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The Magic Number in Geothermal

Understanding the Heating & Cooling Calculations



Working in an industry for decades, we know a lot about heat and cool gain. It is at the core of our business – which it to provide you with the best geothermal designed heating and cooling system for you. The heat load number is the single most important number to us when designing your geothermal system. Heat loss, measured in kW or BTUs, reflects the total transfer of heat through the fabric of the building from the inside out. Knowing what heat loss and heat gain is, how to reduce it, and what it means will help to answer many questions about the internal building environment.


How Do you Find Your Heat & Cool Load?

An engineered Manual J load calculation is a vital prerequisite to determining your heat loss number. “Sizing” in HVAC terms refers to matching the BTU capacity of a particular unit to the specific thermal requirements of your home, known as the cooling and heating “load.”


Rough “guestimates” are not good enough. In fact, rough estimates can severely hinder and misguide you. This, in turn, will not only cause future headaches, but could cost you thousands of dollars more in inefficiencies.

Get it Right the First Time

King Energy, LLC will conduct an engineered Manual J calculation load on your unique building. This is the only way we can be assured we size your geothermal system to the best efficiency and comfort. Oversized units—with too much capacity for the structure—waste energy and also typically provide loud and poor cooling or heating performance. Conversely, undersized units, run almost non-stop to meet thermostat settings, boost monthly operating costs and are also subject to excessive wear and tear and early component failure.



Calculating Your Heat Load

King Energy will perform an Engineered Manual J load calculation which involves a close inspection of the house. If you are building new, we will need PDF’s of your final plans. Data gathered is entered into a computer running load calculation software specific to the geothermal industry. For instance, some data points needed include:

· Geographic location of the house

· Preferred indoor temperatures

· Local climate data

· Orientation of the structure and hours of daily solar exposure

· Accurate square footage of all floors

· Number and type of windows, doors and skylights in the house

· Air-tightness of the structure and amount of air infiltration

· Condition and size of ductwork (if existing, if not, a duct work design is conducted)

· Special features of the home (i.e. plants, solariums, vaulted ceilings, fans, concrete slabs)

· Heat producing appliances and lighting types

· Location, amount, and type of insulation

· Number and age of occupants


Once the data and floor plans are input, the software calculates your specific cooling and heating load expressed as an exact BTU per hour number – voilà, the Magic Number.


The magic number looks like this



We include this number in all of our proposals so you can be assured we performed our job. Providing you with these numbers is important because it demonstrates what will make your home comfortable. We need to have confidence that your investment into a geothermal heating and cooling system is going to perform well.


There is a ton of information on what a Manual J is, check our Information out in, News and Resources page to Dig Deeper.


After the Magic

After the “magic” heat load and cool gain number is calculated, there is still work to be done to narrow in on the exact cost of your geothermal system.


King Energy then conducts a Manual S (Heating and Cooling Sizing and Selection) which allows us to select the proper equipment for your specific job.


Sizing is critical to your cost.

We use in depth technical performance data for all of our equipment. We use only the best that the industry has to offer. We stand by our equipment, Hydron Module manufactured by Enertech – the leader in bringing energy and technology to the geothermal heat pump industry. (Learn more about Our Equipment here)


Manual T or Air distribution basics are then run. This shows us, in step-by-step detail, how to select, size, and locate the supply air diffusers, registers, and the return grilles for your system. Using our manufacturers comprehensive performance data we can calculate pressure losses, and control for noise to ensure the best design.


After running a Manual J calculation, Manual T helps to answer questions like: Where will supply and return registers go? What type of grills, vents, or diffuser will be used? Manual T calculations improve the airflow in your home so you aren’t getting drafts or inadequate airflow. Manual J might be able to calculate proper conditioned air levels, but if the airflow is weak, the air will feel stagnant and uncomfortable.


Finally, King Energy will run a Manual D-Heating and Cooling Duct Design to properly size, design and install duct systems for your home. Ductwork design is extremely important to prevent air and energy leaks, in addition to humidity and moisture problems. Poor ductwork design can seriously affect your comfort and indoor air quality.


Manual D includes information for determining the best duct design for the available space, including how to properly size, seal, and insulate air ducts.


Your Investment

Installing a geothermal system is an investment into your home and future. It clearly demonstrates your commitment to reducing your carbon footprint. It is not a cheap, nor easy endeavor, but it is a smart one. King Energy believes in doing it right the first time, and taking the time, with you, to educate and share our passion for the best geothermal system.



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