Engineering & Knowledge

Pipe Insulation Guideline

Learn the essential standards and best practices for proper pipe insulation to maximize thermal efficiency and prevent condensation in engineering systems.

Refrigerant Piping – part2

Learn the critical steps and best practices for installing and maintaining refrigerant piping systems to ensure optimal HVAC performance and efficiency.

Pipe Pressure Drop Calculations: Essential Equations and Guidelines

Learn how to accurately calculate pipe pressure drops using essential equations and guidelines to ensure optimal fluid flow and system efficiency.

Sensible, Latent, and Total Heat

Master the core concepts of sensible, latent, and total heat to accurately analyze and design efficient HVAC systems.

Water Flow Rate Calculations in HVAC

Learn how to accurately perform water flow rate calculations to ensure optimal efficiency and performance in HVAC systems.

Refrigeration Expansion Valve Sizing and Selection Process

Proper expansion valve selection is critical for refrigeration system efficiency and reliability. This guide outlines the systematic approach to sizing and selecting expansion valves based

Refrigeration Evaporator Sizing and Selection

The evaporator is a critical component in any refrigeration system, serving as the heart of the cooling process. Proper sizing and selection of evaporators directly

Infiltration Rules Of Thumb

Learn the essential rules of thumb for calculating building infiltration to improve the accuracy of your HVAC load calculations and energy models.

HVAC Duct Design: Duct Fittings Friction Loss

Duct fittings friction loss represents critical HVAC design calculations that determine pressure drops through elbows, tees, transitions, and other directional changes within ductwork systems. Professional engineers utilize

HVAC Duct Design: Duct Round to Rectangular Equivalent

Round to rectangular duct equivalency represents a fundamental HVAC design calculation that enables engineers to convert between circular and rectangular ductwork while maintaining equivalent airflow characteristics and

HVAC Duct Design: Duct Friction Loss

Duct friction loss represents a fundamental HVAC design calculation that determines pressure drop through straight ductwork sections due to air friction against duct surfaces. Professional engineers utilize

HVAC Duct Design: Duct Pressure Classification

Duct pressure classification represents a fundamental HVAC design principle that establishes construction standards based on the operating static pressure within ductwork systems. Professional engineers utilize SMACNA pressure

HVAC Duct Design: Duct Sizing by Velocity & Noise Criteria (NC)

Duct sizing by velocity and noise criteria (NC) represents a fundamental HVAC design methodology that determines appropriate duct dimensions based on maximum acceptable air velocities and noise

HVAC Duct Design: Duct Sizing by Equal Friction Method

The Equal Friction Method represents a fundamental HVAC duct sizing approach that maintains constant pressure loss per unit length throughout the main duct runs, providing a systematic

HVAC Duct Design: Duct Sizing SMACNA Recommendations

SMACNA (Sheet Metal and Air Conditioning Contractors’ National Association) duct sizing recommendations represent fundamental HVAC design methodologies for calculating appropriate duct dimensions to deliver required airflow while

HVAC Ventilation Design: Staircase Pressurization + Relief Vent Sizing

Staircase pressurization and relief vent sizing represent critical life safety HVAC design requirements for maintaining protected egress routes during fire emergencies through systematic air pressurization and controlled

HVAC Ventilation Design: Tobacco/Smoking Area Ventilation Rates

Tobacco and smoking area ventilation represents specialized HVAC design requirements for controlling cigarette smoke, odors, and harmful contaminants to protect non-smoking occupants while accommodating designated smoking spaces.

HVAC Ventilation Design: Exhaust Air Ventilation By Rate and ACH

Exhaust air ventilation requirements represent essential design parameters for maintaining indoor air quality by removing contaminated air, moisture, odors, and pollutants from building spaces. Professional standards provide

Digital Tools & Resources

Ductulator and Pressure Loss (friction) calculator

Streamline your HVAC design process with our comprehensive digital Ductulator and Pressure Loss Calculator. This all-in-one tool allows you to instantly convert duct shapes, determine optimal sizing based on friction or velocity constraints, and accurately calculate total pressure loss and airflow rates for complex ductwork systems.

Air mixing calculator

Accurately determine the final thermodynamic state of combined airstreams. Input flow rates and air properties to instantly calculate mixed air conditions, streamlining AHU fresh-air and return-air mixing design.

Vapor pressure deficit (VPD) calculator

Optimize humidity control for HVAC, greenhouse cultivation, and agricultural drying. Use this Vapor Pressure Deficit (VPD) calculator to accurately determine moisture potential, enabling better transpiration rates, crop yield optimization, and precise environmental management.

Psychrometric state calculator

Instantly determine the complete psychrometric state of moist air using just two inputs. Enter dry-bulb temperature alongside any single humidity parameter to automatically calculate dew point, wet-bulb, relative humidity, enthalpy, specific volume, and density for precise HVAC design and analysis.

Plenum Box Size Calculator

Free online plenum box size calculator for HVAC engineers. Enter airflow (CFM or m³/h) and target velocity to instantly get recommended width, height, length, and depth for supply and return plenum boxes, based on ACCA Manual D sizing practice.

Expansion Tank Sizing Calculator

Size bladder, diaphragm, or plain-steel expansion tanks for closed hydronic systems in seconds. This calculator applies thermal-expansion and pressure-ratio principles from Steven T. Taylor’s ASHRAE-referenced sizing method and the ASME Boiler and Pressure Vessel Code, Section VI, to compute the minimum required tank acceptance volume for hot water, chilled water, and mixed-temperature systems. Supports US and SI units, all four major tank styles, an optional piping-expansion credit, and a built-in ASME/UMC/IMC cross-check for 170–230°F systems — with clear pass/warning/invalid status and next-step guidance for tank selection and precharge verification.

Fundamentals & Engineering