Pentair Max-E-Therm ERR SFS Error
The ERR SFS error on a Pentair Max-E-Therm indicates the stack flue temperature has exceeded 480F. This high exhaust temperature suggests venting or combustion problems.
Front panel buttons are disabled. Cycle power to reset this error.
What Causes ERR SFS?
The stack flue sensor monitors exhaust temperature. Excessively high temperatures indicate problems with combustion or venting.
Common Causes
- Restricted exhaust: Blocked vent or flue
- Improper venting: Too many elbows, too long
- Gas pressure too high: Excessive combustion
- Wrong orifices: Incorrect for gas type
- Condensate buildup: Restricting exhaust
- Damaged heat exchanger: Combustion issues
- Stack flue sensor failed: False high reading
This is a Safety Fault
Excessive flue temperatures can indicate dangerous conditions. Investigate thoroughly before restarting.
Troubleshooting Steps
Step 1: Reset the Heater
- Turn off power to heater
- Wait 30 seconds
- Turn power back on
Step 2: Inspect Exhaust Venting
- Check vent termination for blockage
- Inspect entire vent run for obstructions
- Look for disconnected vent sections
- Verify vent configuration meets specifications
Step 3: Check Vent Configuration
Verify venting meets manufacturer requirements:
- Maximum vent run length
- Maximum number of elbows
- Proper vent diameter
- Correct slope for horizontal runs
Step 4: Check Condensate Drainage
- Inspect condensate drain line
- Clear any blockages
- Verify trap is properly installed
Step 5: Gas Pressure Check
Requires qualified technician:
- Verify inlet gas pressure
- Check manifold pressure
- Verify orifices match gas type (Natural/LP)
Testing the Stack Flue Sensor
If venting and gas are correct:
- Locate stack flue sensor
- Test resistance at room temperature
- Compare to temperature/resistance chart
- Replace if readings are incorrect
When to Call for Service
- Vent modification needed
- Gas pressure adjustment required
- Orifice change needed
- Heat exchanger inspection required
- Sensor replacement needed