Thermostat thermometer broke - mercury?

Question moved from Misc.

If it is brand new it is under warranty. Your gas registered installer should have seen it fully working before he left.

https://www.google.com/search?q=Williams+direct+vent+wall+furnace+3003822%2C+pilot+goes+out+when+thermostat+turned+on

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If you have to disconnect the thermostat wire at the gas valve then it is either a shorted thermostat or a short in the thermostat wire.

If you only have to disconnect the thermostat from the wire, then it sounds like a bad thermostat, replace the thermostat

Check if heater has a reset button

Try jumping out the thermostat (red and white wires) that run to the thermostat these tell the heater to come on. Jump them together if you have heat it is the thermostat, if no heat it is the furnace. Should it be the furnace I would first check the thermocouple or some manufacturers call it a flame generator. Clean this with steel wool and position it in the top center area of the flame as this is the hottest part of the flame. Good luck

The red reset button or ECO or energy cut off turns off power to electric water heater.
The ECO responds to temperatures in excess of 150 degrees F.

Preliminary work:
You can use thermometer to check water temperature immediately after ECO trips.
Compare water temperature against the thermostat setting.

There are 4 things that can cause ECO to trip:
1) Bad thermostat is sticking and letting element continue heating water, or ECO is reading incorrect temperature.
2) Factory installed insulation and cover missing from tank, and thermostat is exposed to cooler air and misreads tank temperature.
3) Element shorted to ground in center of element. This completes 120V circuit to ground which will cause element to continuously heat the water.
4) Loose wire near ECO causing high-heat electrical event.

Solution:
Check for missing insulation.
Check screw terminals for signs of high heat and burning >> tighten screws.
Replace both thermostats using detailed instructions given on link below.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

If the problem continues after replacing thermostats, more troubleshooting is needed:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

For more self-help information about your electric water heater:
http://waterheatertimer.org/Do-it-yourself-water-heater-timer.html

For more help, add a comment and I will respond

If it touched a grounded metal surface, it is possible, leave the wires hooked up at the furnace, pull the thermostat off of the wall, disconnect the 2 thermostat wires, and then twist them together, the furnace should fire, if it does, then the thermostat is shot. Replace the thermostat, usually when there is a short, it burns out the heat anticipator on the thermostat.
Good Luck,
Paul Gibson

Jump the two wires going to the thermostat, if it starts , you have either a bad thermostat or a broken thermostat wire. If it does not fire up, you will need to check for 24 volts AC going to the gas valve from the transformer. If you have voltage, you have a gas valve issue. If no voltage, check for a limit switch that may have overheated with an Ohm meter. If they all test good, replace the transformer.

Take the two wires going to the thermostat and cross them. If the unit starts, you have a bad thermostat. If it doesn't, at the heater put a jump wire across the terminals where the thermostat wires are connected to. If the unit starts, one of the wires going to the thermostat are broke. If it still doesn't start you may have a bad transformer. Check for 24 volts AC across the two terminals on the gas valve. If yes, bad gas valve. If no, bad transformer.

can you manually fire the unit w/o the thermostat by shorting 2 of the 3 wires, there may be more wires than that, but you should be able to fire it on 2 to 3 wires alone let me know it sounds like something is floating voltage wise on the unit

Definatly sounds like a bad ground circuit IReplace thermostat you want it to be reliable