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Understanding Static Pressure in my heating system.

JackW
JackW Member Posts: 236
in Gas Heating
I'm trying to understand the static pressure readings of my heating system. I've watched dozens of videos on YT, but I still can't grasp what I'm reading. It's a downflow system; there is no A-coil, and the only obstruction is the furnace filter. As you can see in the photo, I have a hole above the filter and below the furnace. I've also included a picture, a bad one, with the w/c number circled. It reads 0.70 IWC or 0.174 KPA. A one-minute reading produces a .31 max, a .19 low, and a .26 average. Are these readings telling me anything?

Thanks,
Jack





Comments

  • ChrisJ
    ChrisJ Member Posts: 16,462
    You should be measuring after the air filter on the return.
    It looks like you're measuring before it.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    JackW
  • JackW
    JackW Member Posts: 236
    @ChrisJ, I have one below the furnace itself. Is that not the same?
  • ChrisJ
    ChrisJ Member Posts: 16,462
    edited October 2022
    JackW said:
    @ChrisJ, I have one below the furnace itself. Is that not the same?
    Those hoses actually add to each other.

    The top one is measuring suction (before the fan) and the bottom measures pressure (after the fan). The gauge adds them together.

      If you move the top one to just after the filter its going to show more pressure drop, sometimes a lot more.  Right now you're measuring the suction before the filter is having an effect

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    JackW
  • Bob Harper
    Bob Harper Member Posts: 1,099
    The open return is perverting the TESP. Close it with tight fitting magnetic strip, sheetmetal cover or removable tape.
    What is that below the furnace? Looks like an A coil to me with my weak eyes.
  • ChrisJ
    ChrisJ Member Posts: 16,462
    Bob Harper said:
    The open return is perverting the TESP. Close it with tight fitting magnetic strip, sheetmetal cover or removable tape. What is that below the furnace? Looks like an A coil to me with my weak eyes.
    It certainly does look like an evap but it looks like a blank housing with no connections.  

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • JackW
    JackW Member Posts: 236
    edited October 2022
    @ChrisJ, so I need to drill a hole below the filter, and I don't need the probe above the filter? Do I need the probe below the fan, or do I just use one probe? What do you mean by "looking like an evap"? We don't have central A/C, so there is no A-coil.
    Thanks.
  • JackW
    JackW Member Posts: 236
    @Bob Harper, I don't know what you mean by "open return." We don't have central air, so they took the A-coil out when we replaced the old furnace a couple of years ago. Thanks for your help.

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