Noritz Error 20: High Limit Switch Triggered
The high-limit safety switch has tripped, indicating the unit reached an over-temperature condition and shut down combustion to protect the heat exchanger. We diagnose and repair it across Greater Vancouver — same-day and after-hours.
The high-limit safety switch has tripped, indicating the unit reached an over-temperature condition and shut down combustion to protect the heat exchanger.
Noritz fault codes can vary by model and series. Use this as a guide — the same code can have more than one cause. Our Technical Safety BC–licensed technicians read the code, confirm it against your unit's manual, and diagnose the true cause before any repair.
Likely causes of Noritz error 20
- Inadequate water flow or an air-bound heat exchanger
- Failed or stuck circulator pump
- Scale / sediment buildup restricting flow in the heat exchanger
- Faulty high-limit thermostat or thermistor
- Closed zone/isolation valve blocking circulation
What you can safely check
- Check the pressure gauge reads in the normal cold range (about 12-15 psi)
- Confirm heating zones are open and circulation isn't fully shut off
Beyond these checks, do not open the unit or touch gas/electrical parts — BC law requires a licensed gas fitter. Call us for a proper diagnosis.
Error 20 usually leaves you without heat or hot water and can indicate a safety-related fault. Don't keep resetting it — call for priority after-hours Noritz repair.
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For your safety and to keep your manufacturer warranty valid, BoilerPart.ca does not sell loose boiler parts over the counter or for self-installation. Under BC regulations, gas appliance components must be installed by a licensed gas fitter. Every part we source is genuine OEM and is professionally fitted, tested, and certified by our Technical Safety BC–licensed technicians as part of a complete repair or installation.
Parts often behind Noritz error 20
Genuine Noritz parts we supply and professionally install — never for DIY.
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Noritz Error 20 Repair Across Metro Vancouver
Related Noritz Safety & Overheat Codes
Frequently Asked Questions
Fix Noritz Error 20 Today
Licensed Noritz diagnosis and repair with genuine parts — same-day and after-hours across Greater Vancouver.
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