hello to all you heating gurus:

we have just moved into a new house, and the furnace was working fine.
for some reason, this afternoon when i went upstairs to put my son down
for a nap, the thermostat said it was 74. it was hot. it was set at 62.
i turned it down all the way, and i still heard the furnace kick in.

is there any simple explanation to this before i call the plumber??

any help would be appreciated. the furnace is quite old, about 25
years, but our inspector told us that it was fine.

jae