3.5 ton AC installation/quote question

The guys that said you need a larger return vent or more return vent capacity are correct. The current guideline is 400 cubic feet of return air per ton per minute (range: 350 to 450 cfm).

3.5 ton HVAC x 400 cubic ft per min = 1400 cubic feet of return air per min required

Your current return vent is 20 x 20 = 400 sq inches. A 1 inch thick filter will move an estimated 2 cubic feet of air per minute; therefore, 400 sq in x 2 cu ft air/min = 800 cu ft air per min capacity of your existing air return vent.

So you are short 600 cubic feet of return air per min with your current air return vent (1400 - 800 = 600) with a 3.5 ton unit. One of of the worst things you can do is starve a HVAC of proper return air flow - loud noise, high external static pressure, reduced cooling capacity, can shorten the life of the equipment, etc.

They can enlarge the current return air vent or simply add a second return air vent in another location to get you the 1400 cu ft of return air you need. Seems like they would just add a second return vent, like 18 in x 18 in (= 648 cfm) in another location of the house that provides 600 cubic feet of air per min.

ETA: The standard 1 inch filter in the return grill’s primary purpose is to protect the HVAC equipment in the air handler, not improving air quality for the inhabitants. The thicker filter, as an add on item, attached to the air handler will provide some air quality improvements benefits for the occupants, but it won’t increase the volume of return air to the air handler. The issue is not one of filtration, it’s getting the proper amount of return air volume through the air handler.

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I ordered a 3 1/2 ton unit,seer16 and air handler on line. Cost like $2200 total shipped. With a 10K electrical heating.

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Where from? What brand?

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The third guy says not necessary.

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Take this guy out of the mix and go with one of the other two.

Unless I’m missing something sounds like a “win” for you. Bryant and Carrier are the same company, likely the Bryant Furnace is identical/nearly identical to the Carrier Furnace, and a good chance it’s made in the same factory, so there would be no pairing issues.

The “win” is they are going to upgrade your your condensing unit to a SEER 16 from a SEER 14 at no cost for the inconvenience to you. However, I would ask them if the evaporator coil in the air handler will be a matching coil for the upgraded SEER 16 condensing unit so that you get the SEER 16 efficiency. If not a matching evaporator coil, everything will work fine but you won’t get the SEER 16 efficiency just likely the SEER 14 efficiency.

HVAC gas furnaces are so reliable they rarely ever fail or give one problems, and the gas furnace is usually warranted for 20 years, the AC for 10 years. The Bryant Air Handler/Furnace will likely be a different color housing and certainly have Bryant label, but that’s in your attic or closet anyway.

Again, unless I’m missing something I personally would go with their offer b/c you are going get an upgraded, more efficient system at no cost to you.