FlowMax Error Code E12: DHW storage tank (cylinder) sensor fault (Combi Boiler)
FlowMax error code E12 on a combi boiler means: DHW storage tank (cylinder) sensor fault. It is also called FlowMax diagnostic code E12.
Homeowner? What FlowMax code E12 means for you
Check, then call Your combi boiler is reporting: DHW storage tank (cylinder) sensor fault. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
- Look at the pressure gauge on the boiler. If it reads much lower than usual or near zero, or water is leaking, call a technician.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the boiler gas valve is open (handle in line with the pipe).
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
- If only hot water is missing, check that the hot water tap is open far enough to start the heater.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does FlowMax error code E12 mean?
Only on units set up to heat an indirect storage tank (parameter 1 = 01 or 02). The tank sensor reads out of range; sensor is 10 kOhm at 25°C. Lead may be up to 8 m long.
Applies to: FLOWMAX-90, FLOWMAX-120
Common causes of FlowMax code E12
- Tank sensor faulty or wrong type
- Tank sensor wire disconnected or wet
FlowMax models that use code E12
Other FlowMax Combi Boiler codes
All FlowMax Combi Boiler error codes →
FlowMax code E12: homeowner questions
What does FlowMax code E12 mean?
DHW storage tank (cylinder) sensor fault. Only on units set up to heat an indirect storage tank (parameter 1 = 01 or 02). The tank sensor reads out of range; sensor is 10 kOhm at 25°C. Lead may be up to 8 m long.
Is it safe to keep using my combi boiler with code E12?
It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Can I reset FlowMax code E12 myself?
You can try one reset (power off for 30 seconds, then on). If FlowMax code E12 comes back, the cause is still there and a licensed technician should check it.
Who can fix FlowMax code E12 near me?
Aurora Star Tech Inc. repairs FlowMax combi boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Tankless Water Heater No Hot Water: What to Check · Boiler Not Heating: What to Check
Source: FlowMax FLOWMAX-120 Instruction Manual, 6.10 Troubleshooting table, p.66; FlowMax FLOWMAX-120 Instruction Manual, 6.11 Diagnostics error code list, p.67. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.