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Ceiling diffuser help

| Posted in Energy, Heating & Insulation on January 22, 2003 05:14am

With my furnace being in the attic, all my supply diffusers are in the ceiling. The duct contractor included some round diffusers with the package, so I installed them. I liked the idea of round diffusers, as I thought they would be faily flush with the ceiling and blend in with recessed lighting fixtures. Each had two center adjustable baffles.

Unfortunately I am not happy with them. They extend over an inch and 1/4 from the plane of the ceiling and are very noticable. With the internal adjustments, airflow is quite restricted. They are noisy, too, with the supply air tending to whistle.

I am looking for a ceiling diffuser that is as unobtrusive and quiet as possible, round, square, or ?

Has anyone had these problems before? Can anyone recommend a diffuser supplier?

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  1. TLRice | Jan 22, 2003 04:22pm | #1

    Hart and Cooley make just about every shape and size of grille, register and diffuser that you can use in a home.

    Do you have access to the duct work? A properly done system will have volume dampers at the branches and you can cut the flow back at the trunk line and there will be less noise at the diffuser. If there are no volume dampers at the branches, you can add them, if you have access, easily enough. Or have the contractor come back and finish the job.

    If you replace the diffusers with something like ceiling registers (all of which, but maybe 1/8" will be recessed) get good ones with opposed blade dampers. They will be much quieter. In residential applications I prefer registers over diffusers, mainly because of the problems that you are experiencing.

    1. flatthumb | Jan 24, 2003 05:45am | #3

      I've never heard of Hart and Cooley, but I will look into their products. Do you know if they have a web site?

      Yes, I put a damper at each take-off, but have restricted the flow at the diffuser since this was much easier to do. I have to admit, even though I don't like the look of the diffuser, being able to adjust it in the room was a plus. Also, I only have 7'6" ceilings, so I can easily reach them.

      Could you explain what you mean by opposed blade dampers in the grills you mentioned?

      Just to see what it was like, I bought one of the Deflecto diffusers at a local Home Depot, which is rough at $16 a pop! I really like it, though, as it has a much smaller profile. The adjustment is a large solid disc that makes the diffuser look like a recessed light fixture that is not turned on, and it is incredibly quiet.

      1. toolnut | Jan 24, 2003 06:41am | #5

        >I've never heard of Hart and Cooley, but I will look into their products. Do you know >if they have a web site?

        http://www.hartandcooley.com/index.html

        The power of Google

        Edited 1/23/2003 10:42:35 PM ET by Bill_H

        1. flatthumb | Jan 25, 2003 01:23am | #6

          Thanks for the Hart and Cooley website. Unfortunately they seem to specialize in just the kind of ceiling diffuser I am not looking for, the large metal ones that remind me of old Moose meeting halls or of dentist offices.

          I tried the Deflecto website (http://www.deflecto.com) and they are not much better. Does anyone know of a company that makes decorative diffusers? With all the bigfoot houses being built nowadays, it seems that someone must have a line of stylish diffusers.

          1. boykster | Jan 30, 2003 01:53am | #7

            I'm in a similar boat...replacing a ceiling diffuser....but I want a decorative one.

            I was at HomeDepot (I know, not really HVAC mecca, but close by) and they have some floor diffusers that I like in the correct size...any harm in drilling mounting holes in one of those and mounting it up on the ceiling?

            Also, I have to extend the duct down a few inches (adding a new drywall ceiling in place of a suspended ceiling...losing 2" of headroom)...the duct is 4"x10" and all I can find at HD is 3 1/4" x 10"...any ideas?

            Cheers,

            Rich

          2. flatthumb | Feb 01, 2003 03:35am | #9

            Rich,

            You can always take your measurements to a local Heat and Vent shop. They will be happy to make you an adapter any size you wish.

            Good luck!

            Carl

      2. TLRice | Jan 31, 2003 04:41pm | #8

        An opposed blade damper (a register is a grille with a damper behind it, BTW) has multiple blades. When its position is changed, adjacent blades rotate in opposite directions, creating a series of "V"s to restrict the flow. Other dampers have parallel blades, that, as they close create a series of flat, narrow passages. When the air is forced through the flat narow passages, it makes more noise than when it passes through the V shaped passages. Usually, cheap registers only have a single blade or parallel blades. Better quality registers are available with opposed blade dampers. You get what you pay for and the products available at most home centers are poor. I have never seen a quality register at HD, Lowe's or Menard's.

        Decorative grilles and registers are available from several manufacturers, Reggio Register and Wood Ventures come to mind.

        Others that make registers, grilles and diffusers of decent quality: Carnes, Tuttle and Bailey, Anemostat, Price, Titus, Kreuger, Nailor, Kees and Metalaire; that I know about.

        1. flatthumb | Feb 01, 2003 03:36am | #10

          Wow, thanks for all the leads on diffuser makers.

          Carl

  2. Remodeler | Jan 22, 2003 05:17pm | #2

    I am interested in this thread too.  My house has the same set-up, built in the post-WWII boom when the first slab-on grades went in around here.  They didn't realize the mortar would eat sheet metal so most people's duct work eventually eats through and the pea gravel pours in, necessitating through-the-ceiling ducting.  I have 6" round difficusers with the volume baffles above and do not like them.  The house stays cold, even with gas heat.  I have been planning on researching what it sounds like you've got - I saw a little blurg HVAC - High Velocity Air Conditioning baffles.  I always through HVAC was Heating / Ventilation / Air Conditioning.  That's what my license said when I did mechanical.  It was one of the Unico type co's that had that ad blurb, but they showed a jet of air stirring the air up and I wondered, would that help in my situation?

    remodeler

    1. flatthumb | Jan 24, 2003 06:01am | #4

      The duct contractor told me to install the in-line dampers on the main trunk, not at the diffuser. He said it would be quieter this way, and the dampers would, in most installations, be in a much more accessable location.

      On the meaning of HVAC, you are right on both accounts. Unico makes High Velocity systems that can deliver both AC and heat. Their line was developed to enable installation in existing walls. The ducts are usually only 2" in diameter, which is why they use high velocity fans to move the air. They use an open-throat diffuser (one with no adjustment or baffles),installed in ceiling corners, that is so small it almost dissappears. They are EXPENSIVE to deal with, although I believe they have a good product.

      I'm not sure if the Unico system would help you, as there are many other factors that could contribute, singly or in combination, to your lack of heat. Is the furnace sized properly? Is the ductwork sized properly, with reductions and at least a two foot dead space at the end of your main trunk? Is the duct system balanced? If you used flex duct to run to the ceiling diffusers, are any of them kinked? What kind of insulation/windows does your house have? How high are the ceilings? Do you have an open floor plan? Is the ductwork in the attic insulated enough to keep the air warm? Is the gas line that feeds the furnace large enough? These are just the ones that come immediately to mind.

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