HVACopediaRinnai · Boiler
Block 67 Supply/return sensor difference with burner off
What the control is telling you
Temporary block: a temperature difference between supply and return sensors was seen while the burner is not running. It clears when the difference disappears.
Applies to: E50CRN; E75CRN; E75CRP; E110CRN; E110CRP
Likely causes
- Defective supply (T1) or return (T2) sensor
- External heat source warming one sensor
Test and repair steps
- Check the resistance of the supply and return sensors and replace the faulty one.
- Look for an outside heat source acting on the pipes or sensors and remove it.
Other codes on the same units
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Source: Rinnai E-Combi Series Installation & Servicing Instructions (8U516009 V0116), p.71-72 (15.1, 15.2). Summarized in our own words; check the original manual for your model.
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