6 Tips for Choosing the Correct Heat Pump Size

If you’re having trouble with the heat pump in your Denver home, don’t hesitate to contact JC Mechanical for help. Call today!

A heat pump is a convenient HVAC component offering cooling and heating by removing heat from one source and transferring it to another. Still, not all heat pumps are equal. Getting the appropriate equipment for your home means knowing what heat pump size would be best to keep your residence cool in the summer and warm in the winter. 

Installing a heat pump too small for your home will force the system to work harder to regulate indoor temperatures, resulting in discomfort and higher energy costs. By that same logic, an oversized heat pump reduces efficiency and creates unnecessary energy consumption.

JC Mechanical is a top-rated HVAC company offering reliable heat pump maintenance in Denver, CO, so we know about selecting the right heat pump size for any home. If it’s time to upgrade or replace your heat pump, consider the following tips to ensure you choose the right size. 

1. Don’t Rely Solely On Your Home’s Square Footage

The size of your house will undoubtedly play a role in the ideal heat pump size, but it’s not the only factor. The general guideline for using square footage to size heat pumps is to grant one ton of air conditioning capacity for every 500 square feet. A ton equates to 12,000 BTUs or British thermal units, which is how the HVAC industry measures heat pump sizes or cooling capacities.

Here is a guide that shows what heat pump sizes should be according to square footage:

  • 500 square feet needs one ton or 12,000 BTUs
  • 1,000 square feet needs two tons or 24,000 BTUs
  • 1,500 square feet needs three tons or 36,000 BTUs
  • 2,000 square feet needs four tons or 48,000 BTUs
  • 2,500 square feet needs five tons or 60,000 BTUs

Ideally, you should be able to use the chart and your home’s square footage to determine the best heat pump size for your property, but that isn’t the best approach to equipment sizing. Though you should know your property’s square footage and account for it when looking for a new heat pump, it isn’t the only factor that affects the equipment’s size and functionality. 

2. Ignore Common “Rules of Thumb”

Many online calculators use common “rules of thumb” to help readers find the right sizes for their heat pumps, but they’re wildly inaccurate. For example, some calculators only rely on square footage without accounting for other contributing factors for heat pump sizing.

That means a 2,000-square-foot home would need a four-ton or 48,000-BTU capacity heat pump. However, a four-ton heat pump for a modern, airtight 2,000-square-foot home would be oversized compared to an older, draftier home of the same size.  

Other online calculators use formulas and shortcuts that don’t work for everyone. Examples of these so-called tips and tricks include:

  • Starting with one ton for the first 1,000 square feet and adding an extra ton for every extra 500 square feet
  • Multiplying the square feet of your home’s living space by 30
  • Multiplying the square footage total by ten to give 1,000 BTU per 100 square feet

Though these shortcuts account for a property’s square footage, they ignore air leakage, insulation, ceiling heights, and other factors. As a result, people who use these calculations will likely have an oversized or undersized heat pump, which could create problems like uneven temperatures, premature wear from overworked equipment, high utility bills, and wasted energy. 

3. Learn Manual J

The best way to find your home’s ideal heat pump size is to use Manual J. It’s the industry’s heat pump sizing standard that combines the following contributing factors to determine the equipment’s heating and cooling capacity:

  • Home size: Your home’s size includes its square footage and ceiling height. 
  • Home layout: Because heat rises, multistory houses tend to have a smaller load than ranch-style homes that spread horizontally.
  • Windows: The more windows your house has, the greater load your heat pump should have to make up for air leakage and sunlight. 
  • Insulation: If your property has excellent insulation, it will retain heat better, resulting in a lower load. 
  • Air leakage: A well-sealed home would need a lower heat pump load than a drafty residence. 
  • Local climate zone: Know the temperatures on your community’s coldest and hottest days to pick a heat pump that can accommodate those extremes instead of relying on the area’s average temperature. 
  • Number of household members and heat-generating appliances: People and appliances like washers, dryers, and dishwashers generate heat. You can expect your heat pump load to decrease if you have a larger household or many appliances. 
  • Preferred temperature: Every degree you increase or decrease on your thermostat can alter the load by several hundred BTUs. 

4. Use Data From a Blower Door Test

Aside from Manual J, you could assess your home with an energy audit to get a more accurate estimate for your heat pump size. Such an assessment includes the blower door test, which involves a contractor mounting a tarp with a powerful fan to the frame of your front door. 

When the fan blows, it pulls air out of the house to drop its interior air pressure. The change in pressure forces air to flow through unsealed openings, gaps, and cracks around the house that the contractor can detect using an infrared camera or other equipment. The data from the blower door test combines with other essential data to produce the property’s Manual J load calculation to size a heat pump accurately.

5. Don’t Assume a Bigger Heat Pump Is Better

The best heat pump size for your home is one that matches its maximum capacity with your property’s heating and cooling needs. Unfortunately, many assume that maximum capacity means a larger unit, but that’s not always true. Installing a heat pump or any HVAC system that’s too big for the property creates problems with efficiency and comfort. 

Since property owners tend to want bigger systems than they need because they think they’ll be more efficient, some HVAC companies end up installing systems with higher-than-necessary capacities. Regarding heat pump size, it’s better to err on the side of caution and go slightly smaller than to install an oversized system.

The Air Conditioning Contractors of America, the creators of Manual J, say it’s acceptable to understate Manual J load calculations by 10%. 

6. Get Several Size Estimates From Professionals

Determining heat pump sizes can be challenging for most homeowners, so it’s best to leave the job to professional HVAC companies with experience in sizing heating and cooling equipment. All companies have their calculation methods and levels of industry experience. Therefore, you should get multiple estimates from several contractors. 

If the estimates are similar, then it’s safe to assume the load calculations are accurate and most suitable for your home. At that point, you can choose your system according to the load capacity and efficiency rating and hire the best team. If the estimates vary, stick to the smaller model.

heat pump size

Trust JC Mechanical for Your Heat Pump Needs

At JC Mechanical, we have over three decades of HVAC experience helping Denver, CO, residents stay cozy indoors throughout the year. Our family-owned and -operated company can solve all heat pump problems, from determining which heat pump size is right for a home to repairing natural wear and tear to the equipment. 

Our skilled technicians offer 24/7 HVAC services, so call JC Mechanical at (720) 807-8953 today to request an appointment.

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