The furnace will come on but the pilot will not light
When you say: "the Furnace will come on"-- do you mean a burner motor?- or a fan motor?-- or what "comes on"?
WHen you try to light the pilot, what happens?
Do you know where the ThermoCouple (TC) is on this furnace/heater?
Here is a solution/suggestion I wrote on TC-- Maybe it will help?
One possibility is that the Thermo Couple is beginning to fail'
What is a Thermo Couple? (TC)
The Thermo Couple (TC) is a small Rod-shaped device with a couple wires coming out the bottom.
The TC actually generates a small electrical current from the heat of the Pilot.
This electrical current is sensed by the control board, or the Main Gas Valve.
As long as there is a pilot, it is safe for the Main gas valve to open, and admit the large amount of gas into the heating burner.
Now-- What helps this TC work the best?
It needs to be just at the edge of the pilot flame--- Not too much in the flame, or the resulting poor combustion of the pilot flame, results in soot forming on the TC-- which insulated the TC from sufficient heat.
Obviously the TC has to be clean (of soot) in order to receive enough heat, to generate the needed voltage to tell the valve that it is safe to open.
And age does deteriorate the TC-- some last a few years, but that is about the end of life for most.
Replacing requires getting down where the TC is, and with a screw driver (usually)-- loosening the bracket that holds the TC. Pay attention to where the wires are routed, and any polarity indicated on the old wires, and duplicate on the new one. Duplicate routing, and polarity, and position the new TC at the edge of the pilot flame.
Pilot flame is maintained by pushing some over ride button-- for a minute or two, until when you begin to release the button, you can feel that the voltage generated by the TC is now holding the pilot valve open, instead of your pressure on the 'start' button.
Any further Questions, let us know..
Jan 26, 2011 |