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.
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VRF Systems Explained: IEER Rules, the 2026 Refrigerant Date and Design Limits
Variable refrigerant flow, explained for the light commercial buyer: heat pump versus heat recovery, the IEER standards in 10 CFR 431.97, the January 1, 2026 refrigerant date, and…
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Evaporator Coil Replacement: Replace the Coil or the Whole System?
When the indoor coil springs a pinhole leak, the choice is a matched replacement coil or a new system. Federal certification, EPA recovery rules and EIA cost figures…
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Condensate Pump: How It Works, When You Need One and What Fails
A condensate pump lifts the water your cooling or condensing heating equipment produces up to a drain when gravity cannot carry it there. How it works, where it…
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Cold Climate Heat Pump: The ENERGY STAR Criteria and What 5F Ratings Mean
The Cold Climate designation is two measured numbers at 5F, not a marketing phrase. What ENERGY STAR Version 6.2 requires, what DOE’s Challenge proved, and how to check…
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Air Conditioner Decibel Levels: What the Sound Ratings Actually Mean
Air conditioner decibel levels are laboratory ratings on a logarithmic scale. Here is what sound power, sound pressure and sones each mean, and which noise rule actually binds…
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Furnace Flame Color: What Blue, Yellow and Orange Actually Mean
A blue furnace flame means the burner is getting roughly its design air. A persistent yellow flame means it is not. Neither appearance measures carbon monoxide, draft or…
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Water Heater Temperature Setting: 120 vs 140 Degrees, Settled With Federal Data
DOE and CPSC both say 120 degrees Fahrenheit. CDC says store above 140 to control Legionella. Both are right, and a mixing valve is why.
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CFM Per Ton: The Airflow Rule Behind Every AC Diagnosis
A ton is 12,000 Btu/h, and the federal test procedure assumes 400 scfm per 12,000 Btu/h when nothing else is certified. What that means for freezing coils, humidity…
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How Many Watts Does an Air Conditioner Use? Draw by Equipment Class
Running watts and amps for eight classes of home HVAC equipment, derived from ENERGY STAR certified ratings, 10 CFR 430.32 and EIA data, with the arithmetic shown.
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Gas Fireplace Venting, Efficiency and Safety: Direct Vent, B-Vent and Vent-Free
Direct vent, B-vent and vent-free gas fireplaces differ sharply in efficiency and indoor air. What the FE rating means, why no federal standard applies, what a standing pilot…