Hi,

I have an old Honeywell T451A medium line voltage (120V) thermostat for a FHW by oil system. The thermostat mounts vertically and I would like to replace it with a modern (setback) type unit to save energy. I am having trouble trying to find a replacement as most are for straight electric heat or 24V versions. Does anyone know of any replacement units? Any help would be appreciated.

I do not find any at the Honeywell or White Rodgers site.

You could modify the system to use 24 volts with a transformer and a relay that would isolate the 24 volts from the 120 volts. Just a thought.