Suburban NT30SP Hot Ductwork

[boilermaker]

I just replaced the old Suburban NT32 furnace in my '75 Sovereign with a new NT30SP. The furnace works great but I am concerned that the ductwork gets so hot, too hot to touch. I replaced the ductwork with new aluminum flex identical to what was originally installed. I am also adding a 4th 4" round as recommended by a lot of Forum readers.

Should I replace the duct with insulated duct?

Ken

[r carl]

No, its just working good.

[Jammer]

Adding a 4th duct will drop the temperature about 20 degrees.