HVAC System Design

Single Wheel vs. Dual Wheel Energy Recovery in DOAS: A Technical Comparison As Dedicated Outdoor Air Systems (DOAS) become the standard for high-performance buildings, the configuration of energy recovery components has moved to the forefront of mechanical design. Specifically, the choice between a Single Wheel and a Dual Wheel system determines the unit's ability to manage latent loads and maintain precise discharge air temperatures without excessive reheat. The DOAS Challenge: Decoupled Loads The primary purpose of a DOAS is to handle 100% of the outdoor air ventilation load, decoupling the latent load (moisture) from the sensible load (temperature) handled by terminal units (VRF, Chilled Beams, or WSHPs). In humid climates, the latent load of outdoor air is the most energy-intensive component to treat. Energy recovery wheels (ERWs) are the first line of defense. 1. Single Wheel Configuration (Total Energy Recovery) In a standard single-wheel DOAS, a single Enthalpy W...

Grounding and Bonding Retrofits: A Technical Deep Dive for Existing Facilities In the lifecycle of any commercial or industrial facility, the electrical grounding and bonding system is often the most overlooked critical infrastructure—until a failure occurs. For existing buildings, specifically those aging past the 20-year mark, the degradation of grounding electrodes and the loosening of bonding connections pose severe risks ranging from equipment damage to life-safety hazards. This technical deep dive addresses the specific challenges of maintaining and upgrading grounding and bonding systems in existing structures, aligning with the National Electrical Code (NEC) Article 250 . The Core Distinction: Grounding vs. Bonding Before analyzing failures, we must enforce the technical distinction often blurred in field maintenance: Grounding (Earthing): Connecting the system to the earth to limit voltage imposed by lightning, line surges, or unintentional contact with higher-voltag...

Automating NEC 220 Load Calculations: Bridging the BIM-to-Electrical Gap In the modern MEP landscape, NEC Article 220 Load Calculations remain one of the most significant challenges for electrical engineers looking to optimize for design speed and code compliance . While Mechanical and Plumbing workflows have seen significant automation, electrical panel schedules and load summaries often lag, relying on disconnected Excel spreadsheets that create high-risk data silos. The Current State of Electrical Load Analysis Traditionally, an electrical engineer manually extracts square footage data and equipment schedules from Revit, inputs them into an external calculation spreadsheet, and then manually pushes the results back into Revit for panel schedules. This "broken loop" leads to several critical issues: - Data Mismatch : Revisions in architectural layouts (e.g., space usage changes) are often missed in the electrical model. - Demand Factor Errors : Incorrectly applying dema...

Mastering Commercial Kitchen Heat Loads: A Step-by-Step Engineering Guideline Calculating heat loads for commercial kitchens is one of the most complex tasks in MEP design. Unlike standard office spaces, kitchens involve high-density heat sources, massive moisture peaks, and complex airflow dynamics between exhaust and makeup air. This guideline provides a structured approach based on ASHRAE Standard 154 and Chapter 18 of the ASHRAE Fundamentals Handbook. 1. Categorizing Kitchen Appliances Before calculating loads, you must categorize every piece of equipment under the hood. ASHRAE defines four duty levels: Duty Level Examples Typical Exhaust Rate (CFM/ft) Light Duty Ovens, Steamers, Kettles 150 - 200 Medium Duty Griddles, Fryers, Ranges 200 - 300 Heavy Duty Charbroilers, Woks 300 - 400 Extra Heavy Duty Solid Fuel (Wood/Charcoal) 550+ 2. Calculating Sensible and Latent Heat Gain Appliances contribute heat via two pathways: 1. Convective Heat: Heat ...

The 5 Best Vacuum Pumps for HVAC Technicians in 2026 For any HVAC service technician, the vacuum pump is the most critical tool for ensuring a long-lasting, moisture-free system. 1. Fieldpiece VP87 (8 CFM) The industry gold standard with RunDry technology. - Check Price on Amazon 2. NAVAC NP4DP (4 CFM) Lightweight brushless DC motor for portability. - Check Price on Amazon 3. Yellow Jacket SuperEvac Plus II Rugged and pulls to 15 microns consistently. - Check Price on Amazon 4. JB Industries Platinum Series Made in the USA, built for extreme durability. - Check Price on Amazon 5. Robinair 15500 VacuMaster The best entry-level pump for budget-conscious pros. - Check Price on Amazon Conclusion Investing in a high-quality vacuum pump saves you hours on every job.

Balancing ASHRAE 62.1 with Energy Efficiency: The Case for AI-Driven Demand Controlled Ventilation The "Post-Pandemic" era of HVAC design has created a direct conflict for engineers: 1. Health Mandates: Maximize outdoor air intake to dilute pathogens (ASHRAE 62.1 / LEED v4.1). 2. Energy Codes: Minimize outdoor air conditioning load to meet Net Zero targets (ASHRAE 90.1 / IECC). Bringing in 100% outdoor air is the healthiest option, but in peak summer or winter, it is financially ruinous. The solution lies in AI-Driven Demand Controlled Ventilation (DCV) . The Flaw of Traditional DCV Traditional DCV relies on a simple CO2 setpoint (typically 1000 ppm). - The Problem: CO2 is a proxy for human occupancy, but it ignores other pollutants (VOCs from furniture, PM2.5 from outside, etc.). - The Result: Systems often under-ventilate when occupancy is low but chemical loads are high, or over-ventilate when the outdoor air itself is polluted (e.g., during wildfires). The AI S...