Air dryer venting, insulating?

[FDR]

My clothes dryer vent goes up into the attic and then travels about 25 feet before exiting the house. The attic is vented to the outside, so sees roughly the same temperatures as the outisde temperature. In the winter we go as low as maybe 5 below zero F. I've read on the net that the vent should be insulated to prevent condensation in the tube. However, the company hat installed it last year did not insulate it and didn't think it was necessary.

Who should I believe? And if it should have been insulated, what kind of insulation is recommended?

[Brad Bruce]

"FDR" wrote in news:R2g6f.171$ [e-mail]:

25+ feet??? That's a seriously long dryer vent (insulated or not)

Brad

[PHILIPWOLF]

What is the vent pipe made of? If its aluminum I would think that you could get away with not insulating unless you are afraid that the condensation would cause lint build up which is a fire hazard. But you need to vacuum out your vent pipes yearly anyway.

phil

FDR wrote:

[cod]

I think so too. I had lived in a house with such a long dryer vent for some twenty years without knowing it. I had had to replace the drum belt so many times and the dryer motor often enough. I finally realized that the dryer did not get vented at all because the dryer motor was not strong enough to push the air all the way through the roof.

I installed a booster motor near the roof, and I've saved good sum of money by now wasting gas(it takes a lot less time to dry clothes) and not replace motors and drum belts.

I was the original owner of the house which was built by a reputable builder. I can't believe the contractor did such lousy job without installing a booster motor. Noboy told me the vent took a long and tortous route before it ends just above the roof. There were literally tons of wet lint in the vent when it was opened after some twenty years.