text: - 200 degrees). Some boilers may be equipped with a secondary temperature limit and / or a low water cutoff control (LWCO) for additional protection. The circulator pump will run until the thermostat shuts off the boiler. A total failure of the gas valve, temperature controls, low water cutoff (LWCO), water
  Although natural gas boiler explosion accident is very horrible, the accident can be prevented. Firstly, making clear the job responsibilities and operation norms; secondly, making the furnace inspection system; thirdly, improving the boiler protection system.
  Fuel Backup Plan. Make sure you have a backup plan for fuel. For instance, if you're using natural gas, make sure you have a #2 fuel oil or propane line in place as well. You never know when there will be an issue with a cut or disabled fuel line that can put your boiler out of operation.