IBC Technologies · Error codes
IBC SL G3 “Water High-Limit” alert
Error – Water High-Limit
The manual lists this alert when the boiler water temperature exceeds the high-limit threshold (208°F, or 201°F sustained for 15 seconds). The boiler enters a hard lockout and must be reset through the controller's error menu, after checking that the system is full of water, pressurized and free of trapped air.
Applies to
This alert is shown by the V-10 touchscreen controller on SL Series G3 residential boilers (SL 10-85 G3, SL 14-115 G3, SL 20-160 G3 and SL 30-199 G3), as documented in IBC Installation & Operating Manual — SL 10-85 G3 / SL 14-115 G3 / SL 20-160 G3 / SL 30-199 G3, doc 120-276E13, sections 9.2–9.4.
Controller: V-10 touchscreen controller. Source manual: 120-276E13 (2026-08-11).
Why a code is not a diagnosis
A high water temperature can be caused by a pump failure, a closed or blocked heating circuit, air in the system, a faulty sensor, an oversized load mismatch or a control fault. The alert itself does not identify which; the temperature history and the state of the pumps and valves must be checked on site.
Safe things to observe
- Read and note the exact alert text shown on the display.
- Check the boiler pressure gauge reading (a cold, sealed system is usually around 12-15 psig, but follow your installer's guidance).
- Confirm that heating zones are calling and that zone valves or pumps appear to operate when they should.
- If you see steam, scorching, melted wiring or smell burning, turn the boiler off at its service switch and call a licensed technician.
Do not
- Do not reset a high-limit lockout repeatedly without understanding why it tripped.
- Do not remove the front cover, bypass the high-limit device or touch electrical components.
- Do not open any boiler or system drain to 'cool it down'.
How professional service helps
- A technician checks pump operation, zone valves, flow rates and the expansion system before resetting the high limit.
- Temperature sensors and wiring are tested and replaced if faulty.
- After the reset the boiler is run through a heating cycle and monitored to confirm the limit does not re-trip.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Parts and service
Parts commonly involved
These parts appear in the documented text for this alert. A code reports a condition, not a failed part — a technician confirms the cause by testing before anything is replaced.
High-limit switch
A high-limit switch shuts the burner off when boiler water gets hotter than it should, protecting the heat exchanger and the system from overheating.
What a technician checks →
Service for this alert
- Gas Boiler Repair
Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…
- Emergency Boiler Repair
Priority gas boiler repair for homes and buildings in Greater Vancouver with no heat, no hot water, a locked-out boiler or a leak.
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for IBC Technologies SL Series G3.
Frequently asked questions
Can I reset the boiler myself?
IBC documents a reset procedure through the controller menus for a high-limit lockout, but the manual first instructs checking that the system is full, pressurized and free of air. If you are unsure why the limit tripped, call a technician rather than resetting repeatedly.
What if the boiler is making a boiling or sizzling noise?
Turn the boiler off at its service switch and call a licensed technician. Those noises can indicate a no-flow or low-water condition that must be investigated before the boiler runs again.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- IBC Installation & Operating Manual — SL 10-85 G3 / SL 14-115 G3 / SL 20-160 G3 / SL 30-199 G3, doc 120-276E13, sections 9.2–9.4 · 120-276E13 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.