Flame rod fault
Displayed as: 72
Rinnai's RU series installation and operation manual lists diagnostic code 72 as "Flame Rod". The manual's checks are: check the flame rod and wire for damage, and verify the heat exchanger is not leaking.
If you smell gas
- Stop what you are doing. Do not use phones, switches, matches or anything that can spark inside.
- Go outside and leave the door open behind you.
- Call the FortisBC 24-hour emergency line at 1-800-663-9911 or dial 911.
Only after that, call CANRO about the water heater. Official guidance: FortisBC gas leaks and odour.
Applies to
This code and wording come from manual 100000467 for the RU series. The cross-series document 100000652 applies the same code across the generations it covers.
- Rinnai SENSEI RU (Super High Efficiency Plus condensing)
- Rinnai RU130iN
- Rinnai RU160iN
- Rinnai RU180iN
- Rinnai RU199iN
Control platform: Rinnai PC board with digital controller display. Source manual: 100000467 (rev. 07 on rinnai.ca) (2020–2021).
Why a code is not a diagnosis
The control has lost or misread the flame-sensing signal. The manual checks the flame rod and its wire for damage first, then looks at the heat exchanger for leaks, because moisture or combustion changes from a leaking exchanger can corrupt flame sensing.
Same code, other equipment
- Rinnai non-SENSEI series: Same code family per troubleshooting document 100000652. Source
Safe things to observe
- Note whether the code appears during firing or immediately after a reset.
- Look for signs of moisture or leakage around the unit's base and connections.
Do not
- Do not touch or bend the flame rod, and do not clean it with abrasives.
- Do not reset repeatedly; a failing flame signal can mask a combustion problem.
How professional service helps
- A technician inspects the flame rod and its wire for damage, checks the heat exchanger for leaks per the manual, and replaces the rod or repairs the leak as the checks direct.
Diagnostic visit
Repair visits carry a diagnostic service fee that CANRO states is credited toward the repair if you proceed. The amount is confirmed by phone; it is not published. Source, checked September 7, 2026.
Where CANRO provides on-site service
On-site service is currently offered across Metro Vancouver: Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Delta, Langley, Port Moody, Port Coquitlam, Maple Ridge, Pitt Meadows, White Rock, Tsawwassen; plus Anmore, Belcarra, Lions Bay, Bowen Island, Abbotsford with travel or ferry arrangements confirmed by phone. Everything else on this site is reference information you can use anywhere in Canada.
Frequently asked questions
What does the flame rod do?
It proves the burner flame to the control: the rod sits in the flame and the control reads the tiny current through it. Code 72 means that sensing path is faulty.
Why would a heat-exchanger leak show up as a flame-rod code?
A leaking exchanger changes the combustion environment and can wet or foul the sensing path; the manual's checks treat the leak as a possible cause of the flame-rod report.
Locked out with no hot water? Call with the code ready.
The brand, model and this code are passed along when you request service online, so the technician arrives prepared.
On-site service in Metro Vancouver, BC. Call to check availability.
Sources and verification
- Rinnai RU series Installation and Operation Manual, section 5.6 Diagnostic Codes · 100000467 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.