Business
Pricing, margins, hiring, pay and operations for HVAC contractors, built from federal business, wage and enforcement data rather than vendor surveys.
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HVAC Vacuum Pump: How Many Microns, How to Pull a Vacuum and the Decay Test
An HVAC vacuum pump removes air, nitrogen and moisture before a system is charged. What Carrier, Daikin, Mitsubishi and Copeland documents require, why 500 microns, the decay test,…
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Server Room Cooling: Temperature Range, BTU Sizing and the Right System
How to size and run server room cooling from primary sources: ASHRAE’s recommended inlet range, watts to Btu/h arithmetic for a 5 kW rack, system options and what…
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Building Automation System (BAS): How It Works, Who Has One, Savings and Cost
A building automation system runs a commercial building’s HVAC from one network. Our EIA CBECS tabulation shows who has one by building size, plus PNNL measured savings, BACnet,…
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Manifold Gauge: How to Read and Hook Up HVAC Gauges, and What EPA 608 Requires
A manifold gauge reads both sides of an AC system. Here is the hook-up order, a worked R-410A and R-454B reading, analog vs digital specs, and the 40…
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VAV Box: How Variable Air Volume Boxes Work, Types, Minimum Airflow and Reheat Rules
A VAV box meters air from the air handler into one zone. How pressure-independent boxes measure airflow, the box types, what PNNL and ASHRAE 90.1 say about minimum…
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HVAC Transformer: 24V Control Power, VA Sizing, Testing and Why It Blows
The 24 V control transformer explained from maker documents: what 40 VA really carries, how technicians test it, and why a transformer or board fuse that keeps blowing…
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HVAC Apprenticeship: Hours, Pay Schedules and How to Get In
How long an HVAC apprenticeship takes, what it pays, and how union and non-union routes compare, using registered program standards, 29 CFR 29.5 and BLS May 2025 wage…
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HVAC Certification: What Is Required, What NATE Involves, and the Order to Earn It
Only EPA Section 608 is a federally required HVAC certification. We compare NATE, HVAC Excellence, manufacturer training and state licenses on exams, experience and renewal, using the issuers’…
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HVAC Tools List: What Each Tool Does and the Rule or Manual That Requires It
A tiered HVAC tools list for apprentices and journeymen, with each tool tied to the EPA, OSHA or manufacturer requirement that makes it necessary.
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Who Makes Which HVAC Brands? The 2026 Ownership Table, Sourced to Filings
Eight parent groups own or license 48 US residential HVAC brand names. Every row traces to a 10-K, release or brand-site legal line, including the Bosch and Rheem…