Why Does My Furnace Keep Shutting Off?
Is your furnace having trouble staying on once it fires up? Does it quickly shut off, after you start it? Does it do this a few times and then fully shuts down? Many homeowners have this problem every years, it is a dirty flame sensor.
Heating, Ventilation, and Air Conditioning is a complex industry, but this repair is simple enough, that you can perform it yourself.
Our example will be shown by using a gas-fired furnace, but you can find flame sensors in boilers and other gas-burning appliances.
Simple is the keyword in this process, but most furnace related service work is not very simple and show be performed by an HVAC professional.
To get your gas furnace working again check out: http://ottawafurnaceandductcleaning.ca/hvac-video.html
What Is A Flame Sensor and What Does It Do?
What Is A Flame Sensor and What Does It Do?
A flame sensor is a simple device, located at the burner assembly. The flame sensor is a thin, bent, metallic rod which sits in front of the flame stream, while the furnace is running. The purpose of the flame sensor is to confirm that fire is present, in your furnace, when the gas valve is opened. The flame sensor prevents your furnace from emitting gas that has not been ignited and prevent a dangerous build up of gas.
At the start up of your furnace, the burners are ignited and the flame sensor has a short amount of time to detect a flame; if a flame is not detected in this short period of time, your furnace will shut down automatically. The majority of units have a "safety lockout", which means after 3 shutdowns, it will lockout a start up for approximately 1 hour.
For this time, you will be without heat but worse, the repetitive process of starting up and shutting down will wear certain parts of your furnace and will reduce the lifespan and the efficiency of the unit.
What Causes a Flame Sensor To Get Dirty?
At the start up of your furnace, the burners are ignited and the flame sensor has a short amount of time to detect a flame; if a flame is not detected in this short period of time, your furnace will shut down automatically. The majority of units have a "safety lockout", which means after 3 shutdowns, it will lockout a start up for approximately 1 hour.
For this time, you will be without heat but worse, the repetitive process of starting up and shutting down will wear certain parts of your furnace and will reduce the lifespan and the efficiency of the unit.
What Causes a Flame Sensor To Get Dirty?
A flame sensor gets dirty from a build up of carbon; it can become faulty but many times, the build up causes the problem. The flame sensor cannot tolerate many variations in reading the flame, so sometimes the slightest carbon can cause the misreading and the resulting shut down of your system. Many furnace units are located in basements, attics, and laundry areas, this can easily cause debris to build up on the sensor; this creates both carbon and dirt build up on the flame sensor.
What You Need To Make the Repair:
* 1/4" Hex Driver or Wrench (This could vary based on your type of mounting screw)
* Small piece of light grit sandpaper, steel wool, or emery cloth
* Dry and Clean Paper Towel
How To Make the Repair
Let's get started...
What You Need To Make the Repair:
* 1/4" Hex Driver or Wrench (This could vary based on your type of mounting screw)
* Small piece of light grit sandpaper, steel wool, or emery cloth
* Dry and Clean Paper Towel
How To Make the Repair
Let's get started...
To get your gas furnace working again check out: http://ottawafurnaceandductcleaning.ca/hvac-video.html
Power Shut Off Examples
Here you can see a toggle switch that is mounted in the ceiling, next to the furnace for service shut off. Yours may be located on the furnace or you may have to shut off the unit at the breaker panel.
This is an example of a typical breaker panel, where you may also be able turn off the power to your furnace.
Before you begin anything: Shut Off the Power to the Furnace!
Power Shut Off Examples
Here you can see a toggle switch that is mounted in the ceiling, next to the furnace for service shut off. Yours may be located on the furnace or you may have to shut off the unit at the breaker panel.
This is an example of a typical breaker panel, where you may also be able turn off the power to your furnace.
Before you begin anything: Shut Off the Power to the Furnace!
1) To ensure that you prevent any danger, it is VERY important to shut off the power to your furnace (or any other appliance), prior to making any repairs. There will usually be a light switch (toggle switch) on or near your furnace. If this switch is not present, furnaces have a dedicated breaker; locate your furnace breaker and shut your unit down this way.
NOTE: Turning off the thermostat does not shut down the power to your unit. Also, there are many different types of furnaces and appliances; if you gas valve is not electrically controlled, you will need to shut off the gas to the unit as well. Should you be confused about any of the information provided here, because it does not match with what you see on your unit, STOP! Do not guess or assume anything when dealing with your heating system. Call an HVAC professional in your area, in order to complete the repair on your unit.
Furnace Picture
In this picture, you can see 4 burner ports. Between the 1st and 2nd burner ports (from left to right), you can see the wire leading to the flame sensor.
NOTE: Turning off the thermostat does not shut down the power to your unit. Also, there are many different types of furnaces and appliances; if you gas valve is not electrically controlled, you will need to shut off the gas to the unit as well. Should you be confused about any of the information provided here, because it does not match with what you see on your unit, STOP! Do not guess or assume anything when dealing with your heating system. Call an HVAC professional in your area, in order to complete the repair on your unit.
Furnace Picture
In this picture, you can see 4 burner ports. Between the 1st and 2nd burner ports (from left to right), you can see the wire leading to the flame sensor.
2) Remove the Sensor
The sensor is easily accessible and typically mounted by one 1/4" hex head screw. Upon removing this screw, the sensor will slide out so that you can easily clean it. Carefully remove the sensor; it may be necessary to detach the wire fixed to the end of it got more room to work, this is not usually necessary.
3) Clean the Sensor
Once you have removed the sensor, gently rub the metal rod (only) with a very light grit sandpaper. Remember, you are not sanding down an auto body, but simply ridding the sensor of any build up it may have. Then, use a clean paper towel to wipe clean any dust left behind by the sanding.
4) Replace the Sensor
Once you've cleaned the sensor, simply reconnect the wire if you've taken it off, remount the sensor to the burner assembly using the 1/4" screw, replace the door(s) on the unit, and turn the power back on.
5) Check Your Results
If the unit takes a few extra seconds to start up or the fan immediately kicks on and runs for a bit, this is normal. Shutting down the power to the unit can cause it to reset and run through a short series of checks before trying to fire again. Once this check is complete, the unit should begin to operate by command of the thermostat. Make sure the unit re-fires and runs properly until the thermostat is satisfied, at least once before being confident your problem is solved.
How to Replace a Broken Flame Sensor
If cleaning your flame sensor did not work, it's possible that the sensor is broken and that the furnace is operating as it should. You may need to replace the sensor, in which case you can follow these same instructions with the exception that no sanding is involved; just remove one sensor and replace it with a new sensor. Of course something else could be causing the problem and at this point, you should contact a service repair technician.
The sensor is easily accessible and typically mounted by one 1/4" hex head screw. Upon removing this screw, the sensor will slide out so that you can easily clean it. Carefully remove the sensor; it may be necessary to detach the wire fixed to the end of it got more room to work, this is not usually necessary.
3) Clean the Sensor
Once you have removed the sensor, gently rub the metal rod (only) with a very light grit sandpaper. Remember, you are not sanding down an auto body, but simply ridding the sensor of any build up it may have. Then, use a clean paper towel to wipe clean any dust left behind by the sanding.
4) Replace the Sensor
Once you've cleaned the sensor, simply reconnect the wire if you've taken it off, remount the sensor to the burner assembly using the 1/4" screw, replace the door(s) on the unit, and turn the power back on.
5) Check Your Results
If the unit takes a few extra seconds to start up or the fan immediately kicks on and runs for a bit, this is normal. Shutting down the power to the unit can cause it to reset and run through a short series of checks before trying to fire again. Once this check is complete, the unit should begin to operate by command of the thermostat. Make sure the unit re-fires and runs properly until the thermostat is satisfied, at least once before being confident your problem is solved.
How to Replace a Broken Flame Sensor
If cleaning your flame sensor did not work, it's possible that the sensor is broken and that the furnace is operating as it should. You may need to replace the sensor, in which case you can follow these same instructions with the exception that no sanding is involved; just remove one sensor and replace it with a new sensor. Of course something else could be causing the problem and at this point, you should contact a service repair technician.
To get your gas furnace working again check out: http://ottawafurnaceandductcleaning.ca/hvac-video.html
Buying a New Flame Sensor
You can check out http://ottawafurnaceandductcleaning.ca/ottawa-hvac-parts.html orottawafurnacefilters.ca and torontofurnacefilters.ca. We also sell other products for all of your heating needs.
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