The Complete Guide to Water Heaters

Complete Guide 1010 words

Created by Ryan PietrzakIllinois Licensed Plumber · In the plumbing industry since 2009

Updated February 23, 2026

What This Guide Covers

Everything you need to know about Water Heaters — from choosing the right type and buying smart, to installation, ongoing maintenance, and understanding costs.

Types of Water Heaters

There are 4 main types of Water Heaters to choose from:

Heat Pump Water Heaters

Highly efficient systems that use electricity to move heat from air or ground to heat water. Can reduce energy costs by 60%.

Solar Water Heaters

Eco-friendly systems that use solar panels to heat water. Great for sunny climates and long-term savings.

Storage Tank Water Heaters

Traditional water heaters with insulated tanks that store and heat water continuously. Most common residential option.

Tankless Water Heaters

Energy-efficient units that heat water on demand without storing it in a tank. Perfect for homes with limited space.

View all Water Heaters types →

Buying Guide

Tank Water Heaters

First-hour rating (FHR) is the key metric -- how much hot water delivered in the first hour of heavy use. Calculate peak-hour demand: showers (20 gal each), dishwasher (6 gal), clothes washer (7 gal), faucets (4 gal each). Match FHR to that number.

Tankless Water Heaters

Sized by flow rate (GPM) and temperature rise. Add GPM of all simultaneous fixtures. Calculate rise: desired output (110-120F) minus incoming water temp (40-70F by region). Match unit to both numbers.

Quick Sizing Guide

1-2 people: 30-40 gal tank or small tankless (6-7 GPM gas). 2-3 people: 40-50 gal. 3-4 people: 50-65 gal or mid tankless (8-9 GPM gas). 5+: 65-80 gal or large tankless (10-11 GPM gas). Heat pump: size up one tier.

Buying Tips

Use first-hour rating (FHR), not just tank size, to compare.
Cold climates need tankless sized for higher temperature rise.
Heat pump water heaters recover slower -- size up.
When in doubt, size up. Slightly oversized costs marginally more but never runs cold.

View all Water Heaters buying guides →

Installation

Water Heater Installation Costs

What to expect for water heater installation costs across different types and scenarios.

Reference guide See breakdown below

Water Heater Installation Process

Step-by-step walkthrough of installing a tank or tankless water heater.

Intermediate to Advanced $100-$300 DIY / $800-$2,500 with pro

Water Heater Permits & Regulations

What permits and code requirements apply to water heater installation in most jurisdictions.

Reference guide

When to Replace Your Water Heater

Signs it's time for a new water heater and how to plan the replacement before it fails.

Reference guide

View all Water Heaters installation guides →

Maintenance

Annual Water Heater Maintenance Checklist

Complete yearly maintenance checklist to keep your water heater running efficiently and safely.

Anode Rod Replacement

How to check and replace the sacrificial anode rod that protects your water heater tank from corrosion.

Flushing & Draining Your Water Heater

How to flush sediment from tank water heaters and descale tankless units for peak efficiency.

Seasonal Water Heater Maintenance

Season-specific tasks to keep your water heater efficient year-round.

View all Water Heaters maintenance guides →

Costs

Water Heater Operating Costs

Monthly and annual operating costs for gas, electric, tankless, and heat pump water heaters.

$15-$60/month depending on type and fuel

Water Heater Purchase Prices

What tank, tankless, and hybrid water heaters actually cost by type, size, and fuel source.

$400-$3,500+ depending on type

Water Heater Repair Costs

What common water heater repairs actually cost and when replacement makes more financial sense.

$75-$900 depending on repair

Water Heater ROI Calculator

How to calculate the true return on investment when upgrading or replacing your water heater.

View all Water Heaters cost guides →

Top Water Heaters Brands

View all Water Heaters brands →

Frequently Asked Questions

What types of water heaters are available?

There are 4 main types: Heat Pump Water Heaters, Solar Water Heaters, Storage Tank Water Heaters, Tankless Water Heaters.

What are the best water heaters brands?

Top brands include AO Smith, Bosch, Bradford White, Ecosmart.

Can I install water heaters myself?

Some water heaters installations are DIY-friendly, while others require a licensed plumber. Check the difficulty rating of each installation guide.