Why Does My Furnace Keep Blowing the Fuse?

Posted on: April 23rd, 2013

Is your furnace blowing the fuse? This can be due to a number of problems that can vary greatly depending on the type of furnace you have. Electric furnaces for example use electricity to generate heat, so there are a number of issues that could go wrong that causes the fuse to blow. On a gas or oil furnace, the causes are going to be much more limited as electricity only controls a few functions associated with the furnace.

Below are a few common causes of blown fuses in furnaces:


Blown fuses usually result either from an appliance putting too much strain on the fuse or by an electrical short in the system. Since some furnaces can require a lot of electricity, homeowners must ensure that they have an adequate electrical system to support the furnace. After resetting the circuit breaker and replacing the fuse, if the fuse keeps blowing, there might be an electrical short in the electrical system that supplies the electricity to the furnace. In this case, you should call an electrician.


Faulty Transformer

Sometimes the blown fuse in the furnace comes from a malfunctioning transformer. In this case, your will need a technician to come and replace the old transformer with a new one.

Insufficient Fuse Size

If the fuse in your furnace is too small and cannot handle the wattage, it can cause your fuse to blow. If this is your problem, simply replace the fuse with a larger capacity fuse that can handle the electrical demands.

Malfunctioning Thermostat Wire

If your thermostat wire touches the metal frame of the furnace, this can cause a blown fuse. When a thermostat wire touches the metal frame of the furnace, it can deliver more voltage than the wires are designed to handle. This will blow the fuse on the control board, causing the draft inducer to not start, which then stops the rest of the furnace functions from working properly.

Loose Wires

Sometimes, your furnace may seem like it has blown a fuse, but it is actually suffering from loose wire connections.  This is usually a good place to start looking for problems with your furnace as loose wires can usually be detected with a voltage meter. If loose wires are detected, they should be repaired or replaced by an electrical or HVAC technician.

Furnace Repair in Scranton, PA

If your furnace is blowing the fuse and you need furnace repair in Scranton, PA, contact the furnace repair experts at T.E. Spall & Son today! Our heating and cooling technicians will run a diagnostic on your furnace to determine the cause of your problem and fix it right the first time—on schedule and on budget—and usually on the same trip to your home!