Guides
The background behind the tools, written for the moment you're deciding.
- How to read the rating plate on your water heater, furnace or ACWhere the rating plate sits on water heaters, furnaces, AC condensers, heat pumps and boilers, what each field means, and how model numbers encode size.
- What a complete water heater replacement quote includesLine by line, what a complete water heater quote should list: unit, haul-away, permit, expansion tank, pan, straps, venting, relief valve and warranty.
- What a complete furnace, AC or heat pump quote includesWhat a full furnace, AC or heat pump quote lists: AHRI matched system, SEER2 and AFUE, refrigerant, line set, Manual J, permit, charge check and warranty.
- The 50 percent rule: when to repair and when to replaceThe 50 percent rule and the age times repair cost rule for HVAC and water heaters: where they come from, when they mislead, and a better cost-per-year test.
- Home energy rebates by state: what is still availableChecked October 13, 2026: where federal HEAR and HOMES rebates stand in each state, the 2026 DOE rule change, and the end of 25C and 25D tax credits.
- Should I repair or replace my water heater?A leaking tank means replace. For everything else, compare the repair with the tank's remaining years. Worked examples, the 50% rule, and what shifts the call.
- Should I repair or replace my furnace?Most furnace repairs are worth doing until about 15 years. A cracked heat exchanger, repeat failures or an old 80% unit change the math. Worked examples inside.
- Should I repair or replace my air conditioner?Capacitors and fan motors are worth fixing. Compressors, leaking coils and R-22 systems usually aren't. How refrigerant rules, age and warranty change the math.
- Should I repair or replace my heat pump?Heat pumps run all year, so repairs buy fewer years than on an AC. When to fix, when to replace, and how refrigerant rules, backup heat and age shift it.
- Should I repair or replace my boiler?Boilers last decades and most parts are swappable, so repair often wins. A leaking heat exchanger, CO concerns or a very old unit change that. How to decide.