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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Heat Pump Defrost Cycle: How Often, How Long, and What the Manuals Say
Defrost intervals, end temperatures and time caps from Carrier, Rheem and Trane documents, the federal frost test, and PNNL field data on what defrost costs.
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Reversing Valve in a Heat Pump: How It Works, O vs B, and Signs It Failed
A heat pump’s reversing valve swaps which coil gets hot gas so one system heats and cools. Manufacturer specs explain why it needs 40 psi to shift, which…
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TXV Valve: How It Works, TXV vs Piston, Bad TXV Symptoms and the 30% Myth
A TXV valve meters refrigerant into the indoor coil to hold a set superheat. Federal lab data show its real edge over a piston is tolerance of charge…
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Hard Start Kit for AC: What It Does and When It Hides a Failing Compressor
A hard start kit adds torque for the first fraction of a second of a compressor start. Copeland says most scrolls do not need one; here is when…
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AC Short Cycling: Read the Timing, Find the Cause, Fix It in the Right Order
Why an air conditioner turns on and off every few minutes, sorted by timing: the federal cycle benchmarks, the five minute safety delay, night versus hot-day causes, and…
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Furnace Short Cycling: Why Your Furnace Keeps Shutting Off, Sorted by Timing
Why a furnace keeps shutting off, diagnosed by timing: flame proving within seconds, the high limit within minutes, or oversizing and thermostat placement. Built from Goodman, Resideo, ENERGY…
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Furnace Ignitor: How to Test It, and What Glows but No Flame Means
How a hot surface furnace ignitor works, carbide vs nitride and 80 V vs 120 V parts, the ohm test from manufacturer manuals, and what it means when…
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Furnace Limit Switch: Why It Trips, Rollout vs High Limit, and Safe Resets
A furnace limit switch shuts the burners off when the furnace overheats, usually from low airflow. We traced trip causes, fault codes and the never-bypass rules to Goodman…
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Furnace Pressure Switch: Stuck Open, Stuck Closed, Hose and Inducer Checks
A furnace pressure switch proves the draft inducer is venting before the burners light. Manufacturer setpoints, stuck open and stuck closed causes, the inducer motor, and which checks…
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Cracked Heat Exchanger: Symptoms, the Myth, Testing and Warranty
A cracked heat exchanger breaches the wall between exhaust and house air. Federal case files, a Canadian regulator’s investigations and manufacturer warranties show what it means, how it…