Equipment
Heat pumps, furnaces, air conditioners, boilers and water heaters: how they work, what they cost, how long they last and which efficiency standards apply.
-
Spiral Duct: Leakage Classes, Code Tests, Gauges and Double Wall, Explained
Spiral duct is round sheet metal duct with a helical lock seam. DOE figures put sealed round duct at half the leakage class of rectangular; here are the…
-
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,…
-
Duct Board: R-Values, UL 181 Rules, Fabrication and Fiberglass Safety Explained
Fiberglass duct board explained from maker data sheets, the NAIMA standard and code text: R-value by thickness, UL 181 limits, closure rules, where it is banned and what…
-
Filter Drier: What It Does, Liquid Line vs Bi-Flow, and When to Replace It
A filter drier traps moisture, acid and debris before they reach the metering device and compressor. Sporlan, Danfoss and Copeland data on types, clog signs, sizing and replacement,…
-
Walk In Cooler: How It Works, Temperature, DOE Rules and Refrigerant Limits
A walk-in cooler is a refrigerated room under 3,000 square feet. Here is how its refrigeration system works, the 41°F food rule, the DOE R-25 and AWEF standards…
-
Water Heater Element: How to Test It, What Ohms to Expect and How to Replace It
How upper and lower water heater elements share the work, what ohms a good element reads, how makers say to test it with the power off, and how…
-
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…
-
Bipolar Ionization: What Independent Tests, EPA and ASHRAE Actually Show
Bipolar ionization makers cite big lab results; independent building tests found little benefit and some VOC increases. We read the studies, EPA, CDC and ASHRAE guidance, UL 2998…
-
AC Temperature Split: The Right Delta T for Your Humidity, and What It Means
The 15 to 20°F rule is a habit, not a standard. The right AC temperature split depends on return air wet bulb; here is the target table, how…
-
R410a Pressure Chart: R-410A, R-454B and R-32 PT Table With How to Read It
A sourced PT table for R-410A, R-454B (dew and bubble) and R-32 from 0°F to 120°F, how to read it, why the high and low side ranges online…