IBC Technologies · Error codes
IBC SL G3 “Low Water Cutoff” alert
Error – Low Water Cutoff
The manual lists this alert when the boiler's safety and ignition module detects a low-water condition inside the boiler. The boiler locks out to protect the heat exchanger from dry-firing damage, and the manual documents a reset path that starts with confirming the system is full of water and pressurized.
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
The low-water cutoff protects against a genuinely empty boiler, but the sensor can also trip from a wiring fault, an air pocket, a stuck fill valve, or a system leak that dropped the pressure. The alert does not say which; pressure, fill behaviour and the sensor circuit must be checked.
Safe things to observe
- Note the alert text and check the system pressure gauge (a cold sealed system is usually around 12-15 psig; follow your installer's guidance).
- If the pressure reads very low, look for visible leaks around the boiler, pumps, relief-valve discharge pipe and in the mechanical room.
- Listen for running water or hissing that would indicate a leak or a relief valve passing.
- If you suspect a leak inside a wall or ceiling, shut the boiler off and call a licensed technician.
Do not
- Do not keep resetting a low-water-cutoff lockout without confirming the system actually has water.
- Do not open the boiler's automatic fill valve repeatedly or leave it forced open.
- Do not add water to a hot boiler that has just locked out until it has cooled and a technician or your installer confirms the procedure.
How professional service helps
- A technician confirms the system is full, finds and repairs any leak, and checks the expansion tank and fill assembly.
- The low-water-cutoff sensor and its wiring are tested using the controller's documented LWCO test.
- The boiler is refilled to the correct cold pressure and run through a full cycle before the lockout is cleared for good.
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.
Ignition electrode
The ignition electrode creates the spark that lights the burner in a gas boiler, and on many models it also senses the flame once it is burning.
What a technician checks →Heat exchanger
The heat exchanger is where a boiler transfers heat from the burner flame to the water that heats your home.
What a technician checks →Low-water cutoff
A low-water cutoff is the safety device that stops a boiler from firing when there is not enough water inside it.
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.
- Gas Boiler Replacement
ROMA replaces old, failed or inefficient gas boilers in Greater Vancouver, handling removal, venting and gas-supply changes,…
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
Should I add water to the system?
Adding water is a normal homeowner action on a sealed system only when you know the correct cold-fill pressure and the fill method for your equipment. If a low-water alert appears repeatedly after filling, there is a leak or expansion fault that needs a technician.
Why does the boiler keep losing water?
Usually a leak somewhere in the system, a relief valve passing, or an expansion tank that has failed and is pushing water out of the relief valve. Each of those needs an on-site check.
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.