A new home is the easiest time to go tankless, because the gas line, venting and electrical service can be planned from the start instead of retrofitted. Size the heater for the number of bathrooms, choose indoor or outdoor placement early, and decide between gas and an all-electric build. These four whole-house models cover the most common new-build plans.
We compared flow, fuel, installation location and controls using manufacturer specifications and owner feedback. For larger homes see the best tankless water heater for large room guide, or start with the best tankless water heater; our Editorial Policy explains how we choose. Gas units need licensed installation and working CO alarms.
Top 3 Tankless Water Heaters for a New Home
Ranein RH19K-NG 8.5 GPM Natural Gas Tankless Water Heater (Indoor)
- 8.5 GPM
- Indoor
- 4–6 points
FOGATTI FOG-PM18OS 8.1 GPM Outdoor Natural Gas Tankless Water Heater
- 8.1 GPM
- No indoor vent
- 3–5 points
WINTEMP WN27 27kW 240V Wi-Fi Electric Tankless Water Heater
- 27kW
- 6.5 GPM
- Wi-Fi
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New-Home Tankless Water Heaters Compared
| # | Product | Key Features | |
|---|---|---|---|
| 1 |  Ranein RH19K-NG 8.5 GPM Natural Gas Tankless Water Heater (Indoor) |
| Check Latest Price |
| 2 |  FOGATTI FOG-PM18OS 8.1 GPM Outdoor Natural Gas Tankless Water Heater |
| Check Latest Price |
| 3 |  ThermoMate CZ422NG 5 GPM Natural Gas Tankless Water Heater (Indoor) |
| Check Latest Price |
| 4 |  WINTEMP WN27 27kW 240V Wi-Fi Electric Tankless Water Heater |
| Check Latest Price |
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1. Ranein RH19K-NG 8.5 GPM Natural Gas Tankless Water Heater (Indoor)
Best Overall
- 190,000 BTU, up to 8.5 GPM
- Built for 4–6 water points
- Anti-freeze protection
- Fan placed underneath with auto speed control
- Natural gas only
- Indoor venting to plan
- Fuel: natural gas
- Flow: up to 8.5 GPM
- Model: RH19K-NG
Ranein’s 8.5 GPM unit handles several bathrooms in a new build.
Plan the vent route during framing.
Who the Ranein 8.5 GPM fits best
Large new homes.
Who should skip the Ranein 8.5 GPM
Propane builds.
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2. FOGATTI FOG-PM18OS 8.1 GPM Outdoor Natural Gas Tankless Water Heater
Best Outdoor
- 180,000 BTU, up to 8.1 GPM
- Designed for outdoor installation
- Supplies 3–5 outlets
- Remote control panel
- Freeze planning
- Natural gas only
- Fuel: natural gas
- Flow: up to 8.1 GPM
- Model: FOG-PM18OS
Mounting outdoors frees interior space and removes indoor venting.
FOGATTI includes a remote panel.
Who the FOGATTI 8.1 GPM fits best
Mild-climate builds.
Who should skip the FOGATTI 8.1 GPM
Very cold regions.
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3. ThermoMate CZ422NG 5 GPM Natural Gas Tankless Water Heater (Indoor)
Best Mid-Size
- 113,000 BTU, up to 5 GPM
- Two showers at once (per maker)
- ±1°F temperature consistency
- Flame-out, freeze and overheat protections
- Smaller output
- Natural gas only
- Fuel: natural gas
- Flow: up to 5 GPM
- Model: CZ422NG
ThermoMate’s CZ422NG suits two-bathroom homes.
It holds steady temperatures.
Who the ThermoMate CZ422NG fits best
Starter homes.
Who should skip the ThermoMate CZ422NG
Large homes.
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4. WINTEMP WN27 27kW 240V Wi-Fi Electric Tankless Water Heater
Best All-Electric
- 27kW, up to 6.5 GPM
- Wi-Fi control
- Temperature lock
- 3/4″ NPT connections
- Needs 3 x 40A breakers
- 200A service recommended
- Power: 27kW, 240V
- Flow: up to 6.5 GPM
- Model: WN27
WINTEMP’s WN27 fits all-electric builds with ample service.
Plan the panel early.
Who the WINTEMP WN27 fits best
All-electric homes.
Who should skip the WINTEMP WN27
Small services.
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Planning Tankless in a New Build
- Count bathrooms and size GPM.
- Choose indoor or outdoor early.
- Size gas lines or electrical service.
- Add isolation valves for maintenance.
Frequently Asked Questions
Is tankless a good choice for a new home?
Yes, planning gas, vent or power is easier during construction.
What size do I need?
Many 3-bath homes need 7–9 GPM.
Gas or electric?
Gas for high flow; electric needs large service.
Indoor or outdoor?
Outdoor removes indoor venting in mild climates.
Final Verdict: Best Tankless Water Heater for New Home
The Ranein 8.5 GPM is the best tankless water heater for a new home. The FOGATTI 8.1 GPM is best outdoors, and the WINTEMP WN27 is the best all-electric choice.
Best overall: Ranein RH19K-NG 8.5 GPM Natural Gas Tankless Water Heater (Indoor) Check Latest Price
Outdoor: FOGATTI FOG-PM18OS 8.1 GPM Outdoor Natural Gas Tankless Water Heater Check Latest Price
All-electric: WINTEMP WN27 27kW 240V Wi-Fi Electric Tankless Water Heater Check Latest Price
Plan it in from day one.
Looking for something else? Browse all of our Water Heaters guides and the wider Heating & Cooling section.
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