Point-of-Use vs Whole-Home Tankless

When to Use Point-of-Use Tankless in Tampa

Point-of-use (POU) tankless water heaters are small, electric, single-fixture units that mount near a specific tap to eliminate the cold-water wait. Whole-home tankless units are large, gas-powered systems that replace your entire water heater. They serve very different needs and most Tampa homeowners pick the wrong one at least once.

Point-of-use wins when:

• Remote fixtures with long hot-water runs: A kitchen or bath 40+ feet from the main water heater waits 30-60 seconds for hot water. A POU unit under the sink delivers hot water in 2-3 seconds.
• Garage conversions (ADU, in-law suites): Adding a bathroom or kitchen in a garage conversion where running new hot water supply line from the main heater is expensive.
• Pool bath or outdoor kitchen: Dedicated POU eliminates the need to tap the main water heater.
• Water-saving supplement: Tampa homes with WaterSense fixtures. POU eliminates the 1-2 gallons wasted waiting for hot water at distant taps.

Rheem POU Models for Tampa Homes

• Rheem mini-tank: 4 gallon capacity, 120V plug. Not truly tankless but holds hot water at the point of use. $249-$299, $449-$599 installed. Best for hand-wash sinks.
• Rheem tankless: 13 kW electric, 240V dedicated circuit. 3.17 GPM at 35-degree rise. $349-$449, $599-$799 installed. Good for single bathroom sink or small kitchen.
• Rheem tankless: 18 kW, 240V. 4.4 GPM. $549-$649, $849-$1,099 installed. Handles a shower or multi-fixture bathroom.
• Rheem tankless: 27 kW, 240V with two 50A breakers. 6.5 GPM. $949-$1,099, $1,499-$1,799 installed. Small whole-home option for 1-bedroom ADU or very small home.

Electrical Requirements Block Most Whole-Home POU Attempts

Here is where most Tampa homeowners hit a wall. A true whole-home electric tankless needs enormous electrical capacity. An 18 kW POU needs a dedicated 75A 240V circuit. An electric whole-home tankless (Rheem or a comparable brand) needs 150A of dedicated capacity, which often exceeds the main service of older Tampa homes.

Typical Tampa electrical service:

• Pre-1980 Tampa home: 100A main service. Cannot support whole-home electric tankless without full panel upgrade ($2,500-$5,000).
• 1980-2010 home: 150A or 200A main. May support whole-home electric tankless if other loads allow.
• 2010+ home: Usually 200A main. Can typically handle whole-home electric tankless.

For Tampa homes, gas whole-home tankless (Rheem, Navien, Rinnai) is almost always the right whole-home solution. Electric POU makes sense only for specific single-fixture applications.

Cost Comparison: POU vs Whole-Home Gas Tankless

Tampa ADU and Garage Conversion Permit Reality

Converting a Tampa garage into a habitable space (ADU) requires:

• Zoning approval for ADU (Hillsborough County: allowed by right in most zones as of 2024)
• Building permit ($250-$450 depending on scope)
• Plumbing permit ($185-$325)
• Electrical permit if new circuits ($100-$185)
• Inspections: rough-in, framing, insulation, final

A POU tankless often simplifies the plumbing permit because you avoid running new 3/4 inch copper supply line from the main heater. Just local water supply to the POU and the POU handles everything else.

When to Combine Both Solutions

Some Tampa homes benefit from both approaches together:

• Whole-home Rheem gas tankless as the primary system (main bathrooms, kitchen, laundry).
• POU Rheem tankless added at a remote garage bath or pool bath where hot-water wait is 60+ seconds from the main unit.

Combined install: $3,800-$4,800 total. Eliminates wait time at the remote fixture without requiring a recirculation pump loop.