No announcement yet.

Plenum Temp??

  • Filter
  • Time
  • Show
Clear All
new posts

  • Plenum Temp??

    I was on a job yesterday, I am a carpenter, and while in the basement I happened to check out the new Bryant furnace the homeowner installed. When I touched the plenum I was amazed how warm/hot it was. This AM while working at home I touched mine,Lennox, and it felt almost "cold" in comparison.
    So what's up? BTW mine is LP gas and the hot one was natural gas.

  • #2
    Re: Plenum Temp??

    By Plenum I'm going to assume you mean the first metal ductwork section on the air outlet side of the furnaces...

    Some things to consider...

    Newer ductwork will be insulated inside and feel cooler to the touch, your system may be older and not have a lined plenum.

    Newer systems can be tuff to tell they are running at times some of the signs you may see do not mean the burners are firing... Draft fans run pre purge and post purge... blowers run after burners shut off to cool exchanger ect... you would need to make sure you are checking the temperatures at the same points in the heating cycles...

    The older Lennox furnaces (Diplomat) If I remember correctly run a button limit @160 degrees while other furnaces run higher temps (around 200 degrees)... The lennox furnaces run a bit cooler...

    I hope this helps,



    • #3
      Re: Plenum Temp??

      your blower fan speed can make a difference as well,
      also the intake air tempature.
      Push sticks/blocks Save Fingers
      "The true measure of a man is how he treats someone who can do him absolutely no good."
      attributed to Samuel Johnson
      PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and the current state of the economy............the light at the end of the tunnel, has been turned off.


      • #4
        Re: Plenum Temp??

        its possible that your furnace is a downflow and your upper duct would be the cold air return. and the one in the basement may be an up flow meaning the upper duct would be the supply (hot air)