furnace boiler overheating ? Please help !!!?
there so many type of furnaces you never told us what kind you have. if its just hot water furnace you have got something blocking the draft door when it tries to close or if the ashes seals the bottom to make it air tight you may be removing too many ashes when you take them out. you shoukld not try to heat the water hotter than 185 degres if you set water temp any higher it will over shoot and boil the water. i hope this is the type you have and good luck
Bob G is right. Is it a water or a steam boiler? Is it getting hotter than the setpoint and running wild (possible bad operating control and/or high limit)or is the relief valve opening (possible defective pressure reducing valve or flooded expansion tank)? Both water boiler related. Or is it a steam boiler going over setpoint?
Is the relief blowing off water?,, What is it doing,, what do you mean by overheating? Since your not going to answer us,, start here. Check the pressure on the boiler at the gauge,,, it should be around 12 to 18 PSIG,, check the rating on the relief valve,, it should be rated to blow off at 30 PSIG.. watch gauge as you fire the boiler,, if the pressure rises then your expansion tank is water logged,, ( filled with water ). What you will need to do is to shut down the boiler,,, valve off the expansion tank from the boiler, and drain the tank. To do this you will also have to let air into the tank as you drain it. This is like removing your thumb from a straw that is full of liquid,,, when you do, air goes in and the liquid goes out. There should be some kind of air vent that you can open on the tank,, it could be on the drain valve located under the screw that holds on the handle.. if this is the case, it should have a tag telling you this. if none there there might be one at the other end of the tank. With a hose ran to a drain from the drain valve on the tank, start draining and open the air vent as soon as the water from the hose starts to slow down or stops. Keep draining till empty,, Once empty, remove hose,, close vent, and open valve between the boiler and the expansion tank. Start boiler again and check the pressure and make sure it does not rise.
