Heating elements & SSRs
Uneven current, dead banks, stuck solid-state relays.
Heater bank drawing uneven current across phases
A multi-element heater bank pulls noticeably different current on each phase. Heating is uneven, output is low, or a phase reads much lower than the others.
Solid-state relay (SSR) stuck on — heat won't switch off
A heater (or other SSR-driven load) stays on even when the controller commands it off. Temperature overshoots, or the load runs continuously regardless of the control signal.
Heater not heating at all
A heater (element, band, or bank) produces no heat — temperature won't rise, the process stays cold, despite the control calling for heat.
SSR not switching on (load won't energise)
A solid-state relay won't turn its load on even when commanded — the heater/load stays off because the SSR isn't conducting.
Heater overshooting or oscillating around setpoint
The process temperature overshoots the setpoint then cycles above and below it, instead of settling — poor control that can spoil product or trip high-limits.
Thermocouple open or reversed (wrong temperature reading)
A thermocouple gives a wrong temperature — reads way off, shows an open/sensor-break, or moves the wrong way — so the heat control can't work properly.
Heater tripping the RCD / earth leakage
A heater circuit trips its RCD/earth-leakage protection — often when cold and first switched on, or once it's been damp — pointing to leakage to earth from the element.
Band / cartridge heater burnt out or underperforming
A band or cartridge heater (e.g. on a barrel or die) isn't reaching temperature or has failed — one zone stays cold or lags while others are fine.
Immersion / tank heater not working
An immersion or tank heater isn't heating the water/fluid — it stays cold despite the thermostat calling, or trips its protection.