Heating BTU Climate Zones

Understanding HVAC

The sizing of HVAC is still a general principle based on performance specs and outdated data. This has resulted in the disastrous prevalence of oversized systems in various homes. Also, it has caused increased noise levels, energy costs, and bad air quality.


Therefore, accurate sizing, installation, and design of HVAC systems require some improvement. This will play an important role in meeting the performance levels of modern homes. Best of all, it will meet the efficiency and comfort expectations of the occupants.

Before we get to the HVAC sizing, it’s good to have a basic understating of HVAC systems. So, let’s start from there!

The Purpose of HVAC Systems

HVAC (Heating, Ventilation & Air Conditioning) is a system that cools and heats buildings. This gives the occupants a healthy and comfortable living space.

However, this system does more than just controlling air temperature. As the name suggests, it has 3 main functions; heating, ventilation & air conditioning. The air conditioning and heating units control the temperature of indoor living spaces. On the other hand, Ventilation systems exchange or replace the air within a living space. This removes pollutants like smoke, odors, and bacteria to enhance indoor air quality.

These functions provide acceptable thermal comfort and indoor air quality. Also, the system controls the relative humidity and increases the building’s durability.

Heating Systems

Heating systems are available in various forms. Some come as furnaces that burn materials. These units provide hot air that’s distributed through duct pipes. Another popular option is boilers for steam radiators that heat water. There are also forced-water units. They include baseboard radiators, heat pumps, and electric heat. In general, a furnace operates on propane or natural gas. On the other hand, boilers heat the water using oil or gas. Heat pumps and furnaces replace the heat lost across the building.

A hydronic heating system or radiant floor is another option for heating living space. It involves the use of pipes under the floor. It’s made up of flexible pipes that are filled with glycol solution or water.

Heating System Design

Cooling systems/ Air conditioning

Like heating systems, there are many types of air conditioning/ cooling systems. For instance, there are can come as massive boxes that can cool the entire house. Also, there are portable systems that can handle short summers and cooler climates.

For dryer climates, however, most people prefer using evaporative coolers. They draw outdoor air into the unit and pass it through water-saturated pads. These pads moisten and cool the air, then push it into the living area to displace the hot air.

Apart from controlling the room temperature, air conditioning removes moisture as well. To do this, warm humid air in the living space is blown across the cold oil. This causes the water vapor to condense on the coil. It’s then collected and removed through the condensate piping system. However, you need to note this process is time-consuming. Also, if the system is oversized, the thermostat has to reach the setpoint before it removes moisture.

Cooling System Design


AC and heating systems are important in ensuring the comfort of your living space. But, as we stated earlier, they’re not the only units that make up the HVAC system. Besides, as you can see, there is the ‘V’ which stands for ventilation.

Ventilation refers to the source of clean, fresh air intake. This can either be air from within your home or from the outside. This process can happen in 2 different ways; natural ventilation and mechanical ventilation.

Many homes have easy access to natural ventilation. This is how air moves in and out of the buildings through vents, doors, windows, and other openings. This allows an exchange of air to remove excess moisture, odors and replenish oxygen.

HVAC systems, however, use mechanical ventilation. This involves the use of mechanical systems to move air in or out of the building envelope. Traditionally, most homes had plenty of natural ventilation. Unfortunately, many modern homes are tightly sealed. For this reason, ventilation is an important component in buildings’ HVAC systems.

Mechanical ventilation comprises an air handling device. The system draws air from outside or within the living space. The air passes through filters to remove allergens, dirt, dust, and other pollutants. Afterward, the air is either cooled to remove excess humidity or heat. When the fresh air attains a comfortable temperature, it’s directed into the living space.

The ventilation part comprises supply and returns vents, filters, fans, and ductwork. This system is also referred to as a forced-air unit. The circulating fan draws indoor air and forces it into the ductwork through the return vents. That air is cooled or heated by the devices and pushed into the living space through the supply vents. However, some air leaves through the exhaust system.

Overall, ventilation improves the air quality and comfort of the building envelope. Without adequate ventilation, the living space will experience health problems and comfort issues.


A basic HVAC understanding will help you determine the accurate sizing for any house. Remember, HVAC systems have different designs and sizes.

To get help or learn more about HVAC sizing, contact Innodez Design and Engineering. We’re a reputable HVAC service provider based in California for all your home’s comfort needs.

In the next blog post, we’ll talk more about the hazards of improper HVAC sizing. Check out the other articles in the HVAC sizing series by clicking the links below!

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