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Gas Tankless Water Heaters

Find the right gas tankless water heater for steady hot water at home, from compact installs to high-demand households.

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GEN 3 Direct Vent 199,000 BTU Indoor Tankless Water Heater with Smart Wi-Fi
GEN 3 Direct Vent 199,000 BTU Indoor Tankless Water Heater with Smart Wi-Fi Sale priceFrom $1,199.99
Indoor Gas Tankless Water Heater
8.1 GPM 180,000 BTU Natural Gas Outdoor Tankless Water Heater - Valve Kit Bundle | Mizudo Sale price$899.99
Save $100.007.9 GPM 180,000 BTU Natural Gas Indoor Tankless Water Heater - Non-Condensing, Smart Wi-Fi | Mizudo
7.9 GPM 180,000 BTU Natural Gas Indoor Tankless Water Heater - Non-Condensing, Smart Wi-Fi | Mizudo Sale price$899.99 Regular price$999.99
Save $100.005.1 GPM 120,000 BTU Natural Gas Tankless Water Heater - Indoor/Outdoor Convertible, Wi-Fi | MIZUDO
5.1 GPM 120,000 BTU Natural Gas Tankless Water Heater - Indoor/Outdoor Convertible, Wi-Fi | MIZUDO Sale price$599.99 Regular price$699.99
Save $100.00Non-Condensing 5.1 GPM -Indoor Natural Gas/Propane Tankless Water Heater White
Non-Condensing 5.1 GPM -Indoor Natural Gas/Propane Tankless Water Heater White Sale price$599.00 Regular price$699.00
Save $300.99Non-Condensing 5.1 GPM 120,000 BTU -Outdoor Natural Gas/Propane Tankless Water Heater White
Non-Condensing 5.1 GPM 120,000 BTU -Outdoor Natural Gas/Propane Tankless Water Heater White Sale price$399.00 Regular price$699.99
Save $212.00Non-Condensing 4.0 GPM 90,000 BTU -Indoor Natural Gas/Propane Tankless Water Heater White
Non-Condensing 4.0 GPM 90,000 BTU -Indoor Natural Gas/Propane Tankless Water Heater White Sale price$287.00 Regular price$499.00

Select Your Gas Tankless Fit

Internal copper heat exchanger and fan assembly inside a Mizudo gas tankless water heater

BUILT AROUND A COPPER HEAT EXCHANGER

Inside the unit, a TP2 copper heat exchanger and variable-speed fan support stable heat transfer as water demand changes. Water-gas proportional control helps the system adjust output for more consistent hot water.

Rear connection panel of a Mizudo gas tankless water heater

CLEAR CONNECTIONS FOR A CLEANER INSTALL

The rear panel brings the water, gas, power, and grounding connections into a clearly defined layout. This makes it easier to confirm connection points before installation and access the unit for future service.

Gas Tankless Series

Choose Your Fit

Compare three high-flow Mizudo tankless water heaters by capacity, installation type, fuel options, and whole-home use.

Products GEN 3 Direct Vent 199,000 BTU Indoor Tankless Water Heater with Smart Wi-Fi Indoor Gas Tankless Water Heater 7.9 GPM 180,000 BTU Natural Gas Indoor Tankless Water Heater - Non-Condensing, Smart Wi-Fi | Mizudo
Model 10.3 GPM Indoor Direct Vent Wi-Fi 8.1 GPM Outdoor Valve Kit 7.9 GPM Indoor Smart Wi-Fi
Heat Output 199,000 BTU 180,000 BTU 180,000 BTU
Fuel Options Natural Gas / Propane Natural Gas / Propane Natural Gas / Propane
Installation Indoor Direct Vent Outdoor Indoor Non-Condensing
Key Feature Smart Wi-Fi and direct vent setup Premium valve kit bundle Smart Wi-Fi and sealed combustion
Best For
Large homes with high hot-water demand
Outdoor whole-home installations
Indoor whole-home use across 3-5 points

Gas Tankless Water Heater FAQs

Compare gas models
Small homes can usually start with 4.0-5.1 GPM. Family homes often need higher-flow 7.9-8.1 GPM models. Larger propane homes may need a 10.3 GPM tankless gas water heater depending on simultaneous fixture use.
Choose the fuel type your home is already set up for. Mizudo offers natural gas and propane tankless water heater options, including higher-flow choices for whole-home hot water.
Most gas tankless water heaters use gas for heat but still need electricity for ignition, control, fan operation, and smart features. Check the product specs before installation.
Yes, if you choose an indoor-rated model and the venting path is handled correctly. For indoor whole-home demand, compare the 7.9 GPM indoor model.
Indoor models are built for interior installation with proper venting. Outdoor models are made for exterior wall placement. For high-flow outdoor hot water, see the 8.1 GPM outdoor valve kit bundle.
Lifespan depends on water quality, usage, maintenance, and installation conditions. Regular service and correct sizing help a tankless gas water heater perform more consistently over time.

Mizudo in Real Builds

Outdoor Shower Build

A 199K BTU Mizudo tankless heater used in an off-grid shower build.

No More Cold Showers

An off-grid hot-water upgrade focused on everyday shower comfort.

199K BTU Setup Test

A creator installation and test in an off-grid setup.