thanks!

 

[Mxylplyx]

If your house can hold 79 on a 105F day, I'd say you are doing OK.

 

[Red Squirrel]

I live in ny and i have a 5 ton for 1300 sq ft , you guys should be getting like 10 ton 🙂 make it feel like north pole

Haha yeah if I lived in a place like Texas I'd probably get N+1 redundant units even. 5 ton per 1000 square foot of floor surface (including basement) would be a decent rule to go by. While they do say it does not run long enough to remove the humidity, it sure will run long enough if you set the thermostat to like 18C. 😀

 

[KK]

I just had a new unit stuck in our house yesterday. It has a two stage compressor where the one stage is a cooling stage and the other stage is i guess to keep the humidity down. I know with the larger units, like mentioned above, they won't remove the humidity, but I wonder now with the 2 stage units, if that would be a problem anymore.

 

[MtnMan]

Too large an a/c is also a problem.

What one wants is a true heat calculation on their home (I forget the trade name for it). It factors in exposure, windows, roof type/material/color, insulation, etc.

:thumbsup: Neighbor installed a unit the size of a Buick (a 1953 Roadmaster) and gripes about their power bill. We can hear theirs run, and it runs in short spurts, which means it can't dehumidify correctly.

Mine is an old system, installed as an add-on to a forced air oil furnace, and it runs for hours and hours at a time, yet even when we have a really hot month, the power bill is only about a $100 above normal, and this is cooling a 3200 sq/ft house build in the 60's.

 

[Kwatt]

Thanks for the recommendations guys! Looks like I'll be using condenser cleaner (commercial, foam) on both the inside and outside coils. The inside hasn't been cleaned since the air handler was installed before I bought the house. Will provide some feedback tomorrow - hoping that's the case. Otherwise, I'll have to live with it.

For the guy who asked about the blackout curtains - have those in the living room and one of my other rooms. Thanks!

Don't use a condenser cleaner on your evaporator! It would be best (easiest) to use a no rinse cleaner on the evaporator. The condenser cleaner will produce odor. You can use a evaporator cleaner on the condenser.
Your evaporator may be in the attic, take care. The evaporator fan blades may be dirty cleaning them will help.


Post back with the results.


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[dawks]

Yea shading the condenser/compressor is a good idea. Its trying to remove heat. So letting it cook in sun isn't going to help.

Also I dont think black curtains are the best idea since black absorbs light.. thick white ones reflect some back heat/light.

Technically you're best bet for windows is a white shutter of some sort on the outside, since once the light has passed through the glass, even if its reflected back by curtains, the heat is on the wrong side of the glass.

 

[BUTCH1]

You may have good insulation but do you have good airflow in your attic? If hot air can't escape then it could be effecting the temps in your home.

do some rooms get cooler than others. If so, do you have dampers you could adjust?

Sun exposure on the compressor should have no effect.

I had an AC guy replace my capacitor. He also had to put in about 4 pounds of freon, indicating I have a small leak somewhere. I asked him about the temps in the home and he said basic rule of thumb is that an efficient AC system will get the inside air about 20 degrees cooler than the outside (this is the second AC guy that has told me this, though I'm still skeptical), so it's not out of the realm of possibility that your AC is working like it should but it just can't keep up with the heat.

I've been told 18-20 by two service people..