April 26, 2018

How To Know My AC Size

Air conditioning is a necessity if you live in Las Vegas, but you don’t have to overspend to stay cool through the scorching summers. If you’re looking at AC replacement (whether your AC broke down or simply to upgrade your heat pump), it’s important to take the time to find out what your needs are before buying a new one.

It may seem strange to think, but air conditioning is just like any other good, and it’s possible to buy too much of it. Whether you own a home or a business, you can easily figure out your air conditioning needs once know some HVAC rules of thumb.

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How Many Tons of AC Do I Need Per Square Foot?

Las Vegas is known for its heat, so you might think you’re erring on the side of caution if you buy an oversized air conditioner. Unfortunately, this can cause far more problems than it solves. And it leaves people asking questions like, “how to know my ac size” or “what size unit do I need”? If you’re only replacing a broken system, you can simply confirm the model numbers to make sure you get the right size.

HVAC units are designed to run uninterrupted for long periods, during which time they can remove excess humidity while cooling your building. If the HVAC unit is too large, it will constantly stop and start, leading to a decreased lifespan for your HVAC unit along with humidity problems inside your building.

In order to determine the right amount of AC for your building, a contractor will do a Manual J calculation. This takes into account factors that can affect a building’s ability to retain heat and how much air is needed to cool an area. These can include a building’s square footage, its exposure to sunlight, the state of its insulation, and more.

Other factors that can greatly affect the results of a Manual J calculation include the building’s year of construction, its climate zone, and whether or not it is a residential or commercial property.

If you are thinking about replacing your HVAC unit, you can conduct your own estimate to get an idea about your cooling needs. For example, each ton of air conditioning can remove 12,000 BTUs from a building in an hour.

There are a few common formulae and rules of thumb you can apply to different buildings to determine how much air conditioning you’ll need. While your estimate won’t be as authoritative as a contractor’s, it can help you budget and can serve as a source of comparison for any estimates you do receive.

HVAC Tons Per Square Foot – Commercial

A commercial building will have radically different HVAC needs than a residential one. They generally have higher roofs, greater foot traffic, and different insulation, which can radically alter calculations. There is much variation among commercial buildings as well as some require far more cooling needs than others.

However, in many cases, one ton of air conditioning will remove about 12,000 BTUs from 500 square feet in an hour. You can use this to determine the cooling load of your building and the minimum size of your HVAC unit.

Commercial HVAC Sizing Rule of Thumb

To determine your building’s cooling load, simply add up all of the sources of heat, then multiply that by the number of 500 square-foot areas you need to be cooled. Commercial buildings will likely have higher foot traffic than residential spaces, so add 380 BTUs to your calculation for every person who works inside a building. Every window facing sunlight will also add 1,000 BTUs to your estimates. Every additional kitchen in your building will add another 1,200 BTUs to your calculations.

In order to calculate how much air conditioning you will need, divide the square footage of your building by 500. Then, multiply this number by 12,000 BTUs, and then add to that number the additional heat generated by windows, workers or areas such as kitchens. This number will provide you with a good idea of the size of the air conditioner you will need. Some companies now divide the square footage by 1,000, which can give you a range of values for your HVAC needs.

Related: What Makes One AC Unit Better Than Another?

Commercial HVAC System Cost Per Square Foot

Given the higher cooling needs of commercial buildings, commercial HVAC will have different costs than residential. You can expect to pay anywhere between 1.6 to 2 times more to cool a busy commercial space compared to a similarly sized residential area. This can increase dramatically if you run a business that generates lots of heat that would require more from the condenser unit. So you will need a more powerful system. If you run a small business, plan on paying about $3 to $4 per square foot for air conditioning, but larger businesses may pay up to $20 per square foot.

HVAC Tons Per Square Foot – Residential

Residential buildings have different air conditioning needs than larger commercial spaces. You’ll likely have fewer visitors, windows, and sources of heat, meaning there are fewer opportunities to lose cool air. When calculating residential cooling capacity, it’s common to assume an HVAC unit can cool 400 square feet per ton of air conditioner capacity. Given the Las Vegas climate, this number can reach a maximum of about 600 square feet per ton of air conditioner for most buildings.

What Size Air Conditioner Do I Need for 1600 Sq Feet?

Many of the same rules of thumb that apply for larger commercial spaces also apply for residential ones. One major difference is one ton of air conditioning capacity will cool more square footage. So it all boils down to finding the size that suits your need. Given our climate zone in Las Vegas, if you have a 1600 square-foot home, you can expect one ton unit of air conditioning to cool about 400 to 600 square feet. Each section will contain about 12,000 BTUs that need to be removed per hour, similar to commercial spaces.

Assuming the minimum cooling capacity of 400 square feet per ton for your HVAC unit, a 1600 square foot home will require 4.0 tons of air conditioning to cool. Your HVAC unit will need to remove about 4.0 x 12,000 BTUs, or 48,000 BTUs, per hour to keep your home cool. This can change depending on the state of your home’s insulation, ducts, whether or not it has two stories, and its positioning toward the sun. These factors can change your heating and cooling needs by about 25%, so take them into consideration when creating a budget.

What Size Air Conditioner Do I Need for 2000 Sq Feet?

If your home is 2000 square feet, you can calculate your HVAC needs the same as you would for a 1600 square foot home. Assuming one ton of cooling capacity can cool 400 square feet of your home, you’ll need about 5.0 tons of air conditioning capacity. Multiply this by 12,000 BTUs, and you’ll get 60,000 BTUs. Your air conditioner will need to be able to remove this much heat from your home per hour to keep a stable temperature.

Before buying an air conditioning unit, it’s always important to speak with an expert. While your calculations can give you an idea of what you would expect to pay, a host of factors could change what your building needs. If you buy an HVAC unit that produces too much cool air, it could have a shorter lifespan and your building might face problems with humidity. A faulty air AC can also cause an increase in your electrical bills. An expert can conduct a more detailed assessment, which you can compare with your own.

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