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Discussion Starter #1 (Edited)
I just had a new Carrier 16 seer 3 ton condenser and a 2 stage Air handler installed in my 1600sq ft house in South Texas. Its been installed for a week or so, and I don't think its working as well as my 20 year old system before it went bad. I think I paid too much, and now when its 104 degrees out at 5 pm and 77 inside, I turned it down to 67. Two hours later at 7pm and 102 out it has cooled to 75. My old one would cool a few degrees in an hour when it was 110 out. The tech tried to tell me that 20 degree thing, but that's BS. Is this ridiculous for it to be only cooling that little?

Humidity percent is surprisingly in the low 20's right now

I'm about ready to hire someone who can use thermal cameras and such and see if I have some sort of leak that showed up suddenly and not slowly. Is there a way for me to test the "efficiency of how its working"?
 

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If you have a thermometer check the return air temperature at the plenum if possible and the supply air temperature at the closest register to the unit.



This is more of that 20° thing.:smile:




A -- insta read -- digital thermometer is quick and handy but i've used cumbersome thermometers too.




Edit: Edit:
 

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At around 50% indoor humidity you should see a 17 to 22F temperature drop across the air handler. If you want to be more accurate, can measure something called return air wetbulb in addition to drybulb (normal temperature) and determine what the supply temperature should actually be using a chart.

It's possible your unit isn't properly charged and or they never wired up the second stage and it's running on low.

Was the old unit a 3 ton?

Normally a correctly sized unit won't be able to pull the temp down much at 110f outside, but if you kept the size the same, something's wrong. New units of the same tonnage tend to have the slightly lower capacity, but the difference shouldn't be dramatic.
 

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A properly sized ac will lose ground, a few degrees on the warmest day expected. They are sized to big enough for 98% of the time. That means that they will usually be catching up at night. For these heat waves, you shouldn't turn off your ac, and inside leave it running day and night. If it keeps up then it's working as expected.

As user mentioned, there very well could be real problems. Measure the temp as mentioned above. Model numbers will help us be more specific.

Cheers!
 

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I'm about ready to hire someone who can use thermal cameras and such and see if I have some sort of leak that showed up suddenly and not slowly. Is there a way for me to test the "efficiency of how its working"?
Why? It's pretty clear that the problem is with the new unit.
Did you replace the old unit with one of the same capacity? Or did the salesman tell you that you needed a differently sized unit?
And why did you replace a working unit in the middle of summer?
 

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The tech tried to tell me that 20 degree thing, but that's BS. Is this ridiculous for it to be only cooling that little?

/QUOTE]

The "20 deg. thing" is relevant to indoor temperature only.
Cooling relys on the difference between supply and return air.
Yes, outside air does affect the operation of the equipment.
But for the most part if you are getting a 20 deg. difference between the supply and return then the equipment is most likely performing as well as it can.
Perhaps the issue is in blower speed, filtering or some other change made during the installation.
 

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A properly sized ac will lose ground, a few degrees on the warmest day expected. They are sized to big enough for 98% of the time. !
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In TX this is the very best way to only be required to host 1 hot summer evening party with 8 or 10 guests. By the time the guests begin to arrive it's 80°F in the house and within an hour its 83 or 84 degrees. But that's ok because half of the guests have already departed and things are looking up for the remaining drunks that could tolerate the heat.:vs_laugh:
 

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But for the most part if you are getting a 20 deg. difference between the supply and return then the equipment is most likely performing as well as it can.
It's just a preliminary test.

There can be problems despite having a normal drop. (like using first stage only or a combo of low airflow and refrigerant charge issue - the low airflow can cover things up)

I would look further despite having a normal temp drop.
 

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Discussion Starter #10
When he first installed it, he put the air handler on medium, then put it up to med/high after I said it was blowing weak. He didn't seem to be too familiar with it.
 

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Is there a way for me to test the "efficiency of how its working"?
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That Delta T test is the least expensive and best efficiency test you as a home owner will ever do. If you are unable to check the return temperature at the plenum at least use room temperature for a starting point.


If the D T is way off then we might begin looking for a dis-connected or partially dis- connected return duct in the attic if that's where return ducting is. A 6 or 8 inch return sucking 130° attic air will change efficiency in a heartbeat and you'll see it on the D T test.






Edit: Edit:
 

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When he first installed it, he put the air handler on medium, then put it up to med/high after I said it was blowing weak. He didn't seem to be too familiar with it.
The real cost of having HVAC equipment is not the cost of the equipment.....it's living with the result of the company that installed it.
The best company can make even the cheapest equipment work well and do what it is supposed to do.
A poor company can give you a miserable experience for the life of even the best equipment.
 

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Single stage a/c with basic 3 ton ecm air handler.

The fan needs to be on high.

Can't find a install manual right now - installer needs to verify proper airflow, temp drop, refrigerant charge using correct method.

One other thing you can do is measure the suction line temperature - large insulated pipe going to the outdoor unit. It should be below 60F, ideally in the 50s at normal airflow and typical return air temp.
 

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Discussion Starter #15
supposed to be single stage AC, with dual stage blower which allows for humidity control.

I saw when he changed the setting and said it was med to med/high, I know I need to just turn it off, turn off the disconnect and open the panel. I need to find a manual or something on it before I do that so I know which setting it needs to be on for it to be on high. I think the tech thought it should be on the lower setting so the dual blower could kick on higher. Could I guess he had that backwards, and I need it on high, and the dual stage would be lower?
 

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Out of curiosity, does the fan run 24/7 at a reduced speed?
I'm not saying this will solve your problems but it may help keep the temperature and humidity equalized.
 

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The blower has like 5 speeds.

The air handler may be capable of staging the blower and if it wasn't set up or wired correctly, it may be running on a lower speed.

Could also be designed to only use 1-speed tap .
i can't tell, i found the install manual but it has very little info and no schematic.
 

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Discussion Starter #19
The old system the fan would run 24/7. This new one does not. When the temp and humidity are where they should be at, its not running. I haven't bothered to notice when the humidity is far off.

I don't think the thermostat is dual stage, but the thermostat does have humidity control on it. Its an ecobee 5th gen. Its been keeping the humidity right at that percentage very well. The weather over 100 with humidity being in the 90s one day and in the 20s today, over the last week. I have it set at 50%, and its been keeping it right there.
 

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without being there to check it, hard to tell u how it was set up. Talk to the installer.

The dehumidify mode may not even slow the fan down, could just be set up to over-cool.

Do you realize you are talking to a homeowner?
Try helping instead of confusing him.
Yup - a previous post describes exactly what the suction line is. :)
alternatively, just feel the pipe and see if it's cold - that works too.
 
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