HTP Versa-Hydro F01 — Flue Temperature Limit Switch Tripped
F01
Flue temperature limit switch tripped. The flue temperature limit switch of the unit has tripped. Check the flue for obstructions or heat damage and repair as necessary; push the red reset button on the flue temperature switch located on the CPVC vent elbow (switch temperature must be less than 90°F to reset); press RESET on the display. Run the unit and check the flue temperature with an external thermometer - if below 190°F but the switch trips replace the switch; if excessive check and adjust combustion controls. The table classifies it as Lockout (Manual Reset).
If a carbon-monoxide alarm sounds
- Leave the building immediately and get fresh air.
- Call 911. Do not go back inside until emergency services say it is safe.
- Have every fuel-burning appliance inspected before use.
Only after that, call ROMA about the boiler. Official guidance: Health Canada on carbon monoxide.
Applies to
This venting or air-supply fault code is displayed by the 926 SIT control on Versa-Hydro models (PHE130/PHE199), as documented in Versa-Hydro Installation Manual, LP-314 Rev. 012 Rel. 007 (12.8.21), Table 21 (LP-314). Codes can differ between controller generations, so always check the manual that matches your unit.
- HTP Versa-Hydro & Versa-Hydro-Solar (discontinued)
- HTP PHE130-55
- HTP PHE130-80
- HTP PHE130-119
- HTP PHE199-55
- HTP PHE199-80
- HTP PHE199-119
- HTP PHE130-80S
- HTP PHE130-119S
- HTP PHE199-80S
- HTP PHE199-119S
Controller: 926 SIT control. Source manual: LP-314.
Why a code is not a diagnosis
A venting or air-supply code points at the combustion-air path: a blocked terminal, a restricted flue, a failed fan, or a condensate restriction. It does not say which, and running an appliance with a blocked flue is unsafe.
Safe things to observe
- If a carbon-monoxide alarm sounds anywhere in the building, leave immediately and call 911 from outside.
- From a safe distance, check that the vent terminal and combustion-air inlet are not blocked.
- Do not run the appliance while a blockage is suspected.
Do not
- Do not put anything into the vent or air-intake openings.
- Do not remove or modify vent pipe.
How professional service helps
- A technician inspects the full vent and combustion-air path, clears blockages and checks the fan.
- Combustion and safety devices are verified with an analyser and the manufacturer's procedure after any repair.
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 →Boiler venting (flue and air intake)
A condensing boiler vents cool, wet flue gases through dedicated plastic pipe that must meet ULC S636 in Canada and the boiler manufacturer's own…
What a technician checks →Flue temperature sensor
The flue temperature sensor — sometimes called the stack or exhaust sensor — measures how hot the gases leaving the boiler are.
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 HTP Versa-Hydro & Versa-Hydro-Solar (discontinued).
Frequently asked questions
Is this code a carbon-monoxide danger?
The code relates to combustion or venting, so treat any CO alarm as an emergency and call 911 from outside. The appliance itself should be checked by a technician before it runs again.
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
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
- Versa-Hydro Installation Manual, LP-314 Rev. 012 Rel. 007 (12.8.21), Table 21 · LP-314 · accessed September 8, 2026
Facts checked September 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.