Every autumn brings the same run of calls: the first slightly chilly evening, the radiators go back on, and one of them doesn't respond. Before thinking about replacing it, it helps to know that an electric radiator is a simple device — a heating element, a thermostat, a control — and that the fault is almost always outside the appliance itself. Here's how to proceed, in order. For our general method, see the electrical troubleshooting page too.
What the symptom already tells you
A radiator can fail in four ways, and each points to a different cause.
It stays cold, with no indicator light
It isn't being supplied: the heating circuit's breaker has tripped, or a connection has come loose in the wall outlet behind the appliance.
It stays cold, but a light is on
It's supplied but isn't receiving the order to heat — the most common case, and usually the least serious; more on it below.
It heats non-stop and never switches off
The thermostat or its sensor no longer cuts out. The room overheats and the bill climbs.
It trips the residual-current device
Current is leaking to earth inside the appliance: a pierced element on a fluid-filled model, a cracked element on a dry inertia model. Here the radiator itself is at fault.
The number-one cause at the start of the season: the pilot wire
This is the point few people know about, and it explains a good share of October's calls. Recent radiators receive their orders through a pilot wire, connected to a programmer or a central thermostat. That wire carries four to six instructions: comfort, eco, frost protection, off.
It only takes a programmer left on a summer schedule, a flat battery, or a "frost protection" mode switched on in spring and forgotten, for the radiator to sit stubbornly at 7 °C while working perfectly. A radiator in frost-protection mode isn't broken, it's obeying. Before any other check, look at what the central unit or programmer says, and switch one radiator to comfort mode directly on its own panel to see whether it heats.
What you can check yourself
- The heating circuit's breaker at the panel. If it's down, reset it once. If it drops straight back, don't insist: an appliance is putting the circuit into fault.
- The programmer or central thermostat: mode, schedule, batteries. Force comfort mode on one radiator to separate the control from the appliance.
- The radiator itself: its on/off switch, its temperature setting, and on models with a display, any error code — it often points to the sensor or the electronic board.
- The wall outlet: if the radiator moves or was recently taken down, a connection may have loosened. Don't open it live; that's where we take over.
If a single radiator is affected and everything else heats, the problem is local — control or appliance. If several radiators are cold at once, look instead at the circuit, the programmer or the panel.
What needs an electrician
From here on we leave the realm of settings. We measure the supply at the outlet, test the pilot wire's continuity, check that the circuit is sized for the combined power of the radiators it feeds, and test the appliance's insulation when it trips.
On the appliance, what can be repaired depends on its design. A convector or a radiant panel can often be fixed: thermostat, switch, internal connection. A fluid-filled inertia radiator is a closed circuit sealed at the factory — when the element bathing inside it is pierced, we don't open it, we replace the appliance. We tell you that honestly at the diagnosis stage rather than billing a repair that won't hold.
And when the radiator is simply at the end of its life, we replace it with a model suited to the room — power calculated on the volume, correct class and protection rating for a bathroom — on a checked circuit. It's also the moment to fit proper programming, the kind that prevents exactly the pilot-wire failure of the following autumn.
Radiator, panel, or installation?
Heating that trips or heats poorly sometimes reveals something else. Radiators added over the years to a circuit designed for two, a fuse-based panel with no residual-current device, a subscribed power too tight for winter: cases where the radiator is only the symptom. If the power trips when several appliances heat together, our page on a breaker that keeps tripping explains how to identify the circuit at fault; and if the panel is dated, an electrical panel replacement settles the underlying problem.
The electric water heater follows a similar logic — contactor, element, thermostat — and it's often the one found responsible when "it trips at night".
Our intervention
For electric heating that has failed in Paris or the inner suburbs, we come within 24 to 48 hours, faster in the 15th where our base is. Callouts start at €132 incl. VAT, covering travel and the first half hour: enough for most diagnoses and control fixes. If a part or a radiator has to be replaced, we tell you the amount before continuing. And if we don't find the fault, you aren't charged for the callout.
Our electrician pricing in Paris is public; for a slot, contact us by phone or through the form. A photo of the radiator and the panel often lets us answer before we even come out.
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