Hayward Pool Heater SF: Official Meaning and Checks
Direct answer
What SF means
Official Hayward material describes SF as Thermistor error: an excessive temperature difference between the two thermistors (5 degrees F or more), or an 'out of bounds' condition on both sensors (less than 10 degrees F or greater than 180 degrees F). This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Before you begin
Safety first
Contact a qualified service company for assistance.
- Record the complete displayed code and the full model number before clearing the display.
- Disconnect power before touching a user-accessible filter, hose, burner, or electrical connection.
- Stop using the equipment if it leaks, smells burned or of gas, smokes, sparks, or trips a breaker.
Does this guide apply?
- Region
- United States
- Product family
- Hayward Universal H-Series H150FD / H200FD / H250FD / H300FD / H350FD / H400FD / H500FD
- Exact models
- Not listed in the cited source. Confirm the full model in the official manual.
- Scope note
- The cited source scope is Hayward Universal H-Series H150FD / H200FD / H250FD / H300FD / H350FD / H400FD / H500FD. Confirm the complete model number before applying the guidance; an empty model list does not imply all models.
Find the model label and official manual before ordering a part
Common paths to check
These are source-backed possibilities, not probability estimates for your specific unit.
- 01 Official source meaning: Thermistor error: an excessive temperature difference between the two thermistors (5 degrees F or more), or an 'out of bounds' condition on both sensors (less than 10 degrees F or greater than 180 degrees F).
Decision path
Safe checks, in order
- 1
Confirm code and model scope
Compare the complete display and full model number with the cited manufacturer page or manual before applying any troubleshooting instruction.
Expected: The official source explicitly covers the displayed code and product family.
If not resolved: Contact manufacturer support with the full model and serial number.
- 2
Follow the official owner checks
No user repair step is given.
Expected: Only the user-accessible condition identified by the official source is corrected.
If not resolved: Stop repeated resets and arrange qualified service if the code returns or the source directs service.
Reset and test
- Automatic (restart 2 minutes after the error is corrected).
Important: A reset may clear the display but cannot repair the underlying condition; follow only the exact model-specific manufacturer procedure.
Escalation point
Stop and arrange service when
- Contact a qualified service company for assistance.
- The equipment leaks, smells burned or of gas, smokes, sparks, overheats, or trips a breaker.
Model-first repair planning
Components that may be involved
The items below describe the documented diagnostic path. They are not a diagnosis and do not identify a compatible replacement part without the complete model and original part number.
- Thermistors
Official sources
We paraphrase manufacturer material and show the publication scope so you can verify it.
- Hayward Universal H-Series Owner's Manual, Figure 4: ERROR CODES, PDF pages 13-14 (also Install Manual Figure 31, PDF pages 50-51) Hayward · SF · accessed 2026-08-08
Reviewed by Device Fix Guide · Last source check:
Related guides for this equipment
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