Missing heating duct flaps

[Ratdog]

Hi,

I planned to balance the airflow in my ductwork, but have found that a couple of the flaps that portion off the airflow are missing. These flaps are located on the 6" diameter ductwork coming off the boxy main heating duct from the furnace.

Does anyone have experience retrofitting these? I figure a section of the duct must be removed and ducts with flaps installed in its place. I was wondering about degree of difficulty...I'm not even sure about what lengths the flap ductwork would be available in, nor do I have any specific sheet metal tools (at this point).

Thanks,
Richard

[HayZee518]

the adjustable dampers install with just a 1/4 inch bit and drill but you have to remove one section of ductwork.