How to install a smart thermostat on my furnace?

+3
Answered

Furnace is a Slant/Fin VSPH-90 boiler. There are three thermostat terminals at the boiler end, but only two have wires connected to them (see photo). The two wires connect to the W and R terminals in the (old) thermostat (see second picture). There is also a jumper between the R and RC terminals at the thermostat end. There is obviously no common wire, but can this be made to work?

q how to install a smart thermostat on my furnace
q how to install a smart thermostat on my furnace
  5 answers