What is an HVAC heat sequencer and how does it work?
An HVAC heat sequencer prevents voltage from entering your electric furnace and simultaneously turns the heating elements on. Heating elements are electrical coils that warm up when electricity passes through them. When voltage enters your HVAC sequencer, it will divert power to the very first heating element.
What happens when a sequencer fails on a furnace?
A failed sequencer may allow all the heating elements to turn on at once, or it may only permit a few to come on—perhaps none at all. If you think your furnace isn’t getting the house warm enough, you may have only a few heating elements coming on because of a broken sequencer.
How does a sequencer work?
The outer housing of the sequencer is a heat-resistant plastic square through which a small heating coil is passed. And above the heating coil, there are two or more stacked heat-reactive circuits.
How does a furnace heat a house?
Heating elements are what actually heats the air moving through the furnace and then into a house’s ventilation system. Each heating element is an electrical coil; as electric current passes through the coil, it becomes hot. This is called electrical resistance heating, and it’s the same principle you see at work in a toaster.
How do I test my furnace sequencer?
0:114:18How to test a heat sequencer - YouTubeYouTubeStart of suggested clipEnd of suggested clipTest the contacts to see that there is no continuity across any of the terminals. If you hear a beepMoreTest the contacts to see that there is no continuity across any of the terminals. If you hear a beep or continuity as indicated on your tester replace the heat sequencer.
What is the purpose of a heat sequencer?
Sequencers enable heat pumps and furnaces to use a portion of their power in segments so that there is always one part of the device on while other parts can be off. This prevents circuits from tripping or blowing out, motors from overheating, and prevents premature replacement of mechanical components.
What is a furnace heat sequencer?
The sequencer is essentially a series of conduits that prevent the voltage from entering the electric furnace from turning on all the heating elements at one time. The heating elements are the electrical coils that warm up as electricity passes through them; they're what actually heats the air.
What do the numbers mean on a heat sequencer?
The numbers that matter is "H30-90" and "C1-30". They indicate the approximate time for warm-up and cool down. Depending on what the sequencer is being used for you can get different time ratings. At the end of the day, these numbers can be changed and not matter operationally too much.
How much does a furnace sequencer cost?
A sequencer replacement for an electric furnace typically costs around $300.
Does all electric furnaces use package sequencers?
One potential safety hazard that all technicians should be aware of when working on an electric furnace is that there are many exposed electrical connections. The correct answer is 'True'. All electric furnaces use package sequencers.
How many heaters can a typical package sequencer energize?
AS MANY AS 3 SEQUENCERS MAY BE CONNECTED THROUGH THE AUXILIARY SWITCH TO CONTROL UP TO 9 HEATING ELEMENTS. THE SEQUENCER CAN BE USED ON MOST FURNACES USING LINE VOLTAGE LIMITS FOR 240 VOLT AND 240/120 VOLT ISOLATED FAN AND 240 VOLT COMBIN- ATION RATED WIRING SYSTEMS.
What controls the heating elements in most electric furnaces?
thermostatAll types of electric resistance heating are controlled with a thermostat. Baseboard heaters often use a line-voltage thermostat (the thermostat directly controls the power supplied to the heating device), while other devices use low-voltage thermostats (the thermostat uses a relay to turn the device on and off).
What is the advantage of a sequencer over a contactor?
Why is it better to use a sequencer than a contactor to turn on heat elements? Contactors are noisy and do not have capability to space out the heating elements. They turn on all at the same time.
Why is it important to cycle the furnace on and off several times when replacing a sequencer?
Why is it important to cycle the furnace on and off several times when replacing a sequencer? It is important to make sure the heating elements and the blower are switching on and off in the correct cycle.
Can you replace a fan sequencer with a heat sequencer?
The Emerson 24A34-3 Electric Heat Sequencer is a direct replacement for most fan/heat sequencing functions.
How many heating elements are in an electric furnace?
These furnaces have three to six electric-resistance heating elements that are between 3.5 to 7 kW each. These heating elements work a lot like the heating elements in a toaster. Electrically charged particles move through the metal wires, which produces heat.
What is the advantage of a sequencer over a contactor?
Why is it better to use a sequencer than a contactor to turn on heat elements? Contactors are noisy and do not have capability to space out the heating elements. They turn on all at the same time.
How many heaters can a typical package sequencer energize?
AS MANY AS 3 SEQUENCERS MAY BE CONNECTED THROUGH THE AUXILIARY SWITCH TO CONTROL UP TO 9 HEATING ELEMENTS. THE SEQUENCER CAN BE USED ON MOST FURNACES USING LINE VOLTAGE LIMITS FOR 240 VOLT AND 240/120 VOLT ISOLATED FAN AND 240 VOLT COMBIN- ATION RATED WIRING SYSTEMS.
How should you determine the heat anticipator setting on a room thermostat?
The heat anticipator Amps setting should be set to match the current (Amp) rating stamped on the name plate of the primary control that the thermostat is controlling.
Why is it important to cycle the furnace on and off several times when replacing a sequencer?
Why is it important to cycle the furnace on and off several times when replacing a sequencer? It is important to make sure the heating elements and the blower are switching on and off in the correct cycle.
What is a Sequencer?
When these heating elements are first turned on, they require such a great deal of electrical current to heat up that if all of them were to turn on at once, the ensuing electrical current spike would trip the circuit breakers of the home or building. A sequencer acts to stagger the rate at which each heating element receives electricity in turn.
Design
The sequencer sits between the heating elements and the thermostat on the furnace. Its outer housing is a square of heat-resistant plastic through which a small heating coil passes. Stacked above the heating coil are two or more heat-reactive circuits. There is one such circuit for each heating element.
Operation
When the thermostat is activated, it sends an electrical current to the sequencer. The current cannot pass through each of the heat-reactive circuits just yet, as the copper strips are not in place to close these circuits. Because of this, electricity only passes through the heating coil in the sequencer’s base.
Why does my furnace trip the breaker?
An electric furnace requires a large amount of electricity to run, and all this demand on the circuit can cause an overload, which the breaker trips in order to protect the electrical system.
What is a heating element in a furnace?
Heating elements are what actually heats the air moving through the furnace and then into a house’s ventilation system. Each heating element is an electrical coil; as electric current passes through the coil, it becomes hot.
What is a tripped circuit breaker?
Tripped circuit breaker. The sequencer does the job of staggering the heating elements so they turn on one at a time, in “sequence.”. The sequence does this by acting as a series of circuits that close one at a time, allowing electrical power to move farther down the system to each of the heating elements in turn.
What is a heat sensitive circuit?
A series of heat-sensitive circuits expand as they heat up, and when they make contact, they close. The sequencer shuts off the heating elements one at a time as the heating cycle comes to an end.
Can you repair a sequencer on your own?
You cannot repair a sequencer on your own unless you have professional experience with heater service in Bergenfield, NJ along with local New Jersey licensing. Although amateur work on an electric furnace doesn’t present the same dangers as work on a natural gas furnace, it is still complex electrical HVAC work that requires special skills and equipment. If you have an electric furnace that’s tripping the circuit breaker or isn’t coming on at all, get in touch with our experts to arrange for fast and accurate repair work.
Can a broken furnace sequencer cause a furnace to not turn on?
A failed sequencer may allow all the heating elements to turn on at once, or it may only permit a few to come on—perhaps none at all. If you think your furnace isn’t getting the house warm enough, you may have only a few heating elements coming on because of a broken sequencer.
Where is the sequencer on a furnace?
The sequencer is hidden inside your furnace with the wiring to the heating coils. You won't be able to see it, but you'll have signs that something is wrong with your furnace when the sequencer goes bad. Your heating elements may not turn on at all, and then the furnace won't be able to heat your house.
How to tell if a furnace sequencer is bad?
The way to tell for sure if the sequencer is bad is to have a furnace repair technician check it with a meter. If the sequencer is bad, it has to be replaced. This involves opening the furnace, disconnecting the bad sequencer, putting in the new part, connecting all the wiring, and then testing the furnace.
What controls the coils in an electric furnace?
The sequencer controls the heating coils in your electric furnace. The coils are what heats the air that gets circulated in your home, and your furnace has two or more sets of these coils.
How does a furnace sequencer work?
The way it works is that electricity entering the furnace moves first into the sequencer, which then routes the power to the first of the heating elements through a conduit. The sequencer will not allow voltage to move to the next element in the sequence until the conduit reaches a set temperature. The process then repeats with the next heating elements, only lifting “the gate” when the conduit is hot enough. This continues until either all the heating elements are on or the thermostat sends a signal to the sequencer to begin to cycle down the furnace.
What happens if you turn on an electric furnace?
If you turned on your electric furnace and it immediately drew on the maximum amount of volts needed to warm your house, sending electricity to all the heating elements, it would trip a circuit breaker in the electrical panel.
Why is my furnace faulty?
When you run into problems with your electric furnace, one of the possible explanations is that the sequencer is malfunctioning or damaged and needs to be replaced. The sequencer can wear down from use and parts can corrode, and this can cause the furnace to become faulty.
Why is a furnace sequencer important?
A sequencer is essential for proper furnace operation, because if all the elements were heated simultaneously, the demand for electricity would pop a fuse or trip the circuit breaker. If the furnace is not heating normally, or if you can see that some elements are glowing orange but not others, the sequencer may be defective.
Where is the sequencer on a furnace?
Extract the screws in the service panel on the side of the furnace to take off the panel and locate the sequencer. It's at the top, connected to several pairs of wires. Each wire pair attaches to a heating element inside the furnace.
How to replace a furnace sequencer?
Remove the mounting screws holding the sequencer inside the furnace and take the defective part to an HVAC parts supply store for a replacement. Leave the labels on the wires to reconnect them correctly to the new sequencer.
