Hello, I was trying to upgrade my thermostat for my fuel oil, water-baseboard heating system. I fried two programmable Honeywell’s. (I’m not an hvac tech, but can handle most minor projects I’m the house) It’s a two zone system, downstairs went fine, and works perfectly, upstairs has two larger black and white wires, and if I’m using my cheapo volt meter correctly, I’m getting 123 volts. I ordered a line voltage thermostat, hooked it up, digital read out worked for about 5 minutes, and nothing, think I fried it to. Any idea what to do next? Thanks in advance.