Alpha · E-Tec Plus
70Return reading higher than flow due to sensor or circulation error
This code applies to E-Tec Plus 28, E-Tec Plus 33, E-Tec Plus 38. Fault codes narrow down the likely problem, but they do not replace a model-specific diagnosis.
What you can safely check
- Check the system pressure and make sure accessible radiator valves are open.
- Allow an overheated boiler to cool and reset once only if the user manual permits it.
- If the fault returns, stop resetting and arrange an engineer.
How an engineer may fix it
Diagnose water circulation, air locks, pump operation, valves, bypass, blockages, heat exchanger and temperature sensors; restore correct flow and test the safety controls.
Manufacturer source: Alpha Heating Innovation — E-Tec Plus Installation and Servicing Instructions (01/22). Checked 15 August 2026. The appliance manual and an engineer’s on-site diagnosis take precedence. Never remove the boiler case yourself.