Choosing the right size system is crucial if you’re shopping for a new HVAC system for your Las Vegas, NV, home. If you select a system that’s too small, it will struggle to maintain your comfort. Choosing one that’s too large will waste energy and cause unnecessary wear and tear. A home heat load calculation is the key to sizing an HVAC system. It lets you know exactly how much heating and cooling capacity your home requires. Here’s everything you need to know about heat load calculations and how HVAC technicians perform one.
What Is Heat Load?
Heat load describes how much heat you need removed or added to a space to keep it comfortable. Your home’s heat load is a product of various factors, including location, construction, and usage. HVAC technicians use a detailed guide called Manual J to gather the necessary data and calculate your home’s heat load.
What’s an Average Heat Load?
The average home in Las Vegas requires approximately 30 to 35 BTUs of heating capacity per square foot. That’s because we’re in a warm climate that experiences few sub-freezing days yearly. However, the extreme heat we see in the summer means we have higher AC BTU requirements. To stay cool, your home will need 40 to 45 BTUs of cooling capacity per square foot. If your home is on the outskirts of Las Vegas, those requirements could rise to as high as 60 BTUs per square foot.
How to Estimate Your Home’s Heat Load
Although you can’t perform a precise heat load calculation yourself, you can create a reasonable estimate. The following steps will show you how.
Calculate Your Home’s Square Footage
Your first step is calculating the total square footage of your home. To do that, multiply the length and width of every room. Then, add each room’s total to reach your home’s square footage. You should leave out any spaces that your HVAC system won’t serve. So, unfinished basements, crawl spaces, and attics shouldn’t be a part of your calculation.
Factor in Your Average Ceiling Height
Next, you must account for the total volume of the rooms you’re trying to heat and cool. That means accounting for ceiling height. You can use average ceiling height to compute your heat load estimate. Just measure all your ceiling heights, add them, and divide by the number of rooms. Then, multiply your home’s square footage by your calculated average. The result is the approximate volume of the space you need your HVAC system to serve.
Estimate Interior and Exterior Temperature Differential
Now that you know how much space your HVAC system needs to heat and cool, you can next consider temperature. Specifically, calculate the maximum differential you want the system to achieve between interior and exterior temperatures. Most HVAC companies size air conditioners for between 20 and 30-degree differentials. For furnaces, they aim for approximately 40-degree differentials. When you settle on a desired differential, multiply it by your home’s volume.
Factor in Building Air Envelope
Finally, you must account for the quality of your home’s air seal. When you run your HVAC system, your home should retain most of the conditioned air. To account for that, multiply your running total by .135. That conservative figure represents the quality of the average home’s air seal. Yours may perform slightly better or worse. The resulting number will tell you, in BTUs, the approximate size of the HVAC system your home requires.
Why a Manual J Calculation Is More Precise
Professional HVAC technicians can produce a more precise heat load calculation for your home. They use Manual J, a guidebook created by the Air Conditioning Contractors of America. The book contains a more complex and inclusive heat load formula. It also includes BTU figures for virtually any aspect of your home that impacts heat load.
A Manual J calculation analyzes more comprehensive details about your home, including:
- Quantity and quality of insulation
- Orientation relative to the sun
- Local climate
- Major appliances
- Space usage
- Duct leakage
- Number of residents
A Manual J calculation usually yields a lower heat load figure than a DIY estimate. That reflects the specificity of the BTU values contained in Manual J. Those figures replace the generalized assumptions used in the DIY estimation process. Plus, a Manual J calculation uses specific baseline capacity requirements. It specifies an AC system that can keep your home at 75 degrees during summer. It also specifies a heating system that can keep your home at 70 degrees in the winter.
Qualified HVAC technicians can perform a thorough Manual J calculation in as few as 15 minutes. All they need is access to the relevant parts of your home. They’ll typically use a customized calculator to enter your home’s data and output the results.
The Value of a Manual J Calculation
At this point, you may wonder if a Manual J calculation on your home is even necessary. After all, your home has an existing HVAC system, so you can swap it for one with identical capacity, right? Unfortunately, that’s rarely a good idea. One reason is that you can’t know if your existing system is the right size. If it isn’t, you could be making an expensive mistake. Plus, various factors affecting your home’s heat load may have changed since your system’s installation.
If your home has undergone renovations that altered its physical characteristics, its heat load changed. That includes kitchen updates, new windows and doors, or insulation upgrades. Also, the climate here in Las Vegas has changed over the years. An explosion in development has altered the landscape and created heat island effects. In some areas, it’s as much as seven degrees warmer, on average, than 30 years ago. That almost guarantees your home needs more cooling capacity than it once did.
Deterioration of your home’s ductwork is another factor a new Manual J calculation will account for. Over time, small air leaks can sap your HVAC system’s heating and cooling capacity. The evaluation process includes thorough duct leakage testing. The technician may recommend repair work if your ductwork leaks beyond expected levels. Improved duct sealing and insulation may lower your home’s heat load. That can save you significant sums by reducing the capacity of the HVAC equipment you need to buy.
Local HVAC Sizing Experts
If your Las Vegas home needs a new HVAC system, you need a Manual J calculation performed first. Bumble Breeze can handle that by sending one of our expert HVAC technicians to your home. With your specific needs in mind, we can recommend multiple HVAC options. We sell and install central AC systems, heat pumps, boilers, furnaces, and ductless HVAC units. Plus, we carry the latest systems from quality manufacturers like Goodman, Amana, and Daikin.
We can also help you with your home’s plumbing and indoor air quality needs. We have various qualifications that guarantee we can handle your installation as well. We hold a C21 Business License and are members of the NFIB and SNARSCA. We’re also Better Business Bureau-accredited with an A+ rating.
So, for a correctly sized HVAC system for your Las Vegas home, call Bumble Breeze today!
