4 Cooling System Options For Your Home
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How to Choose the Best Heating & Cooling System for Your Home


Let’s face it, buying a new heating and cooling system can be a stressful situation. Choosing just the right units is a big decision that will impact your family’s comfort for years to come. So, before you jump into purchasing the first system you see, we recommend you take a little time to determine exactly what your home comfort needs are, and how to correctly address them. The key factors to the ideal HVAC system for your home are system type, unit size and, of course, budget. Read on for help in identifying these factors and choosing the best system for your needs.

Be Specific About the Space

The first step to determining what system to purchase is to define the type and size of space that will be cooled and/or heated. Being as specific as possible will help you avoid selecting units that will not fit your home’s climate control needs. By answering the questions below, you can more accurately define your space, making the final purchase decision much easier.

  • Is the space residential or commercial?
  • If it is residential, is the home traditional stick-built or mobile?
  • How many total square feet is in the space (including basement)?
  • How many total floors is in the space (including basement)?
  • Is the space new construction or an existing structure? If it is an existing structure, where is the current furnace located? (attic, crawlspace, utility room?)
  • Does the space currently have adequate insulation?

Now that you have nailed down the specifics of your space, you can move on to deciding what type and size of system you need. Read on for details.

Select the Right Type of System  

This step is actually quite simple, and it boils down to just a few points. In fact, the type of system your home requires may have already decided for you. If your goal is to upgrade your current AC/furnace units, then you’ll need to choose new units of the same size, type and air flow configuration of those currently in your home. For example, if the home currently employs a 3.5-ton AC/80,000 Btu upflow gas furnace system, and you have no plans to add on to the home, you’ll need to choose new units with the same specifications. Learn more on this topic by visiting iHeat.co.uk.

In the end, whether you go with a different type of system or not can be determined by asking yourself these three questions.

  • Are you happy with your current unit(s)?
  • Do you like the way your home is heated/cooled?
  • Are your current utility bills affordable?

Using the answers to these three questions, as well as the guidelines below, you should be able to easily decide whether your current heating/cooling system is the right size for your home. If it is, congratulations! You now know exactly which units to buy based on size, type and configuration. If the current system does not match your needs, we suggest consulting an HVAC specialist for help with sizing the new system.

Starting from Scratch

Selecting AC/furnace units for new construction, or an existing home that you will be adding on to, takes a little more thought. However, the process is still fairly simple when you break down the factors that go into it.

What unit(s) do you need for your home?

  • AC only
  • Furnace only
  • Package of both units

If you are purchasing a furnace, what type of fuel source will it be using?

  • Natural Gas
  • Oil
  • Electricity

Which fuel source your new furnace will use comes down to three things: what is available, what is most cost-effective, and what you prefer.

Natural Gas is the most efficient fuel source available and it provides a cleaner burn than oil. But you must have access to a natural gas line in order to use it. Creating new access to a natural gas line is a very expensive and time-consuming task.

Oil furnaces are cheaper than their gas-powered counterparts, and oil produces a higher Btu heat than gas. However, oil must be ordered from a third-party supplier. Plus, an external tank is needed to store the oil once it has been delivered.   

Electric furnaces are less expensive to install and offer ultimate control over heating zones (rather than the “whole-house” approach of gas or oil). But electric furnaces are not an energy-efficient option as they operate at a much higher cost than gas or oil furnaces.


If you are purchasing a furnace, what direction do you need the air flow to take?

  • Up
  • Down
  • Horizontal

The direction of the air flow is an important factor in selecting the right furnace unit for your home. That’s because the location of the furnace directly determines the direction the warm air will take through the ductwork. Typically, you will find furnace units that use one of three air flow directions — upflow, downflow, and horizontal (pictured below).


If you plan to locate the furnace in a basement or on the main floor of your home, choose an upflow unit. These are the most commonly purchased units and you’re sure to find several choices in this configuration. If you are installing the new furnace in a mobile home, you will need to purchase a downflow unit. (NOTE: Some traditional stick-built homes do use downflow units, but this is not the norm. Be sure to check the direction of air flow on the current unit if you are upgrading an existing furnace.) If you plant to install the new furnace in a crawlspace or attic, you will need to source a unit with horizontal flow.

Be aware that some newer furnace models employ a multi-positional air flow feature that allows them to vent warm air in all directions — up, down and horizontally. You may also find units that feature two air flow directions (i.e. upflow and horizontal, downflow and horizontal).

Important: If you are upgrading a furnace in an existing home, be sure to check the current unit’s air flow direction — up, down or horizontal. Your new unit will need to have the same air flow configuration.


A Note About Mobile Homes

The typical mobile home uses a heating and cooling system that is different from those found in traditional structures. This is mainly due to the mobile home’s duct system, which is considerably smaller. Therefore, a mobile home’s furnace or air handler uses a smaller-capacity blower to accommodate the small ducts. So, when choosing a new HVAC system, be sure it is compatible with mobile home ductwork.

Choosing the Right Size System

The last thing you’ll need to do before purchasing your new heating and cooling system is to determine what size you need for your space. Though common sense tells us that choosing a system that is too small for the home is a bad thing because it puts too much stress on the units, resulting in unnecessary wear and tear and higher utility bills. But, did you know that choosing a system that is too big can also drive up your utility bills? Oversized units are known to routinely turn on and off in short cycles, which not only causes excess stress on the system, but also inefficient heating and cooling. A system that is perfectly sized for your home provides constant, comfortable air and even small temperature fluctuations will go by unnoticed.

To find the correct size AC unit for your home, find your geographical zone on the map below. Then use the corresponding color-coded table to determine the number of energy tons it takes to cool a home with your total square footage.




1.5 Tons 600 - 900 sf 600 - 950 sf 600 - 1000 sf 700 - 1050 sf 700 - 1100 sf
2 Tons 901 - 1200 sf 951 - 1250 sf 1001 - 1300 sf 1051 - 1350 sf 1101 - 1400 sf
2.5 Tons 1201 - 1500 sf 1251 - 1550 sf 1301 - 1600 sf 1351 - 1600 sf 1401 - 1650 sf
3 Tons 1501 - 1800 sf 1501 - 1850 sf 1601 - 1900 sf 1601 - 2000 sf 1651 - 2100 sf
3.5 Tons 1801 - 2100 sf 1851 - 2150 sf 1901 - 2200 sf 2001 - 2250 sf 2101 - 2300 sf
4 Tons 2101 - 2400 sf 2151 - 2500 sf 2201 - 2600 sf 2251 - 2700 sf 2301 - 2700 sf
5 Tons 2401 - 3000 sf 2501 - 3100 sf 2601 - 3200 sf 2751 - 3300 sf 2701 - 3300 sf


Heating Square Footage per Zone

For the best-sized furnace unit for your needs, refer to the zone map again. Then use the color-coded table below for the BTU necessary to heat one square foot of area. Next, simply multiply the total BTU from the table by your home’s total square footage. (Example:  40 BTU x 2000 square feet = 80,000 BTU). This is the ideal furnace size needed to efficiently heat your home.

30 - 35 BTUs/sf 35 - 40 BTUs/sf 40 - 45 BTUs/sf 45 - 50 BTUs/sf 50 - 60 BTUs/sf


Purchasing a new heating and cooling system shouldn’t be an overwhelming task. With the right information at your fingertips, you’re sure to choose the perfect system for your family’s needs.


Still not sure which size and type of heating/cooling system you need?
Use our handy System Selector.


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