HTP Elite Premier F05 — Supply Temperature High
F05
Supply temperature high. The boiler supply temperature is excessive (supply sensor exceeded 210°F with the red FAULT light and LOCKOUT). Check circulator pump operation and adequate flow (less than 50°F rise from return to supply), check the direction of flow off the boiler circulator, and troubleshoot the dual supply thermistor by following the F02 steps. Without the FAULT light the message clears automatically when the temperature drops below 194°F. The table classifies it as Lockout (Manual Reset).
Applies to
This sensor fault code is displayed by the 928 SIT control on Elite Premier models (EP-80 through EP-399), as documented in Elite Premier Installation Manual, LP-550 Rev. 3.4.22, Table 32 (LP-550). Codes can differ between controller generations, so always check the manual that matches your unit.
- HTP Elite Premier (discontinued)
- HTP EP-80
- HTP EP-110
- HTP EP-150
- HTP EP-220
- HTP EP-299
- HTP EP-301
- HTP EP-399
Controller: 928 SIT control. Source manual: LP-550.
Why a code is not a diagnosis
A sensor code usually means the sensor, its wiring or its mounting is faulty; the physical condition the sensor measures (temperature, pressure, flow) may be perfectly normal.
Safe things to observe
- Note the code; there is no homeowner-accessible check for sensor circuits.
- If the appliance still runs, watch whether the code returns and report it when you call.
Do not
- Do not open the appliance to test or replace sensors yourself.
How professional service helps
- A technician measures the sensor and harness against the manual's values and replaces the faulty component.
- 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.
Thermistor / NTC sensor
A thermistor is the small temperature probe — technically a negative temperature coefficient, or NTC, resistor — that tells a boiler's control how…
What a technician checks →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 →Circulator pump
The circulator is the pump that moves heated water from a boiler out to the radiators, baseboards or in-floor loops and back again.
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 Elite Premier (discontinued).
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
- Elite Premier Installation Manual, LP-550 Rev. 3.4.22, Table 32 · LP-550 · accessed September 8, 2026
Facts checked September 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.