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Ask the Engineer

Elevator Upgrades

By Stephen Varone, AIA and Peter Varsalona, P.E.

I’m on the board of an eight-story, 64-unit cooperative in the Bronx that has been experiencing problems with our elevator. The elevator moves haltingly and stops abruptly at the called floor, often a few inches short of the hallway floor. In addition, the doors tend to stick and don’t always open all the way. The elevator is approximately 50 years old and breaks down frequently, so we know it’s time for an upgrade. But it would be a huge inconvenience for residents on the higher floors—some of whom are elderly—if our only elevator is out of service for an extended period of time. What repairs will the upgrade entail, and is there a way to keep from completely shutting down the elevator?

An elevator as old as the one in your building has likely reached the end of its useful life. Given the problems you’ve been having with it, it doesn’t sound as if limited repairs will be enough, so it looks as if a full-scale upgrade will be necessary. Unfortunately that means taking the elevator out of service for at least four to six weeks, so your board will need to schedule the work to best accommodate residents who rely on it the most.

A Controller Situation
To understand what a full upgrade entails, it’s helpful to know the basic elements of the elevator system. First off, the halting movements and sudden stops of your building’s elevator are probably caused by an old controller. The controller, the brains of the elevator system, is an electronic component that directs the elevator motor. It detects where the elevator cab is located in the shaft and determines to which floor it should be sent. Controllers typically last about 25 years and are often the major component replaced during an elevator upgrade.

The elevator machinery con-tains the traction sheave, which moves the cab up and down.

The newer microprocessor-based controllers have what are called variable frequency drives. A VFD enables smooth, fine-tuned cab movements, starting slowly, and then maintaining a steady speed until the cab comes to a gradual stop. Because older controllers lack VFDs, they can result in stalling, erratic rides. Over time these rough movements place extra wear and tear on the elevator, leading to breakdowns and frequent servicing. In addition, older relay-based controllers are prone to gathering fine particles generated from the DC motors typically used in aging elevators, resulting in higher maintenance costs.

An outmoded controller may also be the cause of the cab stopping uneven with the hallway floor. Lacking the precise actions of a VFD-controlled system, an aging elevator’s movements are affected by the amount of weight in the cab: With many people inside, the cab tends to stop several inches below the hallway floor. With fewer people in the cab, it can stop up to several inches above.

A VFD-controlled cab is designed to stop within 1/4 of an inch of the hallway floor. To assure accurate stopping, a magnetic strip is sometimes installed along the elevator shaft. The VFD controller reads the strip, called a level controller, to determine exactly where the cab should stop.

Another area frequently addressed in an elevator modernization program is what’s called the collective system. Old elevators use a down collective system, in which the elevator makes all its requested stops going down before its requested stops going up, regardless of who pressed the button first. A down collective system, which has only one hallway call button per floor, is inefficient when two or more people are waiting for the elevator and traveling in different directions.

As part of the typical upgrade, a down collective system is converted to a selective collective system. Selective collective systems, which have an up and a down hallway call button, travel in the direction of the first requested stop. After making the requested stops in that direction, it proceeds to requested stops in the other direction.

Door Jams
The problem you’re having with sticking doors is common with old elevator systems. Doors become creaky with age, failing to open and close properly. In such cases, replacing the door hardware is often necessary, including the door operator (a motor that slides the door open and shut), levers, tracks, and hangers. Some pre-war buildings that have swinging hallway doors need not convert to sliding doors, but the doors should be checked for loose hinges and sagging.

The heavy-duty components that will likely need replacement or refurbishment include the elevator motor itself, which powers the cab up and down; the sheave and cables, which serve as a kind of pulley; the elevator shaft; guide rails; the machine brake, which activates when the cab stops at the requested floor; counterweights; and possibly the governor, an emergency brake activated when the cab travels too fast. Some buildings also have a sump pump in the elevator pit in case of flooding. Most upgrades include refurbishing the elevator machine room, located in either the basement or a roof bulkhead.

Undertaking a full-scale modernization of the elevator system will probably necessitate renovating the interior of the elevator cab at the same time. To get access at much of the “guts” of the system, such as the shaft, guide rails, door operator, wiring, and the like, requires removing and/or demolishing the walls, floors, and ceiling of the cab. Some boards use this opportunity to make cosmetic changes to the cab, installing new wall panels, door coverings, carpeting, handrails, wainscoting, and other finishing touches.

Aside from aesthetic changes, cab upgrades must comply with the American with Disabilities Act and New York City Building Code. For example, the call button panel must be at a wheelchair-accessible height and have Braille or raised numbers, and the cab must use auditory aids such as a bell or a recorded voice indicating the elevator’s direction and floor location. New York City Building Code requires an exhaust fan in the ceiling, adequate lighting, and a dedicated fire call telephone. A grille on the floor of the cab, while not required, facilitates cross ventilation in conjunction with the exhaust fan.

Accelerated Scheduling
Because of the extensive work involved in a complete elevator upgrade, it will be necessary to completely shut down service for the entire installation. Therefore, boards should survey residents well ahead of time to find out their vacation plans, verifying who will be away and for how long. For buildings with elderly patients who travel during the winter, that may be the best time to schedule the upgrade. In any case, it’s critical to keep residents updated on the status of the project and let them quickly know about any delays or problems so they can adjust their schedules accordingly.

A single-elevator upgrade in a building such as yours normally takes approximately six weeks. But by undertaking an accelerated schedule of 60 hours a week (10 hours a day, six days a week) instead of the usual 40-hour week, the contractor should be able to complete the project within four weeks. Extending the number of hours and days in the schedule usually works better than having separate day and night crews.

In choosing a contractor to perform the work, you should look for specialists in elevator repairs and ask for references of projects that the firm has done for other residential buildings the size of yours. (You will probably want to hire a separate contractor that specializes in interior work for remodeling the elevator cab.) Given the importance of getting the elevator back in service as quickly as possible, it’s advisable to include a liquidated damages clause in your agreement to give the contractor an incentive to finish on time. It’s also recommended that you call in an elevator consultant or engineer to initially survey the system to determine the extent of repairs, evaluate bids from contractors, and observe the work.

As a very rough guide, the cost of a full-scale elevator upgrade will run approximately $15,000 per floor, per elevator. Your agreement with the contractor should include a regular preventative maintenance program, which usually entails twice per month visits and servicing. (Maintenance programs are not included in the cost of the upgrade.)

Upgrading your building’s only elevator is a major undertaking and an unavoidable inconvenience. Managed properly, however, the modernization project will address the everyday annoyances and potential safety problems that the aging elevator system now presents to residents.

Stephen Varone, AIA is president and Peter Varsalona, P.E. principal of RAND Engineering & Architecture, PC. This column was originally published in the September 2005 issue of Habitat Magazine.