Economy 7
Economy 7 boost works but overnight heating does not
Why this fault pattern often points to the off-peak switching, dedicated circuit or lower cylinder element.
What the fault pattern tells us
A working boost confirms that at least part of the hot water or heating system can operate from the 24-hour supply. It does not prove that the separate off-peak circuit, contactor or lower immersion element is working.
The system needs to be followed in order
Diagnosis starts at the supply and moves towards the appliance. Testing may include the meter-controlled output, contactor, off-peak consumer unit, final circuit, local switch, thermostat and heating element.
- Supplier or meter switching
- Contactor or time control
- Off-peak protective device
- Dedicated circuit and local isolator
- Lower immersion or storage-heater elements
Avoid repeated boost use as a long-term fix
Boost can cost more to run depending on the tariff and may heat less of the cylinder. Repairing the intended off-peak operation normally restores the way the system was designed to work.
Safety note
Do not remove electrical covers or work on fixed wiring unless you are competent to isolate the circuit and prove it dead. If a breaker or RCD trips again, leave the affected circuit switched off and arrange testing.