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  1. #1
    Join Date
    Aug 2012
    Posts
    11

    High Pressure on supply side?

    I am in a new house and thanks to early advise I've had all of the improperly installed flex duct removed and replaced with sheet metal. At the same time I have a Bryant Evolution 98M furnace and controller installed. The supply and return trunk lines are still ductboard and there is a 5" air filter installed that is MERV 13.

    About every two-three weeks I get a notice that my air filter needs to be changed, and I'm wondering if it is due to too high of pressure in the system on the supply side and what is the best fix to have a company due if I'm correct.

    I ran the system with the filter in and filter door closed, filter out and filter door closed and finally filter out and filter door open to see the various readings. I also took a photo up the supply plenum and I"m wondering if this is the issue. The supply goes straight up into two ductboard runs that are in two seperate joist bays which connect to the main trunk line all of the 6" round connect to to supply each room.

    I'd ask the Bryant and ACCA recommend company (builder selected) that did the install, but after they installed the evolution system and I asked them what I needed to know, I was told. "We don't know, this is only the 2nd system we have installed like this." So I've been trying to learn it as I go.


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  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,572
    Those readings would indicate that your return is the problem.
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  3. #3
    Join Date
    Aug 2012
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    11
    Quote Originally Posted by beenthere View Post
    Those readings would indicate that your return is the problem.
    I had read in another thread about Carrirer/Bryant infinity system that the total pressure should be below .5 with the door off and the filter removed. So that doesn't seem to be a concern. Should I then have a company come out and look at adding additional returns? I have called several companies and nobody seems interested in testing or diagnosing airflow with equipment.

    Currently there are 2 returns in the master bedroom, 1 in the main part of the house, 1 in a side hallway and 1 in each of the other 2 bedrooms. I have a total of 16 supply registers in the same area with a total 2300 square feet finished on the main floor.

  4. #4
    Join Date
    Aug 2012
    Posts
    11
    Makes perfect sense thank you for the explanation.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Either a return added of the one in the hall increased in size. The .78" is not out of line, but is a bit high.

    On a VS blower, if your supply was the problem, then removing the filter and leaving the door off would still give you the same TESP.
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  6. #6
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,035
    .58 static pressure with "basically" only the supply side connected is high. Doing the math you had .78 with everything and .20 less with no filter and filter cover/door off and that would indicate that the return side of the furnace is only adding .20 TESP to the system. The target of a complete residential system is to not exceed .50 TESP, this is the return, filter and supply.

    Don't let the installer off the hook whether it's their 2nd system or their 2000th. They're the ones that charged you to do it and my assumption, I'm sure at least from your persepective, you expected them to do it correctly for the price. If the contractor can't or won't fix the issue then get in touch with Bryant customer service or the supplier the contractor gets the Bryant equipment from.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,572
    Quote Originally Posted by firecontrol View Post
    .58 static pressure with "basically" only the supply side connected is high. Doing the math you had .78 with everything and .20 less with no filter and filter cover/door off and that would indicate that the return side of the furnace is only adding .20 TESP to the system. The target of a complete residential system is to not exceed .50 TESP, this is the return, filter and supply.

    Don't let the installer off the hook whether it's their 2nd system or their 2000th. They're the ones that charged you to do it and my assumption, I'm sure at least from your persepective, you expected them to do it correctly for the price. If the contractor can't or won't fix the issue then get in touch with Bryant customer service or the supplier the contractor gets the Bryant equipment from.
    Only shows that his air filter with the door on is adding .2", not what the rest of the return system is doing. Pics of the return drop would help./ Also knowing if it has central A/C, and what the model number of the evap coil is, and the full model number of the furnace.

    A/C coil could be adding .17 to .3" of PD.
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  8. #8
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,035
    I guess the only absolute known quantity is that the filter is adding .16 to the TESP according to the pictures included of the display. The other picture of the supply plenum makes me suspect of the trunk lines shown and their ability to move 1228 CFM's that were also indicated on the display. Yes, of course, plenty of other things could be and will be adding to the TESP that is being displayed and generating the notice.

    Bottom line, the installation isn't performing to the expectations of the evolution's programmed limits to keep it from displaying the filter notice no matter what is causing it.

    Nice thing about the Evolution is (two of the things it does) notify the homeowner when one of two things happen: (1) That something that was within parameters up until that point has exceeded them for some reason. In a professionally installed and routinely maintained system the homeowner may never see a problem indication. (2) Those same indications will usually notify a homeowner rather quickly that whoever installed their new system didn't realize that with this furnace any shortcomings of the rest of the system, if not identified and remedied during installation, will generate a notice.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

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