From your description, it sounds like it could be a bad thermostat, but
"old" is a relative term. Over the years there have been a number of types
of thermostats and controls used on boilers. The most common type today, is
what Honeywell calls a "series 80" which is low voltage two wire. There have
been series 10 through series 90 thermostats and controls used over the
years. The first thing you need to do is identify what you have. Remove the
thermostat from its base, and if it's for heating only, note how many wires
it has and if they are low voltage or line voltage. Once that's determined
it would be easier to solve your problem



wrote in message
ups.com...
I have a old boiler furnace. I'm having an issue where the boiler
periodically wont come on and the house temperature will continue to
drop. If I turn the thermostat up, the boiler will kick on and will
maintain the set temp for some time but will eventually fail to kick
on again. Based on the fact that I can get it to kick on by
adjusting
the thermostat, I'm assuming the issue is thermostat related but I'm
not sure if the thermostat itself of the sensor...or maybe I''m
totally off base.