A/C Unit size

[Eric Smith]

Had a 2000 sq ft ranch home with a 3 1/2 ton A/C unit. Too big? If so what kind of issues can this cause? Thanks

[Lon Henderson]

As long as it is balanced with the proper evaporator and size furnace, it shouldn't be a problem, That is exactly the setup that I have.

[Eric Smith]

Home has a boiler for floor radiators. Air handler is in attic. Tonsof breaks in the ducts, not insulated properly, and the attic unit is very rusty and dirty. I called those things out of coarse. Just thought I remember hearing something about if a unit is too big it can be an issue.

[Bob Spermo]

No real way to tell unless a load calculation using Manual J, D and S is completed. Without knowing the insulation, the windows, the direction the house faces, etc it is a guess as to the correct size for the A/C.

[Joe Funderburk]

Commenting on the adequacy of BTUs is beyond the scope of a home inspection unless you are a specialist in HVAC. Just tell the client the size and refer it to a licensed contractor. Done.

[Eric Smith]

Thanks a lot guys. I did exactly that mentioned the size and asked for further evaluation from HVAC.

[Garry Sorrells]

Eric,
-Coil freezes stops cooling house.
-System has a short cycle so humidity is not reduced and air feels cold and clammy.
-Duct work super cooled and condensate forms.
quick start of a list.

[Markus Keller]

3.5 ton in 2000 sqft. is fairly standard around here depending on conditions, etc. If it's oversized, then probably not by much. I wouldn't sweat this size on that one.

[Thomas McKay]

1.5 Ton central HVAC system in a 2000 sq. ft. home pretty standard; If moisture is a problem look for something else. Had one inspection where homeowner was really proud he had installed 5.0 ton unit in a 1500 sq. ft. home said it worked real well problem was interior wall were covered with moisture droplets. Asked him if the white pipe next to the condenser ever discharged any water? "No of course not" was his answer, nor would he give me the name of the installer. :eek:

[Tom Rees]

I've always used as a general rule and I mean general, 1 ton per every 550 square feet for this area (Utah). If I were to see say a 5 ton in a 1500 sq foot house as Thomas saw it would raise a red flag. A 3.5 ton in a 2000 square foot house seems just right. If a unit is too big it will not run long enough and won't properly dehumidify as Thomas also alluded to.

[Robert Ernst]

I've always used as a general rule and I mean general, 1 ton per every 550 square feet for this area (Utah). If I were to see say a 5 ton in a 1500 sq foot house as Thomas saw it would raise a red flag. A 3.5 ton in a 2000 square foot house seems just right. If a unit is too big it will not run long enough and won't properly dehumidify as Thomas also alluded to.

There are guys in Vegas that say 1 ton per 400 sqft. I live in the north part of the state 1600 sqft gets 3 ton. This is exactly why I wouldn't use that type of calculation with out knowing the construction and system demands in your own area. As mentioned you have to at least run manual J or something similar to really know. Best to refer it out.

[Stuart Brooks]

I agree with Gary- A lot would depend on the seasonal temperatures in the area, humidity levels, home insulation, number of stories or living levels. In VA, 3.5 Tons for 2000 SF would be a bit overkill. I usually see 2.5 tons. But sometimes the homeowner demands a bigger unit and of course someone will sell it to him.

[Thomas McKay]

Very true Stuart, it is better to slightly under size the condenser; in my market we see many installations where if the condenser, properly sized, is a 3.5 ton unit the air handler is sized for a 4.0 ton system. This seems to give a better movement of air in our hot climate. Over sizing the system can lead to moisture problems. :cool:

[nick alati]

I've always used as a general rule and I mean general, 1 ton per every 550 square feet for this area (Utah). If I were to see say a 5 ton in a 1500 sq foot house as Thomas saw it would raise a red flag. A 3.5 ton in a 2000 square foot house seems just right. If a unit is too big it will not run long enough and won't properly dehumidify as Thomas also alluded to.

I’m in Arizona and I totally agree with your logic. Square foot of home to BTU’s would vary according to type of home, building materiel and technology used. Example – I would recommend using 280 square foot per ton for an older manufactured home (here in Phoenix), older Block home with single glaze windows - 325, 2x4 stick built in the early 80’s to late 80’s - 350 to 400 and newer homes with R30+ in the attic, dual glaze with low E – 500 to 525. I just inspected a Short sale, 2070 square foot, two story built in 2005 in San Tan Valley with a 2012 3 ton Day-Night condensing coil (ground mounted, split system) with living space over the Garage. Listing agent said that someone stole the old unit and she had a Contractor install the new one (Listing agent Translation of Contractor – a guy with a truck & Hammer). According to the HVAC contractor the buyer hired, the home should have had a 48,000 btu unit, the builder (pulte homes) said that they build high efficient homes and a 42,000 btu condensing coil was installed in that home and sized properly. Although I did not talk to the buyers HVAC contractor, he and I did agree on the sizing of the unit and we also agreed on installing two units a new 2.5 ton upstairs and re-ducting the 3 ton for just down stairs.
Question – anyone know of a spread sheet or a online calculator for sizing a condensing coil?

Thoughts are things too!!!

Nick J Alati
Alati's Inspection Service LLC
hhtp:\\Phoenix Home Inspector, Arizona Commercial Inspections, AZ Property Inspectors, HUD, FHA, VA Alati’s Inspection Service LLC (http://www.AzHomeInspectorOnLine.com)