Raypak HL2: Second High-Limit Switch Tripped
HL2 means a second, backup high-limit switch has now opened because the heat exchanger got too hot again.
Raypak wires two high-limit switches into its heaters, not one, and HL2 is the second one talking. If you already cleared an HL1 fault today and now the panel reads HL2 instead, that's not a new, unrelated problem showing up — it's the same overheating condition persisting after the first switch reset, or persisting long enough to also trip the backup. Seeing HL2 on its own, without HL1 first, points to the same root causes, just caught by the second safeguard instead of the first.
High severityApplies to: Raypak Digital ASME and low-profile residential gas pool/spa heaters
What it means
High limit 2 tripped — a secondary high-limit switch opened after temperature at the heat exchanger again exceeded the safe threshold, typically after HL1 has already been an issue. Because this is the redundant safety switch rather than the primary one, a heater showing HL2 has usually already had at least one earlier overheat event that wasn't fully resolved before it was reset and restarted.
Likely causes
- Ongoing flow restriction that HL1 didn't fully resolve
- Scaled or partially blocked heat exchanger passages
- Failed limit switch or sensor circuit
What you can check yourself
- Recheck flow thoroughly (filter, valves, pump speed, water level) before restarting
- Allow the heater to fully cool before clearing the fault
A repeating HL2 after flow is confirmed good is a heat-exchanger or limit-switch issue that needs professional diagnosis rather than repeated resets.
Sources
Related
- All Raypak error codes
- Raypak HL1 — the primary high-limit switch that usually trips before HL2 does
- Raypak PRS — the low-flow fault behind most high-limit trips
- Pentair ERR AGS — Pentair's hard overheat lockout after repeated high-temperature events
- Flow / Low-Flow Error — the underlying symptom in most HL1/HL2 cases