HVAC Design

Types

Window-Mounted These systems are affordable and can be easily installed in a partially open window. They do not require professional design or installation services, but they occupy window and floor space. They may vent some warm air back into the room and generate noise.

window-mounted-ac

Mini-Split, Split, Direct Expansion (DX) (Wall-Mounted, Ductless) These systems consist of one or more wall-mounted indoor units and a nearby outdoor unit. They are usually installed below a window within a sleeve cut into the exterior wall, providing efficient cooling and heating through a direct expansion refrigeration cycle. They provide zoned temperature control for individual rooms or zones without the need for ductwork. The indoor unit contains the evaporator coil and blower, while the outdoor unit houses the condenser coil and compressor.

ductless-mini-split hvac

Packaged Terminal (PTAC) (Wall-Mounted, Ductless) These systems are seamlessly integrated with the building’s hot water system, utilizing the circulating hot water from the boiler to generate radiative heat. This innovative design allows for efficient heating during colder months. Additionally, they incorporate a separate coolant chamber that delivers cool air. They are commonly found in hotels and apartment complexes, and are known for their compact size, ease of installation, and flexibility in temperature control.

packaged terminal hvac

Central (Ducted) These systems efficiently provide heating and cooling to multiple areas or zones within a building. Typically located in a mechanical room or basement, the central unit incorporates a furnace or boiler for heating, an air conditioner or heat pump for cooling, and a network of ductwork for air distribution. These systems are commonly installed in larger buildings, including commercial buildings, office complexes, schools, hospitals, and hotels.

central-hvac

Definitions

Air Filter Inspection Air filters are visually inspected to determine if they need replacing. A technician checks for any visible signs of dirt, debris, or damage. They examine the filter material, frame, and overall cleanliness. They assess the filter’s efficiency in capturing and removing airborne particles. This may involve evaluating the filter’s MERV (Minimum Efficiency Reporting Value) rating and determining if it meets the required standards for the specific HVAC system. They check the airflow through the filters to ensure it is not obstructed or restricted. They may use instruments to measure the pressure drop across the filters, which indicates if the filters are becoming excessively clogged.

Air Handlers (AHUs) AHUs draw in air from the rooms through return ducts, pass it through cooling or heating coils to regulate temperature and humidity, and then distribute the conditioned air back into the rooms through supply ducts. They also feature filters to effectively remove dust, pollen, and other particles from the air, improving indoor air quality. They are typically installed inside a building, usually in a mechanical room or basement.

Indoor unit Consists of the evaporator and blower in a large sheet metal enclosure. Positioned at the top plenum of the enclosure, you’ll find the “cold coil” evaporator coil. As the warm air passes over the evaporator coils, the refrigerant inside them absorbs the heat, enabling effective cooling and dehumidification. Located at the bottom of the enclosure, you’ll find a furnace and a blower. The furnace ensures that the conditioned air is appropriately heated by burning fuel (such as gas or oil) or using electricity to generate heat. Working in tandem with the furnace, the blower propels the heated air through the ductwork, distributing it evenly throughout the space.

Mechanical Piping Clearance To ensure your HVAC system meets code and prevent any potential hazards or interference you should verify that your mechanical and fire protection piping have sufficient clearance from electrical equipment, such as the evaporator and automation control boxes. You should prioritize safety by installing protective ducts or housings, commonly known as wire ducts or wire channels, made of PVC for the black wires to pass through, minimizing the risk of damage or electrical issues.

Outdoor unit Consists of the compressor, condenser, “warm coil” condenser coil, and fan. In the case of heating, the condenser functions as a heat pump. A heat pump can provide both heating and cooling capabilities. For heating purposes, a furnace can be employed as an alternative option.

Preventative Maintenance (PM) Should be performed on a regular basis to ensure the cleanliness and efficiency of coils. It is generally recommended to have PM performed at least once a year. This involves inspecting and cleaning the coils, checking and replacing air filters, lubricating moving parts, and inspecting electrical connections. By keeping the coils clean and free from debris or buildup, their ability to absorb heat from the indoor air, during a cooling process, before being circulated back to the living space ensures optimal HVAC performance.

Rooftop Units (RTUs) RTUs, as the name suggests, are installed on the roof of a building. These self-contained units house all the necessary components, including the compressor, condenser coils, evaporator coils, fans, and controls, in a single enclosure. They draw in fresh air from outside, condition it through the cooling or heating process, and distribute it directly into the building’s interior.

Zone A zone refers to a specific area or section within a building that is served by its own HVAC system. For optimal temperature control in a two-story home, it is recommended to have two separate AC units—one for each level. This allows you to achieve the best level of comfort and maintain consistent temperatures on both floors. Since the second level tends to experience higher temperatures than the first level, having a dedicated AC unit for each level ensures efficient cooling throughout the entire home.