My heil natural gas heater furnace won't shut off. It just keeps running and heating. Installed a new thermostat with no success. Prior to this happening I just had my hardwood floors resurfaced and sealed with polyurethane. Did that get into the system and gum up some mechanical release? I have to manually switch off the unit to stop the heating/blowing or it will get 90 degrees in here. I also noticed the squeal cage is rattling causing the blower to make a vibrating noise. I am in Arlington Va 703 3685466. Thank you

Did you install the new stat before or because of the problem?

Check the gas valve with a volt meter and see if it is getting 24 volts when you don't want it to run. If not your gas valve is bad, but I suspect you have a short which is powering the gas valve on. You either wired it wrong or have a short between "W" and "R."