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Does gas need to be turned off on furnace

Our furnace has been running but only blowing cold air instead of hot air. It’s a natural gas furnace, would there be an issue with any gas leak, now that unit is shut off? Do we need to turn off gas unit to the main? 

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    What shut it off? Do you want it off? Do you want it to run and it's not running? There shouldn't be a problem with a gas leak -- unless the gas valve is failed, but you would most likely smell that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,829
    If you feel safer with the manual gas valve closed, by all means, close it. But the gas valve closed will prevent the heat from operating properly.

    Can you be more specific as to the situation?

    Is it cold outside?
    Is it cold inside?
    Do you want it warmer inside?
    What is the temperature inside?
    What is the thermostat set for?
    Answer these basic questions, and perhaps some here can help
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Therfamily123
    Therfamily123 Member Posts: 5
    It’s just blowing cold air while still running for a long time, would that cause it to blow /leak gas? And now that the system is off, could it be leaking gas or do we need to turn gas off. We do not smell any gas. 
    neilc
  • Therfamily123
    Therfamily123 Member Posts: 5
    Temperature 37 degrees outside. 
    Instead upper 40s

    we are getting it repaired tomorrow. We don’t need it to work today.  

    Just questioning the gas valve? if the system was running for several hours, would it be blowing gas? 
    And now that the system is off, could it be blowing gas? Do we need to shut gas off? 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,829
    No.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,829
    edited February 25
    The reason it is blowing cold air... is because there is no gas getting to the burners

    If you want it to stop blowing cold air, turn the electric switch off.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Therfamily123
    Therfamily123 Member Posts: 5
    No we don’t need to be warmer today but yes tomorrow will be repaired. 

    Cold inside and outside, yes 

    The thermostat is set to 68 degrees. 
    Temperature inside is 47 degrees. 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,829
    OK... To stop the blowing cold air, turn the switch to the furnace OFF
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Therfamily123
    Therfamily123 Member Posts: 5
    That’s been done. We just wanted to make sure there was no risk to gas still running/leaking 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,829
    Gas appliances that have been manufactured after 1950 have safety systems built in that pretty much prevent them from letting out any gas when they fail or are turned off. It is called Fail Safe Designing and is built into the equipment. It is kind of idiot proof. Of course that is based on the typical 1950 idiot. From what I have heard from many manufacturer's reps is that in the past several decades, we have been producing a better class of idiots. So maybe you should turn off that gas valve.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    bburd
  • HVACNUT
    HVACNUT Member Posts: 5,829
    That’s been done. We just wanted to make sure there was no risk to gas still running/leaking 
    Put a bucket under the drip leg. That should be fine until the repair is done.
    EdTheHeaterMan
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,517
    Perhaps the thermostat is set to "fan on"