MIZUDO ‎FDG-CS120BW-LP Propane Gas Tankless Water Heater: Endless Hot Water On Demand

It began, as many great ideas do, with a simple desire to be rid of a nuisance. Picture London in 1868: a city of coal smoke, horse-drawn carriages, and the laborious ritual of heating water for a bath. For a painter named Benjamin Waddy Maughan, this was a problem worth solving. He devised a contraption that used hot gases from a burner to instantly heat water as it flowed through a series of thin tubes. He called it the “Geyser,” and in that moment, the dream of instant, on-demand hot water was born. It was a spark of ingenuity in the Victorian fog, a promise that one day, comfort wouldn’t require planning and patience.

Fast forward a century and a half. While our homes are worlds away from Maughan’s, a peculiar tyrant often lurks in our basements, closets, or garages: the conventional tank water heater. It’s a relic of a different era’s philosophy—the philosophy of storage. This silent, hulking cylinder is a tireless worker, but a deeply inefficient one. It’s the energy equivalent of keeping your car idling in the driveway 24/7, just in case you need to go somewhere. This constant energy draw, known as standby heat loss, perpetually warms dozens of gallons of water that, for most of the day, nobody is using. It’s a thief of both energy and valuable square footage. And its greatest betrayal comes when you need it most—in the middle of a shower on a cold morning, when its finite supply runs out, leaving you in a sudden, shocking chill. Maughan’s dream, it seems, was still a work in progress.

Waking the Volcano: The Art of Taming 120,000 BTUs

To truly achieve on-demand hot water, you must abandon the philosophy of storage for the far more elegant principle of instant response. This requires a feat of engineering: the ability to unleash and control a tremendous amount of energy in the blink of an eye. This is where a unit like the MIZUDO ‎FDG-CS120BW-LP propane heater rewrites the rules. Its power isn’t measured in gallons, but in raw thermal potential: a staggering 120,000 BTUs.

What is a BTU? A British Thermal Unit is a humble measure—the energy needed to heat one pound of water by one degree Fahrenheit. But when you command 120,000 of them, you are wielding a force. It’s the thermal equivalent of igniting three dozen kitchen stovetop burners simultaneously at full blast. When a hot water tap is turned on, this dormant volcano of energy awakens. Propane flows, the burner ignites, and this immense power is channeled directly into the water flowing through its veins. The critical bridge for this transfer is the heat exchanger, an intricate network of pathways forged from oxygen-free copper. Copper, with its superb thermal conductivity, acts as a heat superhighway, ensuring that the energy torrent is absorbed by the water with astonishing speed and minimal waste. The water enters cold and, in a matter of seconds, exits hot. It isn’t storing comfort; it’s creating it in real time.

The Conductor of the Symphony: Perfect Temperature, Every Time

Harnessing immense power is one thing; taming it is another. Anyone who has ever tried to adjust a shower handle knows that a stable, pleasant temperature is a delicate balance. A blast of 120,000 BTUs could easily lead to scalding water or wild fluctuations. The true genius of a modern tankless system lies in its control system, and the MIZUDO’s Built-in Water Proportional Valve 2.0 is the maestro of this operation.

Think of this valve as an expert symphony conductor. Its orchestra is the burner, and its sheet music is the flow of water itself. The moment you open a tap, the conductor senses the precise flow rate, or Gallons Per Minute (GPM). When a second tap is opened—say, someone starts washing dishes while a shower is running, increasing the total flow to the unit’s robust 5.1 GPM capacity—the conductor immediately cues the burner to swell its output, providing more energy to heat the larger volume of water. It does this with such finesse that the temperature at the tap remains unwavering, holding true to its promised ±1℉ stability.

This agility is crucial for handling modern, water-saving appliances. One user, Jeffz, noted his washing machine’s short, repeated calls for warm water would rapidly cycle his old heater. For this system’s conductor, these quick bursts are merely short, staccato notes in the daily symphony. It responds instantly, delivering the right amount of heat for the short duration needed, then rests, ensuring efficiency and protecting the system from unnecessary stress. It’s a constant, sensitive performance, ensuring the harmony of your home’s comfort is never broken.

The Invisible Guardian

For all its fiery power and intricate control, the most important work of a device like this happens silently, in the background. Safety isn’t a feature; it’s the foundation upon which everything else is built. The CSA Certified mark on the unit is not just a sticker; it is a declaration of trust. It means an independent body, the Canadian Standards Association, has subjected the heater to a battery of rigorous tests for mechanical and electrical safety, ensuring it meets the stringent standards for North American homes.

This certification is backed by a nervous system of internal reflexes. Overheating protection acts as the unit’s sense of self-preservation, shutting everything down if temperatures ever exceed safe operational limits. Accidental flameout protection is its failsafe; if the flame is ever extinguished, the gas supply is instantly and automatically cut, preventing any hazard. These are the invisible guardians, the quiet professionals ensuring that the volcano inside remains a force for comfort, and nothing more.

The End of Waiting

Benjamin Maughan’s “Geyser” was a revolution, but it was just the first note in a long composition. The MIZUDO tankless heater, and others like it, are the modern-day echo of his original ambition. They represent a fundamental shift in how we think about a basic necessity. Comfort is no longer a finite resource to be stored and rationed from a tank. Instead, it has a pulse. It’s an intelligent, powerful, and immediate response to our needs.

The true innovation here is not just the elimination of the tank, but the elimination of the wait. It’s the confidence of knowing that the dishwasher, the laundry, and a long, hot shower can all coexist peacefully. It’s the quiet satisfaction of a lower energy bill and more usable space in your home. It’s the realization that the best technology is the kind that works so flawlessly, so intuitively, that it disappears into the fabric of our lives, leaving only effortless comfort in its wake. Maughan would be impressed.