Furnace shuts down after first full cycle

[swabby]

Sent: 4/3/2005

hey everybody,
still got a problem with my furnace on my d-22 Indian a 1972 model.  the furnace lights fine runs fine and heats good.  but when it goes to shutdown to pilot it does this fine, but in about 30sec to 1 minute the gas valve shuts down and it all goes out.  i have replaced the thermocouple and cleaned it all good, but cannot get the pilot and gas valve to stay in the on position.  i have tried a few things i read on here to no avail.  I have heard it could be the sail switch? and does anybody know where it is?
this furnace is driving me nuts.....it works great just won't stay lit.   gas pressure is fine too......any help would be greatly appreciated......swabby

[denisondc]

Sent: 4/3/2005

The sail switch is only used to let the main gas valve know that there is air circulating - draft air for the blower. It is located in the back of the furnace, to feel the air from the blower moving across it, and allow the main burner to come on. I don't think its function would be related to the pilot going out.
You said you have replaced the thermocouple. Could it be you need to re-adjust the position of the thermocouple relative to the pilot light flame, or to increase the size of the pilot flame? The new thermocouple might not be as sensitive as the one you replaced.
Other than a defective main-propane-multifunction-safety- valve ($$$), I cant think of anything else.

[swabby]

Sent: 4/4/2005

thanks Dennison i will try another thermocouple.  the flame seems to be plenty high enough and blowing onto the thermocouple.    thanks again