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How Do You Know If The Heat Sequencer Inside An Electric Furnace Is Broken?

The heat sequencer inside your electric furnace allows it to turn on without tripping your home's circuit breaker. Electric furnaces contain several large heating coils that draw a considerable amount of power. If they all turned on at once, the sudden power draw would trip your circuit breaker. The heat sequencer turns each coil on and off in succession in order to avoid drawing too much power at once.

In order to manage the amount of power sent to the coils, a heat sequencer opens and closes the circuits supplying them with electricity. A heat sequencer relay is made of a metal disc and a small heating element that receives power from your electric furnace's control board. When the heating element inside the relay turns on, the metal disc heats up and expands. It makes contact with two terminals inside the relay, bridging the circuit and allowing power to be sent to the heating coils.

The heating element in the relay will turn off afterward, causing the disc to shrink back down and cut power flow to the coil. Heat sequencers contain a relay for each heating coil inside your furnace, which allows it to rotate which coil is receiving power. By maintaining a steady power draw, an electric furnace can keep them all heated without consuming enough power to trip your circuit breaker.

Heat sequencers can fail, causing problems with your furnace. If the metal disc inside a relay is broken or if the heating element doesn't work, then the heat sequencer won't work properly. To learn the signs that your electric furnace's heat sequencer has failed, read on.

One or More Heating Coils Won't Turn On, Leading to Poor Performance from Your Furnace

The most common issue caused by a broken heat sequencer is one or more coils not turning on. When not all of the coils in your furnace are operating, the air it blows won't be as hot as you're used to.

This problem is caused when one of the relays in your heat sequencer is broken. Your coils don't receive any power because the circuit never opens. This can happen when the metal disc inside a relay is broken. A broken disc won't make contact with the two terminals when it expands, causing the circuit to always remain closed.

A relay can also fail to function if the heating element inside it isn't working. This can happen if the element is broken or if it's not receiving power from the control board. When the heating element doesn't work, the metal disc won't heat up and expand to bridge the circuit and send power to the coil.

Your Furnace Trips the Circuit Breaker Immediately When It Starts

If your heat sequencer is broken, it may also cause your furnace to immediately trip your circuit breaker as it tries to start up. This problem occurs when the circuits in the heat sequencer are stuck open, which can happen if the discs inside the relays are deformed. They always make contact with the two terminals. When the furnace tries to start, power will immediately be sent to the coils because the circuits are open, and the huge power draw will trip your circuit breaker.

If you think that your furnace's heat sequencer is broken, call a furnace repair service and have it replaced. Heat sequencers are very inexpensive, but they need to be replaced by a professional — replacing one requires disconnecting and reconnecting several electrical wires. Once your heat sequencer has been replaced, you'll be able to use your furnace without any issues.