Jim wrote:
Sixty year old furnace.

(Please don't chide me about inefficiency - it is in warm area of
country where for 8 months of the year the furnace doesn't run at all
- so payback for new furnace would be long time from now.)

Rather than inefficiency let me suggest safety.

I suggest you hire a professional to come and take a look at this puppy.
At 60 years old it is quite likely to have some problems with the heat
exchanger exchanging more than heat. This can be deadly. At the very least
buy a few CO detectors. The tech can check out the controls at the same
time and figure out if it is possible to find some sort of replacement or
maybe identify the reason for short thermocouple life.

Frankly I would replace it, but that is going to cost more than a new
thermocouple.


--
Joseph Meehan

Dia duit