How to Repair a Wall-Mounted Electric Heater

Fix Wall-Mounted Electric Heater

Lee Wallender

Project Overview
  • Working Time: 45 mins
  • Total Time: 45 mins
  • Skill Level: Intermediate
  • Estimated Cost: $0

Wall-mounted electric heaters are a popular primary heat source for small rooms such as bathrooms and can serve as a supplementary heat source for large rooms that need extra warmth. Electric heaters help conserve energy by spot-heating particular areas where heat is needed rather than heating the entire home. Solid, dependable, and safe, wall-mounted electric heaters can be expected to provide reliable heat for many years.

How Electric Wall Heaters Work

Wall-mounted electric heaters work in much the same way as portable plug-in electric heaters, and they are among the simplest heater designs. Powered by a standard 120-volt or 240-volt household circuit drawing 15 or 20 amps, these hardwired heaters generate heat through simple electrical resistance passing through heating coils in a unit mounted in the wall. Most heaters have a built-in thermostat that controls the on-off cycle, and a fan blower that circulates air around the heating element and out into the room.

Although very simple in design, over time a wall-mounted heater may degrade in performance or stop working altogether. You may find that the blower is still pushing out air, but the air is no longer hot. Or the reverse: The heating element is hot, yet the blower has stopped working. Sometimes neither the blower nor the heating element will work. 

For minor problems, you can easily fix your wall-mounted electric heater with a combination of cleaning, inspection, and tightening loose connections. These are tasks most DIYers can easily do. In some cases, the problem may lie with a faulty circuit breaker in the main service panel. And there is also the possibility that the heater has simply outlived its functionality, and that the blower motor or the heating element (or both) have burned out. In this case, the only option is to replace the heater. Circuit breaker replacement or heater replacement are usually jobs for a licensed electrician, though a skilled DIYer with good experience can do the work safely.

Safety Considerations

Wall-mounted electric heaters are hard-wired into household electrical circuits, and like any electrical repair, extreme caution is required. Your community may even have code restrictions that forbid homeowners from doing any work involving circuit wiring, though, in most jurisdictions, the simple acts of cleaning, checking wire connections, or even replacing the heating unit are allowed. But working with electricity is inherently dangerous, and you should not attempt heater repair unless you have considerable DIY wiring experience and know-how to test for current using a voltage tester.

What You'll Need

Equipment / Tools

  • Non-contact voltage tester
  • Shop vacuum
  • Drill driver or screwdrivers
  • Wire stripper
  • Flashlight

Materials

  • Wire connectors
  • Electrical tape

Instructions

How to Clean a Wall-Mounted Electric Heater

  1. Turn Off the Power

    At your home's electrical service panel, turn off the circuit breaker that controls your wall-mounted heater. With 120-volt heaters, this will be a single-pole circuit breaker. A 240-volt heater will be controlled by a double-pole breaker, which usually consists of two circuit breakers tied together with a wide toggle switch. Occasionally, you will find that the 240-volt breaker is a slim-line, narrow-body breaker, known as a tandem breaker.

    Flip the breaker lever to the OFF position. However, never assume you have turned off the correct breaker until you have tested the wires inside the heater. It is very common for circuit breakers to be mislabeled in the panel.

    Shut Off Circuit Breaker to Heater
    Lee Wallender
  2. Clean and Remove the Grille

    While the grille is in place on the heater, clean out the slots with the shop vacuum. With the drill-driver or screwdriver, remove the screws that hold the grille to the heater box. Set the grille and screws aside.

    Clean and Remove the Grille
    Lee Wallender
  3. Check for Power Inside the Heater

    After first testing the voltage detector on a known live wire, test the inside of the wall heater to make sure that no power is present. Test at various points throughout the heater, focusing on the connections where the circuit wires and wire leads are joined. If the tester does not light up, then the circuit is off and it is safe to touch the wires.

    Check Heater Current With Voltage Tester
    Lee Wallender
  4. Check the Wire Connections

    The electrical circuit cable that enters the heater box (usually an NM or plastic-sheathed cable) attaches to a set of wire leads that are soldered onto the heater. The two sets of wires are usually joined together with wire connectors (wire nuts).

    Check the condition of these connections. If they are loose, re-attach them. If necessary, you may need to strip away some additional insulation from the circuit wires or wire leads in order to join them securely. Make sure there is no exposed wire visible beneath the wire connector. Some electricians like to wrap the base of the wire connector with electrical tape for a secure hold.

    Check Condition of Pigtail Connections
    Lee Wallender
  5. Examine the Wire Insulation

    The outer insulation of all wires should be solid and free of nicks or cracks that might cause a short circuit. For minor nicks, wrap the wires with electrical tape. Badly degraded wires indicate a heater that has outlived its lifespan and needs to be replaced.

    Examine Wire Sheathing for Nicks
    Lee Wallender
  6. Clean the Heater's Electric Coils

    With a thin nozzle attached to the shop vacuum, clean out the heater's electrical coils to remove all dust. Dusty heating coils can cause overheating and premature failure of the heater.

    Clean Heater's Electric Coils
    Lee Wallender
  7. Inspect the Cleaned Coils

    Check inside of the heater to confirm that all debris has been removed from the coils. The coils must be spotless. Any debris left on the coils will smoke and possibly even catch fire.

    Double-Check Condition of Cleaned Coils
    Lee Wallender
  8. Inspect and Clean the Fan

    Carefully vacuum out the heater's fan with the shop vacuum. Be careful not to dislodge or damage the delicate vanes of the blower fan. Spin the fan by hand; it should spin freely.

    Test Blower for Free Rotation
    Lee Wallender

When the Wall-Mounted Heater Has No Power

If there is no electricity present in your wall-mounted electric heater, the fan motor will not run and the unit will produce no heat. There are several common causes for this problem:

The circuit breaker is off: If the circuit breaker has tripped or been turned off for some other reason, the heater will not function. Check the circuit breaker and reset it to the ON position, then check the heater for operation.

The circuit is overloaded: If the circuit breaker trips at irregular intervals, it is possible that the heater is drawing more current than the circuit is intended to handle. This sometimes occurs if the heater circuit is also supplying power to additional outlets or fixtures. A wall heater generally should be powered by a dedicated circuit that powers no other devices in the house, but even here, a large heater powered by a circuit with insufficient amperage sometimes can cause an overload. If the heater circuit trips regularly, it's probably time to have an electrician look at the situation and make whatever circuit corrections are necessary. Or, the heater can be replaced by one with a lower power demand.

The circuit breaker is defective: Although it is not common, circuit breakers sometimes do fail. AFCI and GFCI breakers, in particular, can be so sensitive that they frequently cause nuisance-tripping. A faulty circuit breaker should be replaced by an electrician.

The wires are short-circuiting: Short circuits are caused when electrical current flows outside the established wire connections and finds a "short circuit" back to the ground. This is potentially quite a dangerous situation that can lead to shock or fire, so it should be addressed immediately. Short circuits are sometimes accompanied by sparking or the smell of burning plastic. And if a circuit breaker trips again immediately each time it is reset, it's likely you are dealing with a short circuit. Some short circuits are easy to spot and fix if they are caused by simple loose wire connections. But problems with the internal wiring of the heater or circuit wiring problems call for an electrician's expertise.

When the Fan Is Slow or the Heat Is Weak

When your wall-mounted electric heater's blower fan runs slowly or the amount of heat is inadequate—and you have already cleaned the unit and checked for physical blockage—the circuit voltage and the heater power requirements may be mismatched. This usually occurs if a 240-volt heater has been incorrectly wired to a 120-volt circuit, and it's almost always a sign that the work was done by an amateur with a lack of understanding. In this instance, you should have the heater replaced with a proper 120-volt model.

However, there are also convertible wall heaters that can be properly wired for either 120-volt or 240-volt circuits. There is nothing wrong with wiring such heaters either way, provided the connections are made according to instructions. Properly wired, these heaters will run adequately in either configuration.

When to Call a Professional

Because repairing a wall-mounted electric heater involves your home's electrical system, call a licensed electrician if you feel uncomfortable with any aspect of electrical work, especially with changing circuit breakers.