Search  for anything...
thermomate

ThermoMate CZ422NG Natural Gas Tankless Water Heater, Up to 5 GPM 113,000 BTU, High Efficiency Instant On-Demand Hot Water for Whole House Use, Indoor Residential Water Heater with Multi-Point Heating - Amazon.com

  • Based on 130 reviews
Condition: New
Checking for the best price...
$399.99 Why this price?
Save $39.99 was $439.98

Buy Now, Pay Later

As low as / mo
  • – Up to 36-month term if approved
  • – No impact on credit to apply
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Zip, Apple Pay, and Google Pay. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

This item is eligible for return within 30 days of receipt

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

Availability: 20 left in stock
Fulfilled by Amazon
Arrives Saturday, Aug 8
Order within 6 hours and 53 minutes
Available payment plans shown during checkout
Protection Plan Protect Your Purchase
Checking for protection plans...

Recently Viewed

Set name: 5 GPM, NG


Features

  • [Max 5 GPM & 113,000 BTU] – The ThermoMate instant hot water heater delivers hot water on-demand for two showers at the same time, maintaining a stable 105°F (based on 65°F inlet temperature). No waiting, no cold-water interruptions—perfect for busy homes. Its smart flow sensor and control chip adjust heating 20,000 times per second, ensuring ±1°F temperature consistency.
  • [Safety & Reliable] - This gas tankless water heater integrates 8 protections: boil-dry, freeze, flame-out, overheating, over-temperature, pipe blockage, high-temperature lock, and excessive air pressure. Equipped with 4 ceramic heating cores, it auto-activates frost protection when temperatures hit 41°F (5℃). The energy-smart system uses minimal electricity to generate gentle warmth, preventing pipe ice buildup without high energy costs.
  • [Energy Efficient & Save Money] - The heat exchanger is constructed from high-quality oxygen-free copper, providing superior thermal conductivity and corrosion resistance compared to stainless steel. It achieves a thermal efficiency of 98% (vs. 80% for stainless steel models) and boasts a uniform energy factor (UEF) of 0.81. This design reduces energy waste, lowering annual operating costs by approximately 30% versus traditional systems.
  • [Smart Diagnostic Display] - Easily adjust water temperature (90–140°F) and keep track of flow, fan, and flame status on the 3.5-inch LED display. Advanced error codes allow fast troubleshooting, while the UL-certified 120V/5-foot cord keeps the system powered and monitored at all times.
  • [Easy to Install & Save Space] – Designed for whole house use, this indoor water heater measures only 21"H × 13"W × 7"D and occupies less than one-third of the space of traditional water heater models. Standard 3/4" NPT water inlet/outlet connections, a 1/2" NPT gas inlet, 3" OD vent, and UL-approved 120V plug make installation simple in most homes.
  • [Wind Resistant] - Engineered with a DC High-speed Fan (360Pa static pressure/3000 RPM), the system ensures powerful exhaust evacuation capable of withstanding winds from a major hurricane (Category 3 and above, >111 mph/178 km/h), eliminating safety risks like backdraft and flameouts during the most extreme weather.

Description

CZ422NG CZ480NG CZ422LP CZ360LP CZ264NG CZ264LP How does a tankless water heater work? A tankless water heater heats water directly on demand without storing it in a tank. When you turn on a hot water tap, cold water flows through the unit, where it is rapidly heated by either a gas burner, providing a continuous supply of hot water. What size tankless water heater do I need? Size depends on your household’s peak hot water demand. Calculate the total GPM needed for simultaneous fixtures (e.g., 2 showers at 2 GPM each = 4 GPM) and the required temperature rise (desired temp – incoming water temp). Can a tankless water heater supply enough hot water for multiple showers at once? It depends on the unit’s flow rate (measured in gallons per minute, or GPM). Larger households may need a high-capacity model or multiple units. For example, a gas-powered unit with 4 GPM can handle 2 showers simultaneously. Are tankless water heaters energy-efficient? Yes! ThermoMate tankless water heaters are more energy-efficient, with a UEF >0.81, saving up to 30% on energy annually. Are any additional parts or components required for installation? Yes, you need to buy a 150 psi pressure relief valve. To vent exhaust gases, you may also need to purchase a 3-inch diameter metal exhaust pipe.

Power Source: Natural Gas


Special Features: Anti-Freezing Protection, Dry Combustion Protection, Flame Failure Protection, High Water Pressure Protection, Integrated Error Code Indicator


Voltage: 120 Volts (AC)


Flow Rate: 5 Gallons Per Minute


Maximum Temperature: 140 Degrees Fahrenheit


Heat Output: 113000 British Thermal Units


Maximum Pressure: 150 Pound per Square Inch


Mount Type: Wall


Is Electric: No


Smart Home Compatibility: Not Smart Home Compatible


Capacity: 5 gallons


Item Dimensions W x H: 13.77"W x 21.65"H


Item Weight: 22 Pounds


Brand Name: thermomate


Model Number: CZ422NG


Manufacturer: thermomate


UPC: 850069925208


Included Components: ‎‎Tankless Water Heater x1, Installation Kits x1, User's Manual x1


Item Type Name: Water Heater


Best Sellers Rank: #86,344 in Tools & Home Improvement (See Top 100 in Tools & Home Improvement) #100 in Water Heaters


ASIN: B0DRDBDS57


Customer Reviews: 4.2 4.2 out of 5 stars (130) 4.2 out of 5 stars


Color: Metallic Silver


Style Name: 5 GPM Natural Gas


Material Type: 5 GPM


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Saturday, Aug 8

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • Zip Pay in 4
  • Financing through Apple Pay
  • Financing through Google Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • Update: They fixed the issue and the seller is awesome. Update: They fixed the issue and the seller is awesome.
Set name: 5 GPM, LP
Review Image by B. Spencer
Review Image by B. Spencer
Review Image by B. Spencer
Review Image by B. Spencer
Review Image by B. Spencer
Update #2 This is working fantastic! I'm very happy with this item, my well water is 55 deg, and it puts out 130 deg water no problem. The video shows it start at 109, but that is because I had just run it and it was still warm from before. Update: Seller support is fantastic, I have fabricated a solution, and the Mfg has found the issue they had and corrected it and we came to a very agreeable outcome. I recommend you use their Vent kit to be sure, but they have been awesome throughout this. This DOES require a Class 3 vent, one thing I could not find was how hot the exhaust is, but I ran a shower with it for a few min at 120 Deg (55 deg supply) water and I could still touch the vent with my hand. It's pretty hot, but not burn you hot. The water temp control seems very good, I think I like this Item a lot, but will need to use it more to say more. I have not put water in the heater yet, but installation was a pain, the Exhaust vent must be a metric size or something, there is no reliable documentation on what vent type is required, the manual says Class 3 Stainless, which is not insulated, but the installation video they sent said Class B which is not rated for pressurized exhaust which this has, They show an adapter in the manual, but they do not sell one, nor the vent pipe itself to match, neither 3" Class 3 nor 3" Class B fits their discharge. I wound up fabricating an adapter out of a 3" exhaust pipe piece but now this would NOT be UL approved installation which could void your insurance. The 3" OD of the pipe fit the 3" Stainless vent I purchased here on Amazon, so I think they have the proper size, but the inside of the exhaust pipe would not fit over the discharge of the Heater, I had to remove about 45 thousandths of an inch and heat it a little to get it to slip over but now it's a press fit, so it stays put well, we'll see what happens when it gets hot from running. Also I can't find ANYTHING that says what the discharge temp will be, nothing, also they post nothing about clearances to combustibles, they only refer you to the vent manufacturer and they don't say anything either. I'll connect water this weekend and add more detail then. Update, major props to the Mfg, they got back to me, they have worked out the issue with the vent and issued me a credit for my cost, a very fair settlement in my mind, still more coming on performance after I test with water. ... show more
Reviewed in the United States on March 10, 2026 Reviewed in the United States on March 10, 2026 by B. Spencer
    • So far so good
Set name: 5 GPM, NG
Havent had it long but it was Really easy to install
Reviewed in the United States on June 6, 2026 by Amazon Customer
    • Thermomate tankless water heater.
Set name: 5 GPM, NG
So far works great as of 2/16/26 .
Reviewed in the United States on June 18, 2026 by hoboken
    • ThermoMate CZ422NG Natural Gas Tankless Water Heater
Set name: 5 GPM, NG
This is the best hot water heater I've ever had. We decided to go from tanked to tankless. Our gas bill went from $70.00 down to $14.00 a month! I recommend setting the temp to 104 deg. It's just hot enough and you won't have as much wear & tear.
Reviewed in the United States on June 17, 2026 by Mark Gullick
    • I don’t recommend this item
Set name: 5 GPM, NG
Do not buy this , totally garbage . I spend money buying this and calling a profesional to install this & and now all my money is en the garbage because this never works good . Give you only hot water for 2 mins and then again cold water.
Reviewed in the United States on March 11, 2026 by Armando Heredia
    • Your gonna need a few things
Set name: 4 GPM, LP
First off this runs off natural gas. This is a city pipe that runs underground and comes up to your house. This is not propane. Propane is always in a tank near the property. Natural gas is mostly made up of methane. These compositions are different so you should only use natural gas. Next your gonna need to purchase water lines, T-shapr shut off valves, and drainage. You will also need your tools, hardware, and space accomadation materials as expected. Now that the tough part is out of the way let me say this. If your not scared off by the before mentioned things then your patience has earned you this treat. Welcome to unlimited hot water. And not just under an RV sink or something. No! I'm talking full on endless showers for the rest of your life.....(Or the rest of the water heaters). That's a long way away because I noticed it has a warranty too. A difficult installation, but pays off big time with how well it works and its reliability. Can fit in small space cuz of thin width. Very dependable. A wonderful deal. ... show more
Reviewed in the United States on April 11, 2026 by Warlord Commander Mike
    • Tankless hot water heater works fantastic.
Set name: 3.06 GPM, NG
Do it yourself installation fairly easy no leaks hot water continuously would buy again
Reviewed in the United States on April 30, 2026 by Joseph Villa
    • Great unit
Set name: 5 GPM, NG
Capacity is great, performance is great, & value is great. No troubles installing
Reviewed in the United States on March 16, 2026 by Mike Hudson

Can't find a product?

Find it on Amazon first, then paste the link below.
Checking for best price...