HES Assa Abloy Preload Electric Strikes
What is Preload?
When pressure is applied to some models of electric strikes, the solenoid may not have the ability to mechanically release the keeper because the pressure binds it against the latch. Even a small amount of this preload can cause problems in the functioning of some electric strikes. Door preload can prevent the smooth unlocking of the electric strike or even disable a strike – preventing a door from being opened.
Preload and Building Security
What Causes Preload?
- An electric strike failing to release when energized is not the only problem preload can cause.
- If the power to the electric strike is interrupted, either by accidental or deliberate means, strong preload pressure can cause a strike in fail safe mode not to function.
- If a serious preload condition is present when the strike is activated, the pressure will move the door slightly into an open position, leaving the door unlocked and the building vulnerable.
- Some of the underlying problems that cause door preload, such as pressure from air conditioning, are not practically or easily corrected.
A number of conditions can cause door preload including:
A strike that does not open or opens only intermittently could be showing signs of a preload problem. If preload pressure causes a strike or multiple strikes to malfunction, many access and security issues may arise.
- Stack pressure caused by HVAC systems
- Misaligned strike and lockset
- Warped wood doors; damaged or bent metal doors
- Thick door seals or heavy weatherstripping
For these unique conditions HES Assa Abloy offers 2 electric strike solutions:
- HES 7000 Series Electric Strike
- HES 7501 Series Electric Strike