Rinnai REP199eN Tankless Water Heater: Endless Hot Water with Smart-Circ Technology

The Endless Hot Water Dilemma

We’ve all been there. You’re enjoying a relaxing shower, and suddenly, the water turns ice cold. Someone else in the house started laundry, or maybe the dishwasher kicked on. With a traditional tank water heater, this is a common – and frustrating – experience. Tank water heaters store a limited amount of hot water, and once that’s depleted, you’re left waiting… and shivering.

Tank vs. Tankless: A Fundamental Shift

Traditional tank water heaters work by constantly heating a large reservoir of water, typically 40 to 50 gallons or more. This is inherently inefficient, because the tank loses heat to the surrounding environment, even when you’re not using any hot water. This is called “standby heat loss,” and it’s a major contributor to your energy bill.

Tankless water heaters, on the other hand, operate on a fundamentally different principle: they heat water on demand. When you turn on a hot water tap, cold water flows through the unit, and a powerful burner instantly heats it to the desired temperature. There’s no storage tank, and therefore, no standby heat loss. This makes tankless heaters generally much more energy-efficient than traditional tank models.

Meet the Rinnai REP199eN: Efficiency and Innovation

The Rinnai REP199eN is a prime example of advanced tankless water heater technology. This non-condensing, natural gas unit is designed for indoor installation and packs a powerful punch in a compact package. It’s roughly the size of a small suitcase, yet it can deliver up to 7.9 gallons of hot water per minute (GPM) – enough to handle multiple showers and appliances running at the same time. With a 199,000 BTU burner, it ensures a continuous supply of hot water, even during periods of high demand.

Smart-Circ: The Brains Behind the Hot Water

One of the potential drawbacks of some tankless water heaters is the “cold water sandwich” effect. This is the initial burst of cold water you might feel before the hot water arrives, caused by the water sitting in the pipes cooling down between uses. The Rinnai REP199eN tackles this issue head-on with its built-in recirculation pump and, more importantly, its Smart-Circ technology.

Traditional recirculation systems constantly circulate hot water through the pipes, ensuring near-instant hot water at the tap. However, this can waste energy, as the pump runs continuously, even when you’re not using hot water.

Smart-Circ takes a different approach. It learns your household’s hot water usage patterns over time. Think of it like this: if your family typically showers between 7:00 AM and 7:30 AM, Smart-Circ will recognize this pattern and start recirculating hot water a few minutes before 7:00 AM, ensuring that hot water is ready when you need it. During periods of low or no usage, like during the workday or overnight, the system intelligently reduces or stops recirculation, saving energy. It’s like having a personal hot water concierge that anticipates your needs.

Under the Hood: How the REP199eN Works

Let’s take a peek inside the REP199eN to understand how it delivers hot water so efficiently. The heart of the unit is the heat exchanger. This is a series of copper or stainless steel (in this, case both alluminum and stainless steel are used) tubes through which the water flows. As the water passes through the heat exchanger, a powerful natural gas burner heats the tubes to a high temperature. The heat is transferred from the tubes to the water, rapidly raising its temperature.

The REP199eN uses four solenoid valves to precisely control the flow of gas to the burner. These valves modulate the gas supply based on the water flow rate and the desired temperature, ensuring optimal combustion efficiency and consistent hot water output.

Water flow sensors and a by-pass flow control device work together to regulate the water flow and maintain a stable temperature, even if the water pressure fluctuates. This ensures a consistent and comfortable hot water experience.

Condensing vs. Non-Condensing: Understanding the Difference

Tankless water heaters come in two main types: condensing and non-condensing. The Rinnai REP199eN is a non-condensing model. The key difference lies in how they handle the exhaust gases produced during combustion.

Non-condensing units, like the REP199eN, exhaust the hot gases directly out of the vent. Condensing units, on the other hand, have a secondary heat exchanger that extracts additional heat from the exhaust gases before they are vented. This makes condensing units slightly more energy-efficient.

However, condensing units are typically more expensive and require a more complex installation, including specialized venting (often PVC) and a condensate drain to handle the acidic water that condenses out of the exhaust gases. Non-condensing units, like the REP199eN, offer a simpler and often more cost-effective installation, particularly in warmer climates where the efficiency gains of condensing technology are less significant.

Safety Features: Protecting Your Home and Family

The Rinnai REP199eN incorporates several important safety features. A flame rod constantly monitors the burner flame. If the flame goes out unexpectedly, the system automatically shuts off the gas supply, preventing a potentially dangerous situation.

A thermal fuse protects the unit from overheating. If the temperature inside the unit gets too high, the thermal fuse will trip, shutting down the system. An overheat switch provides an additional layer of protection.

These safety features, combined with the inherent safety of tankless technology (no large tank of hot water under pressure), provide peace of mind.

Installation and Maintenance: Keeping Things Flowing

It’s crucial to emphasize that the Rinnai REP199eN, like all tankless water heaters, must be installed by a qualified professional plumber. Proper installation ensures the unit operates safely and efficiently, and it’s essential for complying with local building codes.

Maintenance is relatively simple but important. The primary maintenance task is periodic flushing of the heat exchanger to remove mineral scale buildup, especially in areas with hard water. The frequency of flushing depends on your water hardness, but it’s generally recommended annually. The “LC” code on the unit will indicate when scale buildup is detected, and the “SS” (Service Soon) code provides a time-based reminder for service.

The Future of Hot Water

Tankless water heater technology continues to evolve. We can expect to see even greater energy efficiency, smarter controls (including more seamless integration with smart home systems), and perhaps even the development of tankless heaters powered by renewable energy sources.

Conclusion: Smart Hot Water for a Smarter Home

The Rinnai REP199eN Smart-Circ Non-Condensing Natural Gas Tankless Water Heater represents a significant advancement in water heating technology. Its combination of on-demand hot water, intelligent recirculation, compact design, and robust safety features makes it an excellent choice for homeowners seeking a more efficient and convenient way to heat water. By understanding your hot water usage patterns, Smart-Circ delivers hot water when you need it, minimizing wait times and maximizing energy savings. While a professional installation is essential, the long-term benefits of the REP199eN – endless hot water, lower energy bills, and a smaller footprint – make it a smart investment for a smarter home. Consider exploring Rinnai’s resources, including their Ground Water Temperature Map, to determine if the REP199eN is the right fit for your needs.