HVAC Engineering Knowledge & Practical Guides
Practical HVAC engineering articles on fan selection, airflow, duct design, pressure, motors, energy efficiency and building systems — with calculations, charts and real-world examples.
- Practical & real-worldFrom theory to application
- Data-driven insightsCharts, calculations & examples
- For engineers & manufacturersBetter designs and product data
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Energy Efficiency
Oct 21, 2026
How to Implement ErP 2026 in Fan Selection Software
See how ErP 2026 can be calculated dynamically from fan curves: automatic BEP detection, compliance checks, admin verification, product optimization and PDF generation for complete fan series.
Fan Performance
Oct 21, 2026
How to Estimate the Required Fan Airflow and Pressure
Learn how to estimate the airflow and pressure a fan actually needs — from room ventilation and heat loads to fume cupboards, paint booths and industrial extraction systems.
Product Data & PIM
Oct 21, 2026
How to Digitize a Fan Catalogue: From PDF Datasheets to Structured Engineering Data
Learn how to convert PDFs, Excel files, scanned fan curves, drawings and acoustic data into a structured engineering database for online catalogues, fan selection software, PIM and APIs.
Product Data & PIM
Oct 21, 2026
Fan Selection Software API vs DLL: Which Integration Is Better?
API or DLL? Both give other software access to the same fan selection engine, one from a server and one locally. How each works, what it means for updates, offline use, security and maintenance, and when an AHU program needs one, the other or both.
Product Data & PIM
Oct 21, 2026
How Much Does Fan Selection Software Cost?
There is no fixed price for fan selection software. What really drives the cost: product data quality, who prepares it, performance curves, drawings, acoustics, calculation modules, the admin panel and API or DLL integration, plus how to get a first estimate for your own catalog.
Product Data & PIM
Oct 21, 2026
What Is Fan Selection Software?
Fan selection software finds the fans that can meet a required airflow and pressure, using real performance curves. How it works, what it calculates (operating point, FEI, ErP, acoustics, energy cost) and what a good system includes, shown on the live CFB selection platform.
Product Data & PIM
Sep 16, 2026
HVAC Product Configurator vs Selection Software: What Does Your Business Need?
One customer arrives with a duty point, another with a product family and a list of options. How an HVAC product configurator differs from selection software, why a catalogue filter is not a selection engine, where CPQ fits, and how to scope a first release.
Fan Performance
Sep 16, 2026
Fan Array Explained: Fans in Parallel vs Series
Two fans rarely give twice the airflow. How parallel and series curves are built, where they meet a real system curve, and a worked example in which a second fan adds 26.5%, plus what happens when one fan stops, what N+1 really requires and how array noise adds up.
Product Data & PIM
Sep 8, 2026
How to Build a Fan Product Database: From Datasheets to Structured Engineering Data
Qmax changed for 120 models -- and now four systems disagree. Not a file problem but a modelling one: the hierarchy, attribute levels, units, curve storage and validation rules that let one edit reach every channel.
Fan Performance
Sep 7, 2026
Fan Noise Explained: Sound Power vs Sound Pressure and Octave Bands
A catalogue says 65 dB -- but of what? Sound power or sound pressure, weighted or not, at which duty point. A worked spectrum from octave-band sound power to an A-weighted total and an estimated level at a receiver.
Product Data & PIM
Sep 7, 2026
PIM for HVAC Manufacturers: One Source of Product Data for Websites, Catalogs and Selection Software
Manufacturers maintain the same product data in the catalog, the website, the selection program and the ERP -- and reconcile the differences by hand. How a PIM built for technical products replaces that with one source feeding every channel automatically.
Fan Performance
Sep 6, 2026
Backward-Curved vs Forward-Curved Centrifugal Fans: What's the Difference?
Same duty point, two different wheels -- and one of them is usually wrong for the job. Efficiency, non-overloading power curves, dirt tolerance and a worked lifecycle energy comparison between forward-curved and backward-curved centrifugal fans.
Fan Performance
Sep 6, 2026
AMCA 210 vs ISO 5801: Fan Testing Standards Explained
Two fans, similar specs, different curves -- usually not the fan, but the test. How installation type, pressure convention and air density reference determine whether AMCA 210 and ISO 5801 results are actually comparable.
Fan Performance
Sep 6, 2026
How to Select a Fan for High-Temperature Applications
Standard fans are rated for ambient air. This guide covers what actually changes above 100°C -- air density correction, bearing and drive selection, thermal expansion -- with a full worked example at 250°C and links to the calculators for each step.
Fan Performance
Sep 1, 2026
Axial vs Centrifugal Fan — Which One Should You Select?
Both fan types can often reach the same duty point -- the real question is which one reaches it at a better operating point. A technical, decision-focused comparison with worked numbers.
Fan Performance
Sep 1, 2026
AMCA 207 Explained: How to Calculate True Fan System Power (Not Just Motor Input)
Why "fan power" means five different numbers, how AMCA 207 splits air, shaft, motor and grid power apart, and a worked example showing exactly where the losses go.
Energy Efficiency
Aug 24, 2026
Common HVAC Design Mistakes That Increase Energy Consumption
Ten recurring design mistakes that quietly inflate running costs -- oversized fans, undersized ducts, ignored System Effect, throttling instead of VFD control, duct leakage, wrong motor selection and more -- with a real worked example of why cheap to install isn't cheap to run.
Airflow & Ducts
Aug 24, 2026
What Is a Good Air Change Rate for Different Types of Rooms?
What ACH means, the Q = ACH x V formula worked through a real example, typical air change rates for bedrooms, bathrooms, kitchens, offices, gyms, labs, warehouses and more, and why ACH alone isn't always the right design criterion.
Motors & Drives
Aug 24, 2026
How to Choose the Right Motor for a Fan
Shaft power vs motor power, how much safety margin actually makes sense, IE2 through IE5 explained, AC vs EC, direct vs belt drive, poles and RPM, DOL/star-delta/soft-starter/VFD starting, and why oversizing a motor quietly costs you at part load.
Airflow & Ducts
Aug 24, 2026
Static Pressure vs Total Pressure: What HVAC Engineers Need to Know
Static, velocity and total pressure explained simply, with Pt = Ps + Pv, how each is actually measured, a real duct-expansion worked example showing static regain, and why mixing up static and total pressure is a common source of fan-selection errors.
Fan Performance
Aug 24, 2026
Why Is My Fan Not Delivering the Expected Airflow?
A fan selected for 10,000 m3/h reads 8,200 on commissioning -- not a defective fan, a shifted operating point. System Effect, close-coupled inlet elbows, underestimated resistance, duct leakage, wrong RPM and density mismatch, with the operating-point chart and a diagnostic checklist.
Airflow & Ducts
Aug 24, 2026
How to Reduce Pressure Loss in HVAC Ductwork
Where duct pressure loss actually comes from -- friction versus local losses at elbows, tees, dampers and filters -- why diameter and velocity are the two biggest levers, and how bigger ducts trade capital cost for running cost, with a real component-by-component loss breakdown.
Energy Efficiency
Aug 24, 2026
How to Improve HVAC System Efficiency and Reduce Energy Costs
Where HVAC energy actually goes -- fans, heating/cooling, motors, pressure losses, dirty filters, oversizing, heat recovery, scheduling and setpoints -- and why fan speed control gives outsized savings thanks to the cube law, with a real before/after worked example.
Air Properties & Units
Aug 24, 2026
How Temperature and Altitude Affect Fan Performance
Why the same fan delivers different pressure and power depending on where and when it runs -- what air density actually is, why airflow stays constant while pressure and power scale with density, and how to correct a catalogue rating for a real site, with real density-vs-altitude and density-vs-temperature charts.
Fan Performance
Aug 24, 2026
Fan Efficiency Explained: η, FEG, FEI, SFP and ErP — What Is the Difference?
Five acronyms that all claim to measure fan efficiency, and why they can genuinely disagree about the same fan -- explained with one diagram showing exactly where each one draws its line across the power chain, plus a real FEG grade-band chart and a side-by-side comparison table.
Fan Performance
Aug 24, 2026
ErP 2026 for Fans: What HVAC Engineers and Manufacturers Need to Know
Regulation (EU) 2024/1834 is in force from 24 July 2026 and replaces the old ErP 327/2011 -- what actually changed, what the efficiency formula measures, and how to check a real fan against it, with the regulation's full required-efficiency curve.
Airflow & Ducts
Aug 24, 2026
How to Calculate HVAC Duct Size: Airflow, Velocity and Pressure Drop Explained
How airflow, velocity and pressure drop are all connected, why velocity is the number that actually drives noise and fan energy cost, and which of CloudAir's three duct tools to reach for -- with a real Colebrook-White pressure-drop curve and a worked round-vs-rectangular comparison.
Fan Performance
Aug 24, 2026
What Is Fan Energy Index (FEI)? A Complete Guide
What FEI actually measures, where the 'reference fan' comes from, and why it's now a legal minimum under ASHRAE 90.1-2019 and IECC 2021 that can block a permit if a fan doesn't clear it -- with a real worked example.
Motors & Drives
Aug 24, 2026
Motor Starting Methods Explained: Why That First Second Matters Most
What actually happens in the first second after you switch a motor on, why it can dim lights and stress belts and gearboxes, and how DOL, Star-Delta, Autotransformer, Soft Starter and VFD starting each trade speed for smoothness -- with real numbers from a worked example.
Building Physics
Aug 24, 2026
