To access the remainder of this piece of premium content, you must be registered with Locksmith Ledger. Already have an account? Login
Register in seconds by connecting with your preferred Social Network.
Complete the registration form.
Over the more than one hundred year history, door closer designs have been improved and become more efficient in order to accommodate heavier and larger application doors as well as doors whose frames and operating hardware are not necessarily in optimum condition.
Two notable improvements are the adjustable spring force door closers and the cam action door closers that provide extra force in order to close and latch the door in some of the more difficult opening scenarios. The cam action door closer provides an extra “kick” of power at the end to help the closer latch and secure a door.
However, there are some openings that can make closing, latching and securing the door very difficult or nearly impossible. Two situations immediately come to mind where the force required closing a door changes consistently throughout the day or the changes occur from uncontrollable external forces.
This first scenario normally occurs to an exterior hollow metal door that is located on the sunny side of an unobstructed building. As the sun rises, the door is heated. Depending on the construction of the door, it will begin to warp usually between the two hinges. This problem does not happen as often to a door that has three hinges.
As a result the door will bow either towards the jamb or away from with the greatest variation usually at the area of the latch. The greatest variation is usually following the hottest time of the day with the door not being able to close once it has been opened.
When the door cools, the door will most likely be able to close and latch. There can and usually does become a time when the door will no longer return to a fully closed position.
For temperature induced bow, no door closer or even door operator will be capable of closing, latching and securing the door at some point in time.
Another very common problem for many commercial and institutional locksmiths is the “stack pressure”. The term “stack pressure” describes the movement of air within a hermetically sealed (no openable windows) building.
With no openable windows, air pressure builds within the building as the air is forcibly moved through the air conditioning/heating ducts. This pressurization is felt and can often be seen at the exterior doors. The air can be felt by either opening the door about ten degrees or just watching the door closer’s feeble attempt to close, latch and secure the door.
This is a problem as the air conditioning/heating (HVAC) systems do not operate constantly, 24 hours a day. You can attempt to adjust conventional door closers to the period of time when the fans are off. This will probably permit the door to close most of the time. In addition, if the building is in California, you may be able to get the closer to operate using only five pounds. However, when the heating or cooling system is operating, the closer does not have the closing power.
When the door closer is set for the “no fan” condition, there will be a number of requests/complaints that one or more of the exterior doors will not close properly and would the locksmith please fix the problem.
In the past, the other option was to adjust the door closer to close during the “fan on” condition. I have seen adjustable spring force door closers set to more than twenty plus pounds force. The positive side of providing sufficient closing force is the door will close, latch and become secured. There are several problems with this adjustment. It is dangerous; a person could be severely injured by a closing door. The door usually slams shut, often making a very loud noise. The door closer let alone the door hardware and frame will usually not survive this degree of closing force for very long. And again, the telephone calls, emails and instant messaging will happen with the number of requests/complaints that one or more of the exterior doors slams shut and would the locksmith please fix the problem.
To solve this problem, Norton developed the Trinity 9000 Series of door closers that are capable of learning in order to make closing adjustments to accommodate the building’s conditions. The Trinity closer body has the pinion shaft extending from the top and bottom of the housing. One end of the pinion shaft operates the closer arm. The other end of the shaft not only powers the electronics, but it also uses the pinion shaft to determine what adjustments are necessary for the closer to operate at optimum efficiency.
The Norton Trinity door closer is approximately 40 percent larger than a conventional door closer. The hinge end is covered; a ribbon cable and connector extending. Beneath the cover are the motors/mechanisms that control the Delayed Action, Backcheck, Latch and Sweep valves. The wire from these motors becomes the ribbon cable. This ribbon cable connects to the control module that contains the computerized mechanism that can adjust it operation to accommodate varying conditions.
The control module attaches to the closer body using two special screws. The control module is first located onto the pinion end opposite the closer arm.
Carefully slide the control module onto the pinion shaft and rotate ten to fifteen degrees in both directions to be certain the control module seats properly. The on-board computerized control module opens or closes the Latch and/or Sweep valves to keep the closer functioning within a specific operation range in addition to controlling the Backcheck and the Delayed Action.
To operate the system, the Norton Trinity door closer is equipped with a unique, on-board power generation system to eliminate the need to maintain and replace batteries. When the door is opened, power is generated as the Trinity’s pinion is rotated. Several openings during the installation provide sufficient reserve to operate.
These computerized adjustments are designed to dramatically reduce or possibly eliminate the locksmith adjustment calls.
For this article, we installed two Norton Trinity door closers. This first was installed onto a wood door/frame application that was susceptible to “stack pressure” pressure from cross-corridor doors. With minimal adjustment, the installed Trinity closer was adjusted to a little less than five pounds closing force. This accommodated California codes of five pounds closing force for interior doors.
For the wood door application, we used the regular arm installation, replacing a Norton 7500 body that had been Tech screwed to the door/frame. The Trinity is designed to fit the same prep openings as the Norton 7500 Series door closers. To compensate for the added weight and the additional strain, the Trinity body was installed onto the interior side of the door using four sex bolts. Retrofit plates are available for different closer manufacturers bolt patterns. Contact the factory for specifics.
The second installation was on one of two exterior narrow stile glass aluminum doors at the ends of an approximate 150-foot long, narrow hallway. This was the first floor of a multistory building having office doors opening onto each side of this hallway. The force of escaping air when one of the exterior doors was opened required adjusting the conventional door closer in excess of 17 pounds force with almost no differentiation between sweep and latch.
With minimal adjustment, the installed Trinity closer was adjusted to less than 12 pounds closing force and completely eliminating the slamming affect when the HVAC was on or off.
For the glass aluminum door application, the convention door closer was parallel arm mounted onto a custom steel plate using a heavy duty arm. The reason for the steel mounting plate was the door’s top rail was not tall enough to accommodate the lower mounting holes. An “L” bracket had been previously installed onto the soffit to provide sufficient mounting points for the parallel arm soffit plate. To accommodate the Trinity, several new mounting holes were drilled and tapped to accommodate the ¼” – 20 machine screws.
Once the Trinity has been installed, adjust the spring power so the door will close. Further adjustment can be made as the Trinity learns.
The Norton Trinity is designed to make adjustments to the closing operation each time the door has been opened. In order for the unit to make these adjustments it must first learn the basic conditions of the opening.
To “Teach the Unit”
Important: The door must be opened and allowed to close three times to generate power.
Step 1 Set the mode/DA switch for the arm application
#1 Position – Regular Arm
#2 Position – Parallel Arm
#3 Position – Top Jamb
Step 2 Push and release the “Teach” button on the control module WITH THE DOOR CLOSED.
Step 3 Open the door approximately 45°, and allow the door to close and latch.
Wait one minute for the Trinity to calculate.
In addition, there are four adjustment switches on the swing end of the control module. They are the Delayed Action, Backcheck, Latch and Sweep. Delayed Action is either off, 12 seconds or 25 seconds. The Backcheck have five positions from weakest (1) to strongest (5). The Sweep has three positions from weakest (1) to strongest (3). The Latch has three positions from weakest (1) to strongest (3).
Important: After making any changes, the door must be opened slightly and allowed to close.
Changing these switches and re-adjusting the spring pressure can help to fine tune the closing and opening operations. Give yourself a sufficient amount of time to set the Trinity to best possible operating conditions.
The Trinity can be equipped with any of the Norton closer arms and is available in a variety of finishes.
For more information, contact your local locksmith distributor or Norton Door Controls at 3000 Highway 74 East Monroe, NC 28112 Telephone 877-974-2255 Web Site: www.nortondoorcontrols.com
The LCN 4040XP is the second generation heavy duty door closer designed to withstand even more rigorous applications.
Unlike the gear-driven piston type closer, Norton says its cam action closer is significantly more efficient, providing up to four pounds closing force for a five pound opening force.