Thermomate 4.7GPM Tankless Water Heater review – Endless hot water, ahhhh.

REVIEW – Several years ago, a family of four refugees joined my 4-member family for the better part of a year. With eight in the house, without a tankless water heater like Thermomate’s, someone would have been taking a cold shower. How does the Thermomate CZ422NG perform? Please join me for a closer look!

⬇︎ Jump to summary (pros/cons)
Price: $399.99
Where to buy:  Amazon, Thermomate (Save 10% with code: THA10)

What is it?

The Thermomate Tankless Water Heater is a compact appliance that utilizes flammable gas to raise the temperature of water within a home’s plumbing system.

What’s included?

• Tankless water heater
• Wood screws and drywall anchors (5 each)
• Washers (3)
• Expanding concrete anchors (2)
• Installation and instruction manual

Tech specs

• Model: CZ422NG Tankless water heater
• Voltage: 120 V
• Frequency: 60Hz
• Current draw: less than 12 Amps
• Fuel type: Natural gas (other fuel types available)
• Maximum input rating: 102,000 BTU/hour
• Minimum input gas pressure: 4.0″ wc, 1.0kPa
• Maximum input gas pressure: 3.5″ wc, 2.6kPa
• Manifold pressure: 3.5″ wc, 0.87kPa
• Maximum working pressure: 150PSI

Design and features

I’ve had a tankless water heater in my home for about a decade. At the time, my teenage daughters would occasionally take marathon showers, leaving old dad praying for three more minutes of tepid water to get the soap off my face.

When the 40-gallon tank water heater sprang a leak, it was time for an upgrade. Virtually limitless hot water and reduced energy costs made a tankless heater an attractive upgrade. When four more moved in, the tankless heater saved the day, every day. Man, I hate cold showers.

Thermomate has been in business since 2018, debuting with mini tankless water heaters. I recall using similar models when I lived in Japan. I always thought they were cool, reliable, and efficient. They now offer whole-house gas and electric models that fit most residential applications.

I initially made a mistake and purchased a liquid propane version that wouldn’t work. Thermomate was gracious and professional, sending the natural gas model compatible with my home’s fuel supply. It arrived in a large box. The body of the water heater is made of metal and feels solid. It’s surprisingly small – about the size of a suitcase.

There are large installation/warning labels on the sides. Speaking of warnings, I suppose this is a good time to talk about them:  The CZ422NG uses natural gas, produces dangerous exhaust, and produces hot water at temperatures that are capable of causing burns. I wholeheartedly recommend professional installation because errors could be deadly. Please, let’s be careful out there, folks.

The exhaust port is on the top. The stainless steel exhaust lines, with condensate drains (if applicable), and a wall pass-through thimble are not included and can be pricey. Thermomate does an excellent job of explaining the process in the manual. Please note that the tankless water heater can’t share exhaust with other appliances, so don’t cut corners here – it can kill you.

When the water heater is operating, a fan discharges the exhaust. I was surprised by how quiet it is.

On the bottom are the water inlet and outlet, power cord, and gas inlet.

It’s an added expense, but do yourself a favor and purchase an isolator valve set (not included). The system required periodic back flushing to maintain peak performance. Several companies manufacture flush kits that attach to the valves to help remove sediment and scale.

As a bonus, the temperature and pressure valve connects to the valve kit. Thermomate doesn’t include one, but you shouldn’t operate any water heater without one. MythBusters did a segment on the catastrophic results (you can see it here).

My initial intention was to install the Thermomate into a friend’s house (he has seven kids), but the logistics didn’t work out. I did a temporary installation to test all the functions. I’m pleased to declare it worked better than expected.

After finishing plumbing and power connections, I let the water flow. Within seconds, piping hot water flowed. I measured a temperature rise of 36° with an output temperature of 106.3° at a flow rate of 2.7 GPM (the maximum rate my plumbing setup would permit). I have no doubt the Thermomate is capable of the full 4.4 GPM spec. Set at 110°, I measured 108.5°. Nice!

Controls for the CZ422NG are on the front, with three buttons for raising and lowering the temperature and turning the system off. The display indicates exhaust fan status, water flow (shower icon), heat active (flame icon), and temperature.

Final thoughts

After a stressful workday, grubby day in the garage or garden, or to get the cobwebs out of your brain after a night’s sleep, there’s nothing like a long, hot shower. Making water hot efficiently with the Thermomate Tankless Water Heater is the icing on the cake! It heats water very quickly, is simple to operate, remarkably compact, and a tremendous value for the money. The CZ422NG is one of those products that requires some substantial effort to install, but once everything is running correctly, it is an absolute pleasure. I even replumbed my pipes so I could have hot water in my garage, allowing me to give my chariot a thorough cleaning. I love it! Great job and thank you, Thermomate!

What I like about the Thermomate Tankless Water Heater

• Reasonably priced
• “Unlimited” hot water
• Heats water remarkably fast
• Very efficient

What needs to be improved?

• Not so much an improvement suggestion, but a “heads up” – There will be additional costs associated with the installation. Professional installation recommended.
• When plumbed into my home’s water system, there is a longer delay between the delivery of hot water compared to tank water heaters (another heads up).

Price: $399.99
Where to buy:  Amazon, Thermomate (Save 10% with code: THA10)
Source: Thermomate provided a free sample for this review, but did not provide input, guidance, or editing before publication.