HVAC BROS

HVAC Design Engineer Interview MCQs – Answers & Explanations HVAC Design Engineer Interview MCQs – Answers & Explanations A curated set of 75+ advanced questions covering fundamentals, loads, duct/piping design, hydronics, VRF, controls, energy, codes, acoustics, and commissioning. Fundamentals and thermodynamics 15 questions 1. What is the primary law governing heat transfer in HVAC systems? a. Newton’s Law b. Pascal’s Law c. Fourier’s Law d. Bernoulli’s Law Answer & explanation Answer: c. Fourier’s Law. Governs conductive heat transfer, central to envelope and insulation calculations. 2. Which type of heat changes the temperature of a substance without changing its phase? a. Latent heat b. Sensible heat c. Hidden heat d. Specific heat Answer & explanation Answer: b. Sensible heat. Used in sensible ...

Complete HVAC Formula Guide — expanded sections, worked examples. Contents Cooling and heating equations R‑values and U‑values Water system equations (hydronic) Air change rate (ventilation) Mixed air temperature (air mixing) Ductwork equations and equivalent round size Fan laws Pump laws and NPSH Condensate, humidification and humidifier heat gain Expansion tanks (hydronic) Air balance and economizer mass balance Efficiencies, COP and EER Cooling towers and heat exchangers (range/approach) Moisture condensation on glass (surface temperature) Electricity (power calculations) Transient heating (loading docks / vestibules) Refrigeration room ventilation (refrigerant leak control) Flat‑oval duct formulas and equivalent diameter Pipe expansion allowances (L, Z, U loops) Steam and condensate (mass & pipe sizing) Psychrometrics (humidity ratio, enthalpy) Pools and domestic water heater sizing Relief valve sizing and venting rules Steel pipe geometry & unit...

📐 HVAC Duct Sizing Methods: Imperial & Metric Guide for Engineers Learn how to size HVAC ducts using Equal Friction, Velocity Reduction, and Static Regain methods. Includes formulas, velocity benchmarks, and ASHRAE-compliant tips in both Imperial and Metric systems. 🔍 What Is HVAC Duct Sizing? Duct sizing determines the dimensions of air pathways that deliver conditioned air throughout a building. Proper sizing ensures: Adequate airflow (CFM or L/s) Acceptable velocity (FPM or m/s) Minimal pressure loss Energy-efficient fan operation 📊 Common Duct Sizing Methods 1. Equal Friction Method Used for: Residential and commercial systems Goal: Maintain a constant friction rate across all duct sections Steps: Choose a friction rate: Imperial: 0.1 in.wg per 100 ft Metric: 0.8 Pa/m Use Ductulator/ Mcquay Duct Sizer or charts to find duct size for each airflow rate. Apply the same friction rate throughout the system. Formula: Imperial: Friction Loss = (Total...

  🌀 Download McQuay Duct Sizer for Free – A Handy Tool for HVAC Designers If you're an HVAC engineer , technician , or student working on duct design , you've probably heard of the McQuay Duct Sizer —a classic utility that simplifies duct sizing calculations with just a few clicks. In this post, I’ll walk you through what it is, how it works, and how to download it for free (legally and safely). 🧰 What Is McQuay Duct Sizer? The McQuay Duct Sizer is a lightweight Windows-based tool developed by McQuay International (now part of Daikin ). It helps HVAC professionals quickly size air ducts based on airflow, velocity, and friction loss. 🔑 Key Features: Calculates duct dimensions based on CFM and friction rate Supports both round and rectangular ducts Easy-to-use interface with instant results Ideal for quick field calculations and design checks 🎯 Who Uses It? HVAC design engineers Drafting professionals Students learning duct design Contractors verifying ...

  🏗️ CarerHAP 4.9 (Free Download) HAP (Hourly Analysis Program) is a software developed by Carrier Corporation to assist HVAC professionals in designing systems and analyzing energy performance. Version 4.9 , released in the early 2000s, became widely adopted for its reliability, simplicity, and dual-purpose functionality. 🕰️ A Brief History of HAP Initial Release: HAP was first introduced in the late 1990s as a successor to Carrier’s legacy design tools . Version 4.9: Published around 2003 , this version refined the interface and added deeper integration with ASHRAE standards . Legacy Impact: Though newer versions like HAP v6 exist today, v4.9 remains popular in many firms due to its lightweight setup and proven accuracy. 🔧 Key Features of HAP 4.9 Dual Functionality: Combines HVAC system design and energy modeling in one package. Hourly Load Calculations : Uses detailed hourly weather data to simulate building performance. ASHRAE Compliance: Aligns wi...

🚀 Career Options After B.Tech/Diploma in Mechanical Engineering Mechanical engineering is one of the most versatile and evergreen branches of engineering. Whether you've completed a B.Tech or a Diploma , your foundation in mechanics, thermodynamics , materials science , and design opens doors across industries. Here's a comprehensive guide to help you explore your career options and choose a path that aligns with your strengths and aspirations. 🏭 Core Engineering Roles These are traditional mechanical engineering jobs that leverage your technical knowledge: Design Engineer : Use CAD tools like AutoCAD , SolidWorks , or Revit to design mechanical components and systems. Production Engineer : Oversee manufacturing processes, optimize workflows, and ensure quality control. Maintenance Engineer : Responsible for the upkeep and troubleshooting of machinery in factories or plants. HVAC Engineer : Design heating, ventilation, and air conditioning systems for residentia...