About HVAC System Designs

PE Load Calcs designs Residential & Commercial HVAC systems.

HVAC design services provided:

• Load Calculations (Manual J, N, ASHRAE CLTD, RTS)
• Thermostat Location & Zoning Strategies (Manual Zr)
• Equipment Sizing & Selection (Manual S)
• Terminal Selection & Location (Manual T, ASHRAE ADPI)
• Duct Sizing & Design (Manual D, Q, ASHRAE)
• Mechanical Ventilation Requirements & System Design (ASHRAE 62.2)
• Indoor Pool & Spa Equipment Sizing & Selection (Manual SPS)
• Nationwide HVAC System Designs

Some common HVAC system design flaws:

• Improperly sized equipment: undersized equipment will not heat or cool the building enough on hot or cold days. Oversized equipment will cost more upfront and cost more to operate. In addition, oversized equipment will short cycle causing wear, poor air distribution and filtration, and higher room humidity.
• Poor duct design: poor duct layouts can be very restrictive to airflow. Less airflow means less heating/cooling to a room and less return air for the equipment to run efficiently. The same is true for undersized ducts. A duct layout can appear to look nice but if it was not truly designed (i.e., engineered), it can still be too restrictive.
• Random grille selection and placement: finding any grille to fit a hole in the wall may not seem like a big deal, but choosing a grille that does not take into account the quantity of airflow, the room size and the manufacturer guidelines is be a very big deal. This means noisy supplies and returns, reduced airflow, poor mixing between room air and supply air, drafts, all causing discomfort.
• Overlooking thermostat(s) location and zoning: there can be several reasons why some rooms are hotter or colder than others. However, an engineered design will minimize room-to-room temperature differences, determine the optimal location for the central thermostat, and can also determine any incompatibility where two or more thermostats are recommended (i.e., zoning). Zoning, an option in most residential designs, will give the occupants better temperature control and may reduce operating costs when using temperature set-back controls.
• Advanced air filtration after-thoughts: HEPA’s, electronic air cleaners, and high-efficiency filters are great products to have. However, they do create a significant amount of resistance to airflow. If these advanced filtration systems were not integrated in the initial design, the airflow through the equipment, and hence the heating/cooling efficiency, will be reduced. These afterthought accessories will reduce the equipment efficiency and may also cause the equipment to be shut off by their safety control, regardless of the thermostat setting.

Defining the HVAC system

It is often assumed that the HVAC system is just the equipment (furnace, air conditioner, heat pump, etc.), but that is not correct. The equipment is just a part of the system. The HVAC system is the entire system, which includes the equipment, ductwork, grilles, thermostats, dampers, air filters, coil, blower, the refrigerant, etc. When all these components comes together, it’s what makes the HVAC a system. If any one of these components has been improperly selected or installed, there will be system penalties and potentially big issues that can be difficult to diagnose after installation.

A complete HVAC system design is an engineered design that includes:

1. A detailed and accurate load calc of the building.
2. Proper thermostat location and/or zoning based on load calcs.
3. Equipment sizing and selection based on the load calcs, zoning method and expanded engineering performance data.
4. Duct design (layout & sizing) based on the equipment and accessories selected.
5. Terminal selection & location from grille/register/diffuser engineering data.
6. Duct layout, air volume balance report and bill of materials.

About the Designer

Anthony Amadio, designer and owner, has his bachelors and masters in mechanical engineering, and his professional engineering license (Alabama, Arkansas, Connecticut, Florida, Georgia, Illinois, Louisiana, Michigan, Mississippi, Tennessee, Texas, and Utah). As a student, his specialty and research were in the subjects of thermodynamics, fluid flows, heat transfer, and combustion with applications in gas turbines and propulsion. In addition to his graduate research, he has over 8 years technical design experience ranging from jet engine blade cooling, compressor blade aeromechanical design, high temperature structural equipment and hot gas flow piping designs. Beginning in 2009, Anthony took an interest in the HVAC thermal sciences due to the similarities with his current work. He purchased the ACCA design manuals and ASHRAE handbooks to read, study and apply. He is ACCA certified in Residential & Commercial HVAC System Designs, ASHRAE Levels I & II HVAC Designs, Diagnostic Energy Tests (DET), Wrightsoft trained, and was a faculty member at the College of DuPage where he taught HVAC courses in load calculations, equipment selection, duct design, and airflow measuring and balancing.