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What Size Heat Pump Do I Need For My House

Views: 862     Author: Site Editor     Publish Time: 2024-06-13      Origin: Site

A heat pump is a device that moves heat from the outdoor environment to indoors, serving as a cost-effective medium to regulate your home’s temperature. But with the varied sizes and capacities of heat pumps, it can be hard choosing the right fit for your home.

Different Sizes of Heat Pumps

In this article, we will unfold the key factors that would help you with heat pump sizing for your home.

Heat Pump’s Size – Measured in BTU or Tons

Installing a heat pump in a building is an important decision and a significant financial step, so it’s essential that you carry out due diligence before buying. This includes knowing heat pump sizes and which one is right for your home.

How to size a heat pump for your home is measured by the British Thermal Units (BTU) or tons.

Basically, BTU measures the heat output of an energy source. Thus, the BTU of your house heat pump denotes its amount of heating or cooling power.

On the other hand, a “ton” is an equivalent of 12,000 BTU. So a 2-ton heat pump is equal to 24,000 BTU, and so on.

When you install the right heat pump size for your house, you will enjoy maximum comfort through the year and save energy costs.

Ignore the Simple Heat Pump Sizing Rule

Shortcuts and rules of thumb around sizing a heat pump for a house should be ignored. Oftentimes, they are wrong rather than right. And this has worsened, especially as the first page of Google is now filled with different terrible opinions about how do you size a heat pump? Some of these wrong opinions are:

  • Multiply your living space square feet by 30.

  • Multiply your house square footage by 20.

  • Depending on your climate, multiply the square footage of your home by somewhere between 30 to 60.

  • Begin with 1 ton for the first 1,000 square feet, then include an additional ton for the following 500 square feet.

It’s important you know that every house needs are different, so there is no general rule of thumb or shortcut.

Importance of Picking the Right Heat Pump Size for Home

R290 heat pump

Source:SPRSUN R290 heat pump

In the world of HVAC (Heating, Ventilation, and Air Conditioning) systems, heat pump wholesale sizes matter. Thus, installing a heat pump unit that is undersized or oversized can be a problem.

Here are key reasons why the size of a heat pump matters:

  • Energy Efficiency: A properly sized heat pump operates efficiently, maintaining the desired in-house temperature without struggling. This minimizes energy consumption and reduces utility bills.

  • Comfort: Sizing a heat pump right ensures that there’s even heating and cooling distribution in your house. You will enjoy a consistent and comfortable indoor temperature. The heat pump won’t be going ON and OFF, meaning that a constant air inflow will be circulated throughout your home.

  • Durability: A correct size heat pump for a house experiences less stress and strain, resulting in reduced need for repairs. With little to no maintenance, your heat pump will last very long.

  • Environmental Impact: An efficient sizing heat pump for houses ensures that there are no harmful acts on the environment. For example, when the power generated by your R290 air to water heat pump is equivalent to the energy needed at home, the heat pump will consume less power. This results in lower greenhouse gas emissions, contributing to environmental sustainability.

What Happens If Undersizing a Heat Pump?

If the heat pump size for a house is too small, you will end up paying a higher utility bill because the heat pump system will continually struggle to work. Since it has used much energy in cooling or heating your home, there will be an increased energy cost, as well as a higher maintenance and repair cost.

Perhaps you’ve installed an undersized heat pump, you can manage it till you install the right size. Simply lower your thermostat to a temperature that your undersized heat pump can handle efficiently. Another alternative is to leave the heat pump at your desired temperature and allow it to use its electric resistance heater to make up for the undersizing.

Note that a heat pump’s electric resistance is not designed for continual usage. If used continuously, it causes wear and tear that can eventually damage the whole heat pump system.

What Happens If Oversizing a Heat Pump?

If you fail on how to size a heat pump for a house and end up installing an oversized heat pump, it will produce more energy than needed. This results in energy waste and undue costs.

Heat pumps operate more efficiently when running continuously in heating mode. They use variable-speed blower motors and compressors that automatically change the operation speed to meet your house demands. But if your heat pump is oversized, its lowest speed may be too fast for your current demand. This will make your heat pump go ON and OFF like a conventional heating and cooling system, resulting in more energy costs with zero to no comfort gain.

Bigger is Not Better for Heat Pumps Size

The goal is to match the demands of your home on the coldest or hottest days with the right heat pump. Therefore, when seeking for how big of a heat pump do I need, you should focus more on the maximum capacity of the heat pump and your home’s maximum heating and cooling needs.

NOTE: A higher heat pump capacity does not mean better efficiency. It just means higher costs if it’s oversized for your home needs.

Sadly, most homeowners are in this category. They focus more on how big a heat pump is, with the mindset that their best option is choosing a heat pump that exceeds their maximum house heating and cooling needs.

One of the reasons why this notion is rampant is because most HVAC equipment installers don’t take measurements. Banking on their years of experience and technical know-how, they recommend the heat pump to use. Whereas, every home need is different. Factors like, the size of the house, the numbers of people living in the home, and the number and location of the windows should be considered.

How to Size a Heat Pump for House

size heat pump

Source:SPRSUN EVI heat pump

Almost every HVAC installer will have a different solution when you ask: what size of heat pump do I need for my house? This is because there are different methods that can be used. But the most widely used methods on how to figure heat pump size for a home are the Square Footage and Manual J standards.

Square Footage

There are a lot of factors you need to consider before choosing the size of a heat pump for a house. This can become complicated when using the Manual standard. Fortunately, the Square Footage is a simpler method if you are not ready to handle complications.

Generally, every 500 square feet of your house requires 1 ton of heating and cooling. Here is a breakdown of how to derive at heat pump sizes for homes using this medium:

  • 500 square feet = 1 ton

  • 1,000 square feet = 2 tons

  • 1,500 square feet = 3 tons

  • 2,000 square feet = 4 tons

It’s crucial to know what each ton is in BTU, which is the primary measurement used for how to calculate heat pump size.

1 ton is equal to 12,000 BTU, so:

  • 500 square feet = 12,000 BTU

  • 1,000 square feet = 24,000 BTU

  • 1,500 square feet = 36,000 BTU

  • 2,000 square feet = 48,000 BTU

When you know your house's central heating pump sizing, you can start shopping for the right one. It’s imperative that you also work with one of the best heat pump manufacturers for additional advice.

Manual J

This is an industry standard, consisting of principles established by the Air Conditioning Contractors of America (ACCA). These principles are made as a guide for how to determine heat pump size using your home’s structural and thermal characteristics, such as:

  • Size of your home: The total square footage of your home is a major factor in choosing the fitting heat pump size. The volume of air the house can accommodate also matters, especially in houses with high ceilings since more space needs to be cooled or heated. Generally, larger homes require more heating and cooling capacity.

  • Layout of your home: Heat goes up to the sky, so homes that are structured horizontally tend to have a higher load than multi-story homes.

Also, the number of rooms and arrangement impacts how air circulates. For example, if you have a large open-plan living area, there will be better airflow. But if the layout of your home is small with enclosed rooms, you will need higher heat pump capacity for air distribution.

  • Numbers, size, and location of windows: More and larger-sized windows increase your heating load because they leak out heat fast, making cool air to enter. Also, the location of your windows can influence the amount of heat that enters into your home. The most efficient window placement is one that allows solar heat to enter the home in cooler months and reduces inflow of heat in warmer months.

Based on the sun’s positioning during the day, windows facing the south allow more heat into the house. Therefore, if your house has large windows facing the south, your heat pump will use less energy when heating, but more energy when cooling. With this, you can minimize the energy cost needed to heat and cool your house.

  • Insulation quality: Insulation is your house defense against outside temperature during winter and summer. A house with greater insulation has a higher heat retention value, thereby causing less workload on your heat pump. Thus, in a properly insulated house, you can use a smaller heat pump because it won’t require much energy to maintain the warmth of the home.

But some homes, especially older houses are terrible at keeping warm in winter because of poor insulation and air sealing. For these types of homes, you will need to install additional insulation. This will help on how to lower the energy bill in winter.

  • Air leakage: This is one of the most difficult factors to get accurately. Oftentimes, the derivation is based on an estimate. You need to answer questions like: how much air leakage (air infiltration) occurs in your house? Is your house cooler on windy days than calm days? Are there spaces or leakages in certain locations of your house?

After answering all these questions, if you discover that a significant amount of air from the outside flows into your home, you should get a larger heat pump system. This is because you will need more heating and cooling to be comfortable all through the year.

  • Local climate: Heat pumps are produced in different sizes and with varying capacities. But they are not designed to operate efficiently in very cold areas. Since they use low energy to move heat from the outside environment to indoors, they are best used in moderate climates.

Heat Pump in Cold Climate

Source:SPRSUN heat pump

It’s important you do your research to know the lowest annual ambient temperature in your area. If it’s an extremely cold location with a climate that’s typically below 10⁰ F to 25⁰ F, you may need to install an auxiliary heating system for premium comfort.

  • Ductwork for ducted heat pumps: According to Energy Star, about 20 to 30% of air that moves through the duct system of a typical home is lost due to leaks, holes, and badly connected ducts. Also, an undersized or poorly laid out duct system can restrict airflow, lowering the heat pump’s functionality. So, it’s essential you have a properly sized and connected ductwork to guarantee efficient air distribution.

  • Body heat and heat-generating appliances: The more people living in your home, the more body heat that will be generated. Homes with higher occupancy require heat pump sizing that cools more and produces less heat.

Also, heat-generating appliances like ovens, refrigerators, and computers contribute to the cumulative heat in the home. You should put them into valuation when considering the heat pump size.

  • Heat pump efficiency: There are different ratings used for heat pump efficiency. The Seasonal Energy Efficiency Ratio (SEER) measures the cooling efficiency, while the Heating Seasonal Performance Factor (HSPF) measures the heating efficiency. Heat pumps with higher ratings signify better capacity to meet high loads. This can influence the heat pump size and type you choose.

  • Preferred temperature: Your preferred temperature greatly determines the heat pump size you choose. While some people feel comfortable at a lower temperature, others need a higher temperature to be comfortable.

Note that setting the thermostat to higher temperatures increases the heat pump load, which can affect its efficiency. So, you need to choose a heat pump size for a house that can handle your preferences.

  • Number of people living in the house: The more people in your home, the warmer it gets. But commonly used places in the house will generate the most amount of heat and will in turn, require more air flow for cooling. This also has a significant impact on the size of a heat pump for houses. The occupants' daily activities, such as indoor workout, smoking, and other activities that cause an increase in heat should also be considered.

  • Shade and sunlight: The direction your house faces determines the amount of shade and sunlight it receives. Typically, homes facing the south receive more sunlight, helping to keep the house warm in winter. However, more cooling will be required in summer.

This can also be influenced by the landscaping around your home. Trees and shrubs provide natural shade, which blocks direct sunlight from entering into the house. Limited sunlight means you will have more cooling loads.

Heat Pump Size Calculator

This is an estimate of how to calculate the size of a heat pump based on the Square Footage, House Insulation, and Cooling/Heating Region.

Square Footage

To calculate your home’s heat pump square footage, simply multiply the length by the width.

If your ceilings are less or more than 8 feet, divide the figure by 8. Then, multiply it by the total square footage.

For example, if the length is 40, the width is 30, and the ceiling height is 7.5.

40 x 20 x 7.5/8 = 750 sq. ft.

House Insulation

The insulation of your house keeps the energy inside your home and ensures the energy outside doesn’t enter. There are 3 different levels of house insulation – Poor, Good, and Excellent.

  • Poor (1.2): You should rate your house insulation ‘Poor” if it’s 30 years or older, and you haven’t updated the insulation in the last 10 years.

  • Good (1): Rate your house insulation “Good” if it’s less than 30 years.

  • Excellent (0.8): Rate your house insulation “Excellent” if it’s less than 10 years old, or you’ve updated the insulation in the last 10 years.

Cooling/Heating Region

There are different cooling and heating demands for various regions. Choose the best cooling and heating condition that fits your region. Here’s a breakdown of the regions rating:

  • Region 1 = 1.3

  • Region 2 = 1.15

  • Region 3 = 1

  • Region 4 = 1.15

  • Region 5 = 1.3

Estimation: 750 sq. ft. x 1 (Good Insulation) x 1.15 (Region 2) = 862.5 sq. ft.

BTU: 862.5 x 25 = 21,562.5 BTU (approximately 2 tons).

Heat Pump Size Guide

Another approach to the heat pump sizing guide is to calculate the BTU from CFM or Tonnage.


Source:SPRSUN heat pump

Sizing a Heat Pump Based on CFM

You can calculate your heat pump BTU using the Cubic Feet per Minute (CFM) of your house. In a residential base, every CFM equals 30 BTU.

Here is a breakdown of how to derive at the BTU of a residential heat pump using this medium:

  • 1 CFM = 30 BTU

  • 100 CFM = 300 BTU

  • 200 CFM = 600 BTU

  • 400 CFM = 12,000 BTU

  • 500 CFM = 15,000 BTU

  • 600 CFM = 18,000 BTU

  • 700 CFM = 21,000 BTU

  • 800 CFM = 24,000 BTU

  • 900 CFM = 27,000 BTU

  • 1,000 CFM = 30,000 BTU

Sizing a Heat Pump Based on Tonnage

Another heat pump size guide you can use to calculate the BTU is Tonnage (ton). Each ton equals 12,000 BTU.

Here is a breakdown of how to derive at the BTU of a heat pump using this tons:

  • 1 Ton = 12,000 BTU

  • 1.5 Tons = 18,000 BTU

  • 2 Tons = 24,000 BTU

  • 2.5 Tons = 30,000 BTU

  • 3 Tons = 36,000 BTU

  • 3.5 Tons = 42,000 BTU

  • 4 Tons = 48,000 BTU

  • 4.5 Tons = 54,000 BTU

  • 5 Tons = 60,000 BTU


Are you still asking what size of heat pump for my house? These are estimates of the size of heat pumps ideal for different square footage:

1. What size of heat pump for 2000 sq. ft.

  • Each 500 sq. ft. is equal to 12,000 BTU.

  • Determine the BTU per square foot by dividing 12,000 BTU by 500 sq. ft.

  • 12000 BTU/500 sq. ft. = 24 BTU per sq. ft.

  • Then, calculate the total BTU heat pump size needed for 2000 sq. ft.

24 BTU per sq. ft. x 2000 = 48,000 BTU

2. What size of heat pump for 1800 sq. ft.

  • Each 500 sq. ft. is equal to 12,000 BTU.

  • Determine the BTU per square foot by dividing 12,000 BTU by 500 sq. ft.

  • 12000 BTU/500 sq. ft. = 24 BTU per sq. ft.

  • Then, calculate the total BTU heat pump size needed for 1800 sq. ft.

24 BTU per sq. ft. x 1800 = 43,200 BTU

3. Size of heat pump for 1500 sq. ft.

  • Each 500 sq. ft. is equal to 12,000 BTU.

  • Determine the BTU per square foot by dividing 12,000 BTU by 500 sq. ft.

  • 12000 BTU/500 sq. ft. = 24 BTU per sq. ft.

  • Then, calculate the total BTU heat pump size needed for 1500 sq. ft.

24 BTU per sq. ft. x 1500 = 36,000 BTU

4. What size of heat pump for 1200 sq. ft.

  • Each 500 sq. ft. is equal to 12,000 BTU.

  • Determine the BTU per square foot by dividing 12,000 BTU by 500 sq. ft.

  • 12000 BTU/500 sq. ft. = 24 BTU per sq. ft.

  • Then, calculate the total BTU heat pump size needed for 1200 sq. ft.

24 BTU per sq. ft. x 1200 = 28,800 BTU

5. What size of heat pump for 1000 sq. ft.

  • Each 500 sq. ft. is equal to 12,000 BTU.

  • Determine the BTU per square foot by dividing 12,000 BTU by 500 sq. ft.

  • 12000 BTU/500 sq. ft. = 24 BTU per sq. ft.

  • Then, calculate the total BTU heat pump size needed for 1000 sq. ft.

24 BTU per sq. ft. x 1000 = 24,000 BTU

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