Slant/Fin Error Lockout 85: Inlet/Outlet inversion limit — flow in wrong direction
The control detected the inlet sensor reading hotter than the outlet (an inversion), meaning water is circulating through the boiler in the wrong direction. The documented corrective action is to ensure water flows through the boiler in the correct direction per the manual's piping diagram (Figure 10-1). We diagnose and repair it across Greater Vancouver — same-day and after-hours.
The control detected the inlet sensor reading hotter than the outlet (an inversion), meaning water is circulating through the boiler in the wrong direction. The documented corrective action is to ensure water flows through the boiler in the correct direction per the manual's piping diagram (Figure 10-1).
Slant/Fin 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 Slant/Fin error Lockout 85
- Circulator pump installed or wired to push water the wrong direction
- Supply and return piping reversed at the boiler
- Pump installed backwards relative to required flow
- Inlet/outlet sensors swapped
What you can safely check
- Most common right after a new install or pump replacement — note recent work for the technician
- Do not re-pipe or rewire the pump yourself; this is a licensed-technician correction
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.
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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 Slant/Fin error Lockout 85
Genuine Slant/Fin parts we supply and professionally install — never for DIY.
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Slant/Fin Error Lockout 85 Repair Across Metro Vancouver
Frequently Asked Questions
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