In tandem operation two window actuators move one sash together. If they run electronically matched, this is called synchronous operation. For larger groups, three or four actuators on one sash are also possible.
When do you need two actuators?
- Wide wings: one actuator in the middle would twist the sash
- Heavy sashes: the force is distributed over two actuators
- Tight closing: two actuators pull the sash evenly against the seal
Why synchronous?
If two actuators do not run at the same speed, the sash tilts. This strains fittings and actuators and can damage them. Synchronised actuators match speed and position with each other and switch off together if one is blocked. Therefore: for tandem operation, only use actuators designed for it, and do not connect any two actuators in parallel.
Solutions from Vent Systems
- VS-KA-i smart chain drive: with integrated synchronisation for several actuators on one sash
- VS-ZA 800 rack-and-pinion drive: also available as master-slave version
- VS-DKA 800 double-chain drive: two chains in one housing
Practical example: wide fanlight
A wide fanlight is opened by a single chain actuator in the middle. The sash twists, the corners lag behind and the seal no longer closes evenly. Two actuators in tandem operation, each mounted towards the outer part of the sash, distribute the force and keep the sash straight.
Common mistakes
- Two separate actuators simply connected in parallel without synchronous control – over time they drift apart
- Actuators with different stroke or different speed combined
- Brackets not mounted at the same height
Tip: For wide or heavy sashes, plan two actuators from the start. Retrofitting is usually more work.
Frequently asked questions
Do I need a special control unit for tandem operation?
The actuators must run synchronously. This is handled either by synchronous control in the actuator or by a suitable control unit. Ask us which combination suits your window.
Can I add a second actuator to an existing one?
Only if both actuators can be synchronised. It is often easier to install two new, matching actuators.
Read more
Not sure which actuator fits? Call us: 040 50694631 (Mon–Fri 8 am–5 pm) or use the actuator finder.