Our dryer is located in the center of our house. The current vent situation has tubing that makes several bends between the dryer and the crawl space before hitting metal duct that takes it about 25' across the crawl space to exhaust under our deck. There are several elbows in this run.
We have converted from gas heat to an electric air-to-air heat pump in recent years and have closed up exhaust flue from the old furnace that starts almost directly above where the dryer vent leaves the dryer and comes into the furnace area before going through the floor to the crawl space. If I redirect the vent up to the flue and out the roof, we'll cut a lot off the distance the air has to travel and remove most of the elbows.
Is this a good idea?
Ceiling – Is it safe to use a former furnace flue to vent the dryer through the roof
ceilingdryerroofvent
Related Solutions
In general, the shorter the vent, the better, so moving the dryer next to the basement wall would be the optimal solution. If you can't do that, then moving the vent as you said would be a lot better than your current set-up.
This article covers the whole topic in a lot of detail, see especially the sections on why to keep the length as short as possible:
Running the vent to the new location shouldn't be a problem; my preferred tool for cutting the hole would be a hole saw, but they can be expensive. Looking at your photographs, it seems like don't have any plumbing or electrical stuff to complicate the job.
Your duct is probably too long, and not constructed properly. Installing a proper exhaust system may increase the dryers performance, though this is not guaranteed.
Vent length and installation requirements will vary slightly from manufacturer to manufacturer, but International Residential Code (IRC) gives us a conservative starting point.
International Residential Code 2009
Chapter 15 - Exhaust Systems
Section M1502 Clothes Dryer Exhaust
M1502.1 General. Clothes dryers shall be exhausted in accordance with the manufacturer's instructions.
M1502.4 Dryer exhaust ducts. Dryer exhaust ducts shall conform to the requirements of Sections M1502.4.1 through M1502.4.6.
M1502.4.1 Material and size. Exhaust ducts shall have a smooth interior finish and shall be constructed of metal a minimum 0.016-inch (0.4 mm) thick. The exhaust duct size shall be 4 inches (102 mm) nominal in diameter.
M1502.4.3 Transition duct. Transition ducts used to connect the dryer to the exhaust duct system shall be a single length that is listed and labeled in accordance with UL 2158A. Transition ducts shall be a maximum of 8 feet (2438 mm) in length. Transition ducts shall not be concealed within construction.
M1502.4.4 Duct length. The maximum allowable exhaust duct length shall be determined by one of the methods specified in Section M1502.4.4.1 or M1502.4.4.2.
M1502.4.4.1 Specified length. The maximum length of the exhaust duct shall be 25 feet (7620 mm) from the connection to the transition duct from the dryer to the outlet terminal. Where fittings are used, the maximum length of the exhaust duct shall be reduced in accordance with Table M1502.4.4.1.
M1502.4.4.2 Manufacturer's instructions. The size and maximum length of the exhaust duct shall be determined by the dryer manufacturer's installation instructions. The code official shall be provided with a copy of the installation instructions for the make and model of the dryer at the concealment inspection. In the absence of fitting equivalent length calculations from the clothes dryer manufacturer, Table M1502.4.4.1 shall be used.
Basically what all this means, is that in general the overall length of the duct can be 33'. 25' of the duct system; measured from the exhaust hood to the dryer connection, must be 4" rigid metal duct. You can then have an 8' section of "transition duct", which can be flexible duct, but must be UL listed and labeled for the use. For each elbow, subtract the value from Table M1502.4.4.1 from the overall 25' length.
When you use flexible "transition duct", make sure the duct is fully extended and trimmed to fit. Don't leave the duct compressed and coiled.
Manufacturers Installation Instructions
If you look at the Maytag installation instructions (PDF), they tell you what type of exhaust hoods you can choose from.
The instructions then provide a table to determine the maximum duct length, based on the hood used and the number of bends.
Gas dryers need gas to dry, so make sure the gas is on before you spend too much more time or money on repairs. It might also be useful to make sure it's not user error, by making sure the tenants know how to use the dryer properly. Don't forget to make sure the tenants aren't overloading the dryer.
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Best Answer
I have a funny feeling that local codes might preclude it. The problem is that lint will quickly clog the vent since once any lint collects on the walls, it will slow down airflow enough that lint will accumulate at the bottom of the vent. This can cause a fire.