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  1. #1

    Problem w/closing vents on 14 vent air handler system?

    Everything done in this house was wrong. It is a long, high, old, one story with no wall insulation. It has a 1-1/2 story addition; walk down to FR, walk up to large Master and big bathroom.

    It is 2500 sq. ft. & has a boiler, so there is an air handler system in the attic and a Trane 1000 (11 years old) outside.

    Before I started closing some vents, and even with some closed, the air flow into the FR is pathetic. Yet, this area is closest to the air handler. For 5 years, I have been closing 3 of the 14 vents off, with slight improvement, but it is ridiculous to have it cooler in the old part of the house then in the FR.

    I'm spending up to $175 on AC bills a month. Recently, I decided to close two more vents, which improved the FR some. However, after reading this site and others, I am afraid if this will cause the compressor to burn out or the coil to freeze.

    There is even a flapper near the air handler, which I have for 10 years turned at a 45 degree angle to try to send less air to the old part of the house, which is furthest from the air handler. For whatever reason, things are the way I describe above. Why the air wants to go to the old part? I wonder if that is because the largest air return is located there? There are only two other normal vent size air returns in the newer part, which sounds like bad engineering.

    So, from 14 open vents & 3 closed ones, I went to 5 closed ones. Is that too much and will cause major strain and problems? I don't even know where the coil is on the outside Trane unit. There is an external pipe running up the side of the house to the air handler, and one section is covered with a black foam sleeve, and I think there is a coat-hanger size copper wire from the Trane unit to around the external pipe mentioned.

    I don't understand how the vent closure can damage the system when the air flow out of some vents is less than half that of others. I could see if I had every open vent blowing like mad, but they all are not. Closing the 5 off increases the flow to the weak ones, but those weak vents still are not blowing that hard at all, though the help is enough to satisfy us, as I don't know if I've gone too far already or not. I'd appreciate any help.

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    Have you changed your indoor filter lately?

    Have you ever had the indoor blower and coil professionally cleaned?

    Closing off supply register dampers increases the risk of freezing the indoor coil due to a decrease in total air volume moving over the coil. You may see more air out of the remaining registers that are open, but the total volume of air moving through the ducts is less, due to higher static pressure.

    Finding someone competent to evaluate residential duct systems is tough. But an intelligent analysis of what could be done to improve or rework your system to meet your comfort goals is what you need to move forward with this problem.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  3. #3
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,157
    Agreed, you have airflow issues that a tech needs to address. Sometimes ductwork was not installed correctly or has become crushed/disconnected.

  4. #4
    The problem is I'm financially strapped, and HVAC outfits charge a lot, and like other contractors, can be dishonest and tell you that you need $XXXX worth of work.

    Going into this dreadful attic that I have to walk down a narrow plankway and duck my head to get to the darn air handler (would be on the opposite end of the whole attic) is impossible until we get a couple days not in the 90's, or I'd die.

    Where do I find the coil? I didn't think it was in the air handler, and if it is, maybe it is way inside the unit itself. There is a pan hanging for drips underneath.

    I do know that I have checked the silver-bubble-wrap covered tubes. They are taped together in sections with ducttape. I didn't find any significant leakage the years I examined them, though I did on some put more tape around them. Who knows, they may leaking now.

    This was an old, long very high-raised 1890 ranch that a split level addition was added to. Don't buy a house that has an addition, because these garbage contractors do everything wrong. I could write a whole chapter on everything done wrong from the roof to the foundation joining. Then, the stupid boiler guy tells them why change the old American Standard boiler when they don't make them with cast iron anymore. Why? Because a 1975 boiler is not efficient. We freeze in the winter and don't even use the old part of the house because the heat it turned down so low and the lack of wall insulation, that the heating bills would be $800 a month instead of $250. In the part we live in, which is basically a Family Room and Master Bedroom, the heat is turned down to 62-64 degrees. I won't tell you what I have it at in the old part.
    Last edited by jpsmith1cm; 07-16-2012 at 05:52 AM. Reason: Pricing

  5. #5
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    You can always just open up all the vents and then get a window unit for the FR.

    Otherwise, living with poorly done rennovations is once of hte joys of home ownership... that sadly is not unique to old houses, or even new houses. Unless you custom build a house and have a engineering firm draw up the HVAC specs, its' a crap shoot...sadly. Many new construction tract homes are as bad or worse that your house. Althouhg it sounds like your addion fits that description. Poor quality modern construction.

    That 1975 boiler might not be as inefficient as you think. You could add some imrpoved boiler contorls, but it's already near the end of it's service life. Find another boiler contractor. They do still make cast iron boilers.

  6. #6
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,260
    OK at first glance it sounds like you have return air problems. I am just guessing here, but is the central return air located in a hallway? If so you will need some return air in the FR.
    I r the king of the world!...or at least I get to stand on the roof and look down on the rest of yall

  7. #7
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,260
    As for the boiler, if there is not a properly installed bi-pass the flue gasses are condensing and rotting out the heat exchanger at those temperatures.
    I r the king of the world!...or at least I get to stand on the roof and look down on the rest of yall

  8. #8
    I think I already mentioned that the returns are as follows:

    A 28" x 28" return in the hallway of the old part of home.

    A small, normal vent size return in FR.

    A small, normal vent size return in upstairs bedroom.

    My 1975 boiler is near the end of its life? I was told boilers last 50-60 years.

  9. #9
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    37 years out of 50, is still getting there. Do you want to invest $$$$ in controls upsgrades, or save that for a new boiler that already has those features 5-10 years down the road.

    As monetioned above, if you keep running cold tempratures in the rooms, depending on your setup, the return water tmep may be too cold and cause the boiler to operate "too efficiently" fore it's design and rust out the heat exchanger. I'ts the same reason you sholdn't set the thermostat below 55-60F on a home with a forced air furnace.

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