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  1. #1

    Excess static pressure stagedown, but airflow set to MAX

    I'm hoping I can get some insight into what is going on with my system, a Carrier Infinity unit. I have been getting a code "161 Excess Static Pressure Stagedown" in the LAST 10 SYSTEM EVENTS section of the Infinity service menu. No faults, but just this code and one other in the system events--Thermal Cutout in Low Stage. However, the thermal cutout in low stage event does not seem to be happening on a routine basis.

    Can someone tell me what the Excess Static Pressure Stagedown message means, and under what conditions it might be happening? I have my airflow limits set to maximum on all my zones (3 zones total), so I don't really understand why this is going on.

    Also, what causes the thermal cutout in low stage message?

    Thanks,
    Rob

  2. #2
    Join Date
    Jul 2010
    Location
    Andalucia
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    Check your air filter first

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,090
    As above. Check air filter.

    Then, what static pressure is it operating at?

    Could be your duct system is undersized, or your unit is oversized.
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  4. #4
    Join Date
    Jul 2010
    Location
    Andalucia
    Posts
    3,223
    How old is your system? was it working ok before? Is air coming out of all zones?

  5. #5
    Air filter is brand new.

    Currently the unit is running in high stage with the following...

    Bedrooms - zone damper at position 3 (barely open) and 281 CFM

    Living, Dining, Kitchen area - zone damper at position 15 (fully open) and 1418 CFM.

    This error had been occurring a lot, so I switched the airflow limits to MAX on all three zones. Basement is the third zone, but it never gets a call for cooling since it is already cold. With the airflow limits set to MAX, the problem has decreased a lot, but hasn't stopped completely.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    So what static pressure is it reporting. At those CFMs?
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  7. #7
    Air comes out of all zones, including the basement even though it never calls for cooling. I guess the dampers stay open, even when they are closed, for cool air to leak through.

    The system is about 4 years old and has done this since day 1. The installer came on a couple occasions to make some changes to ductwork (i.e., eliminated right angle turns) and this helped some, but not entirely. Because I had the intention of closing my crawlspace and creating a conditioned area, it was decided that a dump zone in the crawlspace would solve the problem. Time passed, I sealed up the crawlspace real well and put in a dump zone. This helped, but again not entirely. Changing airflow limits to MAX has helped even further, but hasn't completely resolved the issue. Short of increasing the opening of my dump zone register, I'm not sure what to do??

  8. #8
    Quote Originally Posted by beenthere View Post
    So what static pressure is it reporting. At those CFMs?

    Ooops. the static pressure was around 1.12 - 1.15

  9. #9
    BTW, the call for cooling is much less now (fewer CFMs being pushed out, static pressure down to .48) and a new Excess Static Pressure Stagedown event did NOT occur. I thought that this event occurred anytime static pressure was greater than 1.0? Is this not the case? Apparently not, since it was up to 1.15....

  10. #10
    Join Date
    Feb 2010
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    Sounds like undersized ductwork, you could increase the outlet in the crawlspace but you probably don't want to waste evergy dumping a lot of air down there.

    What size is the A/C?

  11. #11
    5 ton HP.

    Sounds like a may need to add a register or two in order to avoid dumping too much into the crawlspace?

  12. #12
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,123
    5 ton, I hope its for a large house.

    Need to know how much of that static is from supply and how much return.

    Without seeing it I would recommend more registers or more return instead of dumping it in the crawlspace.

  13. #13
    Join Date
    May 2010
    Location
    SF Bay Area, CA
    Posts
    390
    i'm surprised setting airflow to Max helped. seems like that would increase the static pressure and cause this error more often.

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