Tankless Water Heater Replacement Solutions
Efficient Heating Solutions
Licensed & Insured
5-Star Rated
Same-Day Available
All Brands Serviced
Expert Diagnostics
Key Steps That Make Replacement Matter
A careful replacement process helps ensure the new heater performs properly and fits the home's hot water needs.
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Unit Assessment
The current heater is reviewed to determine whether replacement is the practical option.
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Connection Review
Unit shows fault codes (E1–E9 range common on most brands).
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Proper Removal
The outdated heater is safely disconnected and removed from the work area.
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System Fit
The replacement is positioned according to the home's existing setup and requirements.
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Performance Setup
The new heater is configured for dependable hot water operation.
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Connection Checks:
Important connections are reviewed to help prevent operating problems.
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Temperature Testing
Water temperature and system response are checked after installation.
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Final Inspection
Tankless Heater Pros. reviews the completed replacement for proper operation.
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Customer Walkthrough
The homeowner receives a simple explanation of basic system operation.
Our Proven Process
5 Steps During Tankless Water Heater Replacement
Following each step carefully helps ensure reliable hot water, proper system operation, fewer future problems, and better everyday performance.
Inspect the Existing System
The old heater and connections are checked to identify problems and determine what needs to be replaced.
Disconnect and Remove the Old Heater
The existing unit is carefully shut down, disconnected, and removed to prepare the area for the replacement.
Prepare the Installation Area
The setup is reviewed and prepared so the new tankless water heater can be properly positioned and connected.
Install and Connect the New Heater
The replacement unit is installed and connected, with attention given to proper operation and system compatibility.
Test the New System
The heater is tested for water flow, temperature, and overall performance before the replacement is considered complete.
Expert Repair Solutions
Root Causes & How We Fix Them
Click any item below to see the likely symptom, repair action, and part replaced.
Faulty Igniter / Ignition Module
Likely Symptom: Unit won't ignite — clicks but no flame
Repair Action: Replace igniter electrode or ignition module
Typical Part Replaced: Ignition assembly
Failed Flow Sensor
Likely Symptom: No hot water — unit won't activate when taps are opened
Repair Action: Clean or replace the flow sensor
Typical Part Replaced: Flow sensor / turbine
Clogged Heat Exchanger
Likely Symptom: Error codes displayed, reduced heat output
Repair Action: Chemical flush and descale the heat exchanger
Typical Part Replaced: Heat exchanger (if cracked or corroded)
Blocked or Improper Venting
Likely Symptom: Unit shuts off mid-use or throws combustion errors
Repair Action: Clear obstructions and re-route vent if needed
Typical Part Replaced: Vent pipe fittings
Gas Valve Failure
Likely Symptom: No ignition, possible gas smell near unit
Repair Action: Replace the gas valve assembly
Typical Part Replaced: Gas valve assembly
Temperature Sensor Failure
Likely Symptom: Inconsistent water temperature — hot-cold swings
Repair Action: Replace the thermistor
Typical Part Replaced: Thermistor / temperature sensor
Printed Circuit Board (PCB) Failure
Likely Symptom: Error codes, no power, or erratic behavior
Repair Action: Reprogram or replace the control board
Typical Part Replaced: PCB / control board
Pressure Relief Valve Leak
Likely Symptom: Water dripping from the relief valve discharge pipe
Repair Action: Replace the pressure relief valve
Typical Part Replaced: T&P relief valve
Certified Brand Expertise
We Repair All Major Brands
Our technicians are trained on the specific quirks and error codes of every major manufacturer.
Rinnai
Navien
Noritz
Rheem / Paloma
Bosch
EcoSmart / Other Electric
Rinnai
Common Error Codes: Code 11 (ignition failure), Code 12 (flame loss), Code 25 (water temp too high)
Known For: Excellent reliability but scale-prone heat exchangers in hard-water areas like Knox County.
Rinnai requires OEM parts for warranty compliance.
Navien
Common Error Codes: E003 (ignition failure), E012 (flame loss), EO47 (low water pressure)
Known For: Built-in recirculation pump; condensate trap clogs are common on Navien units.
Navien units have a pre-filter that needs quarterly cleaning.
Noritz
Common Error Codes: Code 11 (no ignition), Code 90 (combustion abnormality), Code 73 (PCB failure)
Known For: Durable build quality, though gas valve failures are noted after 8–10 years of service.
Check venting configuration on older Noritz units — many Knoxville homes have outdated setups.
Rheem / Paloma
Common Error Codes: Code 13 (abnormal combustion), Code 29 (heat exchanger outlet sensor), Code C8 (scale buildup)
Known For: Budget-friendly, but heat exchanger scale is very common with Knox County's hard water.
Annual flushing is strongly recommended for Rheem units in the Knoxville area.
Bosch
Common Error Codes: A7 (overheating), EA (fan motor error), 1E (flame loss)
Known For: Compact units popular in condos; venting restrictions are a frequent cause of unexpected shutoff.
Bosch discontinued some residential lines — parts availability may vary on older models.
EcoSmart / Other Electric
Common Error Codes: No display, tripped breaker, heating element failure
Known For: 100% electric units with modulating elements — element failure is the #1 repair we see.
Element replacement is straightforward but requires a full system drain before service.
Don't wait for a cold shower.
Our Knoxville technicians are ready today.
Trusted Local Service
Why Knoxville Trusts Tankless Heater Pros
We've built our reputation on honest work and reliable service — every call, every time.
Same-Day Service
We dispatch technicians across Knox County daily — often within hours of your call.
All Brands & Models
Gas, propane, and electric tankless units. If it heats water, we fix it.
Upfront Pricing
No surprises. We quote before we wrench, so you know the cost before we start.
Licensed & Insured
TN-licensed plumbers with full liability coverage on every job.
Proudly Serving Our Community
Serving Knoxville & Surrounding Communities
We've built our reputation on honest work and reliable service — every call, every time.
Tankless Heater Pros proudly serves homeowners and businesses throughout Knox County and the surrounding East Tennessee communities. Whether you're in downtown Knoxville, the suburbs of Farragut, or across the county line in Maryville or Oak Ridge, our technicians are just a phone call away at (865) 407-1147
We understand the unique plumbing challenges of our region — from hard water mineral deposits common throughout the Tennessee Valley to the specific building codes and venting requirements in Knox County. That local expertise means faster, more accurate repairs for your tankless water heater.
Call (865) 407-1147 to confirm service in your area
Knoxville
Farragut
Hardin Valley
Karns
Cedar Bluff
Oak Ridge
Clinton
Lenoir City
Kingston
West Hills
Bearden
Sequoyah Hills
Northshore
Concord
West Knoxville
Maryville
Alcoa
Tellico Village
