Dorex closers are sold under both the Dorex and Canaropa hardware brands. The company sells door closers for the North American residential market, as well as some commercial products. Dorex door closers are available in several sizes and configurations, many of which are fully adjustable to fit most doors.
Examine your Dorex closers. Most units have a removable cover that snaps on and off. Use a screwdriver to pop this cover off the closer so you can access the closer body itself. The most basic Dorex units, the 700 series, do not have this cover.
Check the spring power. At one end of the closer, you'll see a nut with a series of arrows printed on or around it. This spring power adjustment nut is located at the end of the unit, parallel to the edge of the door rather than to the face. Use an Allen wrench to turn this nut clockwise to increase spring power or counterclockwise to reduce the power. Turn the nut several full turns to make an impact on the spring power. Heavier or larger doors require higher spring power, while lighter doors require less.
Adjust the closing speed. Closing (swing) speed determines how fast the door will close. It includes the speed from the point where the door is fully open until just before it latches. Look for a small valve marked with a C or an S located on the front of the closer body. Using an Allen wrench, turn the valve clockwise to slow down the door closing, or counterclockwise to speed the door up.
Set the latch speed. Next to the closing speed valve is a similar valve used to adjust latch speed. The latch speed determines how fast the door will close and latch. The door falls at the end of the closing speed cycle. Turn this valve clockwise to make the door latch more slowly, or counterclockwise to make the door latch quicker. If your door is slamming shut, slow down the latch speed. If it is failing to latch, the latch speed should be increased.
Open the door fully and allow it to close. The average door closer should be able to close and latch a door in less than 7 seconds. If yours is too slow, adjust the spring power, closing speed and latch speed as needed to speed it up. If the door is closing too quickly, adjust one or all of these valves to slow it down.
Determine if backcheck is needed. Dorex closer models 754 and 755, as well as all 1700 and 1900 models, are equipped with backcheck. This feature keeps the door from opening too far or too fast and damaging walls or furniture nearby. The backcheck valve is located on the top of the closer body, and is adjusted with an Allen wrench. Turn this valve clockwise to reduce backcheck, or counterclockwise to increase backcheck.
Replace the cover on the closer body. Slide it over the closer and press it into place by hand until it snaps against the door.