Lint trap allows too much lint to pass thru.

Hi Paul

At the very least, it could be that lint has collected in the vent hose.
There have been cases where lint has bypassed the lint trap and gone places that it shouldn't be.

Worst case scenario is that your dryer motor is checking out.

I'd have a pro look at this if there is no lint in the vent hose.

-Steve

Dear Emily.
Several problems.
First, did this dryer ever work properly hooked up as it is?
I mean hooked to the roof event?
If it used to work just fine, then I suspect the vent to the roof is clogged with lint and is not allowing the heat to escape.
If it never did work right,(for example: it is new to us) then I'd venture dryers are not supposed to vent their hot air that far away, they do not have a strong enough blower to push that air that distance.
Then, you might try to find another place to vent the hot air, with a total distance of only 10 feet from the dryer, even if you only vented it while you were actually drying clothers.
I doubt if the last item is for you, but I have sometimes seen where the washing machine did not spin all the water out of the clothes, and then the dryer needed all day to get the clothes dry.
Be blessed.

did you clean the inside venting circuit inside the dryer from the blower housing.lint trap etc if the dryers full of lint a clean outside vent system wont help

Check the venting, if it is blocked or if the venting is bend it will not allow the moisture to leave the dryer and it will end up in the lint trap and on the door

venting issue, you can disconnect vent tube and run a load of clothes if it dries then it is the vent tube, if not then the dryer will need disassembled and all the lint clean out from the lint trap to the end of the dryers vent tube, if is recommended to clean the lint out of the inside of the dryer at least once a year, varying on usage, and the lint screen each time before/after use. Hope this helps Tim

Frequently there's an obstruction in the vent duct from the dryer to the outside of the house. For the dryer to heat properly, the duct must be clean and clear of lint or any other substance. Your dryer has some internal ductwork. If it gets clogged, your dryer can't dry properly. In most dryers, to get to the internal ductwork to clear the clog, you have to substantially disassemble the dryer. A quick way to check for internal clogs is to remove the lint filter and use a flashlight to inspect the inside of the duct. If it looks clogged and you can't clear it using your vacuum.

If your machine is running properly and you have heat as you say then you may have a clog in the main vent line from the dryer through your house.

Try running the dryer once with the vent hose disconnected. If it dries your know the clog is in the house's vent line. Unusual but it does happen if you have a lot of lint.

Check first at the immediate opening point in the wall there is often a 90 degree elbow where lint can trap.

The other place is the cover plate on the outside of your house. Some at are static and others have vents that open and close. Those too can trap lint and cause a problem.

If you know you have a clog in the house line somewhere but the opening and exit are not clogged then take a drain auger (same as used to clear a clogged toilet) and run it through. If you don't have one try your garden hose.

Good luck.

Please rate if this gives you some direction.

This is common on all dryers. Not lint screen will catch all the lint although some are better than others. If you haven't already, you will need to clean or have your home vent cleaned (with a brush that goes all the way through the vent). If vent is not cleaned the lint will back up all the way into your dryer and cause a mess. You have stated your vent goes up to your roof so you will need to clean it every 6mths to 1yr. Aside from this there is no fix that I am aware of. Please rate me after reading this.

Besides drying clothes, dryers also remove lint. This fine, fuzzy material can cause trouble because it blocks dryer lint traps, clogs vents, and fills blowers. Lint can also gather around and in the tracks of the drum rollers, or in and under the pulleys and the drive belt. The result is poor clothes drying or -- sometimes -- no drying. To avoid lint problems, clean out the dryer's lint trap system every time you use the dryer.
To clean the lint screen, remove it from the unit. The screen may be located near or under the door sill, or in the top of the dryer near the control panel. It can usually be removed by pulling it up and out of its housing. Remove the accumulated lint to clear the screen; then replace the screen.
The exhaust vent also collects lint. Vent maintenance involves cleaning the lint from a screen in the dryer's vent exhaust collar and/or at the end of the exhaust vent where it sticks out through a basement window or through an exterior wall. To clean the screen, remove the clamp that holds the vent to the collar, or back out the screws that hold the vent to the collar, or pull the vent straight off an extended collar. Clean the screen thoroughly and replace it in the vent assembly.
To clean the vent itself, use a vent-cleaning brush (available at hardware stores) to pull out any lint deposits. Also check the vent run to make sure that the vent piping or tubing isn't loose at the joints, or -- in the case of flexible plastic venting -- isn't sagging between hanging brackets. Breaks or sags cause undue strain on the dryer's blower system, and can cause drying problems. If the vent pipe or tubing has become clogged with lint, remove the lint by pushing a garden hose or a drain-and-trap auger through the vent to a convenient joint. Disassemble the joint to remove the debris. With this procedure, it isn't necessary to disassemble the entire vent to find the blockage.You can head off problems before they become too serious by providing routine maintenance for your dryer's door gasket, thermostat, timer, and other frequently used parts. Let's discuss how to service these important components in the next section.  
THANK U.. RATE IT...

Are you getting little or no lint on the lint screen? Are the clothes coming out nearly as wet as they went in, but feel warm? If so, you probably have a blockage somewhere in the vent/duct. Don't just check the back of the dryer, but also check the duct thru the wall and the point where it exits the house (exterior wall or roof). Many times birds will nest in the exterior vents or if they have a screen to keep the birds out it may become clogged with lint. If you have a window nearby try drying a load with the vent hose disconnected from the wall and hang it out the window (you COULD vent it into the house, but you may end up with lint everywhere and a lot of moisture in your house).