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Problem: My furnace ignitor is going out too much!


Below we have listed some reasons why your furnace ignitor might be going out so often. We hope this will help you from having to replace your ignitor so often!

*Please remember to turn off all electrical power to your HVAC system when trouble shooting or working on HVAC equipment. We most certainly do not want to see anyone get hurt or damage their equipment!

Below are listed some reasons that might cause your ignitor to go out prematurely:

1. Handling the ignitor improperly by touching the gray glass part.

2. Installing an ignitor that is not made for the furnace. A furnace control board where the ignitor relay on the control board is stuck closed and keeps the ignitor burning all the time. The ignitor never gets a break and will burn out quickly.

3. High home line voltage. Check your voltage to see that you are in the 110 to 125-volt
range. Anything over 125 volts is going to cause premature light bulb failure and furnace ignitor failure. Call your electric company if you are getting high voltage in your home. Your electric company should be able to place a transformer on your line to lower your line voltage.

4. Debris from the heat exchanger or bugs/spiders can get on the ignitor while the furnace is not calling for heat and when there is a call for heat the debris/bug can short the ignitor out. It is a good idea to keep your furnace and heat exchanger clean so this does not happen.

5. The ignitors have just so many on-off cycles in them. The reasons listed below concern the furnace cycling off and on too much. These reasons if they occur will also cause you to have a high heating bill.

1. Over-sized furnace. A furnace that is too large for your home cycles too much. If your furnace is sized properly on your coldest day the furnace should run almost continuously. Shutting off very few times. I went to an HVAC training meeting on energy conservation. The speaker said, “The inefficiency of a furnace is in the On, Off cycling.” He made this statement that on the coldest day your furnace should almost run continuously if sized properly.

2. A dirty filter or blower squirrel cage causes too much cycling. Your furnace will go off on high limit continuously because it is not getting enough airflow through the heat exchanger. The furnace goes off on high limit to keep from overheating the furnace and possibly causing a fire. This is why it is very important to keep those filters changed.

3. A dirty restricted air conditioning evaporator coil causes restricted airflow that causes too much cycling. Make sure your coil is not stopped up on the underneath side. I usually have to take off the coil end plates and use a vacuum cleaner and coil cleaner to get all the lint and dirt off. Make sure you clean in the direction the coil fins are running. If you do not, it will bend the fins over and cause more restrictions. A good tool to use is our coil fin cleaning tool.

4. Improper thermostat heat anticipator setting. Look at your gas valve and see the amp draw. Set you thermostat’s anticipator setting to this amp draw plus one amp more. If your gas valve says, “.4 amps” then set your thermostat to “.5” amps. This will give you a little longer run time and a longer off time. If you have an electronic thermostat: Many of the electronic thermostats have temperature differential adjustments or like on the Honeywell thermostats have screws where you can adjust to make your furnace cycle a little longer.
Below we have a pictures on the left of a label off a White Rodger’s gas valve and on the right a Honeywell Round thermostat anticipator. The label shows that this White Rodgers gas valve model #38C03 Type 300 draws .23A or .23 amps. The anticipator shown in the picture on the right is set on .4 amps. If I were using this White Rodgers Gas Valve and the Honeywell Round thermostat I would set the anticipator one amp more than the gas valve draws, on .3 or a little past the.3. The little copper looking pointer can be moved to make your furnace stay on longer by using your finger to move the pointer. Again, you should look at your gas valve’s amp draw to determine your setting.

anticipator upclose2

White Rodgers Gas Valve label on valve

6. Too much gas pressure causing the furnace to overheat because too much heat is being produced. This causes the furnace to cycle too much on high limit. Does your furnace’s gas pressure sound like a jet when it is running? Your gas pressure on your gas valve might be set too high. This produces too many BTU’s or too much heat. I would recommend a HVAC technician adjust this problem. Turning the adjustment screw clockwise gives more pressure. Counter clockwise gives less gas pressure. If you attempt to adjust this yourself, do not adjust more than 1/4 turn clockwise or counter clockwise. Delayed ignition, blow back, and a mini explosion, could occur. Again, I would recommend an HVAC technician do this adjustment. Getting this adjustment right will save you gas utility costs, and wear and tear on your furnace in the long run.

valve with pressure screw cap removed

7 thoughts on “Problem: My furnace ignitor is going out too much!

  1. I got a trane ex90 furnace and i am having trouble with the ignting after it comes on it will kick on the first 2 chambers but to get it on 3 to kick the rest i have to turn it off and on tell it takes every time it shuts off

    1. Hi Latoya! It sounds like your problem could be caused by dirty burners or not having enough gas pressure. I would suggest that you try cleaning the burners by blowing them out with compressed air if you have an air compressor. Here is a really good YouTube video that shows how to clean burners: Here is a good YouTube video on how to adjust Natural Gas gas pressure: If you still have problems you might try cleaning the flame sensor. We have a post about this on the following page: I hope this helps you out. Steve

  2. My hot surface igniter on my Goodman has a short cycle. I can hear the gas valve opening but at the same time the igniter goes out. The valve then closes

    1. Hi Mr. Moses! This could be anyone of several problems. I would start with checking to make sure the pressure switch is staying closed. You would need to test this with a volt meter to make sure it is staying closed because something is causing the ignitor to go off before it has the chance to light the burners. This could be a control board problem or a flame sensor problem, but since the gas is never igniting then I do not see how it could be a flame sensor problem. We have lots of furnace troubleshooting advice on the following page: I would suggest going through the troubleshooting flow chart to see what is wrong: We also have lots of troubleshooting questions and answers on the following page: If you have any specific questions please let me know. Thanks! I hope you can easily find and fix the problem. Steve

  3. I have a brand new m7rl Miller furance. The furance just turn one year old. The ingniter as fail three times already. The service man just comes out and replaces the ingniter, I told him that something is going on I never had this problem before with the old Miller furance.He just tell me I didn’t make it.Can you please let me know what you think is going on. Thank you

    1. I am very sorry to hear that your furnace ignitor is going out so often. We have a list of six reasons why furnace ignitors go out too often on our site about half way down on the following page: I hope this helps you find out why your ignitor is going out so often. Steve

    2. funny my year and a half miller h e is doing the same thing just bough 2 more igniters ,Who knows the answer LARRY

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