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Furnace Cycle Issues

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KeupMittenFamily
KeupMittenFamily Member Posts: 3
in Gas Heating

Looking for some confirmation of my suspicions of an issue I'm having with our furnace. First, my specs:

Janitrol Furnace: Model: GMNT100-4B

Honeywell Zone Controller: Model: HZ322

I am having the issue where the furnace will follow this cycle sequence intermittently (2-5 times a week, maybe more!) I notice this when I am home in the evenings and during the night, but it could be happening quite a bit more during the day.

Screenshot 2025-01-12 at 12.55.30 PM.png


Actions Description:

Induction = Induction Fan

Burn = gas ignition and burning

Blower = fan blower running

My assumptions and this is where I need help diagnosing:

  1. Gas valve regulator failure
  2. Motherboard failure

Any help and direction would be helpful. I plan on calling a professional in my area to do some, if not all, of the work necessary. I can replace a few things, but I prefer not to work with black iron/natural gas.

Thank you!!

Comments

  • HVACNUT
    HVACNUT Member Posts: 7,305

    No codes?

    Does it sound like there's water in the inducer assembly? All drains are clear?

  • 109A_5
    109A_5 Member Posts: 3,684
    edited January 2025

    Dirty flame sensor ? Loose or poor ground for the flame sensor return.

    Intermittent pressure switch, loose wiring, partially blocked vent.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,748

    You may be experiencing a micro-zoning issue. This is when there is a call for heat from one zone that gets satisfied within 3.5 minutes then after a short delay another zone calls for heat and gets satisfied within 3 minutes, and that can go on because that Honeywell control logic does not include necessary logic that will allow for delaying a call for heat from any given zone for a given specified time limit so that another zone may also call for heat and the total cycle can be longer.

    There is a purge feature that will allow excess heat in the system to purge after the furnace gas valve shuts off, but that does not do what is needed to eliminate the short cycling that you are describing.

    To document this you need to watch the LED indicators of the Honeywell HZ322 and see what zones are calling when the "short cycling" is actually happening. This will confirm that the same zone is calling the entire time or if the micro-zoning problem is the cause since the zone that is calling changes when that "short cycling" event happens. You do not actually need to watch it in person if you have a GoPro camera or some sort of camera that you can set up and forget about it while it records the "short cycling" event.

    Since this is not a regular event, and may only happen once in a while, that is my suggestion. Then you can see the results in real time when thermostats from each zone are calling at the same time and when they may be calling at different times. Once you have confirmed (for example) that the same zone thermostat is calling the entire time as the "short cycling" event, then you will have eliminated the Micro-zone as the problem.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • KeupMittenFamily
    KeupMittenFamily Member Posts: 3

    Good morning. I am resurrecting this thread again because we're having somewhat of the same issues we had last January, but now with a twist. All of what I am about to describe occurs intermittently, because sometimes the furnace will operate normally for a time.

    We have two Sensi Wifi Thermostats, one upstairs and one downstairs. What we have noticed over the past few months is that when a zone calls for heat, the induction fan turns on, the glow plug will initiate after a few seconds up to a minute or two, but the gas will not ignite. This will happen for about 5-10 minutes and then the induction fan just turns off, yet the thermostat (and zone panel - red) is still orange (calling for heat). It will stay orange for quite some time with no response from the furnace.

    We've also noticed that when both zones are calling for heat, the furnace won't do anything sometimes at all or will go through the sequence I described above. We have cleaned the flame sensor in attempt to make sure that isn't the culprit. The condensate pump is functioning properly and there does not seem to be any water in the pipe from the condensate box. So, I'd like to get a little more of an idea as to how I can focus the HVAC technician in an attempt to weed out the problem possibilities. OR, maybe it is something that I can just replace and fix DIY.

    Any help would be appreciated. Thank you.

    Janitrol Furnace Model: GMNT100-4B

    Honeywell Zone Controller Model: HZ322 (with 3 zone dampers)

    Sensi Thermostat Model: ST75U (1 upstairs and 1 downstairs)

  • HVACNUT
    HVACNUT Member Posts: 7,305

    If the HSI powers up, see if there's 24 volts to the gas valve, while at the same time watching the static pressure drop on the inlet side of the valve.

    If there's no 24 volts to the valve and gas pressure is within range, start going backwards on the burner circuit.

    KeupMittenFamily
  • 109A_5
    109A_5 Member Posts: 3,684
    edited January 11

    Assuming the call for heat from the HZ322 is valid and consistently getting to the furnace, I would want to know if the furnace is locking out. If so why ?

    No hour lockout delay, I'd check the call for heat from the HZ322.

    image.png

    https://wizard.youngsupply.com/files/25-9846.pdf

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    KeupMittenFamily
  • KeupMittenFamily
    KeupMittenFamily Member Posts: 3

    HVACNUT and 109A_5, thank you both for your responses. Looking into what you both suggested, I will be limited on what I can check. I won't be able to check the volts on the gas valve and static pressure. I'll have to leave that up to the HVAC Technician. The lockout theory though sounds like that may be closer to what we are experiencing. There aren't any flashing lights though on the HZ322 at any point. They are always solid. I will take off the front panel on the HZ322 to monitor if there are any error codes that are displayed on the screen. I didn't see any last time this happened, but maybe something is coming up this go around. The lockout description is a very plausible theory that I will present to the technician.

    Thank you again for your help!

  • 109A_5
    109A_5 Member Posts: 3,684

    The flashing Status light (or LED) is for the furnace and you may have to look through a small clear plastic view port to see it.

    Without a multimeter to measure system voltages, troubleshooting may be severely limited.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • pecmsg
    pecmsg Member Posts: 6,877

    Measure the temperature rise

    Should be less then 60°F

  • 109A_5
    109A_5 Member Posts: 3,684

    Clogged air filters ? Although the symptoms may not be intermittent.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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