Tophat and blow-in insulation

[Jerico]

I have been re-doing my attic insulation up in Canada after tromping around up there a bunch installing surround speakers, lighting, and fixing some grevious builder mistakes.

I choose cellulose and have been picking away at it as I can afford it.  I did my garage (which is heated but had no insulation) and my dining room (which was a stunning R10 before... now R60).  I'd like to save and "refluff" the existing fiberglass up there rather than spending extra cash to blow over the compressed fibre with cellulose.  Anyone tried a Thien tophat on a shopvac with a monster barrel to separate the insulation?

The machine I rented will blow both, so that's not an issue.  And the shop vac (no top hat) has reasonable suction through the 100 foot hose that came with the blower.

[galerdude]

Never played with it but seems one might need to experiment with the slot width to achieve optimal performance.

[Jerico]

Has anyone ever made one with a variable slot that you could easily change it to find the optimum?

[phil (admin)]

Has anyone ever made one with a variable slot that you could easily change it to find the optimum?

I've really only done variable length slots, which is two discs that can be rotated in relation to each other.  But to widen the slot, it was always back to the bandsaw.

[Jerico]

I suppose you could make a quick swap system with a set slot of one length on top then cut variable inserts or a piece on the bottom that could be quickly replaced...

I need to stew on this some more.  I have until aprilish to figure it out when I do the next insulation stage (garage has been done!!).

[Schreck]

You could have a baffle made of two thin pieces of masonite.  One would be fixed at the typical slot width.  The second would be a circle, attached to the first  at only one point, but slightly off center so that as it was rotated, it would make the slot more narrow.  The resulting slot would not be uniform in width, but that may not matter. 

[BernardNaish]

Top hats have top and bottom plates that trap the walls. Under that the baffle plate. Under that a plate that engages with the top of the collection bin. The baffle is glued to the bottom and bin plates that also seals these joints. I suspect that if the plates extend somewhat beyond the outer edge of the wall and are made of MDF then you may not need the glue to get an airtight seal. This is because oil tempered hardboard and MDF are smooth on both sides and are flat with consistent thickness. These three plates would need to be bolted together with at least eight bolts to get an even spread of clamping pressure.

If this works then you could simply make several baffles with different slot widths and try them. It could be that the seal is good enough to find the slot width that best suits your needs.

If it leaks too much you can cut a circular groove to trap an "O" ring in the bin and bottom plates. Large "O" rings can be made from special compressible round material that is cut to length and the ends glued together. A thin rubber gasket might also work.

BTW a similar method would also allow experiments with different heights between the baffle and the bottom of the inlet rectangle in double height designs

Good luck and please let us know how you get on.