From Error Code to Root Cause
in Under 2 Minutes
The diagnostic copilot for HVAC technicians and plumbers. Search any water heater error code or describe your symptom — then follow guided repair steps built for your exact model.
Error E11
Navien NPE-240A
Step 3 of 5
Gas pressure
8+
Supported brands
50+
Models covered
<2 min
Average diagnosis
100%
Offline capable
Supported brands & systems
Rheem
Tankless & Tank
A.O. Smith
Tank & Hybrid
Navien
Gas Tankless
Rinnai
Gas Tankless
Bradford White
Tank Gas
Bosch
Electric
Noritz
Gas Tankless
Takagi
Gas Tankless
Rheem
Tankless & Tank
A.O. Smith
Tank & Hybrid
Navien
Gas Tankless
Rinnai
Gas Tankless
Bradford White
Tank Gas
Bosch
Electric
Noritz
Gas Tankless
Takagi
Gas Tankless
The problem
Troubleshooting shouldn't start with a 100-page manual
Every minute a technician spends searching a PDF is a minute they're not fixing the unit. The industry needed a better way.
Manuals are 100+ pages
Technicians spend 20+ minutes searching PDFs for one procedure. Every minute costs money on a service call.
Every brand is different
Error codes, test sequences, and wiring diagrams vary across Navien, Rheem, A.O. Smith, Rinnai, and more.
No guide for apprentices
Junior technicians lack the experience to follow the correct diagnostic sequence without close supervision.
Repeat service calls
Wrong diagnosis on the first visit means a callback — costing time, money, and customer trust.
How it works
Three steps from problem to fix
Whether you're tackling tankless water heater troubleshooting or a no-hot-water complaint — this is the fastest path to a confirmed fix.
Identify your unit
Scan the rating plate or pick your brand and model. Works for all major tankless and tank systems.
Search the issue
Enter the error code or describe the symptom — E1, E11, no hot water, ignition failure.
Follow guided steps
Get a step-by-step water heater repair checklist built for your exact unit. No manual needed.
See it in action
Built for the field, not the office
Every screen is designed to get you from symptom to fix as fast as possible — on a phone, in a mechanical room, with gloves on.
Your field diagnostic HQ
Open recent jobs, start a new diagnostic, or scan a unit — all from one clean home screen built for how technicians actually work.
- checkQuick access to active jobs
- checkRecent diagnostic history
- checkOne-tap scan or search
Dashboard
HeatDiagnoses
Instant error code and symptom search
Type an error code like E11 or describe the problem in plain words. HeatDiagnoses surfaces the right diagnostic flow for your exact unit.
- checkSearch by code, symptom, or keyword
- checkCovers all supported brands
- checkResults in under 3 seconds
Error Code Lookup
HeatDiagnoses
Follow the diagnosis, step by step
Navigate yes/no decision branches that mirror OEM service procedures. Each step includes measurements, safety notes, and what to check next.
- checkYes/No branching logic
- checkMeasurement-based decision points
- checkSafety checks built in
Diagnostic Flow
HeatDiagnoses
Keep every job fully documented
Save diagnostic progress, repair notes, and outcomes to a job record. Build a history you can reference on callbacks or share with your team.
- checkPer-job diagnostic records
- checkNotes and repair outcomes
- checkTeam visibility for service companies
Job Tracking
HeatDiagnoses
Features
Everything a field technician needs
From error code to confirmed repair — all the tools to diagnose water heater problems fast, on site, without manuals.
Error Code Lookup
Search any fault code across all supported brands. Get the definition, affected subsystem, and exact diagnostic steps — instantly.
Guided Diagnostic Flows
Follow clear yes/no decision trees based on symptoms, live measurements, and equipment type. Built directly from OEM service procedures.
Multi-Brand Support
One interface for Rheem, A.O. Smith, Navien, Rinnai, Bradford White, Noritz, Takagi, and Bosch. No switching between apps.
Model-Based Filtering
Filter by brand, series, model number, fuel type, and component. Always get the flow built for the unit in front of you.
Repair Procedures
Required tools, safety notes, step-by-step repair actions, post-checks, and related parts — all on one screen.
Job Notes & History
Save symptoms, diagnostic outcomes, photos, and repair notes per job for future reference and team visibility.
Scan to Identify
Point your camera at the rating plate. HeatDiagnoses auto-identifies the model and opens the correct diagnostic flow.
Offline Mode
Mechanical rooms and basements kill signal. Full diagnostic access with no internet connection required.
Who it's for
Built for every level of the trade
From apprentice to service company — HeatDiagnoses adapts to how you actually work in the field.
Fix water heaters faster — first time
Stop juggling PDFs on residential callouts. Search the error code or symptom and follow the exact test sequence for the unit in front of you.
- check_circleError code lookup for tankless and tank units
- check_circleModel-specific test sequences
- check_circleOffline support for basement jobs
- check_circleSave notes per job for warranty callbacks
Diagnose heat-pump and tankless systems confidently
Guided flows for heat-pump water heaters, sensors, ignition systems, and control-board faults — no guessing, no skipped steps.
- check_circleHeat-pump and hybrid unit diagnostics
- check_circleSensor, igniter, and gas valve checks
- check_circleSafety notes in every step
- check_circleSource-linked repair procedures
Learn the right way while in the field
Follow the correct diagnostic sequence on every job. Build real knowledge from OEM service procedures — not guesswork or YouTube shortcuts.
- check_circleStep-by-step yes/no guidance
- check_circleMeasurement-based decision points
- check_circleSafety and post-check reminders
- check_circleBuilds diagnostic knowledge over time
Standardize diagnostics across your entire team
Reduce repeat calls and inconsistent outcomes. Every technician follows the same proven procedure regardless of experience level.
- check_circleConsistent procedures across all techs
- check_circleJob history and diagnostic logs
- check_circleReduce repeat service visits
- check_circleOnboard apprentices faster
Coverage
Supported water heater systems
From tankless water heater troubleshooting to gas and electric tank diagnostics — one tool, all systems.
Gas Tankless
Navien, Rinnai, Rheem RTGH, Noritz, Takagi
Electric Tankless
Rheem RETEX, Bosch Tronic
Gas Tank
A.O. Smith, Bradford White, Rheem Classic
Heat-Pump Hybrid
Rheem ProTerra, A.O. Smith Voltex, Bradford White AeroTherm
Electric Tank
A.O. Smith, Bradford White, Rheem
Ignition Systems
Spark igniter, hot surface, standing pilot
Sensors & Thermistors
Inlet, outlet, exhaust, flame sensors
Control Boards
Main board fault diagnostics, PC board tests
Supports diagnostic workflows for Rheem, A.O. Smith, Navien, Rinnai, Bradford White, and more.
Why HeatDiagnoses
Old way vs HeatDiagnoses
See how HeatDiagnoses changes the diagnostic experience for every technician on every service call.
Source-based knowledge
Diagnostic flows built on OEM service knowledge
Every diagnostic step in HeatDiagnoses is structured from manufacturer service procedures, not guesswork. Technicians follow the same logic as the OEM — just faster and in a format built for the field.
- checkSteps organized by brand, model, component, and fault type
- checkRepair procedures include tools, safety notes, and post-repair checks
- checkReduces diagnostic guesswork and repeat service visits
- checkBridges the gap between novice and experienced technicians
Multi-brand
8+ major brands in one interface
Decision trees
OEM-mirrored diagnostic sequences
Repair steps
Safety notes and post-checks built in
Fast to fix
Root cause in 2–5 minutes average
FAQ
Common questions
Answers to the most frequent water heater repair and HVAC troubleshooting questions.
Why is my water heater not producing hot water?expand_more
Common causes include a tripped circuit breaker, faulty heating element, failed thermostat, or a gas supply issue. Use HeatDiagnoses to search your error code or describe the symptom for a step-by-step diagnosis.
What does the E1 error code mean on a water heater?expand_more
E1 typically indicates an ignition failure on tankless water heaters such as Navien, Rinnai, and Noritz. It means the burner failed to light. HeatDiagnoses walks you through the exact checks for your specific model.
How do I reset a tankless water heater?expand_more
Most tankless units have a reset button on the front panel. Power cycle the unit, wait 30 seconds, then restart. If the error code returns, use HeatDiagnoses to diagnose the underlying cause.
What brands does HeatDiagnoses support?expand_more
HeatDiagnoses supports Rheem, A.O. Smith, Rinnai, Navien, Bradford White, Noritz, Takagi, and Bosch — covering gas tankless, electric tankless, gas tank, electric tank, and heat-pump hybrid water heaters.
What is the ignition failure error on a water heater?expand_more
Ignition failure means the burner failed to light within the allowed time. Causes include low gas pressure, a blocked flue, dirty flame sensor, or a faulty igniter. HeatDiagnoses provides guided troubleshooting steps specific to your unit.
What types of water heaters does HeatDiagnoses support?expand_more
HeatDiagnoses supports gas tankless, electric tankless, gas tank, electric tank, and heat-pump hybrid water heaters across multiple brands. New models are added regularly.
Can HeatDiagnoses work without internet?expand_more
Yes. HeatDiagnoses includes offline mode for field technicians. Mechanical rooms and basements often have poor signal — you can diagnose without Wi-Fi or cellular data.
Does HeatDiagnoses replace manufacturer manuals?expand_more
HeatDiagnoses structures and surfaces the same diagnostic knowledge found in OEM service manuals — but as guided, interactive flows tailored to your specific model. It complements the manual with faster, model-specific navigation.
Can service companies use HeatDiagnoses for their whole team?expand_more
Yes. Service companies can standardize diagnostic procedures across all their technicians, track job history, and reduce repeat service calls with consistent outcomes.
Is HeatDiagnoses available on mobile?expand_more
HeatDiagnoses is mobile-first and designed for field use on iOS and Android. It also works on desktop browsers for office review of job history and diagnostic logs.
Bring Faster Diagnostics
to Your HVAC Team
Search any water heater error code or describe your symptom. Get step-by-step guidance in seconds — built for technicians, apprentices, and service companies.
Works on any device · Mobile-first for field use · Covers Rheem, Navien, A.O. Smith, Rinnai, Bradford White