Ultimate Guide: Installing Your i12 4.0 GPM Tankless Water Heater

Ultimate Guide: Installing Your i12 4.0 GPM Tankless Water Heater

In the world of small living spaces, where every square inch counts and efficiency reigns supreme, the choice of home appliances becomes paramount. When it comes to providing a continuous supply of hot water while saving space and energy, Eccotemp's i12 series (i12-LP. and i12-NG) tankless water heaters stand out as the perfect solution. In this blog, we will explore how these innovative tankless water heaters from Eccotemp can elevate the water heating system and convenience of your mid-size or tiny home. Designed to meet the unique demands of compact living, these heaters not only fit seamlessly into your limited space but also enhance your overall quality of life.

The design of Eccotemp's i12 Indoor Tankless Water Heaters was centered on crafting a solution that perfectly caters to the distinctive requirements of mid-size and tiny homes. This technological approach aimed to deliver a space-efficient, top-performing, energy-conserving, and user-intuitive system. The design thinking behind this approach reflects a deep understanding of the challenges and aspirations of individuals living in compact living spaces and a commitment to providing them with an ideal solution for their hot water needs.

Versatile Performance

With a rating designed to accommodate 1-2 applications, you can effortlessly enjoy the convenience of taking a shower and running two sinks simultaneously. The Eccotemp i12 proves to be the perfect fit for heating hot water in smaller residential settings, including single-family homes, condos, cabins, apartments, and even light commercial use. Boasting an impressive 4.0 GPM output at 80,000 BTUs and a 38-degree temperature rise, this exceptionally efficient tankless water heater is well-suited for every tiny or single-family home, delivering reliable and consistent hot water on demand.

Flexible Options

You have the freedom to choose the fuel source that best suits your preferences and requirements. The Eccotemp i12 series offers both liquid propane and natural gas configurations to cater to your individual needs.

Natural gas is typically more budget-friendly than electricity, presenting a cost-effective solution for water heating. It offers a swift and consistent supply of hot water, particularly suitable for larger households. It's worth noting that access to a natural gas supply line is necessary, which may not be available in all regions. In cases where a gas line extension is needed, there might be slightly higher installation costs.

On the other hand, propane offers versatility, often serving as a reliable alternative in areas where natural gas isn't accessible. It efficiently powers your water heater, ensuring a dependable source of hot water. Keep in mind that propane tanks require periodic refilling, which can result in additional expenses. Nonetheless, many homeowners value the independence and self-sufficiency that comes with having their own fuel source.

Eccotemp's i12 Indoor Tankless Water Heaters are meticulously crafted to seamlessly integrate into compact living environments. Whether you opt for an indoor or outdoor installation, you enjoy the convenience of selecting the configuration that aligns perfectly with your requirements. Don’t forget to look at our recommended installation location map to help you in selecting the ideal product configuration based on factors such as groundwater and external temperatures in your area.

Product Selector

When it comes to choosing the perfect water heater, our product selector proves to be a valuable asset. It aids customers in pinpointing the most fitting water heater model tailored to their precise location and demands. By gathering essential details about the customer's residence and hot water requirements, this tool provides customized suggestions, guaranteeing that customers make well-informed choices. This ensures that customers discover a water heater that not only satisfies their requirements but also harmonizes with their location, be it a spacious family home or a compact dwelling in a specific climate zone.

Indoor Venting

When purchasing an Indoor Tankless Water Heater one must consider the proper type of venting, which is essential for the safe and efficient operation of indoor tankless water heaters. The i12 tankless water heater comes with a uses a 2.5 inch stainless steal horizontal vent kit. This type of venting enhances safety by effectively channeling combustion gases, such as carbon monoxide, out of your living space, preventing potential health hazards. This type of venting also saves valuable indoor space, making it a practical choice for various settings. Eccotemp offers two variations for installing our i12, use our included Horizontal vent kit (additional vent pieces may be needed) or purchase separately a Vertical Vent Kit to ensure proper installation. Sold separately are our condensation drain pipes which must be used for areas where outdoor temperatures fluctuate during summer and winter months. When cold air is mixed with hot are produced from your tankless water heater it causes condensation which if no condensation drain pipe is installed will go back into your water heater causing rust, corrosion and even permanent damage.

Efficiency and Quality

The i12 series shines with its remarkable specifications, offering a 4.0 GPM (gallons per minute) flow rate and an 80,000 BTU rating, accompanied by an impressive 38-degree temperature rise. This ultra-efficient tankless water heater ensures the luxury of instant hot water in diverse scenarios, all while maintaining a strong focus on energy efficiency. While the water heater provides immediate hot water, it's important to remember that hot water must travel through your plumbing to reach its destination. For those who share our impatience, it's worth noting that we offer POUs (point of use) mini-tank water heaters, effectively eliminating the wait time and delivering hot water instantly.


The Eccotemp i12 has undergone rigorous testing at elevations up to 2,000 feet. Installing and using the Eccotemp i12 beyond 2000 feet could potentially impact the product's overall efficiency and performance, which may not be advisable. This adherence to altitude recommendations aligns with the Department of Energy's dedication to advancing energy-efficient technologies and ensuring that our products consistently meet the most stringent quality and safety standards.

Why choose Eccotemp?

When choosing the ideal water heater for your home, Eccotemp outshines lesser-known brands by a substantial margin. What sets us apart? It's our unwavering commitment to crafting the aesthetics and functionality of our products in-house, right here in South Carolina. This means that each and every water heater we deliver is meticulously designed with an emphasis on precision, quality, and innovation. But that's not all. We recognize the vital role that genuine support plays. Our dedicated team of customer support agents is always on hand to address any inquiries or concerns, ensuring a personalized and responsive experience. Combine this with our 20 years of industry experience, robust warranties, extended protection plans, and complimentary shipping, and you'll receive an unbeatable package in terms of value. And let's not overlook our exclusive direct-from-manufacturer discounts, making ownership of an Eccotemp water heater an even smarter choice.

Installation Requirements

Our tankless water heaters offer hassle-free installation with convenient features like easy wall mounting and compatibility with a 110/120-volt UL-listed power cord. The i12 tankless water heater, has ½ inch NPT water and gas connections simplify the installation process further. We only recommend steel gas lines for proper installation. When using any type of flex steel gas line, it must be rated properly, or this will cause your water heater to not work correctly. For the i12 tankless water heater you must use a flex steel gas line rated at a minimum of 80,000 BTU for the product to operate properly. We recommend a higher rating if possible. We also recommend limiting any 90 degree turn on your steel gas line because every 90 degree turn in your steel gas line will drop the maximum btu output below the 80,000 btu required for your i12, which will cause gas error codes.

Avoiding common installation mistakes, such as improper sizing, wrong vent material, and neglecting proper gas line size and water connections or electrical connections, is crucial to ensure optimal performance and safety of your water heater. Always follow the Manufacturer's Guidelines and consult a professional if needed to avoid these common pitfalls during installation. We also recommend installing a Service Valve Kit for periodic descaling and damage preventative maintenance. These easily connect to our EZ-Flush System Descaling Kit.

When it comes to indoor venting for the i12 tankless water heater, this product comes with a 2.5 inch vertical vent kit. Please note, additiaonal venting may be needed based on your installation. Local code also may require the purchase of additional venting. To change the included vent kit based on your specific needs we recommend purchasing our 3-inch vertical or horizontal vent kits with 2.5-inch Adapter. Proper venting is crucial for the safe and efficient operation of your water heater. The included horizontal kit allows you to vent exhaust gases through a sidewall, ideal for spaces with limited vertical venting options. On the other hand, switching to the venting to a vertical installation allows for venting through the roof, a suitable choice for multi-story buildings or instances where vertical venting is preferred. Choosing the appropriate venting ensures that combustion gases are safely expelled, contributing to the optimal performance and safety of your indoor tankless water heater.

Common mistakes in venting tankless water heaters, whether in horizontal or vertical installations, can lead to reduced efficiency and potential product damage. Condensation occurs when hot exhaust gases cool as they exit the vent, forming moisture. In horizontal installations, one common mistake is an improper vent slope, which can cause condensation to pool and drain back into your tankless water heater causing catastrophic product damage not covered by your manufacturer's warranty. This is why we always recommend the proper slope away from your tankless water heater and installing a vertical condensation drain pipe or horizontal condensation drain pipe (sold separately).

Improper horizontal installation: No drain pipe, wrong venting materials (must be stainless steel), no backflow preventer

In vertical installations, overlooking proper venting installation will also lead to damage to your tankless water heater. A condensation drain pipe is always recommended for any tankless water heater installation where temperatures fluctuate. Also make sure with any installation you have a backflow preventor installed on your installation stopping cold air from blowing back into your water heater during freezing temperatures and windy days. Warning: the i12 does not have freeze protection included with the product. Finally, with any tankless water heater, always have the proper sized drain pan located under your tankless water heater should it break, freeze or be damaged so that if a water leakage occurs it will not damage your home.

Improper vertical installation: No drain pipe, no backflow preventer, no downward slope to avoid condensation returning to the water heater.

Tips and Tricks

Adhering to the maintenance recommendations provided by the manufacturer is a significant step in ensuring the longevity of your tankless water heater. Periodic flushing is essential to prevent the accumulation of minerals and should be performed at least annually, although the frequency may vary based on your water source. If your water supply comes from a well, we strongly advise descaling your tankless water heater at least twice a year. Our dedicated EZ-Flush System Descaler Kit is an invaluable tool designed precisely for tackling even the most stubborn buildup. Consistent maintenance practices not only prolong the lifespan of your tankless water heater but also preserve its operational efficiency.

Warranty and Quality Assurance

At Eccotemp, we don't just provide cutting-edge water heating solutions; we back them up with a robust warranty that reflects our confidence in the quality and durability of our products. You can find detailed information about our warranty program on our website. With our comprehensive manufacturer's warranty for the i12 series tankless water heater, you're covered for 5 years on the heat exchanger, 2 years on parts, and free accessories, including fittings, hardware packs, and more, within 30 days of purchase. Additionally, we offer various support channels such as live chat, product support appointments, and self-help guides to offer peace of mind, ensuring that your Eccotemp i12 Series will supply you with hot water reliably for many years to come. We always recommend scheduling a Free Post Purchase Installation Consultation to guarantee proper installation, provide helpful tips and tricks, and address all your questions before use.

Even in cases of improper installation, you can have confidence in our commitment to your satisfaction. We firmly support our products and offer assistance, even if they are no longer under warranty or have incurred incidental damage. Your contentment remains our foremost concern, and we're always here to aid you, irrespective of warranty status or the extent of damage to the product.


In the world of tankless water heaters, the Eccotemp i12 Series Tankless Water Heater is a prime example of innovation and efficiency. It caters to both homeowners seeking a continuous hot water supply and small business owners with commercial needs, offering a technologically advanced yet budget-friendly solution. Ideal for compact living spaces like tiny homes, the i12 series features a space-saving design, allowing flexible installation while maintaining performance. With a flow rate of 4.0 GPM, it ensures a steady hot water supply for various purposes. Additionally, Eccotemp's energy-efficient technology aligns with sustainability principles, reducing utility costs. Backed by impressive specifications, ease of installation, and dedicated support, it's the preferred choice for those seeking top-tier hot water solutions. Experience the convenience of endless hot water with Eccotemp's 4.0 GPM tankless water heaters, tailored to meet the unique needs of your mid-size and tiny home.

Find The Right Water Heater

Our agents are here to help find the right water heater for your installation and needs. Tankless water heaters are not a one size fits all!

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