Infinity -- How much is too much for tweeners

[westm64]

Contractor is recommending Carrier Infinity 21, 3.0 tons and Infinity 58MVBO60 gas furnace. The J analysis came up with 40,000 BTU for heating and 19,000 for cooling with a recommended 2.3 ton.

Previous unit was a 2.5

Is the 3.0 too much even if it's the only way to get the variable cooling?

Novice here, thanks for any input.

[dash]

Is 19000 the total cooling load or just the sensble?

What indoor and outdoor design temperatures?

What city/state?

[westm64]

I think it's the cooling load (listed as 19,000 btuh, 100% of load)

Design TD is 66 F for heating, 22 F for cooling

Northeast of Baltimore, MD

Thanks

[dash]

Sounds low ,based on you had a 2.5,nominal btus of 30,000.

Assuming you meant 72°F instead of 22,Here's what the three ton is .

After adjusted data for 75 indoors,it's 19236 btus on high and 13870 on low.

Above is at 95°F outdoors ,goes up as outdoor drops,doe it get to 95?


Above is not exact as I don't know what cooling coil will be used ,but it very close.

I'd say if 19000 is total and correct ,a two ton should come close to doing the job,but likely a little small.So you would have to add some insulation or settle for 75° indoors on the 95° days.

[westm64]

Sorry, in re-reading the report I realized that 22 was the difference:

For cooling,

Outside db 97

Inside db 75

Design TD 22

All in degrees F

The actual total btuh 19196

So a 3 ton would be too much?

[jrbenny]

The design temperature for summer in Baltimore, MD is 91°F. Why are you using 97°F?

[Dave14666]

Infinity only comes in full ton sizes-a three ton will run alot on low stage(1.5 tons). if you use the infinity control you can adjust your dehumidify to allow the system to run on lower stage longer.

[acmech13]

the contractor may be trying to keep your house at 70 on that 100 degree day? instead of your house being 75 degrees on a 95 degree day and you calling in a service call.

[dash]

Infinity only comes in full ton sizes-a three ton will run alot on low stage(1.5 tons). if you use the infinity control you can adjust your dehumidify to allow the system to run on lower stage longer.

Except for the package units ,they come in 2.5 and 3.5 tons,go figure!!

[jrbenny]

the contractor may be trying to keep your house at 70 on that 100 degree day? instead of your house being 75 degrees on a 95 degree day and you calling in a service call.
Sounds like a plan for mold and uncomfortable living in part load conditions.