NTI Trinity TFTN 209 — Storage Tank Overheat
209
Storage tank overheat. The storage tank sensor temperature is above 175°F, so check for boiler water circulating through the IWH coil during CH serving, confirm the tank sensor is fully inserted into the well, and check the wiring and sensor readings. The table classifies it as Warning.
Applies to
This overheating code is displayed by the NTI HMI control (R30) on TFTN floor models (TFTN500, TFTN600, TFTN725, TFTN850), as documented in TFTN 500–850 Installation and Operation Manual, doc 99987545 V.2025-04-24, section 18.0 Table 18-1 (99987545). Codes can differ between controller generations, so always check the manual that matches your unit.
- NTI Boilers Trinity TFTN
- NTI Trinity TFTN085
- NTI Trinity TFTN110
- NTI Trinity TFTN150
- NTI Trinity TFTN199
- NTI Trinity TFTN285
- NTI Trinity TFTN340
- NTI Trinity TFTN399
- NTI Trinity TFTN500
- NTI Trinity TFTN600
- NTI Trinity TFTN725
- NTI Trinity TFTN850
Controller: NTI HMI control (R30). Source manual: 99987545 (2025-04-24).
Why a code is not a diagnosis
An over-temperature code protects the heat exchanger or venting; it does not reveal whether the cause is low water flow, a failed pump, trapped air, fouling or a sensor fault.
Safe things to observe
- Note the code and whether rooms or hot water are still working.
- If you see steam, melted wiring or smell burning, switch the appliance off at its service switch and call a technician.
Do not
- Do not reset the appliance repeatedly while the cause is unknown.
- Do not remove covers or bypass any high-limit device.
How professional service helps
- A technician checks pump operation, flow, system pressure and the cleanliness of the heat exchanger.
- 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.
Boiler sensors (thermistors)
Boiler sensors are small temperature probes, usually thermistors, that tell the control how hot the water and flue gases are so it can fire safely…
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…
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for NTI Boilers Trinity TFTN.
Frequently asked questions
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
- TFTN 500–850 Installation and Operation Manual, doc 99987545 V.2025-04-24, section 18.0 Table 18-1 · 99987545 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.