Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
If our community has helped you, please consider making a contribution to support this website. Thanks!

Furnace Turning off before reaching Temperature

Options
Kaitlyn
Kaitlyn Member Posts: 10
in Oil Heating

My furnace turns off before reaching temperature. It will run for 3 mins and then starts to cycle but then turns back on and starts the process all over again. Any ideas why that might be. I have replaced the filter so I don’t think it is that.

Comments

  • pecmsg
    pecmsg Member Posts: 6,708

    temperature rise?

  • HydronicMike
    HydronicMike Member Posts: 217

    Probably oversized. When the temperature hits the high limit setting, the burner shuts off. The fan keeps running until the temperature in the heat exchanger drops, then it keeps repeating until the call for heat is satisfied.

    There can also be other reasons-clogged air filter, problem with the blower motor, closed dampers, etc.

    Best to have your service provider come check it out and take some measurements.

    hot_rod
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,279

    Hard to tell there are so many things it could be.

    Do you have a thermostat that has a "fan on" position? You could turn the fan on and see if you think it is blowing normally. That would be a start.

    mattmia2
  • BDR529
    BDR529 Member Posts: 369

    Timer relay? Dose it have a PCB? Bunch-o-wires?

  • DanielDAY
    DanielDAY Member Posts: 35

    If you have a Honeywell thermostat I believe there is a setting that will turn the system off before reaching temperature but I could be wrong. Maybe see if it’s a thing. Do you know if it eventually reaches the temperature once the system shuts off?

  • Dave Carpentier
    Dave Carpentier Member Posts: 633

    When did the furnace last run 'normally' ?

    "I have replaced the filter"

    Unclear if you did this as part of pre-season service, or as part of troubleshooting the issue.

    If pre-season, then the MERV rating of the filter might be way too high.

    30+ yrs in telecom outside plant.
    Currently in building maintenance.
  • Kaitlyn
    Kaitlyn Member Posts: 10

    Sorry I should have been more clear in my explanation. The furnace starts and will run for two or three minutes and then shuts off before it reaches the desired heat. The fan then starts to cycle but then the furnace starts right back up again and will then run normally and reach the desired heat. I replaced the filter just a few days ago as I thought that might be the issue. None of the dampers are blocked. I have a nest thermostat. I have a serviceman coming in to check but I thought I would ask here as well as we are puzzled why this keeps happening.

Categories