Have a typical Honeywell Thermostat that controls our home's gas forced hot water heating system.
Can't find the manual for it, or a model number on it. Model is probably on the back, and I really don't want to take it off of the wall.
It's a rectangular unit, about 2 years old. Has a digital display showing the Set Temp., and what it senses as the actual temp. Runs off of two AAA batteries. Nice green backlighting when the button that sets the Set Temp is pushed.
Would like to have a better understanding of how it works.
a. Question: Do these thermostats, when turning on, merely provide, in effect, a contact closure for the control box mounted on the furnace ?
And that there is a 24 transformer inside this control box, as well as a relay to control the 110V Circ..
When turning on, therefore, the thermostat just closes its contacts allowing the voltage from a transformer in this furnace mounted box to then provide 24 volts to a relay, via the thermostat, also in this control box ?
Is this the way it probably works ? With only two 1.5V AAA batteries, I cannot see how the thermostat could provide any 24 V.
So, it only closes a set of contacts in its (the thermostat's) case when it is calling for heat ?
b. If the batteries go dead, will the thermostat still function ? I realize the display won't light up anymore.