Furnace return plenum "bangs" when blower motor starts/stops

[clare]

For oil canning, go across corner and it will be about twice as evvective as either horizontal or vertical.

[blueman]

I ended up using aluminum angle iron but mounted it on the inside so I got all the stiffness I needed without any protrusions -- all I had to do was to remove one of the ducts which gave me access to the interior of the plenum. I then used sheet metal screws to secure two horizontal pieces of angle iron.

[blueman]

Parts of our house are over 200 years old in fact... and the central heating was probably put in about 100 years ago.

We do plan to put in AC which as you note requires returns on the higher floors to work properly -- in fact, one of our reasons for not investing in the HVAC work now is that we want to do it all right when we add AC and do renovations rather than doing it half-assed multiple times...

[Stormin Mormon]

That way, you're not ripping clothes when you walk by. Good idea.

[Michael B]

[The Daring Dufas]

Aluminum angle iron? Could you tell me where I might find such an interesting metal alloy? *snicker*

TDD