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  1. #1
    Join Date
    Apr 2005
    Location
    Sacramento, CA
    Posts
    8
    I had a 4 ton Carrier Infinity heat pump (2 speed with VS fan coil) installed (attic) two months ago. Just turned on the AC two weeks ago. The system is qreat - cools well, even temperature throughout house, and is quiet (except on high). Checking the system through the stat, I noticed that static pressures were higher than I expected based on general information I have picked up on this site.
    882 CFM -- 0.35
    1400 CFM --0.97
    1600 CFM --1.19
    The system typically operates in the 800 to 1400 CFM range and only goes to the highest speed when there is a >2F difference in actual and demand temperatures. The installer says these readings are normal. Also, the stat called for filter cleaning after only 1 week of operation. I cleaned it even though it looks brand new. After 1 more week it is calling for cleaning again. No faults are reported. Any thoughts?

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    1400 at .97,is too high,little room left as the filter gets dirty to stay below the limits..70 is the max we leave them at ,with a clean filter.1600,will likely be so few times,if set for 350 cfms,that it can be over the limit.



    It's likely a simple duct modification to get it down,can you post pictures of the ducts?


    What city/state are you in?

  3. #3
    Join Date
    Apr 2005
    Location
    Sacramento, CA
    Posts
    8
    Thanks Dash,

    Location: Sacramento CA (currently 107F)
    Ducts are all flex with a centrally located 20 x 30 return grill (alergy gold electrostatic filter) and a 16"dia duct. There are 6 supply ducts off the plennum: 1-5", 2-6", 1-8", 1-10", and 1-14". The 6" and 8" ducts have dampers. Looks like the size on the return duct is limited by the roof line in the attic.

  4. #4
    Join Date
    Mar 2004
    Location
    Gone
    Posts
    5,340
    Through away the electrostatic, and use a plain old blue fiberglass filter until you can have a media filter installed. The electrostatic is way to restrictive.

    Your return flex is undersized and you need to have a contractor correct this.

    Your supply looks like it would be ok as long as there are not to many turns etc.

    A contractor who understands how to diagnose using a magnehelic meter could determine exactly where and what side your problems are on. Changing the filter will help you greatly just for a start.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,739
    Put a regular air filter in and see if that doesn't drop your static pressure.

    Your return duct is just a bit small also.
    Contractor locator map

    How-to-apply-for-Professional

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

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    What "made' said is correct.

    Magnehelic,manometer will do,Theyneed to test the static,for the supply and return,then decide which is easier tor reduce,usually it's the supply.

    Adding a second return may be all thats needed,and is an opportunity to get a return in the master suite.

    Now they likely could just increase the existing return duct and grill,to do the same,so if you want a second reurn,ie in the master,it would be fair that you pay the extra cost for that solution.


    If they have no idea ,about static ,your may need to call 800-CARRIER,but please let them try to resolve it first.Talk to the owner or service manager.

  7. #7
    Join Date
    Apr 2005
    Location
    Sacramento, CA
    Posts
    8
    Thanks all,
    I tried a merv 8 pleated filter that they had left as an alternate and it actualy increased the static pressure from .97 to 1.18 at 1400 CFM. I'll contact the installer again next week.

    Thanks

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Been theres ,suggestion of a "regular" filter is the best till they correct the ducts.


    size and thickness of the merv 8?

  9. #9
    Join Date
    Apr 2005
    Location
    Sacramento, CA
    Posts
    8
    The merv 8 filter is a naturalaire 1" thick. I put a cheap fiberglass filter in and the SP dropped to 0.82. Without any filter the reading was 0.71. I guess filters do make a big difference

  10. #10
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by rkmx5
    The merv 8 filter is a naturalaire 1" thick. I put a cheap fiberglass filter in and the SP dropped to 0.82. Without any filter the reading was 0.71. I guess filters do make a big difference

    Yes they do spread the word!!!LOL

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