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.
-
Whole House Fan: Where It Works, Where It Fails, and the Numbers
A whole house fan pulls cool outdoor air in through open windows and exhausts it through the attic. DOE sizing in cfm, the attic vent area it needs,…
-
Wood Stove Rules and Data: What EPA Certification Actually Means
EPA certification is an emissions test, not an efficiency floor. What 40 CFR part 60 subpart AAA requires, what the certified database shows, and how many US homes…
-
Dehumidifier Sizing, Efficiency and Running Cost: A Federal Data Guide
The 2019 federal test procedure changed what a pint rating means, so an old 70 pint unit now rates near 40 to 45. Here is how to size,…
-
Wall Air Conditioner vs Window Unit, PTAC and Mini Split: How Each Installs
A wall air conditioner is a through-the-wall room unit rated on CEER. We compare it with window units, PTACs and ductless mini splits on installation, circuits and the…
-
HVAC Filters: Types, Sizes, MERV Ratings and How Often to Change Them
A practical guide to HVAC filters: the five types, where the filter lives, nominal versus actual size, how often to check and change it, and EPA’s MERV 13…
-
Portable Air Conditioner Without Hose: Why No Real AC Cools a Room Without Venting
No refrigerant air conditioner cools a closed room without exhausting heat. Hoseless and ventless units are evaporative coolers or fans, which help only in dry air and can…
-
Heat Pump Water Heaters: How They Work, What They Need and the 2029 Rule
A heat pump water heater moves heat from room air into the tank. What UEF measures, what it costs to run against an electric tank, what it needs,…
-
Tankless Water Heater vs Tank: How It Works, Sizing and the 2026 Federal Rules
How a tankless water heater works, how it compares with a storage tank, how to size one by flow rate and temperature rise, and why the federal gas…
-
BTU Calculator: What Size Room Air Conditioner You Need, From ENERGY STAR’s Chart
A CSS lookup built on ENERGY STAR’s 14-band room air conditioner sizing chart and its four adjustments, with the ton conversion and why the chart does not apply…
-
DIY Mini Split Kits: What EPA Says About Connecting Pre-Charged Lines
Pre-charged DIY mini split kits are legal to buy, but EPA’s Section 608 Q&A says connecting or disconnecting hoses or pre-charged lines during installation requires technician certification.