On Feb 29, 8:37�am, ransley wrote:
On Feb 29, 5:54�am, topswage wrote:

My home is heated with a gas fired hot water boiler. �The system is
presently controlled with a 1950's style bimetal thermostat. I'd love to
replace the thermostat with an electronic set-back unit, but have
discovered that the thermostat is directly controlling the hot water
circulating pump--there's 120volt current running through the
thermostat, enough to fry most electronic ones. �I see though that there
are electronic thermostats designed to control electric baseboard
heaters, and will control 120 volt circuits--can I use such a thermostat
to control my circulating pump?

I dought 120 is going to the thermostat, its likely 12v or so, to a
relay. Do you have a Honeywell round thermostat.

there are 120 volt and even 240 volt thermostats in use today.

ww grainger sells them

call a local HVAC company they should have the set back type, not
usually sold in stores because of the hazards installing. line voltage
heavy current etc