Tankless Water Heater Installation by Certified Professionals

When you’re investing in one of the best tankless water heaters, the quality of the installation often makes—or breaks—the entire experience. It’s not just about mounting a unit and hooking things up; a proper tankless water heater installation ensures safety, efficiency, longevity, and peace of mind. Done poorly, it invites callbacks, leaks, performance issues, and frustration.

At Aaron Plumbing, Heating & Cooling, we see many service calls that trace back to faulty installations—especially in new homes, where builders or general contractors install tankless systems without specialized training. That’s why we believe true value comes when an experienced plumber, certified by brands like Rinnai or Navien, handles the job from start to finish.

An Important Note: Do not let this or any other guide substitute the advice and work of a professional when it comes to your tankless water heater installation. Our website offers generalized advice. Improper gas, venting, or other plumbing work can result in injury or death. Leave plumbing and HVAC work to the professionals.

Why Professional Installation Matters So Much

Water heater manufacturers themselves often require installation by a certified or trained professional in order to honor warranties. For example, Rinnai’s installation manuals stress that the appliance should be installed by a qualified, licensed professional or service agency, and warn that an improper installation can void warranty coverage. media.rinnai.us+1

Because tankless units demand precise gas sizing, venting, water flow calibration, and clearance planning, the margin for error is small. We often find that many of the callbacks we respond to stem from under-sized gas piping, poor venting setups, neglected combustion air design, or incorrect positioning of the unit. When those mistakes compound, they show up as inconsistent hot water, frequent fault codes, or eventual breakdown.

Further, many newer homes have tankless water heaters installed by builders as part of construction, but those installs frequently cut corners. The team installing HVAC, carpentry, or general plumbing may not fully understand how a tankless system’s gas, venting, internal sensors, minimum flow, and water pressure tolerances all must interplay. As tankless systems have grown in popularity, these often flawed installs have become common. A professional plumber certified in these systems can avoid those pitfalls from day one.

Key Considerations for Tankless Water Heater Installation

A successful tankless water heater installation requires careful planning across multiple dimensions. Here are the most important factors we always address during the install process:

Gas Meter & Line Size

One of the first checks is whether your existing gas meter and piping can support the higher BTU demand of a tankless system. Many older meters or small gas lines are sufficient for furnace or stovetop usage but fall short when you add a high-demand gas water heater. A certified plumber will calculate the total BTU load, verify pressure drop limits, and ensure the gas line is sized correctly—not guessed.

Location of the Water Heater

Where you place the unit impacts performance, venting needs, and maintenance access. Indoor vs. outdoor placement, proximity to walls, and how far water must travel all matter. A good install positions the heater so that venting runs are minimized, service access is easy, and cold water doesn’t have excessive travel time before reaching fixtures.

Venting Requirements & Options

Venting in tankless installation is more complex than standard exhaust systems. Options include concentric (air + exhaust in one pipe), twin-pipe, direct‐vent, or PVC schedules, depending on your model. Exhaust runs must maintain proper slope (often ¼ inch per foot toward the unit), avoid combining incompatible materials, and stay within the maximum equivalent length specified by the manufacturer. Improper venting is a frequent source of installation failure and service calls.

Some installs require special vent terminations, balance of combustion air, condensate drainage, or protective materials. A certified installer understands how to route air intake, exhaust, and handle corrosion or condensate issues. Other considerations are the location of doorways and windows in relation to where the vent comes out of your home.

Water Supply & Flow Matching

Your tankless must be properly sized based on your household’s peak demand (how many fixtures might run at once) and the expected incoming water temperature. The plumber will confirm your flow rates, ensure you meet the minimum activation flow, and handle pressure drop issues. If the shutoff valves, piping layout, or filters aren’t handled correctly, you’ll see flickering temperatures or “cold water sandwich” effects.

Clearances & Local Code Compliance

Each model’s install manual and local codes will mandate specific clearances for vent terminations, wall proximity, roof penetrations, and combustible materials. Certified plumbers know how to balance those constraints, and they stay current with local code changes to ensure safe and legal installs.

Electrical & Controls

While the gas side is major, many tankless units also require electrical hookups for ignition, control boards, recirculation systems, and diagnostic wiring. Certified installers integrate power, grounding, and control wiring to meet manufacturer spec. They also calibrate control settings (temperature, error codes, recirc options) to final system configuration.

What We See When Installation Goes Wrong

Because tankless systems are more technical, many mistakes happen at the installation stage. Here are some common issues we run into on service calls:

• Under-sized or poorly configured gas lines causing unit starvation under high demand
• Venting runs that exceed maximum length or use wrong materials, leading to exhaust issues or condensation damage
• Insufficient combustion air, causing error codes or inefficient burning
• Improper slope or drainage of condensate leading to clogging or corrosion
• Incorrect positioning or clearance violations that void warranties or trigger faults
• Poor water piping design that results in pressure drop, flow instability, or cold water gaps
• Control settings left in factory defaults, not tuned to the home, reservoir, or recirculation system

In many of these cases, the homeowner assumes the unit is faulty, but the root issue is poor installation. A certified plumber can often correct those errors while others are left chasing symptoms.

Certification, Training & Brand Requirements

Leading tankless brands like Rinnai and Navien offer training, certifications, and installer levels to ensure high-quality installations. For instance, Rinnai provides installer training events and requires that installation follow exact guidelines (gas, venting, clearances, control wiring) in their manuals, warning that warranty may be void if installation is improper.

Certified or factory-trained installers typically receive updated product knowledge, special clearances, technical support access, and better parts sourcing. A homeowner using a brand-certified plumber reduces their risk and ensures that the installation matches the manufacturer’s intent.

Why Hiring Aaron Plumbing Matters

When we perform a tankless water heater installation, we bring real experience, brand knowledge, and quality assurance. Our plumbers are trained to handle every nuance — gas sizing, venting, water flow, diagnostics, and code compliance. We’ve seen and corrected many flawed installs, and we know exactly where problems come from early on. For homeowners in Cumming, Roswell, Lawrenceville, or anywhere in North Atlanta, our goal is that your tankless system works reliably day one — not after multiple service calls.

Your Tankless Water Heater Installation, Done Right

When it comes to tankless water heater installation, the difference between a reliable system and one that constantly needs attention almost always comes down to who installs it. A unit from a top brand like Rinnai or Navien can only perform at its best if it’s installed by a plumber who understands gas sizing, venting, and how these systems work in real homes — not just on paper.

At Aaron Plumbing, Heating & Cooling, our certified plumbers bring years of hands-on experience with both brands and have seen every kind of setup — from builder-installed systems that need rework to complete replacements that transform a home’s comfort and efficiency. When we install your tankless system, we handle everything correctly from the start, so you get steady, endless hot water without the headaches.

If you’re ready to upgrade or need your current system evaluated, we’re here to help. Call or schedule online today, and our team will walk you through your options, explain the installation process, and make sure you get a tankless water heater that fits your home — and your family’s needs — perfectly.

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Tankless Water Heater Installation, Repair and Maintenance in the North Atlanta Area

American Mechanical was founded in 1978 by Timothy W. Adams, a third generation Master Plumber. Today he works with his son, Aaron, a fourth generation Master Plumber to manage a team of highly trained, licensed technicians committed to customer satisfaction and providing high quality service.

We offer tankless water heater installation in Alpharetta, Cumming, Johns Creek, Marietta, Roswell, Suwanee, and other North Atlanta areas. See a full list of our service areas on Aaron Services homepage.

We offer tankless water heater installation in Alpharetta, Cumming, Johns Creek, Marietta and other North Atlanta areas. See a full list of our service areas on Aaron Services homepage.