Ok 50 years or so and this is a new one for sure. People were not getting enough cooling mostly to additions with one 6" round. Anyway checking the rest of the house they showed me these things with the registers off.
Now the first thing is that around here there were a number of homes that used rounds that were sized around 4" but they terminated in regular boots. If I recall they were more like an in-between 3" and 4". Everything else was like your typical system with the exception of the small runs.
THIS is what they had in all of the rooms of the original house. The boots were obviously manufactured and not some crazy notion done on the job. From the attic they come down with 4" into and through the top of the boot. This 4" round ends a couple inches below the top register. Now from what I saw, the original registers could not be opened or closed. Also the thing was almost acting like a venturi drawing in hot air at the ceiling and mixing it with the already tepid supply running through a hot attic. Needless to say air flow out the bottom even with the top blocked off with cardboard.
Just for fun I unscrewed that short damper section and blocked the bottom of the top boot with a scrap of metal to throw all the cooling out at the ceiling. Told them to let me know if it helped and we would go from there. Anyone know the logic behind this mess?
It's about the oddest forced air I have seen since the forced air radiant heat I ran into in a slab once. Yes. No heat came into rooms through registers. Imagine hot water radiant using 6 inch round forced air.
[IMG]https://farm2.staticflickr.com/1888/...df6a5268_b.jpgregister by Glenn Hanson, on Flickr[/IMG]
