Who could fix this?

[supadaveo]

Originally Posted by BEANZ

You sir are incorrect. A straight exaust pipe in our climate will result in moisture dripping thru the fan on a regular basis. As Sliver stated the pipe needs to be bent to allow any condensation to collect rather than drip onto the ceiling/floor.

This is also incorrect. A properly installed exhaust fan and exhaust duct will not have any condensation whatsoever. You need to have the exhaust duct insulated completely and sealed. You also need to have a nice short run (if possible) to the exhaust hood in your exterior wall or roof. Your exhaust hood must also be equipped with a back draft damper so that cold outside air can not flow back into the house.

Any condensation inside or outside of the duct means trouble, you will be asking for mold/water damage issues. The duct must always keep a steady rise up to the exhaust hood, you can not have any water traps. Hope this helps!

[DuffMan]

Originally Posted by Bindair Dundat

BTW? I insulate all the ventilation ducting I install myself, wrapping it in 6 mil poly (on the warm side, i.e. tight to the pipe itself), then wrapping R-12 batt insulation around that, secured with baling wire. The "premade" crap they sell (while "technically" meeting code), is NFG for our climate...I mean the vapor barrier is on the wrong freaking side...just for starters.

that #### grinded my gears.
I installed a new fan and had to make like a circular slide type thing out of my exhaust because it was not lining up with the existing hole. I tried getting that stuff on the spiral setup and it drove me nuts. If finally ended up doing pretty much what you said you normally do.

[Bindair Dundat]

Originally Posted by supadaveo

This is also incorrect. A properly installed exhaust fan and exhaust duct will not have any condensation whatsoever. You need to have the exhaust duct insulated completely and sealed. You also need to have a nice short run (if possible) to the exhaust hood in your exterior wall or roof. Your exhaust hood must also be equipped with a back draft damper so that cold outside air can not flow back into the house.

Any condensation inside or outside of the duct means trouble, you will be asking for mold/water damage issues. The duct must always keep a steady rise up to the exhaust hood, you can not have any water traps. Hope this helps!

Is there an echo in the room?

The shortest route is always the best route...

Last post on this...I promise

In an attic situation (providing the roofer put the vent termination in the proper location), then you should almost always be able to get out with a maximum of two adjustable 90's and straight ridgid pipe. The fittings provide all the flexibility you should need to create a tangential offset, directly from fan to vent termination. Girder trusses (in "hip roofs") can sometimes require a couple of additional adjusted "offset" 90's if a truss web happens to fall in the wrong place. Unimpeded airflow is the critcal factor...if the warm moist air moves through the (properly insulated) duct at the highest efficiency rate, the ductwork does not retain heat.

In buddy's "moisture trap" design...the warm air slams into a hard 90; this heats the pipe dramatically. The airflow also loses velocity and this allows for greater thermal transfer as it continues up the ducting. Reduced airflow rates and bad insulation practices, will result in a large amount of condensation forming at the vent termination...this runs back down the pipe and into the "trap", where it will leak through the collar connections in the fitting, saturate the insulation and...eventually leak onto the drywall.

But I only make my living doing all of this kind of stuff ...what would I know about it?

Ron

[DuffMan]

what's a hard right in ducting?