Tag Archives: furnace troubleshooting

Furnace Starts Then Stops – Troubleshooting | Repair and Replace

Hi, I’m Vance and welcome to Repair and Replace. If your furnace starts, then stops, and doesthis several times, then it’s likely a safety switchhas tripped or has failed. In this episode, we’ll look at the causesof short cycling. We’ll briefly cover each repair, but if youneed more information then watch the videos linked in the description. To troubleshoot short cycling, we’re goingto look at a few specific scenarios, 1: the furnace shuts off before ignition,2: the furnace ignites but the flames won’t stay lit, and 3: the furnace ignites, blows warm air but shuts off after a minute.Lets begin. Modern furnaces have a set of safety switchesthat shut down the furnace when it detects an unsafe condition. This includes the pressure switch, flame sensor,flame roll out switch, and limit switch. If a switch is tripped, it will cause thefurnace to lockout. It will cycle on and attempt ignition several times before going into a hard lockoutfor up to an hour. Every time a lockout happens, the furnacewill use flashing lights as codes to identify the source of the shutdown. These codes are unique to each model, so checkyour furnace manual to see what each code means. Even without any furnace codes, you can stilltroubleshoot the problem by observing the furnace. Keep in mind, if you are going to troubleshootyour furnace, always be safe and turn off the power and gas to your furnace before doingany repairs.If the draft inducer fan runs, but the furnaceshuts off before igniting, it could be a problem with the pressure switch. When the thermostat calls for heat, the draftinducer pulls fresh air into the burner. This clears the burner of exhaust gases andallows for safe combustion When the pressure is low,the switch will stay open and will prevent the furnace from igniting. Try to identify anything that might causea change of pressure inside the heat exchanger. Check to see if there’s any obstructions inthe flue vent or in the inducer motor port.Next check to see if there are any blockagesor water in the pressure switch tubing. If the airflow is good, then the pressureswitch might be faulty. Alternatively, if the burners still don’t ignite,then the furnace ignitor might of failed. The ignitor can be tested for continuity with a multimeter to see if a continuouselectrical path is present. If there is no continuity,then replace the furnace ignitor. If the burners shut off shortly after igniting,then the flame sensor could be dirty or defective. When the airflow is good, the hot surfaceignitor will heat up, the gas valve will openand the burners will ignite. The flame sensor monitors the burners, and will shut the furnace off if there’s no flame present after 7 seconds.If the flame sensor is dirty, the furnacemight shut off even when there’s a flame. Remove the sensor and clean it with a softabrasive pad. Now if the burner still doesn’t stay on, thenreplace the flame sensor. After ignition, the blower fan will run andcirculate the warm air around your home. If the furnace ignites, the blower fan runs, but the furnace shuts offbefore the house warms up, then the filter could be dirty,or the limit switch may be faulty.The limit switch monitors the temperatureof the air passing over the heat exchanger and will shut off the furnace if the systemoverheats. Any restriction of airflow might cause theheat exchanger to overheat. This is why it’s essential to replace thefurnace filter every 3 – 6 months. If you’ve replaced the filter, and the furnace still continues to shut off, then check the limit switch. The limit switch can be tested for continuity. If the switch has continuity, the multimeterwill show zero ohms. Even if the limit switch has continuity, itmight still be faulty. As a limit switch fails, it can start shuttingthe furnace off at lower and lower temperatures.So if the limit switch has failedor is starting to fail, then it’s best to replace it. If you liked this and want to see more tutorialsand informational videos, then subscribe to our channel. And if you need help, you can call or visitan AMRE location to talk with ourknowledgeable staff. Thanks for watching..

How a Furnace Works | Repair and Replace

Hi, i’m Vance and welcome back to restore and replace. Furnace is whatever you certainly not particularly feel about unless it stops working, however with a little bit little bit of advantage,it is a lot less difficult to troubleshoot problems. So at present we ‘re gonna study how a gas furnace works. First we will cover the fundamentals, then we’ll dive somewhat deeper into the sequence of operation. So which you can fully grasp what every component does. Let’s begin ! Although there are some variations, all gasoline furnaces work in the equal common means. Ordinary gasoline is burned to heat up the heat exchanger. The exhaust fumes are launched via the flue gasoline vent. The blower fan then pushes air over the warmth exchanger and circulates it around your residence. The furnace runs until the thermostat detects the correct temperature and shuts the furnace off. Brand new furnaces use a draft inducer fan to aid exhaust the emissions, this drive draft also increases the efficiency.Condenser furnaces use a twin warmth exchanger to condense water vapor , this extracts much more heat out of the combustion. Furnaces are rated with the aid of AFUE or (Annual fuel Utilization effectivity). This quantity is a ratio of the fuel burned versus the gas changed into heat. Older furnaces will have an efficiency score of 70 AFEU or much less, which means that handiest 70 percent of the gas is was usable warmth. Mid efficiency furnaces are around eighty and high-effectivity condenser furnaces are frequently ninety and above. Furnaces can also be single stage or dual stage. Single stage furnaces run at one velocity, which means it can be both full warmth, or no warmth. Two stage furnaces can run at full velocity or a diminished velocity when less warmth is needed.This permits for the furnace to run quieter and may contain a more constant temperature. Modern furnaces have a collection of protection switches that shut down the furnace, when the system is compromised. If a switch is tripped, it will rationale the furnace to lockout. The furnace will strive ignition, a number of occasions earlier than going right into a difficult lockout for as much as an hour. Whenever a lockout happens the furnace will use flashing lights, as codes to determine the supply of the shutdown These codes are precise to every mannequin so check your furnace manual to look what each code method. When the thermostat calls for warmness, voltage is distributed to the manipulate board. Next the draft inducer fan pulls contemporary air into the burner, which makes it possible for for clean and effective combustion. When the draft motor reaches full pace the stress switch will shut, enabling for the sequence to proceed. The pressure change ensures that there’s ample airflow inside the warmness exchanger to securely operate the furnace.If the stress is low, the change will keep open and will avert the furnace from igniting. If the stress is good, then voltage is sent to the hot surface igniter. Some furnaces might use a spark igniter alternatively. After the igniter heats up the fuel valve opens and the burners ignite. When the flame will continue so long as the security switches remained closed.If the flame is not detected after 7 seconds the flame sensor will shut off the gas. When the burner is lit, the blower fan is simply too late from going for walks to permit the heat exchanger to heat up. This prevents the furnace from circulating cold air. The blower fan then pushes the air over the warmness exchanger and circulates it around your home. The limit switch displays the temperature of the air passing over the heat exchanger and will shut off the furnace if the process overheats.Any restriction of the airflow might reason the warmth exchanger to overheat. That is why it is major to interchange the furnace filter every three to six months. As soon as the thermostat alerts that the temperature of the residence is normalized, the fuel is shut off and combustion stops. The blower motor will continue to run for a number of minutes until the furnace is cooled down. Eventually the unit is positioned in standby except the thermostat requires warmth once more. Hopefully, this has given you a better working out of how a furnace works. Now if your furnace is having hindrance running, then watch our troubleshooting guide for a step-via-step breakdown and there’s a hyperlink to this in the description under. If you observed this video priceless then subscribe to our Channel.We’re always filming new content material per week, so let us know what repairs you’d like to see subsequent and if you would like an element for that repair then discuss with our website. We stock thousands of tough-to-in finding elements, and we’ll ship it out to you the same day. Thanks for gazing.