Everything in your home is a heat load. From people to furniture and curtains to flooring, everything absorbs heat. If your home heated up while the unit was being installed, your a/c has to work not just to remove heat from your home, but from every object inside of it as well. There‘s really no good answer for this. The more heat in your home and the more ”heat loads” you have in your home, the longer your system will need to remove it.

If you haven't had the AC running for a couple of days then what you're seeing is about right. If the AC has been running and the house hasn't warmed up too much, then a correctly sized AC should reduce temperatures about 1 degree per hour or a little faster.

The rate of cooling is affected by a number of factors so a rule of thumb like one degree/hr. will have limitations.

One of the biggest factors affecting the rate of cooling is the outdoor air temperature. If it's 98 F outdoors it will take longer to cool to 77 F indoor conditions than if it were 80 F outdoors. The quality of the insulation and air sealing of your home will affect the cooling rate, too. The heat stored in furniture and construction materials will affect it as Andrew noted above. Finally, the size of the air conditioner will affect the cooling rate. Faster is not always better. Equipment which is properly sized will have longer run times than oversized units and will remove more moisture during the cooling process. That reduces indoor relative humidity and improves occupant comfort.

The installation was done around 1:30 and I had set it at 77 (started at 82). It’s been about 3 hours and it’s currently at 80. Is that normal? Usually how long does a newly installed AC take to cool to desired temperature? Thank you

So the installation was done at 1:30 pm then 3 hours later 4:30pm --- so you're talking of times of the day with the most heat outside. (Heat of the day) --- it's really hot in many places right now with record temps. Those outdoor temps are what create the heat to begin with.

Everything posted above from previous commenters counts as well.

Typically with this question I often say you may have to wait until the sun goes down so the system has a chance to catch up. That is of course assuming the installation was performed properly --- that said you have to give it at least several days before you'll be able to determine it.

To get an idea without waiting..... take a temp drop reading with a thermometer.

With the HVAC system running get your indoor temp by the thermostat or take a temp reading at the filter grill where your system filter is. Then once you have that temp, take another one from a supply vent.

Return temp minus Supply temp = temp drop.

This number should be 15F to 20F degrees. I like to see 20F temp drop for my climate.

I service the Katy, Texas area.

Hold on to your ten-gallon hat, pardner....

Temperature differential is certainly a way to assess the performance of an air conditioner, and a 20 F differential would be a good target, but it doesn't tell you whether the air conditioner is properly sized for the application. I think that's the heart of the OP's question.

Once a steady state condition is achieved (which might take a day or so) the performance of the system is assessed by comparing its ability to maintain the desired indoor temperature and relative humidity at outdoor design conditions. Outdoor design conditions are being exceeded in many areas of the county at the moment.

You question is difficult to answer without additional information.

1. What was the outdoor temperature at 1:30 when you first turned on the AC?
2. Is your townhouse fully detached?
3. What was the size of your old AC and were there occasions when your tried to lower temperature under similar conditions?

The fact the AC is newly installed does not mean it is in the break in period and will continue to perform better as time goes on. This is how the AC will perform. It could be the case it has been installed incorrectly and changes are required in order to improve the performance. My thinking is something is not right and you should monitor this for the next several days. Measuring the supply and return temperatures is an easy way to start the troubleshooting process.

@485reno

After only three hours of operation it's a little soon to conclude there's a problem with a newly installed system. Please give it 24 hours before making an assessment. If it doesn't hold the setpoint temperature and the outdoor conditions are within the design range, give the installing contractor a call. Troubleshooting the system is their problem, not yours.

Hold on to your ten-gallon hat, pardner....

Charles you're reading things that aren't there again. (Sized properly from a forum board?)

Getting a temp drop is an easy way to 'get an idea' of how well / not so well an AC is performing.

Is it the end all be all test?

UH NO.

That is why you call the old pro in Katy, Texas.

Any updates on how long and the time when the temperature reached 77 degrees and the AC shut off?

"To get an idea without waiting..... take a temp drop reading with a thermometer."

Ray,

measuring the temperature differential across the coil can give a good assessment of the performance of the equipment, but it isn't a reliable predicter of the cooling rate for the living area nor whether the system will be able to meet the cooling need. That depends on the equipment sizing and the outdoor conditions. By way of example, if you have a 1.5 ton system and the cooling load is 3 tons, the temperature differential across the coil can be 20F, but it won't be able to cool the space if outdoor temperature is at the high end of the design range.

but it isn't a reliable predicter of the cooling rate for the living area nor whether the system will be able to meet the cooling need.

That is why you hire someone known for fixing and installing things properly.

I am not an order barker. I handle it all in person.

For 28 years in Katy, Texas.