I asked this under the energy section but got no responses so I’m aking here. Anyone know of any good quality, tight fitting, dampered, preferably insulated ceiling diffusers available for air conditioning ducts? I’ve got a customer with ac in the attic, insulated ductwork, but in the cold of winter you still get warm moist air escaping thru those cheap ceiling diffusers everyone carries. Not only is it a heat loss, but it can condense inside the ductwork and eventually leak. I’ve tried searching the internet. So far, the only solution has been to stuff the ducts with fiberglass each season when the temp drops, not a very good solution.
I am planning on blowing in insulation to cover the ductwork but it makes sense to try and stop the air at the diffuser.
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Replies
Have you consider a magnetic panel? Not the most attractive solution, but definitely effective.
-Don
I hadn't thought of that. It would probably work. I guess I'm just surprised that with all the high efficiency systems and high tech new insulations, no one seems to have a ceiling diffuser designed to close tightly enough to effectively stop most of the heat loss at the ceiling level. Maybe this is my calling. Stop beating myself up swinging a hammer after all these years and design the latest, greatest ceiling diffuser, and go live on an island beach somewhere.
Kind of like an idea I had many years ago when they first came out with VCRs. Buy up a bunch of movies and rent them out kind of like a paid library. But, then again, who would ever go for that!
The best fix is at with the diffuser, but rather make the attic conditioned space.But that is often expensive as a retro fit. But for new home with any hvac in the attic (either ducts or equipment) it should be conditioned space.
That's not an option in most cases for us, altho in our new homes I typically don't let the ac units go in the attics. In this case, it's existing, and as I have said, it seems ridiculous to me that no one has designed a better way of sealing off these diffusers during the heating months. Anything would be better than just the current plastic damper type setups. This house isn't even that big but there are still 12 6" ducts and a large return duct.
it seems ridiculous to me that no one has designed a better way of sealing off these diffusers during the heating months
Well, you're talking about a pretty narrow "market" for a specific hvac "device." The places where there's a separate cooling system from heating are not "very large" in terms of a plant stamping out sheet-metal registers at 10K the day.
The number of people actually concerned about their registers beyond whether they "look nice" (or make a "fan" on the ceiling/wall) is also pretty small.
The truly concerned are moving to a conditioned attic, so they won't need a specialized register--so that limits the market a tad, too.
Now, down in this part of the world, not installing the a/c & ducts in the attic is novel. Not particularly bright in my book, but "The Way It Is Done." Even less "swuft" with the ridiculous 12/12 "circus tent" roofs too typical in 'builder design' here, too (gee, let's put an 18-24' tall, covered in dark shingles, heat sink on top of a single-story structure, and then run R4-insulated, half-donkey taped & sealed in the can-be-as-hot-as 140º attic).
I personally like to dedicate the 33"x30" of floorspace needed for a vertical hvac unit, if only to encourage filter changing--but, it's a fight every time. Being able to refer customers back to the BuildingScience site, and it's recommendations is helping, a little bit--the next hurdle is convincing the builders.Occupational hazard of my occupation not being around (sorry Bubba)
This IS the reason that installing HVAC equipment in an unconditioned space is always a bad idea.
However, the best that I know of is made by Hart&Cooley, the round ceiling diffuser and butterfly damper http://www.hartandcooley.com/grd/all_grd.htm are both all steel and give a reasonable seal.
Edited 5/26/2006 9:59 am by Tim
"This IS the reason that installaing HVAC equipment is always a bad idea."Did you leave something out of that sentence?
Yes, "in an unconditioned space" is missing. IF I could only type!
In my case it is that my brain is running faster than my fingers and I often have the same problem.I typically will leave off a NOT in the sentence.
You need an insulated boot and seal it to the drywall. Then the diffuser isnt an issue.
Our codes require them insulated. Also to be sealed off with caulk or tape . A diffuser should have a foam base that helps to seal too. Add foam if it doesnt have it with spray contact adhesive.
Tim