Tankless Water Heater Repair in Toronto & the GTA
Toronto & the GTA • Call 647-784-8448
Tankless units throw fault codes when something is off — scale in the heat exchanger, intake or vent restriction, sensor failure, low gas, condensate drain blocked. The fault code on the display tells the technician where to look. Tornado Plumbing & Drains diagnoses and repairs tankless water heaters across Toronto and the GTA — Rinnai, Navien, Noritz, Bosch, and other major brands.
Last updated April 24, 2026
When this service makes sense
Part of Water Heaters & Hot Water in Toronto & the GTA
Book this service when
Book this when the unit shows a fault code, gives no hot water, produces a cold-water sandwich during multi-fixture use, or ignites slowly or not at all.
Common signs
- Fault code on the display.
- No hot water.
- Cold water sandwich (hot, cold, hot during multi-fixture use).
- Slow ignition or no ignition.
If you're not sure, compare these too
- Tankless Water Heater Descaling - when the fault code points to scale rather than a failed part
- Tankless Water Heater Installation - when a heat exchanger or board replacement approaches the cost of a new unit
On this page
Quick guide and key details
What changes price and scope
- Which component failed and the brand.
- Whether a heat exchanger or control board replacement approaches the cost of a new unit.
How a professional visit usually unfolds
1. Read the fault code
Confirm what the unit is reporting. Narrows the diagnosis.
2. Inspect intake / vent
Check for blockage, debris, or improper venting. Common cause of repeat fault codes.
3. Test gas pressure
Verify gas supply at the unit. Inadequate gas causes ignition and combustion faults.
4. Inspect for scale
Visual or descale check on the heat exchanger. Hard-water scale is the #1 long-term cause of fault codes.
5. Sensor / component test
Test flame sensor, flow sensor, fan, ignition system. Identifies failed components.
Recent Tankless Water Heater Repair work
These real project photos show the kind of work this service involves, so you can see examples before you book.
Technician handling a residential interior plumbing service call
This is a useful general indoor-service photo for interior plumbing pages where homeowners want to see a real technician on site instead of generic brand graphics.
Tankless repair pricing (Toronto 2026)
| Service | Starting from | Typical range |
|---|---|---|
| Diagnostic visit | $220 | $220 to $450 |
| Sensor / fan / ignition repair | $350 | $350 to $900 |
| Heat exchanger descale | $320 | $320 to $600 |
| Major component replacement | $650 | $650 to $1,800 |
Ranges are for planning and triage. Final pricing depends on access, urgency, materials, and whether the visit stays isolated once the area is opened.
Cities Where This Service Is a Strong Fit
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Related Guides
- Hard Water and Water Softeners in Toronto & the GTA: A Homeowner Guide
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- How to Know When Your Water Heater Needs Repair in Toronto
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Licensed, insured, reviewed Toronto plumbers
- Serving Toronto & the GTA since 2015 — over 1,200 completed jobs.
- Master plumber T95-4969603 · Plumbing contractor T94-4992639 · Drain contractor T87-4722944 · Building renovator T85-4728632 · Plumbing license FI6216638.
- 4.9-star Google rating from 320+ reviews. 400+ HomeStars reviews (Best of 2019–2025). BBB-accredited.
- Same-day and after-hours dispatch across Toronto, Etobicoke, North York, Scarborough, York, Mississauga, and Burlington.
25-year workmanship warranty
Every job Tornado Plumbing & Drains completes in Toronto and the GTA — repair, install, replacement, drain work, sewer work, fixture work — is backed by a 25-year workmanship warranty. The written terms are provided with every quote. If our work fails within 25 years of the install date, we come back and make it right.
Repair, descale, or replace — we tell you which
Most tankless faults come down to one of three fixes: a descale to clear mineral buildup from the heat exchanger, a single failed part (flame sensor, flow sensor, igniter, fan motor, or gas valve), or — when the heat exchanger itself is cracked or scaled shut — replacement. We carry common Rinnai, Navien, and Noritz parts, so many repairs finish in one visit. If a 10-year-old unit needs a heat exchanger, we'll tell you straight whether repair or a new tankless water heater is the smarter spend.
Common tankless issues:
- Fault code on the display.
- No hot water.
- Cold water sandwich (hot, cold, hot during multi-fixture use).
- Slow ignition or no ignition.
- Loud rumbling or popping (scale in heat exchanger).
- Error during high-demand use (undersized or scaled).
What's included
- Fault-code diagnosis matched to your unit's manufacturer service manual (Rinnai, Navien, Noritz, Bosch, and others).
- Combustion check: gas pressure verified at the unit and intake/vent inspected for blockage.
- Component repair or replacement — flame sensor, flow sensor, igniter, fan motor, control board, or gas valve as the fault dictates.
- Heat-exchanger descale (vinegar or pump flush) to clear hard-water scale, the GTA's most common cause of recurring faults.
- Condensate drain and trap cleared on condensing units so a blocked drain isn't tripping the unit.
- Full test cycle after the fix and the area left clean, with the resolved fault code confirmed gone.
- Written 25-year workmanship warranty on the repair labour.
Tankless repair cost
Diagnosis is straightforward. Repair varies by component and brand. Major component replacement (heat exchanger, control board) can approach the cost of replacement on older units.
What to share when you call
- Brand, model, and approximate age.
- Fault code on the display if any.
- Symptom (no hot water, slow, fluctuating).
- Last descale date if known.
- Whether you have a softener.
- Photos of the unit and the display.
Toronto context
Tankless repair calls in Toronto cluster on flow-sensor faults, ignition failures, and scale-driven heat-exchanger problems — the third one is the one that points to descaling neglect. Most tankless brands have parts in Toronto for at least 10 years; beyond that, replacement often pencils out cheaper than chasing parts.
What to confirm before approving repair
- Repair on units 10+ years old should be quoted alongside replacement.
- Descaling should be considered before replacing major components.
- Vent and intake should be inspected — they cause recurring fault codes.
Useful info on the call: brand, model, fault code, symptom, last descale date.
Frequently asked questions
What does the fault code mean?
Each manufacturer uses its own codes for ignition failure, flame sensor, flow, vent, scale, and other issues. Tell us the code when booking and we can come prepared.
Why does my unit fail during showers?
Often scale buildup in the heat exchanger or insufficient gas supply during high demand. Descale and gas pressure test usually identify the cause.
Should I repair or replace?
Under 10 years and the issue is one failed component — repair. Older units with major component failures, or units that have not been descaled and have heat exchanger damage — usually replace.
Do you work on all brands?
Yes. Major brands (Rinnai, Navien, Noritz, Bosch, Takagi, A.O. Smith, etc.). Some brands need specific manufacturer-trained service for warranty repairs.
How much does tankless water heater repair cost in Toronto?
A diagnostic visit starts at $220, which puts a licensed plumber on the unit to read the fault code and pinpoint the failed component before any parts are quoted. You get the repair cost in writing before work proceeds, so the diagnostic is never a blind charge. Every repair is backed by our 25-year workmanship warranty.
Do you repair conventional hot water tanks too, or only tankless?
This page covers on-demand tankless units; if you have a standard storage tank that is leaking, lukewarm, or not heating, that is a different repair and lives on our Water Heater Repair page. Tell us the brand and what it is doing when you book and we will route you to the right visit. We service both across Toronto and the GTA, open 24 hrs Mon-Sat for urgent no-hot-water calls.
Related services
Tankless Water Heater Repair: real customer reviews
Recent Google reviews from Tornado customers across Toronto and the GTA, in their own words.
Mark Rowe
May 2022“Service above and beyond expectations, and competitive value! Serhiy and his staff, including Peter, are timely, professional and trustworthy.”
Mimi Lam
December 2024“Here’s the updated review with the details you provided: I recently hired Tornado Plumbing, led by Sergei, to waterproof and patch a shared laneway with my neighbor, and I couldn’t be happier with their work. From the first consultation to the completion of the project, Sergei and his team demonstrated professionalism, skill, and exceptional customer service. Sergei took the time to explain the entire process clearly, ensuring both my neighbor and I were on the same page. His team went above and beyond—not only addressing the immediate issue but also implementing solutions to prevent future problems. Their attention to detail was remarkable, and the quality of their workmanship is outstanding. What truly set Tornado Plumbing apart was their commitment to customer satisfaction. Upon the initial digging we discovered that the addition to my house couldn’t be waterproofed because there was no foundation. Sergei provided me with options and allowed me to make an informed decision based on the options available, understanding that money was tight and my need to balance finance with optimal protection for my home. Sergei and his team made sure every aspect of the project was handled with care. It’s rare to find such a combination of expertise and genuine dedication. I wholeheartedly recommend Tornado Plumbing to anyone in need of reliable and high-quality plumbing services. Thank you, Sergei, for making this process so smooth and stress-free!”
nelson antunes
July 2020“Excellent service, quick and well done. Will hire again.”
Authoritative sources for this service
Public references — City of Toronto programs, federal guidelines, and standards bodies — used for the rules and figures cited on this page.
- NRCan — EnerGuide ratings for water heaters(federal)
- TSSA — Technical Standards & Safety Authority (gas-fired equipment)(regulator)
- Enbridge Gas — Service connections and meter locations(industry)
- Ontario Building Code — Part 7: Plumbing Services(regulator)
- City of Toronto — Priority Lead Water Service Replacement Program(city)
- CSA B125.3 — Plumbing fittings(standard)
Other services homeowners often compare with this one
If your situation could fit one of these adjacent services instead, open the page that matches more closely before you book.
Fast answers before you call
What does the fault code mean?
Each manufacturer uses its own codes for ignition failure, flame sensor, flow, vent, scale, and other issues. Tell us the code when booking and we can come prepared.
Why does my unit fail during showers?
Often scale buildup in the heat exchanger or insufficient gas supply during high demand. Descale and gas pressure test usually identify the cause.
Should I repair or replace?
Under 10 years and the issue is one failed component — repair. Older units with major component failures, or units that have not been descaled and have heat exchanger damage...
Do you work on all brands?
Yes. Major brands (Rinnai, Navien, Noritz, Bosch, Takagi, A.O. Smith, etc.). Some brands need specific manufacturer-trained service for warranty repairs.
Book Tankless Water Heater Repair today.
Tornado Plumbing & Drains handles Tankless Water Heater Repair across Toronto and the GTA. Call 647-784-8448 or book online for a clean diagnosis, written scope, and the 25-year workmanship warranty on every install and repair.