HVAC is an abbreviation for heating, ventilation, and air-conditioning. It is an integrated system carrying out all of the above mentioned functions and more often than not, designed to be controllable through a single interface. Modern HVAC systems include an air filtration and cleaning element in addition to those mentioned above.
The most common way HVAC systems cool your home is through a central air conditioning system, which is often used in conjunction with forced air systems for heating. The HVAC system is also responsible for keeping your home well-ventilated. Ventilation can either be forced or natural. The ventilating part of the HVAC system controls moisture levels, removes unwanted smells, and prevents stagnation of air due to passage of time.
HVAC systems are essential parts of every residence. A properly designed and installed HVAC system can be much more effective, both cost and energy-wise. It means that in the long run, the system will be more reliable, easier to maintain, and fully optimized to your requirements.
Design
Before exploring the three types of heating and cooling loads, it is important to first outline the difference between two terms that are easy to confuse: load and capacity. Heating load refers to the amount of heating or cooling a building needs, while heating capacity is the amount of heating or cooling an HVAC appliance can provide. HVAC systems must be sized to satisfy three different kinds of loads: design load, part load and extreme load.
Design Load
Design load serve as a guide for HVAC professionals. The load typically includes details of the home that do not fluctuate such as the layout of the building, insulation levels, its overall energy efficiency and its orientation to the sun.
Part Load
For the majority of the day, and throughout the year, heating and cooling loads fall below the design load. This means that properly-sized equipment may cycle on and off, which can hinder energy efficiency, humidity control, and comfort. So more often than not, an HVAC system is required to run at partial load.
Extreme Load
As the name implies, the extreme load occurs when experiencing extreme weather conditions, that is the hottest and coldest temperatures at any given location. However, since there is often a buffer built into the load calculations, extreme loads rarely occur.
Equipment Selection
Once the heating and cooling loads have been calculated, the HVAC equipment can be selected. If the system is over or undersized, it will waste energy, underperform, and increase utility costs for the homeowner. Therefore, accurately calculating heating and cooling loads, in addition to selecting adequate appliances are essential part of every HVAC design. While selecting the equipment factors like capacity, efficiency, durability and noise level should be considered.
Duct Design
Another important part in an HVAC design is the duct design. The air distribution system should be designed in way to ensure the house gets the right amount of heating and cooling delivered to each area. Ductwork that is improperly sized can cause uneven air distribution and introduce dust or mold into a house. Designing a good distribution means looking at a lot of variables such as placement of supply and return vents, location of HVAC equipment and framing obstructions.
If installed correctly, an accurate and proper HVAC design will reduce energy usage without compromising health and safety of the individuals living in the house.
Installation
Once the design is complete, it is time to install. A well-designed system can still be ruined with improper installation. It is important to work with a contractor who employs experienced and licensed technicians. The contractor should know how to safely install HVAC systems according to manufacturer instructions. A professional installation includes a thorough inspection of the duct system. Installing an energy efficient system without making sure the ducts are properly sealed is futile. Additionally, the type of material and fittings used can significantly affect the performance of an HVAC system. Modifications to the ductwork including changes to duct sizes as well as the number and locations of registers/grilles must be coordinated with the design engineer in order to prevent issues with the air circulation in the house.
