Furnace prob

[bodhizafa]

Anyone know about gas furnace? Woke up this morning and it won't turn on, pilot light is on (nice blue flame) cleaned off thermocouple but nothing. Fan turns on from the thermostat (when turned on by itself).

Probably going to get a new thermocouple at Lowes, but if that was bad wouldn't it shut off the pilot light too?

[Dr. Joe Siphek]

you probably did these things, but did you change your filter? Is your T-stat digital? maybe it needs a new battery? that's all i got.

[Kim-n-Dean]

Anyone know about gas furnace? Woke up this morning and it won't turn on, pilot light is on (nice blue flame) cleaned off thermocouple but nothing. Fan turns on from the thermostat (when turned on by itself).

Probably going to get a new thermocouple at Lowes, but if that was bad wouldn't it shut off the pilot light too?
The thermocoupler will turn off the pilot. So, it's most likely not that.

My funace does the same thing every now and then and there are two round sensors with what looks like glass inserts. They have a reset button on them. Pull your cover where the pilot is and look for the popped button. Maybe you just have one button, dunno...

Hold on a sec. I'll take a pic...

[TinkerinWstuff]

check fresh air intake and exhaust on the outside of the house. If the wind is blowing in the exhaust or they are plugged somehow, there's a differential pressure sensor that will shut the furnace down to prevent carbon monoxide poisoning.

Best bet is to call a furnace professional.

[Kim-n-Dean]

The red arrows point to the sensors.
http://home.comcast.net/%7Etk4480/CSC/furn1.JPG

This is the bottom of the sensor and if you push on the round center, a red button pops up on top.
http://home.comcast.net/%7Etk4480/CSC/furn2.JPG

The arrow points to where you should see a red button if it is popped up.
http://home.comcast.net/%7Etk4480/CSC/furn3.JPG

[bodhizafa]

I'm gonna copy this stuff down. The furnace is about 25 years old so I"m sure its near the end :( It just needs to survive till 2011!

I think it was the thermostat though. There is a little button you can press with a pen to reset it and it seems to be working after the reset. I'll probably change the batteries too, no clue how long they have been in there (longer than I've owned the house).

[Tylar]

Dean, you do HVAC work?

[Canuck]

Anyone know about gas furnace? Woke up this morning and it won't turn on, pilot light is on (nice blue flame) cleaned off thermocouple but nothing. Fan turns on from the thermostat (when turned on by itself).

Probably going to get a new thermocouple at Lowes, but if that was bad wouldn't it shut off the pilot light too?
It's the Gas Valve or Safety(s); not the Thermocouple. If Blower motor is controllable via the Thermostat, then its (most likely not the stat) and that you have control power (24v) out of the secondary side of the transformer.

[Canuck]

The red arrows point to the sensors.
http://home.comcast.net/%7Etk4480/CSC/furn1.JPG

This is the bottom of the sensor and if you push on the round center, a red button pops up on top.
http://home.comcast.net/%7Etk4480/CSC/furn2.JPG

The arrow points to where you should see a red button if it is popped up.
http://home.comcast.net/%7Etk4480/CSC/furn3.JPG

Dean, if you have to reset one of those Flame Rollout switches, then you have bigger issues going on. It's getting too hot in that area of the heat exchanger or you are having a rollout in the combustion chamber. Also, those rollouts may not be the correct ones, (ie, not OEM spec).

[Kim-n-Dean]

Dean, you do HVAC work?No. I do all my own work, though. Whenever something breaks, that I know nothing about, I buy a manual.



Dean, if you have to reset one of those Flame Rollout switches, then you have bigger issues going on. It's getting too hot in that area of the heat exchanger or you are having a rollout in the combustion chamber. Also, those rollouts may not be the correct ones, (ie, not OEM spec).That's the only thing that has ever gone wrong with the furnace. It's a 25+ yr. old Ruud. The switches pop after electrical storms or when the power to the house fluctuates real bad.

[bodhizafa]

Thanks for the info. Seems to be working well now after reseting the thermostat. Been ok for 24 hours now.

[Ricky]

The other thing is if a cover switch becomes loose. Many furnaces won't run without the cover securely in place.