If the whole VRF charge leaks into the smallest room, is the concentration still safe? Here is the five-step EN 378 check, a worked store-room example that fails, and the fixes that work.
Refrigerant Leak Safety to EN 378: The Smallest Room Check Read More »
The connection ratio tells you whether an indoor/outdoor combination is allowed, not whether it is big enough. Here is the conservative rule we design with and a full outdoor unit selection you can copy.
VRF Connection Ratio: How to Select the Right Outdoor Unit Read More »
The NFPA 13 spacing and location rules for standard-spray sprinklers in one place, from S × L protection area to obstructions, with a worked 15 × 24 m office layout.
Sprinkler Spacing Rules: Areas, Wall Distances and Obstructions Read More »
How to run a sprinkler hydraulic calculation by hand, from the most remote sprinkler to the supply, with a fully worked six-head OH2 example and supply check.
Sprinkler Hydraulic Calculation: A Step-by-Step Worked Example Read More »
A practical guide to NFPA 13 occupancy hazard classes, with typical design values, a repeatable classification method and a worked example of how the class drives tank size.
Sprinkler Hazard Classification: LH, OH1, OH2, EH1 and EH2 Explained Read More »
A practical workflow to turn one model space with many title blocks into correctly named layouts and PDFs, with a 24-sheet electrical set as a walkthrough.
How to Split a Multi-Sheet AutoCAD Drawing into DWG and PDF Files Read More »
Detector spacing is a distance rule, not an area rule. Here are the smoke and heat detector radii, corridor, beam and slope rules, the NFPA 72 equivalents and a full office floor counted step by step.
Smoke Detector Spacing (and Heat Detectors): Practical Rules Read More »
A practical guide to the psychrometric chart for air handling unit design: reading the seven properties, the room SHR line, mixing, coil ADP and bypass factor, fan heat, humidification and a full summer worked example.
Psychrometric Chart for AHU Design: Mixing, Coils and Reheat Read More »
How to measure phase unbalance on a distribution board, why boards drift out of balance, and a minimal-change method that fixes most panels with one or two swaps.
Phase Balancing in Panel Schedules: Measure and Fix Unbalance Read More »
Five checks for choosing an MCB, from rating and curve to breaking capacity, and what discrimination between MCBs can and cannot achieve, with a worked example.
MCB Selection and Discrimination: A Practical Design Guide Read More »