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  1. #1
    Join Date
    Jul 2006
    Posts
    206

    Carrier Infinity Zoning -- Static Pressure?

    I have a carrier infinity variable speed furnace, a single stage comfort series a/c unit; and we just added the basement as its own zone. Previously, the bedroom was 1 zone, and the main floor/basement was another zone. So now we have 3 zones off this system (each floor its own zone).

    Now that I have 3 zones (instead of 2), I've been paying attention to what the Infinity Thermostat says as to static pressure.

    When only 1 zone is calling for cooling, I've seen static pressure from .8 to over 1.1.

    But when I run the AC checkout test on the thermostat, which I assume runs the whole system (all 3 zones at once), static pressure is okay, as its around .55 .

    So is it bad that when only one zone is calling I have way above the recommended (from what I see on this site) static pressure of roughly .50 ?

    Or is high static pressure to be expected when only one zone on a 3 zone system is calling? Note that the zone capacity is shown as:

    main floor 43%
    bedrooms 33%
    basement 16%
    damper leakage 8%

  2. #2
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    Have your contractor dump air to the main floor when only the basement is calling and maybe when only the bedroom is calling. Enough extra flow to the main floor to keep the static below .75 .

    See if the pro's here have a better suggestion??

  3. #3
    Join Date
    Jul 2006
    Posts
    206
    Quote Originally Posted by Daltex View Post
    Have your contractor dump air to the main floor when only the basement is calling and maybe when only the bedroom is calling. Enough extra flow to the main floor to keep the static below .75 .

    See if the pro's here have a better suggestion??
    Is it really really bad for it to be above .75 when only one zone is calling? What is all the down-side of this?

    The thing cools nicely and seems to run fine. I wouldn't know that above a certain number was bad if I didnt' read this forum.

  4. #4
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    The static over 1.1 is not good for efficiency or the blower motor. I don't know the magic static point that is acceptable but the furnace manufacturer does and it is below 1.1.

  5. #5
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,021
    If it's just one zone calling, I wouldn't sweat it.

    If it was that high with all zones, you'd have problems.
    Perhaps you should have read the instructions before calling.

  6. #6
    Join Date
    Jul 2006
    Posts
    206
    Quote Originally Posted by jrbenny View Post
    If it's just one zone calling, I wouldn't sweat it.

    If it was that high with all zones, you'd have problems.
    Yeah, with all zones (based on the A/C checkout test that you can do via the Infinity thermostat) its around .55 or .56 (sometimes less).

    When one zone calls it gets over 1.1. No big deal for that?

    If it was bad, wouldn't I get faults or errors in the system. The Infinity T-Stat shows errors and warnings. If no fault, error or warning, does that mean the unit is happy?

    Isn't carrier infinity smart enough to alert if static is too high?

  7. #7
    Join Date
    Apr 2008
    Location
    Alberta Canada
    Posts
    2,246

    Depends on tonage

    Quote Originally Posted by eap View Post
    Yeah, with all zones (based on the A/C checkout test that you can do via the Infinity thermostat) its around .55 or .56 (sometimes less). When one zone calls it gets over 1.1. No big deal for that?If it was bad, wouldn't I get faults or errors in the system. The Infinity T-Stat shows errors and warnings. If no fault, error or warning, does that mean the unit is happy? Isn't carrier infinity smart enough to alert if static is too high?

    Heating is .5 and cooling is .2 but can be higher as long as you have enough CFMs at sp in fan chart tables in manual.
    Do it right the first time.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,808
    Whats the static for the main zone alone.
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  9. #9
    Join Date
    Apr 2008
    Location
    Alberta Canada
    Posts
    2,246
    Quote Originally Posted by eap View Post
    If it was bad, wouldn't I get faults or errors in the system. The Infinity T-Stat shows errors and warnings. If no fault, error or warning, does that mean the unit is happy?

    Isn't carrier infinity smart enough to alert if static is too high?
    Only lets Installer know on start up and you can hide it.
    Do it right the first time.

  10. #10
    Join Date
    Jul 2006
    Posts
    206
    Quote Originally Posted by 21degrees View Post
    Only lets Installer know on start up and you can hide it.

    I know how to go to the advanced menu and look at all faults and warnings for the entire history of the sytem.

    I see nothing re: static pressure -- except when system was first brought on line 1.5 years ago.

    Nothing is hidden from me. I know every menu on the stat and have the installation manuals. I know more about my system than some of the techs who work for my HVAC company -- sadly.

  11. #11
    Join Date
    Jul 2006
    Posts
    206
    Quote Originally Posted by 21degrees View Post
    Heating is .5 and cooling is .2 but can be higher as long as you have enough CFMs at sp in fan chart tables in manual.
    Cooling is .2 or 2.x ? I never see it as low as .2 ?????

  12. #12
    Join Date
    Jul 2006
    Posts
    206
    Quote Originally Posted by beenthere View Post
    Whats the static for the main zone alone.
    Static for the main zone alone is .75

    So is that bad? That's at 1750 CFM.

    I also set my zone airflow limits to max (from the default of "high") for the main zone. So that may help static be lower than it might be. Not sure if that has an effect on static.

    So what's the deal with .75 on the main zone alone? Good, bad, so so?

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,808
    .75", Thats ok.

    You max want to set the air flow to max for the other zones also.

    jr, and 21 can inform you better on that then I can.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

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