GPM & Flow Rate
Learn how flow rate relates to simultaneous hot-water use.
Explore ArticlesWater heating resources
Water Heater Knowledge
Plain-language explanations of key concepts, performance terms, and system basics.
Browse by Topic
Temperature Rise
Understand how incoming water temperature affects required heating.
Explore ArticlesTankless vs. Tank
Compare the basic operating differences between system formats.
Explore ArticlesEnergy & Efficiency
Understand efficiency terms without relying on unsupported savings claims.
Explore ArticlesFeatured Article
What Size Water Heater Do You Need?
Use simultaneous flow and required temperature rise to build a practical sizing estimate.
Read ArticleLatest Knowledge Articles
What Size Water Heater Do You Need?
Use simultaneous flow and required temperature rise to build a practical sizing estimate.
Read Article
How Incoming Water Temperature Affects Performance
Understand why seasonal and regional inlet-water temperature changes affect available hot-water flow.
Read Article
Tank vs. Tankless Water Heater Explained
Compare how storage-tank and tankless systems heat and deliver hot water.
Read Article
What Is Temperature Rise?
Learn the basic temperature-rise calculation used when reading water-heater performance data.
Read Article
How Does a Tankless Water Heater Work?
See how tankless systems sense flow and heat water as it moves through the unit.
Read Article
What Does GPM Mean?
A simple explanation of gallons per minute and why simultaneous use matters.
Read ArticleNo guides match that search. Try a broader term.