Well, this rule of thumb should work on most applications. AC units are predesigned for certain areas of the country. Doing the heat load calculation is the best way to figure out what you really need. As far as a profit margin per ton, the larger the unit doesn't mean more profit. But the price can go up for the SEER rating and what extra items you get with your system. Most contractors put more profit on the medium SEER rating. They call it, Good, Better, Best. Financing plays a big part in this also. The biggest issue coming up soon, the changing of the freon, also they want to eliminate all gas furnaces and package units. In California people pay hidden cost for gas furnaces and package units. Just for general knowledge, the manufacturer raises prices every 4 months. That's why prices have increased so much, inflation.

Your helping a lot of people there is a bed thing related to the AC of a house and the alarm of what is going on not too many honesty around thank you again

IDK this installer, but I am impressed with the candid openness. If I lived in that area, I would buy from this vendor.

Central FL here. New DRH build, 1 story multiple vaulted ceilings, 2800 SF and they went with a 3.5 ton, and I swear this thing is running all the time right now for A/C.

The takeaway here is, if you are in the market for an A/C system or soon will be, do what you can to improve the insulation and air sealing of your home first. You will then have a double benefit, where you can buy a smaller, less expensive A/C AND spend less on electricity to run it.

Thanks for the video and the chance to get a rough idea how big a unit a house needs.

thanks for your videos! yes, i am in SW FL in what you are describing as Zone 1. our home is 1961 sq. ft. and is built on a 10' plate. most of the ceilings are tray design and extend another 1 to 1.5 feet higher, so... when the HVAC company did our load plan, they had to take into consideration cubic feet of cooling along with square footage. i don't hear a lot of HVAC pros talking about cubic feet. our home faces NE, so we get morning sun. the back of the home faces SW so we get quite a bit of radiant heat in the afternoon through the rear windows and lanai area. our load plan calculated 3.5 tons, and it has been spot on! the system has the ability to pull down 20˚+ from outside temp and our humidity hovers in the 45 to 50% range. run times are long, but this keeps the humidity at bay. we are very comfortable.

This is a very good video. I replaced our HVAC system about 6 years ago. Our home is 1800 sq. ft. and was built in 1988 with vaulted ceilings. We live in Sacramento where temperatures often reach 106 degrees Fahrenheit. Sizing was a big issue. The old system had a 3 ton unit and it never cooled the house when temperatures were above 86 degrees at which time It would run from 1 to 7 p.m. without cycling on and off. Most of the dealers wanted to replace our AC system with a 3 ton unit. I did not want to do so. However, American Standard and Trane dealers suggested a 4 ton unit. In the end I installed a totally new system, including new ducts, with a 4 ton unit. It works like a champ. It cycles on and off until the temperatures exceed 103 degrees and it cools the house even on the hottest days. I can set the home thermostat at 72 degrees and I can achieve this temperature on the hottest days.

In the caribbean we use a rule of thumb of 300 sf to 350 sf per tone and that is for residencial. Now proper insulation makes a difference of course.

LOVE the inclusion of a manual J (or heat load calculation)! Size your units properly and your house will thank you

Could you please do a video on selecting the correct size AC units with split system install for both larger one story and two story homes

I remember back when Sears sold furnaces and A/Cs there used to be a gag thing going around about how the Sears salesman sized them. Basically it was a piece of cardboard with 3 square holes cut in them. You'd stand at the curb, look through the holes and if the house fit in the smallest hole it was 2 1/2 ton, the medium hole was 3 ton and the large hole was 3 1/2 ton. You could also use it to size the furnace, 75,000 BTU, 100,000 BTU, 125,000 BTU respectively. I have a 3 ton Condenser with a 3 1/2 ton evap coil which gives you better dehumidification because with more coil area it pulls more humidity out of the air per cooling cycle.

We recently replaced our 30+ year old 2 ton AC unit with a 2 stage 3 ton AC for our two story 950 square foot house. When the old AC was working it's not enough to cool the upstairs so we went with 3 ton. Glad we did as it made a big difference. The house was built in 1989 but it had alot of insulation improvements over the years. It's not really about square footage but actual air volume in the home. Multiple stories also makes a difference. Wish we could afford a two zone AC system but considering it was already expensive as it is we went with 3 ton 2 stage to cover the entire house.

Thank you for this. I live in a mobile home 43 miles north of Florida in southeast Georgia. IMO, mobile homes need 20%-33% more tonnage for cooling, maybe for heat, too. They are just not built as well, not insulated as well, & ducts are not sized properly, usually. Have a GREAT day, Neighbor!

I live in Abilene, TX. Too bad you are too far away to help us with our HVAC issues. You seem to be knowledgeable and honest. I enjoy watching you videos. I've added it to my DIY Mini-Split project knowledge base.

Thanks

I really like those two pictures hanging behind him.

Never go off of Sq Ft. Use a manual J load calculation and size it properly. I install in Oklahoma and most houses require about 1 ton per 400sq ft. It's better to oversize (with supporting ductwork) using a multistage or variable system rather than under sizing and running 100% all the time. Using multi staging or variable systems will allow the system to dehumidify and cool properly. But if you are using a professional to do your install, demand a manual J load calculation and do it right!

Shade from trees also plays into it

Relative humidity is a very important part of the formula. A unit's sizing could be drastically different when living in Arizona, or on the Florida Gulf Coast.

Thanks for help 🤙🕊🕊🕊

In ew york tri-state area the installers usually calculate 400 sq feet per ton, not 500. Plus the ceiling height, plus big windows and south side and etc.

I'm 2/3 of the way through the video and I'm already stuck on the thought "just enough information to be dangerous" I wish life were simple but if you really want good performance and efficiency forget you ever saw this video. As far as sizing goes you need to talk to a contractor that is willing to do a detailed manual J heat load calculation. PS- equipment sizing and brand are SOME components of a more complex evaluation of the cost to the homeowner. Look for quality first then price second. Good luck everybody!

Excellent

Interesting thoughts. We discussed square footage when replacing the furnace and I had to argue with them that CUBIC ft is the proper analysis. 10 ft ceilings and sloping cathedral ceilings are becoming popular, and that means more heat for the same floor space in my house.

SEER rating does save money, I did it in my own home is I would know for sure.

Its volume !! Im surprised you didnt mention variable of ceiling height

I’ve got a 2,300 sq ft 2 story home I’m Arizona, built in 2007 with two AC units (upstairs and downstairs). Had one AC contractor trying to sell me two 3.5 ton units but seeing this video I’m thinking maybe they’re overselling me? Current units are 2.5 tons each and that has worked generally well. Thanks for the video!

in the south, when you figure out the size, then double it for the humidity

outstanding

i got a system size for the house like explain in this video, when it was 104 outside the system will continue to run and will not drop the indoor temp below. 80. had company come out that installed it, would say the system performing as it should. it was under sized when in USE but on paper it was correct size.

Thank you for the video 😊 Does it change if you have a flat one floor plan or a 2 storey house on the size of the AC unit? Thanks 😊

Perform an ACCA Manual J block load analysis followed by Manual S equipment selection guidance or you're simply guessing! There are SO many other factors than simply square footage and climate zone. Oversizing an AC unit is the worst thing you can do!

I live in a single story home 1270sq ft with vaulted ceiling living room/ dining room . Zone2. 2 ton or 2.5 ton. Currently 2ton unit 25 years and can’t keep up when 93 degrees outside

What you overlooked here which is most important is when the house was built. Homes today are built very tight an energy efficient. A 2000 square foot home built 30 years ago would require a 4 ton unit. A new home, same size and area will only require a 3 ton unit to work efficiently. Rule of thumb is generally 1 ton for every 500 square feet on an older home and 1 ton for every 700 square feet on a new home.

In my thoughts, a climate like Arizona your dealing with a lot more sensible and no latent heat load. in that case I would size that system at 600 sqft per ton. In a case like Texas where you have very high latent heat and high sensible heat load I would size the system at 800 to 850 sqft/ ton. Yes you will have longer run times for the system, but you will bring the RH levels down significantly in the house. That makes for a more comfortable environment. Nobody likes a cold and damp feeling inside the house. It makes for longer run times for the system but that's why the manufactures invented higher SEER units. The Idea is to deal with the humidity first, or the latent heat load. then bring down the sensible heat load. Once you pull the humidity out of the space the temperature automatically feels colder. Here in central Canada/ the parries, we have a very low latent heat load, low humidity. We size residential A/C at 600 sqft/ton. When you move further down east to Ontario, Quebec and the Maritimes they have a very high latent and sensible heat load. In this case its in your best interest to under size these systems for longer run times to deal with the latent heat loads/ humidity first . The worst case scenario is when RH and Temperature intersect at 85 and 85, = instant black mold growing. Nobody wants the in their home. Keep the RH low and everything will be healthy in the house.

HVAC contractors will invariably oversize an A/C system. There's two reasons why. 1) They earn more on the sale of a larger system, and 2) they do not want to run the risk of a customer complaining it can't cool down their house fast enough.

Thanks for this. I live in Austin, TX. Our 2 story house was built in 1992, has a 15 ft front entryway and dining room and then 9 ft ceilings on the first floor. The stairway is very open to the second floor but thankfully we have a small landing and then all bedrooms and bathroom doors are close to each other. We have a hard time keeping the downstairs cool. We have 2 units and use the downstairs during the day and then take the thermostat up when we go upstairs for bed and vice versa during the day and night. Our downstairs is almost 1600 sq ft while our upstairs is almost 2000 sq ft. The upstairs does OK but our downstairs can be a struggle especially when we have people over for a gathering. Would would be recommended for this type of scenario? High ceilings in Austin, TX? Thank you.

After 35 yrs here In fl for the ideal sq ft is 500 ft per ton for a block home . If you have vaulted or high cielings adding 1/2 ton wouldnt hurt . A wood frame house that is raised with old windows i use 400 ft per ton . I have never had a home complain unit is not cooling properly . If you go oversized add a thermostat with humidity control

When I purchased my new home, they had Put in 3 new units. Home size over 3K, I questioned the servicer he said 2 units would be hard for the home, house built in 2001.

Excellent video. a lot of useful information. I currently have a 100,000 btu gas furnace which I need to replace due to 3.5 ton compressor going bad along with 400sqt addition which bring the house to around 1800sqt with 10 big windows. What size btu furnace and compressor would you ruffly recommend for the size house. I think the unit is 28+ years old. Do i go with 115 or higher btu furnace n a 4 ton compressor or stay with the 100btu n the 3.5 ton compressor.

HVAC tech here. Most companies in my area size their equipment wrong.

As other stated there are so many other factors here that are not mentioned, a manual load calc is needed as a starting point. I also would argue that anyone installing a new HVAC system should only consider a variable speed unit and slightly oversizing is a good idea knowing that the system will be able to more quickly bring the home to temperature and then run at 30-50% load to maintain the setpoint. An oversize unit will also be able to keep up with the weather extremes that seem to happen with climate change.

If one is using the square feet method that is fine if one has 8 foot ceilings. However if one has 10 to 12 foot ceilings then that will require more BTU's from a unit. Because more inside cubic feet of air has to be run through the unit. Also a two story house should have two smaller home units to be efficient instead of just one. One unit for the down stairs and another for the upstairs as they are complete different zones.

A schedule J calculation should be done on any house before choosing a unit. Our new house has 2500sf downstairs and only needed a 3 ton unit. Located in South Alabama, with 2x6 exterior walls with a complete spray foamed envelope. Wrap around porches on threes sides. House lined up on a true East / West axis. All windows E-336 glass. Upstairs has 2080sf, fully foamed and needed a 2 ton unit.

Hello like your videos, lots of information. I got one question so I have a manufactured home in sahuarita Arizona, very close to Tucson az. is a 1997 what size of ac compressor you recommend. The ac now is a 3 ton, is as old as the house it does all right is still cooling but is lacking a little so I’m in the hunt for a new system. If you can tell me what size of unit I would need, like you said in the video, older the house go bigger. So it’s 26 years old plus a mobile home insulation is very minimum on manufactured homes. Any info I’ll be very helpful. Keep up good work.

Two things, first it is the starting and stopping that wears out an a/c, longer runtime equates to longer life expectancy. Second, it's not what zone you live in, it's how the home was constructed. You wouldn't put the same size system in a home built 50 years ago as the same size home built 10 years ago. Do a load calculation on the home and size to that. By the way sir, NCI, National Comfort Institute, has excellent classes that teach just that, take one, please!

Great video! We had someone out looking at our home and they are trying to sell us a 4 ton (which is an upgrade) but we are in northern VA and our house is 3300 sqft. Why would they be trying to give us a 4 ton?

please talk about cubic feet of air conditioned space along with square footage. tall ceilings can make a big difference in load plan.

Based off this video I think I need a 4 ton vs the current 3.5 ton. Central Florida home built in 2007, two-story, 2260 sqft.

As HeatGeek below notes - the thermal envelope is what matters . . .effectively the rate of heat transfer between the inside and the outside of the house. This can be calculated using the heat transfer coefficients for the various elements of the building - walls, doors, windows, foundation and roof - the areas of these elements individual elements (ft2) x the differential temperature (deg.F) and the Heat Transfer Coefficients (btu/ft2/deg.F). The volume inside the building x the specific heat capacity of air x the differential temperature allows you to calculate how much heating or cooling the fluid requires in addition to the heat losses from the building envelope and the speed at which you want it to cool also affects the size of the unit but also the heating/cooling system cycling time.

I got a 4-5 ton switchable because I planned to do multiple additions. My house is only 2000 sq ft. Not sure if I wasted money too soon.

I have a 1000 square foot house with a 2 ton heat pump. It keeps up up to 90 degrees then above 90 degrees then runs almost all the time. 14 year old house post and beam construction. So 2 1/2 or 3 ton when it fails

It’s a lot more factors that play a part. A manual j should be performed. Your area elevation average temp etc. your roof , windows , doors , foundation, insulation , roof color , finish on house, Which way your house face all play a part

depends on where you live!!!!!!!!! im here in phoenix try a 3 1/2 ton on a 2000 sq ft home here!!! your going to be pulling that out the first summer.....

I have a DRH home with a 2.5 ton unit on a 2.083 square foot. The funny thing is all the house have a 2.5 ton even the smaller homes.

All right let me ask you this I have garage about the size of a 2 car, it’s really more like a one and a half. I have a 1 1/2 ton unit all new install also insulation all been put in at the same time of the install. It won’t get below 78 runs all day long never shuts off even at night sounds undersize to me but it’s less than 800 ft.², does not have a garage door. I turned it into a workshop.

I live in El Paso. My house is 1500 sqft and was built in 2006. My AC is a 1.5 Ton unit. This is the original system and "overall" the house is cooled and heated without an problems. We do have hot and cold spots. This is a single stage unit. If the website is correct I would need a 2.5 ton system. My concern is that all the ducting will have to be redone to handle the larger Ton size and to balance the system with a 2.5 ton system.

Here is a quick formula to figure what size a home needs. This was passed onto me by the smartest HVAC engineer I’ve ever known. I will say this; that a heat/cool load manual J is the best method. With that said a quick guess can be figured by this simple formula. The home volume x one of these three multipliers, 2.6, 2.8 or 3.0. 2.6 multiplier is for modern well insulated homes. 2.8 for your average 80’s insulated home. 3.0 for older poorly insulated homes with single pane windows. Sounds crazy but it’s remarkably pretty accurate when compared to a load calc.

I am in round rock we have a 4 ton system and it is short cycling our house is 2300 sf

how do you determine the ton that you need on homes built before the 60s?

Got a question for you. 10-12 years ago found a contractor I *really* like. Was very knowledgible on our situation. 2 story house.. Built in 1981. We're in the concrete jungle of DFW area and bought house in 1997. The HVAC was original from 81 with 2 units; 1 up and one down. I don't recall what tonnage each unit was, but it was not enough on top of 2 system barely functioning. The house was an investors quick flip, and basically it was indeed a pig with a lot of lipstick as we learned. After doing double pane windows and all doors replaced it didn't seem to work so hard. The insulation in each part of upper and lower floors is lacking at best. Rockwool average 3 inch. Masonry siding from bottom of 2nd floor up. Downstairs brick up to ceiling+ a little.. No insulation on attic walls nor any radiant barrier on roof. Upstairs is around 1400 Sq Ft and downstairs is around 1750 sq ft. Contractor suggested a 2.5 ton upstairs and wanted us to do a 3.5 ton downstairs, both single stage systems. For just a little more we went with a 16 SEER 4 ton 2 speed down stairs, which has been perfect match. Downstairs rarely kicks into high stage and can hardly even tell it's on. The upstairs 14 SEER 2.5 ton single stage does the job really well, but it does run quite a bit more during the warm to hot days. These units were installed in 2008 and have for the most part been trouble free. The 4 ton burnt up a compressor about 5 years ago, so he recommended we drop down to 3.5 ton single stage. I really didn't want to do that as we _love the quietness_ of the 2 stage system. So we opted for the 4 Ton 2 stage. Indoor humidity on the really hot days both up and down run in low 40% range during AC season. Over past few years, a new coil and outdoor unit goes thru CAPs ever couple of years.. Thus we are at a crossroads again, as to what to do. _Wondering why he seems insistent on dropping down to a 3.5 ton?_ Cant underdstand the push.. I know the #'s dont line up and a 3 ton would probably be the proper unit, but it does not come in a 2 stage compressor. IDEAS, SUGGESTIONS?

Interesting to look at this rule of thumb, as I bought an older house with a recently replaced HVAC system that was sold to the prior owner. SW Oklahoma, so in the northern part of Zone 1 on that chart. 1969 build, ~1200sq/ft, concrete slab foundation with wood frame construction. Mostly updated to double pane windows, though a couple older aluminum single pane ones. The system installed is a 3.5 ton system, which makes me wonder just why the system was chosen, as it's apparently a full ton oversized for the application. Profit margins? It doesn't run all that much of the time, often only a few hours a day during the middle of the summer.

Please don’t do rule of thumb. Add a smart stat to add data for a working unit. It will record runtime and outside data. A year would be nice. Not all together wrong, but the variables can cause problems. Heat load is good. Still a fancy guess.

Could you do on video on deciding factors of whether to go with one or two ac systems for 2 story homes?

Without Manual J calculation?

If I were going to upsize any component it would be the evaporator coil.

Should the finished basement square footage be considered if ALL the vents feeding that space are CLOSED when we run the A/C because it's naturally cool (almost cold) downstairs and doesn't need cooling? House is approximately 2900 sq ft total split evenly upstairs and down, 20 years old in southern Wisconsin.

How about a log home with 1500 sqft downstairs with open living room and a separate unit for loft upstairs of 300 sqft? Built in 2002. In S.C.

Is it better measuring in cubed feet

I can understand that heat load can be a factor for the difference of around 20%. I live in India and our general prescription is around 12000 BTU for 150 square feet This is for concrete buildings with moderate insulation. I still don't understand why the difference is up to three times. Can you please explain?

How does a dehumidifier fit the picture? Also foam insulation. I have a 4,000 sq home but a 4-ton unit and it feels like it's always running. The A/C company says it's perfectly designed, but.... doesn't feel like it.

Just a question We have a 3 ton outside but in the attic it’s 3.5 or #46 not sure why they don’t match,any reason

ASHRAE has calculations for sizing. Typically on 95% of the worst extreme days the unit should run continuously. So essentially the most extreme few days of a summer the AC will run continuously in afternoon.

What if you have a finished basement. Should that be included in your living space.

Does home structure matter, like one story vs multiple stories?

What is a heat load?

I have a 3 ton 16 seer for 2700 square feet in a fully spray foamed house. It’s a new home and the system ran for 6 hours and didn’t drop the temp from 78 to 76. The builder had a 6 inch duct unregulated fresh air coming in and he’s using the whole attic as a return air system. In my gut something feels off and that ac runs all the time. Any ideas? The charge is correct and it’s zoned with 5 thermostats

Midland, it's too hot too long. "Refrigerated air" is a must.

If your home is properly insulated, go UP 1/2 size. If you had a large tree that was cut down, go up one size. If your home is not insulated well, INSULATE IT FIRST, especially old leaky windows. THEN see if you need a new A/C. Remember to have attic venting checked for proper installation including soffit vents. Sizing can be difficult. Depends on window sizes and location, type of windows, attic, insulation, trees, etc. Can't simply go by a universal chart. Remember, summers are getting hotter every year. As an A/C ages, it's capacity goes down. Oh and if you have kids or cook a lot, go up one size. Kids do love to run in and out, throwing your expensive conditioned air right out the door.

Manual J

This is why almost every single AC system is so severely undersized. I followed these recommendations once and ended up with a system so badly undersized that it couldn’t keep the temperature at 60 degrees on a 95 degree day. The temperature would rise up towards 70 degrees with the damn unit running 24/7. Ended up running window units on top of the central unit just to keep the damn house at 55 degrees. You can’t oversize an AC. I have a 10 ton unit on my tugboat and it works awesome. It will freeze you right out of the boat if you want it to. I’ve been able to pull that boat down to 45 degrees on a 100 degree day!

Great video! Thanks. When considering the size of the system I was hoping you would address the volume of a room, high vaulted ceilings plus 9 foot flat ceilings increase the volume we are cooling vs 8 foot ceilings throughout.

Odd result, IME. I’m in zone 4, 3700 total square feet and was manual J sized at, and have been living with for 25 years, a 2.5 ton system. The chart says 5 tons isn’t enough. It’s a pretty standard house - ceiling height, number of windows, number of doors, occupants, etc.

I have two units with a two story family room

A buddy of mine was a mechanical engineer and pilot. He got his HVAC license and used it as a side gig and between career job. He would actually run heat calculations and was surprised most HVAC tech only used the “rule of thumb”. He also found that techs would not properly size the ductwork. This is why there are hot and cold spots in homes. My house is an ice box in my room and the kids are warm because the afternoon sun is shining on their rooms.

What if my Air Handler is sized for 4 ton but the compressor is a 3.5 ton? I have 1800 Sqft house and I live in Orlando, Florida. I've been getting quotes for 3.5 ton and 4 ton Units. What size should I get?

Do you count the basement when you are counting square feet

Hello, I want to replace my HVAC heat pump, it died. My house is 1456 sqft. and was built on a Slab in 1992. I live in Richmond, VA. Based on your chart, what's the best Ton? Thank you.

Live in the San Antonio area. Have a single story, 3000 sq ft home (built in 1999), with two HVAC systems (3 ton + 4 ton). How do you compute tonnage need for a long, single-story home such as mine? Does that configuration (3 ton + 4 ton) sound right to you? Also, if I should decide to try to switch my HVAC service to Atlas AC Repair LLC, how does that work regarding the existing warranties (parts + labor) on my existing systems that were installed and serviced by another AC company? Last question -- if one of my units (401a refrigerant) is about 10 years old with some occasional repair-need hiccups, should I try to replace it with a new 410a refrigerant system before the 2025 mandated A2L refrigerant HVAC systems take effect (I've heard the cost of the new A2L systems may be 30% higher than a comparable-capacity 410a refrigerant system)? Thanks in advance.

Two story homes present a different problem in regard to size also

this assuming an average setpoit of 72-73? i know plenty of people that keep it 70 or even lower and may need to bump it up an extra half ton... also for houses with two units, two stories, and two air handling units splitting the sqft for each, and if the upstairs is on the edge may need to bump it up being on the second floor, unless good insulation in attic, newer build, or a good tree canopy to keep house cooler. i like to ask my friends does the unit run 100% for long periods at a time maybe in the summer but not 100+ good sign they are undersized as is.

We have 7 tons counting attached garage in a 1400 square foot home, upgrading to 8 this year.

My son has a 1640 Sq ft home in South Miss. Built in 1987 that has a 3 ton a/c unit that he just had serviced and the refrigerant is charged properly,duct work looks ok,insulation looks OK but his a/c unit runs all,the time in the summer,so you still think a 3 ton unit is Big enough? Doesn't seem so to me is what I'm afraid of and of course the a/c guy is pushing for him to buy a new system. I don't want him to have to buy window or portable a/c units but I'm trying to think of other options to a brand new unit as that is way too expensive

The results the Manual J calculation.

better to have more rather than not having enough, especially when it comes to air conditioning and heating your home.

I'm done with central air. Midea u shaped. 2 are cooling my whole house. They shut on and off. It is awesome.

There is no set btu/ft^2 at all. You have to model the house with manual J to get that value and maybe even manual D

One ton is not 12,000 BTUs. It is 12,000 BTUs per hour. There is a big difference between saying Des Moines is 100 miles away vs 100mph away. You did not mention one of the more important negatives about oversizing. The unit may not run enough to remove sufficient humidity-or latent heat-from the house. You said if the unit is too small it will run continuously and wear it out faster. I was told that a right-sized system would run continuously on the worse day. The less it has to start and stop the more efficient it operates. Plus, a smaller unit even though running more will cost less in electricity than a larger motor and compressor having to spin.

I've got a 1400 sq ft home with vaulted ceilings in half the house. The old system is 2.5 tons. Am I crazy to put in a 3.0 ton. The house was built in 96