Guides
Plain-English background to the numbers behind the calculators — what size water heater you need, tank vs tankless, how to size a tankless, what it costs to run, how long it takes to heat up, what a replacement costs, repair cost by component, why a water heater leaks, heat-pump savings, anode rods & flushing, the 120 °F setting, expansion tanks, and how to read a plumber’s quote.
What size water heater do I need?Size a water heater by the busiest hour of hot-water use, not the headcount: the First-Hour Rating method, worked with real numbers, plus tankless GPM.Tank vs tankless water heater: cost, sizing and lifespanTank vs tankless, decided on the numbers, not adjectives: upfront and operating cost, sizing (FHR vs GPM), lifespan and the payback math, with a worked example.How to size a tankless water heater (GPM and temperature rise)Size a tankless by flow, not gallons: add up simultaneous fixture GPM, subtract your inlet for the rise, and read the right unit — worked warm vs cold.How much does it cost to run a water heater?Running cost is delivered heat divided by efficiency times your rate. Worked for gas, electric and heat-pump, so you can compare on your own bill.How long does a water heater take to heat up? (recovery and reheat)Reheat time is straight physics: gallons times 8.33 times the rise, over the input times efficiency. Worked for gas and electric, and why it sizes the tank.How much does it cost to replace a water heater?Replacement cost is unit plus labor plus add-ons, times a contingency. See the line items that swing the total, and where a tankless conversion adds cost.Water heater repair cost: what is the part, what is the laborMost water-heater repairs are a cheap part plus a service call. See typical costs by component, and the one time a repair means you should replace instead.Why is my water heater leaking? (repair or replace)Where the water comes from decides it: a leaking valve or fitting is a repair; water from the tank body is rust-through, so replace. Trace the leak first.Heat-pump (hybrid) water heaters: how much you saveA heat-pump water heater uses about a third the electricity of a resistance tank. See the yearly saving worked out, the space it needs, and who should buy it.Anode rods and flushing: how to make a water heater lastThe two cheapest ways to reach the top of a water heater's lifespan: replace the sacrificial anode rod on schedule and flush the tank yearly.What temperature should a water heater be? (120 °F and why)120 °F is the common guidance: hot enough to be useful, low enough to limit scald risk and standby loss. See the tradeoffs and how to set it.Do I need an expansion tank? (closed systems and pressure)On a closed plumbing system, heated water has nowhere to expand — pressure spikes. An expansion tank absorbs it. See when you need one and how it is sized.How to read a water-heater quote (unit, labor, permits, add-ons)Break a water-heater quote into its parts — unit, labor, permit, venting, add-ons — so you can compare bids fairly and spot what is missing.