2.5 Ton vs 3.0 Ton

[Mary9921]

I have a 1100 square foot house(excluding the garage).
We currently have a 2.5 ton unit. We are looking to replace our current unit which was installed in 1994 due to not cooling when it's 100 degrees outside.
Contracters are differing on 2.5 and 3. units. Does it really matter?

[gregp]

it could matter. How often does it get 100 degrees in your area? If the system is oversized, it may not de-humidify properly. The important thing is not to size a system based on a few days of higher then normal temperatures.

[precision hvac]

Yes it does.

[Mary9921]

I live in Miami, Florida

[MM#7]

I have a 1100 square foot house(excluding the garage).
We currently have a 2.5 ton unit. We are looking to replace our current unit which was installed in 1994 due to not cooling when it's 100 degrees outside.
Contracters are differing on 2.5 and 3. units. Does it really matter?

curious, on those 100 degree days, what temp, do you think the unit should get to, that would make you comfortable/happy? and on those 100 degree days what does your current system reach with the 2.5 ton unit?

[udarrell]

Miami, FL, 2.5% summer design 90-F dry bulb, 77-F wet bulb 56% relative humidity.
That figures to be a high 120.69 grs moisture per lb of air.

In that humid climate, a Home Energy Audit should be performed with a blower door test.
After any retrofit work, a manual J ought to be performed.
With that high a humidity, the Infiltration Rate must be kept as low as possible.

The duct system must be examined & airflow tested before selecting a new condenser & matching indoor coil.

From that data, you & your contractor select the best combination of equipment & components that will work best in your climate, with your home, the final duct system & those humidity control needs.

Good Luck...

[amd]

I have a 1100 square foot house(excluding the garage).
We currently have a 2.5 ton unit. We are looking to replace our current unit which was installed in 1994 due to not cooling when it's 100 degrees outside.
Contracters are differing on 2.5 and 3. units. Does it really matter?

Sorry, 3 tons is crazy for 1100 sq ft.

If you really require that much cooling, fix the house and ductwork. Throwing larger equipment at the problem won't make it go away.

Chances are that the ductwork isn't sufficient for the 1000 cfm a 2.5 ton unit needs to move, let alone 1200 cfm for 3 tons.

[BaldLoonie]

The duct system must be examined & airflow tested before selecting a new condenser & matching indoor coil.

Chances are that the ductwork isn't sufficient for the 1000 cfm a 2.5 ton unit needs to move, let alone 1200 cfm for 3 tons.

There's the answer.

[2old2rock]

As others have stated, make sure your insulation is top notch, infiltration is at a minimum, duct-work is tight.
Then put in a 1.5 or 2 ton, depending on manual J.
Even 2.5 ton, in 100 degree heat, for 1100 sq ft is crazy.
Also as stated here by someone very wise - insulation is something you pay for whether you have it or not.
I have a 1000 sq ft rental, well insulated, with a 32 year old 1.5 ton A/C.
It performed wonderfully when we recently hit 99 degrees. Renter was never uncomfortable.
Keep in mind, a smaller unit will run longer cycles, and therefore de-humidify very well, which is ideal for your climate. On the hottest days, it will run nearly non-stop. That is a good thing.

[Mary9921]

78 degrees is comfortable

[Mary9921]

We are having the electric company come in and perform a test on the ducts before we hire the contractor to install the unit.

the outside model is:Bryant 126BNA03600/inside:FV4CNF003T00

[udarrell]

We are having the electric company come in and perform a test on the ducts before we hire the contractor to install the unit.

the outside model is:Bryant 126BNA03600/inside:FV4CNF003T00

That is only ONE piece of the total data needed... listen to what the professionals & others have suggested on your thread...

[MM#7]

78 degrees is comfortable

so how low is your existing system bringing the tempature on a 100 degree day!