How to Install a Heavy-Duty Commercial Door Closer Using a Parallel Arm

Written and demonstrated by Gary at Door Closers USA. This article explains the complete installation process shown in the video below and is intended for contractors, facility managers, and maintenance teams working with commercial doors.

Why parallel arm mounting is commonly used in commercial buildings

Parallel arm door closers are widely used in commercial applications because they offer durability, security, and a cleaner appearance. In this configuration, the closer body mounts directly to the face of the door while the arm bracket installs beneath the frame stop.

This keeps the arm protected from abuse and tampering, making it ideal for schools, offices, healthcare facilities, stairwells, and high-traffic corridors. Parallel arm installations are also commonly specified on fire-rated and panic hardware openings.

Tools and materials required

Before beginning installation, gather the following tools and materials:

• Tape measure and pencil
• Installation template provided with the door closer
• Center punch (recommended for steel doors and frames)
• 3/16" drill bit for starting holes
• Self-drilling self-tapping screws or through-bolts as required
• Drill or impact driver
• Wrench or locking pliers for indexing the spindle
• Hex keys or Allen wrenches for adjustments
• Hand screwdriver for installing the cover

Step-by-step installation process

Confirm the mounting orientation

Verify that the closer will be installed in a parallel arm configuration. This determines which side of the template you use and how the arm components are assembled.

Lay out the closer body on the door

With the door fully closed, use the installation template to mark the mounting holes for the closer body. Measurements typically reference the frame stop and hinge pivot point. Carefully mark all hole locations and double-check spacing before drilling.

Lay out the parallel arm bracket on the frame

Measure from the hinge pivot point, not the face of the frame stop. Mark the first hole, then use the bracket itself to mark the remaining holes so the bracket stays square.

Center punch and pre-drill the first hole

On metal doors and frames, a center punch prevents drill bit walking. Pre-drilling the first hole with a 3/16" bit makes starting self-drilling screws easier and more accurate.

Mount the closer body

Attach the closer body to the door using the appropriate fasteners. Ensure the adjustment valves are oriented correctly according to the template. Start with one corner screw, then move diagonally to pull the closer down evenly.

Install the bracket under the frame stop

Secure the parallel arm bracket beneath the frame stop. Start with one screw to hold position, then install the remaining screws while keeping the bracket straight.

Install and index the arm

Install the main arm onto the closer spindle. Slightly rotate, or index, the spindle so the arm seats with tension against the door. Attach the forearm to the bracket using the supplied screw and washer, ensuring the washer is installed to prevent future slippage.

Connect the arm sections

Bring the arm sections together, start the connecting bolt, and pull the arm until it runs roughly parallel with the door. Tighten the connection securely.

Adjusting sweep speed, latch speed, backcheck, and power

After installation, adjust the closer to ensure safe and consistent operation:

• Sweep speed controls the main closing cycle
• Latch speed controls the final closing action
• Backcheck cushions the opening motion
• Spring power adjusts overall closing force

Make small adjustments and test the door after each change. Spring power should always be adjusted with the door in the closed position.

Final checks and completion

Install the closer cover using a hand screwdriver and avoid over-tightening. Cycle the door several times to verify smooth movement, proper clearances, and positive latching.

When installed and adjusted correctly, a heavy-duty commercial door closer provides controlled closing, improved safety, and long-term reliability.