Rinnai i-Series (previous generation) 631 — DHW Recirculation Pump
631
DHW Recirculation Pump. • Ensure the DHW recirculation matches the Parameter 12 setting. • Ensure the dedicated return line is properly installed. • Ensure the inlet water filter and bypass filter are clean and free of debris. • Ensure the DHW recirculation pump is connected to the DHW Pump Terminal. • Ensure the capacity of the recirculation pump is sized appropriately for the piping (DHW recirculation pump should be higher than 1.3 GPM). • Ensure air is removed from the recirculation line. The table classifies it as Diagnostic Code.
Applies to
This domestic hot water fault code is displayed by the I-Series control (numeric diagnostic codes) on Previous-generation I-Series combi models (i060CN, i090CN, i120CN), as documented in Rinnai I-Series Condensing Combi Boiler Installation and Operation Manual, doc 800000111 (hosted on the Rinnai Canada i060CN product page), Section 12.8 Diagnostic Codes (800000111). Codes can differ between controller generations, so always check the manual that matches your unit.
- Rinnai i-Series (previous generation)
- Rinnai i060CN
- Rinnai i090CN
- Rinnai i120CN
- Rinnai i060SN
- Rinnai i090SN
- Rinnai i120SN
- Rinnai i150SN
Controller: I-Series control (numeric diagnostic codes). Source manual: 800000111.
Why a code is not a diagnosis
A DHW code involves the hot-water side: sensors, flow, the mixing/bypass valve or the DHW heat exchanger. It does not say whether the fix is a sensor, a valve or a flush.
Safe things to observe
- Note the code and whether the problem follows a hot-water draw or appears at all times.
Do not
- Do not open the appliance to test DHW components yourself.
How professional service helps
- A technician tests the DHW sensors, flow switch and valve circuits, and cleans the DHW path where the manual directs.
- 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.
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
- Rinnai I-Series Condensing Combi Boiler Installation and Operation Manual, doc 800000111 (hosted on the Rinnai Canada i060CN product page), Section 12.8 Diagnostic Codes · 800000111 · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.