Flame Sensor in house furnace!

[catmando]

Come home yesterday too a cold house, change batteries in thermostat, didn’t work so step 2 . Clean and re-install flame sensor. 15 minute job saved me likely around 400 bucks . (Thanks for the tip Ron) With the weather turning super cold this is a good idea too figure this out and pick up a spare. My furnace is only 4 yrs old so clearly if yours is older than that be prepared and save your self a ton of money on a easy fix.

 

[Frosty19]

Had an issue with the flame sensor in my furnace last year (furnace was 6 years old at the time) and luckily was able to just clean up the lead with some Emery cloth and has been good since (knock on wood)

Side note, batteries dying and taking out an entire furnace system is a terrible design IMO. Had that happen earlier this winter.

 

[rknight111]

This is a common issue with all new furnaces, its either a flame sensor or an ignighter. I always have a spare on hand of each item now. The flame sensor is typically from $30 - $70 and the Ignighter is around $150 - $250. When cleaning the flame sensor steel wool works best as this is used to transfer the heat to milivolts that is picked up by the furnaces electronics. You only need to remove the film of it, otherwise what they are desinded to do may not be working properly anymore. They typically can be cleaned a few times but I wouldnt take that chance in the winter and would have a new one on hand.

 

[CatMan16]

Had a Lennox furnace in my first house and I had to take that out every year and scotch bright the rod. Luckily I have a relative that was a furnace installer and he saved me calling in someone the first time it went down.

 

[sledn]

One should also keep a spare hot surface igniter on the shelf. They are cheap on Amazon($30). Expensive when you need one at midnight from the repairman and it's -30'.

 

[fj40]

I clean mine in the fall
Just regular maintenance

 

[52weekbreak]

It definitely is best just to treat as regular maintenance but is a fairly simple fix as described above. Both of my homes have two furnaces hopefully one keeps working in this weather

Having said that, the sewage pump out float packed it in on Christmas Eve and the high level alarm float did the same thing. Luckily we caught it before it became too much of an issue. Everything almost back together and I don't know about the rest of you but any repair, even a minor one, seems to kick off another renovation.

Just about time to go somewhere warm

 

[AreWeThereYet]

Some are a combo ignitor/sensor, you do not want to touch the end with your fingers.

 

[Cyle]

Are they generic at all, even to say a brand of furnace? Or would each model be specific? Between my house and my 3 rentals i've never had a furnace issue, but with them being between 5-9 years old i'm guessing it's only a matter of time before I have to.

 

[sledn]

Are they generic at all, even to say a brand of furnace? Or would each model be specific? Between my house and my 3 rentals i've never had a furnace issue, but with them being between 5-9 years old i'm guessing it's only a matter of time before I have to.

this fits many models.

 

[Caper11]

Some are a combo ignitor/sensor, you do not want to touch the end with your fingers.

This^^^^. Be careful not to touch the sensor.

My lennox will flash a code indicating my sensor needs to be cleaned.

 

[team dirt]

This is a common issue with all new furnaces, its either a flame sensor or an ignighter. I always have a spare on hand of each item now. The flame sensor is typically from $30 - $70 and the Ignighter is around $150 - $250. When cleaning the flame sensor steel wool works best as this is used to transfer the heat to milivolts that is picked up by the furnaces electronics. You only need to remove the film of it, otherwise what they are desinded to do may not be working properly anymore. They typically can be cleaned a few times but I wouldnt take that chance in the winter and would have a new one on hand.

There actually not thermocouples anymore. Those are flame ionization rods. The controller sends a mA signal out through the rod and uses the carbon in the fire to pass the signal through and most times read it back on ground. By code appliances must shut down within 4sec of a flame failure. Thermocouples could take up to 60sec sometimes before shutting down due to having to cool. If your furnace lights and runs for 4-10 sec before shutting off it’s most likely that flame rod.

 

[YamaDad]

Lots of good comments here so far. Let me add this:

1- NEVER touch the ignitor if it a hot surface one of any style. That is one that glows orange as opposed to clicking a spark. They are very fragile and cleaning is not necessary. A spare is a good idea and should be specific to the brand and model of furnace. Otherwise the wires will not hook up and it may not sit in the gas stream correctly.

2-Flame sensors rarely need to be replaced, but do need to be cleaned periodically. This is true of all brands. Emery cloth is my choice but anything abrasive and clean is fine. Something like an sos pad is a poor choice. Some are easy to remove and get access to but some models are not. Older Lennox mids and some Carrier high efficient models depending on installation are challenging.

3- flame sensors always have 1 wire where ignitors always have 2 if you are unsure which is which.

 

[busted2x]

I wAs told by a friend who works for the gas company that we have crappy natural gas in western Canada, contains lots of nitrogen, and it contaminates flame sensors. He told me not to use anything that leaves scratches like sand paper, cus it will allow deposits to form faster. Told me to use an old (paper) 5$ bill to rub the sensor. Works great, just leave it pinned to the wall in utility room. Have to rub the sensor about every 2 years.

 

[MP Kid]

I wAs told by a friend who works for the gas company that we have crappy natural gas in western Canada, contains lots of nitrogen, and it contaminates flame sensors. He told me not to use anything that leaves scratches like sand paper, cus it will allow deposits to form faster. Told me to use an old (paper) 5$ bill to rub the sensor. Works great, just leave it pinned to the wall in utility room. Have to rub the sensor about every 2 years.

Sorry... but that’s just not true. Natural Gas is mostly comprised of C1 & C2 (methane & ethane). Typically, producers are required to have some type of hydrocarbon dew point control (refrigeration plant of some sort) if they’re selling rich gas to major transporters such TCPL.

 

[hbar218]

I wAs told by a friend who works for the gas company that we have crappy natural gas in western Canada, contains lots of nitrogen, and it contaminates flame sensors. He told me not to use anything that leaves scratches like sand paper, cus it will allow deposits to form faster. Told me to use an old (paper) 5$ bill to rub the sensor. Works great, just leave it pinned to the wall in utility room. Have to rub the sensor about every 2 years.

Universal hot surface igniters(HSI) are available and come with different mounting brackets. You do not want to touch the HSI end as it will get oil from your skin on it and burn out prematurely, they are also very brittle and break easily. Direct spark ignition(DSI) is not as critical if you touch it and are generally trouble free. Some manufacturers use the igniter as the flame sensor orfkame rectification. I always try to sell a customer a spare HSI($50-$80) to have with the furnace even if they are not comfortable changing it , best to have it on site so it can be changed by service person or by google mechanics, lol. I also find it is a good idea to clean flame sensor in the fall and not have to worry about it.

 

[X-it]

Thanks guys ... i ordered mine yesterday from repairclinic.com. Not sure if that site is any good or not but the had the exact name and model for my furnace.

 

[Caper11]

I wAs told by a friend who works for the gas company that we have crappy natural gas in western Canada, contains lots of nitrogen, and it contaminates flame sensors. He told me not to use anything that leaves scratches like sand paper, cus it will allow deposits to form faster. Told me to use an old (paper) 5$ bill to rub the sensor. Works great, just leave it pinned to the wall in utility room. Have to rub the sensor about every 2 years.

Doubt that very much. Its very rare to have nitrogen in natural gas and when its in there its very low in concentration. Im not positive but I think it gets knocked out during the sweetening and the drying process anyway.

 

[Ronaha]

Natural gas lines are dirty that’s why you should have a drip leg on the line right before it goes into the furnace. I had to do my flame sensor and it was only 2 years old.

 

[busted2x]

Doubt that very much. Its very rare to have nitrogen in natural gas and when its in there its very low in concentration. Im not positive but I think it gets knocked out during the sweetening and the drying process anyway.

Good to know, I just went with what I was told, seems to work just cleaning it. I had to change the sucker twice in the first 2 years I was in my house, but maybe it was just bad luck, or dirty lines, or something else entirely.