Tankless Water Heater Size Calculator

How to Use Tankless Water Heater Size Calculator

Calculate the optimal tankless water heater size for your home based on your hot water usage patterns. Proper sizing ensures adequate hot water supply while maximizing energy efficiency.

How It Works:

The calculator uses the formula: BTU = GPM x 8.33 x Temperature Rise x 60, considering all your fixtures and their flow rates to determine the total hot water demand.

Key Factors:

• Fixture Count: Number of showers, sinks, appliances
• Flow Rates: Each fixture has different GPM requirements
• Temperature Rise: Difference between incoming and target temperature
• Climate: Cold climates need more heating capacity
• Simultaneous Usage: Multiple fixtures running at once

Flow Rate Guidelines:

• Shower: 2.5 GPM (standard)
• Sink: 1.5 GPM (hand washing)
• Dishwasher: 1.0 GPM (cycle average)
• Washing Machine: 2.0 GPM (hot water cycle)

Temperature Guidelines:

• Cold climate: 40-50 degrees F incoming
• Moderate climate: 50-60 degrees F incoming
• Hot climate: 60-70 degrees F incoming
• Target temperature: 120 degrees F (standard)

Pro Tips:

• Consider peak usage times (morning showers)
• Factor in future additions (new bathrooms)
• Check local building codes for minimum requirements
• Consider gas line capacity for gas units
• Electric units may need upgraded electrical service