Step 1: Enter Simultaneous Hot Water Usage
Add all fixtures that might run at the same time (peak demand). FL ground water temp: 70โ75ยฐF. Target output temp: 120ยฐF (FL recommended โ prevents scalding and Legionella).
0.0 GPM
Total simultaneous demand
FL temp rise: ~48ยฐF (75ยฐF โ 120ยฐF + 3ยฐF buffer = 48ยฐF ฮT)
FL GPM Reference โ Fixture Flow Rates
| Fixture | Standard GPM | WaterSense GPM | FL Rec |
|---|
| Shower (standard) | 2.0โ2.5 | 1.8 | 2.0 |
| Bath Tub Fill | 4.0โ6.0 | โ | 4.0 |
| Kitchen Faucet | 1.5โ2.2 | 1.5 | 1.5 |
| Bathroom Faucet | 1.0โ2.2 | 0.5 | 0.8 |
| Dishwasher | 1.5โ2.0 | โ | 1.5 |
| Washing Machine | 1.5โ3.0 | โ | 2.0 |
| Utility/Mop Sink | 2.0โ4.0 | โ | 2.5 |
| Outdoor Shower (pool) | 1.0โ1.5 | โ | 1.5 |
FL Note: WaterSense fixtures required for new construction and replacement per FBC 2020 P2903.2. Using WaterSense fixtures reduces total GPM demand significantly โ factor in when sizing new unit.
Top Tankless Brands in Florida โ 2024
๐ Rinnai
Japan | #1 in FL
โ
โ
โ
โ
โ
Reliability ยท โ
โ
โ
โ
โ Value
โ
Pros: Largest FL service network, most FL plumber experience. RUR199iN (11 GPM) and RU199iN (11 GPM) are FL workhorses. Circ+ built-in recirculation (no separate pump needed). 12-year heat exchanger warranty. WiFi control via Rinnai app. Most parts available at FL plumbing supply same-day. Most common FL pool heater brand.
โ ๏ธ Cons: Premium price ($1,100โ$1,800 unit cost). Some models require minimum activation flow rate (0.26 GPM) โ can cause cold-water sandwich effect. Proprietary parts.
๐ง FL-Popular Models: RU199iN (9.8 GPM), RUR199iN (11 GPM w/ recirc), CU199iN (commercial), V75iN (7.5 GPM value)
โญ Navien
South Korea | Best Tech
โ
โ
โ
โ
โ
Efficiency ยท โ
โ
โ
โ
โ Reliability
โ
Pros: NPE-A2 series โ highest ENERGY STAR rating (0.97 UEF). Built-in NaviLink WiFi. Advanced ComfortFlow buffer tank eliminates cold-water sandwich. NaviCirc built-in recirculation. Best-in-class condensing efficiency (up to 98%). Industry-leading 15-year heat exchanger warranty on NPE series. NaviTech diagnostic display shows all parameters in real time.
โ ๏ธ Cons: Smaller FL service network than Rinnai โ some rural FL areas have limited service availability. More complex electronics mean higher repair costs if control board fails. Requires specialized technician for certain repairs.
๐ง FL-Popular Models: NPE-240A2 (11.2 GPM), NPE-180A2 (8.4 GPM), NPN-199A (9.4 GPM), NPE-150A2 (7.0 GPM)
๐ง Noritz
Japan | Pro Choice
โ
โ
โ
โ
โ Reliability ยท โ
โ
โ
โ
โ
Value
โ
Pros: Longest-running FL distributor history. NRCP199 condensing series competes directly with Navien at lower price. Simple, serviceable design preferred by FL plumber-plumbers (vs. Navien's electronics complexity). Noritz America (US HQ Buena Park CA) fast parts distribution. Good FL hard-water performance with descaling port access.
โ ๏ธ Cons: Smaller brand recognition than Rinnai/Navien. Less WiFi feature set. Limited consumer-facing app ecosystem.
๐ง FL-Popular Models: NRCP199 (9.8 GPM condensing), NRC199 (9.8 GPM), EZ111 (5.3 GPM budget)
โก Rheem
USA | Best Value
โ
โ
โ
โ
โ Value ยท โ
โ
โ
โ
โ Availability
โ
Pros: US brand with widest FL retail availability (Home Depot, Lowe's). RTGH-RH11DVLN (11 GPM) condensing model competitive with Japanese brands. LeakGuard auto-shutoff feature unique in category. Parts at hardware stores vs. plumbing supply house (big advantage for emergency service). RTG-95DVLN popular mid-range FL option. Rheem EcoNet WiFi app.
โ ๏ธ Cons: Heat exchanger warranty 12 years (vs. 15 for Navien NPE series). Historical quality perception below Rinnai/Navien among FL professionals. Some FL plumbers avoid recommending (brand loyalty to Rinnai).
๐ง FL-Popular Models: RTGH-RH11DVLN (11 GPM), RTG-95DVLN (9.5 GPM), RTGH-RH10DVLN (10 GPM)
Gas vs. Electric Tankless โ FL Comparison
โฝ Gas Tankless
Best forFamilies, 2+ showers simultaneous
GPM Cap8โ14 GPM
Install Cost$1,200โ$3,500
Unit Cost$800โ$2,000
FL UEF0.82โ0.97
VentingPVC/CPVC direct vent
FL GasNG or LP (propane)
โก Electric Tankless
Best for1-2 person, point-of-use
GPM Cap2โ8 GPM
Install Cost$500โ$2,000
Unit Cost$200โ$900
FL UEF0.96โ0.99
VentingNone needed
FL Electric240V, 150-200A service needed
โก FL Electric Note: Whole-house electric tankless requires 150-200A service. Most FL homes have 150-200A panels โ but verify panel capacity before installing. Electrical upgrade ($1,500โ$3,000) may be needed for older FL panels. South FL homes without natural gas supply are electric by necessity.
Why Florida is the Best US State for Tankless
๐ก๏ธFL Groundwater Temperature Advantage: Florida's Floridan Aquifer maintains a groundwater temperature of 70โ75ยฐF year-round (vs. 37โ55ยฐF in northern states). This is the single biggest factor in tankless performance: a 40,000 BTU unit that produces 2.0 GPM in Minnesota produces 4.5โ5.0 GPM in Florida, because the required temperature rise is half. FL homeowners get more hot water from smaller, cheaper units.
๐ฐEnergy Savings โ Bigger in FL: Standard tank water heaters lose heat through the tank walls constantly (standby losses). In FL's heat, the tank's surroundings are warmer (garage temps 85โ100ยฐF in summer) โ but the tank still loses 20-40% of energy to standby losses. Tankless heats on demand only. Average FL household: $200โ$500/year savings on water heating vs. standard tank. In all-electric FL homes, water heating is typically 15-20% of electric bill โ tankless reduces this significantly.
๐ Space Savings โ Critical in FL: FL homes often have small utility closets or garage-mounted water heaters. Tankless units are wall-mounted, roughly the size of a small suitcase (20"ร14"ร9"), replacing a 40โ80 gallon tank that occupies significant floor space. In FL's cramped garages, this space recapture is significant. Outdoor installation possible in FL's warm climate (exterior wall mount) โ eliminates any interior space use entirely.
๐No Flood Loss โ Hurricane Resilience: FL homeowners with garage-mounted tank water heaters lose them in flooding events (Hurricane Irma, Ian, Idalia all caused water heater losses). Tankless units mounted high on garage walls or exterior walls are above typical FL flood levels. After Hurricane Ian (2022), tankless units mounted at 5+ feet survived while tank water heaters on garage floors were total losses.
โป๏ธFL Utility Rebates โ Available: Several FL utilities offer rebates for high-efficiency water heater replacement: FPL โ $50โ$100 for ENERGY STAR certified tankless. Duke Energy FL โ $100โ$200 for qualifying gas tankless. TECO (Tampa Electric) โ rebate program varies. Gainesville Regional Utilities โ up to $200. Always verify current rebate at utility's website โ programs change annually.
FL Hard Water Warning โ Scale Is Tankless Enemy #1
๐ชจFL Hard Water Reality: Central and South FL has some of the hardest water in the US โ 15โ25 grains per gallon (GPG) in many areas (anything over 7 GPG is "hard"). Calcium carbonate scales deposit inside the tankless heat exchanger, progressively reducing efficiency and flow. An unprotected tankless in FL hard water may need descaling every 12โ18 months; a properly conditioned system descales every 3โ5 years.
๐ก๏ธScale Prevention Options: (1) Water softener (salt-based ion exchange) โ most effective but adds sodium to water; requires backwash drain. (2) TAC (Template Assisted Crystallization) โ salt-free, changes calcium crystal form so it doesn't adhere to surfaces. No drain needed. Most FL tankless installers now recommend TAC system pre-filter. (3) Phosphate feeder โ inexpensive, adds trace phosphate that coats surfaces; EPA-approved for potable water at low doses. (4) Descaling service โ annual citric acid flush if no prevention system.
๐Warranty Implications: Most tankless manufacturers (Rinnai, Navien, Noritz) VOID the heat exchanger warranty for scale damage if water hardness exceeds 11 GPG without documented water treatment. Get your FL water hardness tested (free via county extension office or home test kit $15) before installation. If hardness is 11+ GPG, document your water treatment system for warranty protection.
FL Permit & Code Requirements
๐Permit Required: FL Building Code requires permit for water heater replacement (tankless or tank). Gas tankless additionally requires gas line inspection. Many FL counties have online permit portals โ licensed contractors pull permits as standard practice. DIY water heater installation without permit is illegal in FL and voids homeowner's insurance coverage for related damage.
๐Venting Requirements: Direct vent (sealed combustion) gas tankless: requires Category III or IV stainless vent pipe โ not standard PVC. Some FL models use CPVC vent for condensing units. Vent must terminate minimum 12" above any air intake, 12" above grade, 1" from any combustibles. FL's coastal areas: use stainless (not aluminum) vent components โ salt air corrodes aluminum.
๐ฅGas Sizing: High-output gas tankless (199,000 BTU) requires ยพ" or 1" gas line depending on run length. Most FL homes have ยฝ" gas supply to water heater location โ upsizing required at $300โ$900 depending on run length. Gas meter upsizing may be required โ utility service involvement.