[harley4noble]

The limit switch is a safety control switch located on the furnace just below the plenum. If the plenum gets too hot, the limit switch shuts off the burner. It also shuts off the blower when the temperature drops to a certain level after the burner has shut off. If the blower runs continuously, either the blower control on the thermostat has been set to the ON position or the limit control switch needs adjustment. Check the thermostat first. If the blower control has been set to ON, change it to AUTO; if the blower control is already on AUTO, the limit switch needs to be adjusted.

[freetx]

Step 3: Tightly screw the nut into place, but do not over-tighten. Both the bracket nut and connection nut should be only a little tighter than if hand-tightened. [links]

[friendartiste]

If the pilot light won't stay lit, the thermocouple may be faulty and should be adjusted or replaced. To adjust the thermocouple, you must tighten the thermocouple nut with a wrench. Take care not to apply too much pressure to the nut -- just tighten it slightly. Then try lighting the pilot. If the pilot won't stay lit, replace the thermocouple with a new one of the same type. Here's how to replace a faulty thermocouple: here

[yommys01]

Step 1: Unscrew the copper lead and connection nut inside the threaded connection to the gas line. Under the mounting bracket at the thermocouple tube, unscrew the bracket nut that holds the tube in place.

[DanielLeerasiri]

Step 2: Insert a new thermocouple into the hole in the bracket. Be sure the steel tube is up and the copper lead is down. Under the bracket, screw the bracket nut over the tube. Push the connection nut to the threaded connection where the copper lead connects to the gas line. Make sure the connection is clean and dry. [links]

[KristofN1]

The thermocouple is a gas furnace component located near the pilot light burner. It is a safety device that shuts off the gas if the pilot light goes out or the electric igniter fails.

[Hooquai8]

If the pilot light won't stay lit, the thermocouple may be faulty and should be adjusted or replaced. To adjust the thermocouple, you must tighten the thermocouple nut with a wrench. Take care not to apply too much pressure to the nut -- just tighten it slightly. Then try lighting the pilot. If the pilot won't stay lit, replace the thermocouple with a new one of the same type. Here's how to replace a faulty thermocouple:

[amps]

Step 3: Tightly screw the nut into place, but do not over-tighten. Both the bracket nut and connection nut should be only a little tighter than if hand-tightened. [links]

[beatfocus]

Step 2: Insert a new thermocouple into the hole in the bracket. Be sure the steel tube is up and the copper lead is down. Under the bracket, screw the bracket nut over the tube. Push the connection nut to the threaded connection where the copper lead connects to the gas line. Make sure the connection is clean and dry. here

[maddox1085]

Most recently, the workaround hasn't, & the burners fail to ignite 100% of the time. The pilot is fine. more

[wirher]

Since I had it open already, I immediately installed a spare switch I had lying around. This worked well at first, turning the fireplace on & off 100% of the time on that first day. However, the next day, it was acting up again and failing most of the time. [links]

[methodeux]

Years later, it started acting erratically: Sometimes, the switch worked, other times, no luck. We'd try turning the switch off & on again a few times ("Hello, IT. Have you tried turning it off & on again?") and occasionally that would get it going.

[wobber]

Knowing the fireplace doesn't use the house power (we could use it even during an outage), I figured the voltage was low enough for me to troubleshoot. I disconnected the switch and tried to turn on the fireplace by carefully joining the conductors. This worked 100% of the time. So, I believed the fireplace was OK and decided the switch needed to be replaced. here

[otalesak]

Most standard light switches have brass contacts. At 120VAC level operation, there is usually no concern about residue build up because the high voltage/low resistance load level keeps the contacts clear enough by self cleaning the residue through arcing at every ON/OFF cycle. [links]

[chorchonga]

Sent from my Transformer TF101 using Tapatalk 2 more

[Ryo]

Call a tech and get it serviced properly. To start with, there are special millivolt rated wall switches that work much better than a standard wall switch.

more

[akaz456]

After doing lots of research, and refusing to pay exorbitant prices for "millivolt" switches, I ended up installing a "commercial" grade SPST light switch I got at the local home center. The "commercial" grade switches (Decora Plus, in my case) have silver alloy contacts which do not have the same characteristic residue production over time. In fact, I have read that the oxides that develop on silver actually improve connectivity. I am not 100% sure of that, but time will tell.

[z]

At millivolt level operation, the internal contacts tend to oxidize over time and create a high resistance (up to several ohms) which causes lots of problems for systems working at the millivolt level. The system that operates your fireplace is operating on a circuit that is dependent upon a voltage level that is probably 1/5 to 1/2 that of a AAA battery. As well, this voltage is capable of only a minute current production, so any losses are much more likely to cause performance problems.

[tomdetroit]

Not sure on the brand of the fireplace -- I'm away on business at the moment.