Water Heater Sizing Guide for Fort Lauderdale Homes

Sizing tank water heaters

Tank water heaters are sized by gallon capacity, but the real spec that matters is the first-hour rating (FHR). This measures how much hot water the unit can deliver in the busiest hour of the day.

FHR recommendations by household size

• 1-2 people: 40-gallon tank, 40-50 gallon FHR
• 3-4 people: 50-gallon tank, 50-60 gallon FHR
• 4-5 people: 65-80 gallon tank, 60-70 gallon FHR
• 6+ people: 80+ gallon tank or multiple units, 75+ gallon FHR

Gas tanks recover hot water faster than electric, so gas units can often be sized smaller than electric for the same demand.

Sizing tankless water heaters

Tankless units are sized by gallons per minute (GPM) flow rate at a specified temperature rise. Fort Lauderdale groundwater is 70-72°F. Target shower temperature is 105°F. That is a 33-35°F rise.

Typical flow rates

• Shower: 2.0-2.5 GPM
• Kitchen sink: 1.5 GPM
• Bathroom sink: 1.0 GPM
• Dishwasher: 1.5 GPM
• Washing machine: 2.0 GPM

Tankless sizing by bathrooms

• 1 bathroom: 140,000-160,000 BTU, 6-7 GPM
• 2 bathrooms: 180,000-199,000 BTU, 8-9 GPM
• 3+ bathrooms: 199,000 BTU (max residential) or consider two units

Common sizing mistakes

• Buying the cheapest unit. Undersized units run constantly in hot Florida weather
• Ignoring simultaneous use. A 40-gallon tank handles one shower, not two plus a dishwasher
• Oversizing for peace of mind. 80-gallon tank for a 2-person household wastes energy every day
• Matching the old unit. Your needs may have changed, or the old unit may have been wrong

Let us size it for you

Every installation we do starts with a free in-home sizing assessment. We measure your actual demand, check gas or electrical capacity, and recommend the right unit. See our installation service for details.

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