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  1. #1
    Join Date
    Jul 2008
    Location
    TX
    Posts
    32

    New installation concerns

    I've been lurking here the last couple of months to learn more in preparation for the inevitable failure of my (then) limping system. I'm not an HVAC-savvy person, just a customer.

    My old system finally failed so I just had a new one installed. The condenser, furnace and coils were replaced along with one of the line sets.

    There's a few things that concern me that I'd like to follow up with the installer but was curious into seeing what some of you experts thought.

    First, the new furnace/coil unit was roughly 8 inches taller than my old unit and the tech was not able to wrestle it into my AC closet without removing the filter base. He assured me that a filter grille would be an adequate substitute for this install. The area under the furnace is unfinished space and the tech sealed it with some kind of poly foam, caulked the furnace base and any holes for the line set or wires. The grill was installed and caulked. I'm attaching some photos. The water damage seen underneath there is years old and happened when the old unit had a clogged drain line. My main concern is that the return air going back into the furnace isn't as clean as it would be using a base-mounted filter.

    Another concern is also related to the filter grille. It uses a 12x24 filter. My old system was 2.5 tons and used a 16x25 filter. The new unit is a 3 ton system. Is this filter too small for this application?

    I'm also experiencing a weird harmonic hum that sounds like its coming from the coil. It only happens when the thermostat is set to cool. The fan setting can be either "On" or "Auto". Even when the compressor is off outside, the harmonic hum is still there. I noticed this when the tech was working on the outside unit and had the condenser safety disconnect pulled. The inside unit was on and humming noticeably even with the compressor off. The service company has contacted the manufacturer and will follow up but I was wondering if anyone here has seen this before.

    Again, I'm not very handy when it comes to these sorts of things so please forgive any descriptive errors. If more photos or information is needed, I can update this post. I did read the site rules but if this post is inappropriate in any way, please let me know.

    Thanks guys...




  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,765
    The filter is too small. The hum may be from the transformer.
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  3. #3
    Join Date
    Jul 2008
    Location
    TX
    Posts
    32
    Danke for the reply, beenthere. I'll take up the filter size issue with my installer.

    I also wanted to add that I'm not so much concerned about the cosmetics of the return air solution but rather on how technically sound it is and that it's providing adequate flow and filtering for my new system.

    BTW: the hum doesn't sound electrical in nature. It sounds like some kinda flow noise. Sorta like someone recorded a leaf blower or vacuum cleaner and turned the volume down. My description stinks but I can't think of another way to describe it.

  4. #4
    Join Date
    Dec 2006
    Location
    Dallas
    Posts
    189
    How did this guy determine that he should use 3 tons instead of 2.5? Did he perform a lod calc, or did he upsize because the old unit wasn't adequate (old = not producing 12,000 BTU / ton like it did when it was new).

    Let me guess - during the install this guy realized the air handler size was an issue? He didn't talk to you about this issue before the install.

    Can you take a few pictures from further away.

  5. #5
    Join Date
    Dec 2006
    Location
    Dallas
    Posts
    189
    3 tons would mean 1200 CFM through 2 Sq Ft = 600 Sq Ft sucking through the filter = Not 600 CFM = Leaf Blower noise

    If you test it with the filter open, does it still sound like a leaf blower?

    Ask him to test for static pressure. Ask what he is reading and what it should be.

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Can he add another grille in a different wall,that's opn to a common area of the home?

    The area looks well sealed sothe filter grile should be fine.

  7. #7
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,614
    the installer should have replaced the platform and the closet measured before they gave you a quote. the install looks a little rough from the pic

  8. #8
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    From what I can see.....

    The hole underneath your airhandler may be a little too small....it should have been cut out more.

    The filter grill isn't big enough as stated by others.....maybe you can add-on as suggested.

    An electrical hum shouldn't be hard to find or diagnose....especially since you can eliminate the blower causing it since it does it regardless of it being fan on/off.

    Hope this gets resolved for you...
    If everything was always done "by the book"....the book would never change.

  9. #9
    Join Date
    Jul 2008
    Location
    TX
    Posts
    32
    How did this guy determine that he should use 3 tons instead of 2.5? Did he perform a lod calc, or did he upsize because the old unit wasn't adequate (old = not producing 12,000 BTU / ton like it did when it was new).

    Let me guess - during the install this guy realized the air handler size was an issue? He didn't talk to you about this issue before the install.

    Can you take a few pictures from further away.
    gonekuku,

    I'm not sure what's involved in a load calc but a tech did come out to look at the old system, the number of registers and the insulation in the attic. With that information and based on the square footage of my house (1200), the install company did recommend a 2.5 ton system. I have to fess up and say that I did push the issue on a 3 ton system, so if the unit is oversized, the fault would be entirely mine. This was based on my possibly inaccurate perception of the original 13-year-old system and on the fact that I have a few PCs and vacuum tube audio amps that kick out some pretty good heat. He said that the 3-ton would be ok in this situation, so I went with it. So far, I've noticed that with the 3-ton, humidity inside seems higher when the outside temps are cool and humidity is high (i.e., during the few-and-far-between central Texas summer showers). Under more typical central Texas summer circumstances (i.e., blazing heat), the unit seems to cool and dehumidify like a champ.

    At any rate, you called it when the air handler size problem was discovered too late and during the install process. I understand that mistakes happen but I'm just trying to make sure any mistakes made by the installer are properly addressed.

    3 tons would mean 1200 CFM through 2 Sq Ft = 600 Sq Ft sucking through the filter = Not 600 CFM = Leaf Blower noise

    If you test it with the filter open, does it still sound like a leaf blower?

    Ask him to test for static pressure. Ask what he is reading and what it should be.
    There is noise associated with the filter and that's eliminated with the filter open. However, the noise that sounds like it's in the coil above the furnace persists.

    Can he add another grille in a different wall,that's opn to a common area of the home?

    The area looks well sealed sothe filter grile should be fine.
    dash,

    Thanks for the reassurance on the filter grille solution. Yes, another filter grille could be installed around the corner of the current one (see the attached photo).

    the installer should have replaced the platform and the closet measured before they gave you a quote. the install looks a little rough from the pic
    catmanacman,

    Yeah, the install looks rough but as long as it's a proper install, I'm fine with it. My main concern when I see not-so-pretty work is that I wonder if any other corners were cut that aren't readily apparent. This is a general comment for any kind of work, not a shot at this particular installation.

    Here's a photo from further out. The hallway is narrow so that's as far back as I could get.


  10. #10
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    You could add anoter one and have 4" thick pleated filters adapted to fit the filter grilles for better filtration.

    I'd also ask for the static pressure of the supply and return to be measured,as you supply ducts could be undersized for 3 tons,or even too small for 2.5 tons.

  11. #11
    Join Date
    Jul 2008
    Location
    TX
    Posts
    32
    dash,

    Thanks for the suggestions. I will ask the installer about adding another filter grille.

    When you say "have 4" thick pleated filters adapted to fit the filter grilles", would that involve modifying off-the-shelf 4" filters or fitting a new filter grille that could hold a 4" filter?

  12. #12
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by mallard View Post
    dash,

    Thanks for the suggestions. I will ask the installer about adding another filter grille.

    When you say "have 4" thick pleated filters adapted to fit the filter grilles", would that involve modifying off-the-shelf 4" filters or fitting a new filter grille that could hold a 4" filter?
    We modify the grille to hold the 4" filter,and order undersized filters.However Honeywell makes certain sizes where the filter is modified,has an extra lip,to fit the 1" filter grille,easier way to go,if they have your size.


    Filter grilles that will hold a 4" filter is special order,an very pricey,so the above works better for us.

  13. #13
    Join Date
    Jul 2008
    Location
    TX
    Posts
    32
    The tech is coming out this week to add another 12x24 filter grille. That will give me 576 sq in of filter area. I'm hoping that will be enough and that the grille noise will be reduced.

    He's also going to be taking another look at the coils and the weird harmonic hum that's happening in there. For the musically inclined, it sounds very close to A3 (220 Hz).

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