How to set up a Belimo actuator switch for an HVAC system

A quick guide on how to set up and replace an auxiliary switch S1A and S2A on a Belimo actuator.

What is an actuator switch?

An actuator switch is an auxiliary switch for damper actuators and rotary actuators. In this guide, we will focus on how to install the device to the Belimo actuators.

What is an auxiliary switch used for? Actuator switch applications

An auxiliary actuator switch is used on the actuator to signal when the requested position of a damper is reached. This device is applied directly by the shaft clamp, for damper actuators, or on the position indications, on rotary actuators. A carrier plate, supported by an adapter, fits positively on the shaft clamp of a damper actuator or on the position indication of rotary actuators. The scope is the transfer of the position to the switching cams of the micro switches.

What does an actuator switch do? How an auxiliary switch works applied to a damper or valve actuator

The Belimo S1A and S2A actuators switches are set up onto their compatible actuators, such as an LM, NM, GM or AN type and are locked from the sides of the actuator by four stops. 

A driver disk is applied to the shaft clamp of the actuator and communicates the position of the actuator to the switch cams. The user can set the switching points from 0 to 1 by the set up of the slotted discs.

How to wire an actuator switch

In this quick guide, we will share how to set up specifically the actuator switches designed by Belimo, the types S1A and the S2A. These two switches, even though have the same functioning, differ in the number of switches.

The parts of the actuator to consider in the installation are:

Gear disengagement: this is the button to press to disengage the gear and allow manual override.

Shaft clamp: part of the actuator, it requires to be turned into the required switching position.

How to install an auxiliary switch s1a on a Belimo damper actuator step by step

Here is a video made by Belimo showing, in practice, how to apply the actuator switch on the actuator. Also, these files created by Belimo provide all the information required to use these add-ons. In this paragraph we will break down the process and follow step by step the process:

The devices used, for this explanation, are the S1A auxiliary switch and a Belimo Damper Actuator.

Step 1: From the damper actuator, remove the orange indicator with the related black bracket.

Step 2: On the top side of the actuator, there is a black button for the manual override, press it down.

Step 3: Rotate completely the actuator counterclockwise.

Step 4: Place the switch on the top of the actuator, slide the device and make sure that the pins of the switch apply on the sides of the actuator, fitting into the actuator brackets.

Step 5: Set up the indicator, the one removed in step 1, back on the switch.

Step 6: Regulate the switch: move the actuator shaft a couple of degrees. Then, use a screwdriver to adjust the dials.

How to set up an auxiliary switch s2a on a Belimo valve actuator step by step

The installation of a Belimo switch on a valve actuator is mostly similar to the previous process that has been described in the previous paragraph. However, there are a few little details that are worth mentioning.

The second part of the video previously shared describes in detail all the steps.

Step 1: Remove the handle from the valve attached to the actuator.

Step 2: Under the handle, there is a rubber O-ring. Remove this ring carefully.

Step 3: Move the actuator to the fully counterclockwise position.

Step 4: Place the plastic adapter plate on the actuator

Step 5: Apply the switch S2A on the top of the actuator. Make sure that the pins of the switch fit with the actuator holes.

Step 6: Push the override down, and check if the handle moves as expected.

Step 7: Turn the rotary knob until the arrow is in the same direction as the vertical line. 

Switch actuator types

In our catalogue, there are different types of switches:

The Belimo S1A is a device with one switch with a 1-meter cable with adjustable switching points.

The Belimo S2A is composed of two switches with a 1-meter cable with adjustable switching points.

The Belimo  S2A GR is composed of two switches and a 3-meters cable with adjustable switching points.

Conclusion

In this article, we have provided an overview of what an actuator switch is, how it works and the applications in an HVAC system and an AHU unit. All the types of switches here mentioned are available in their specific category, the main brand is Belimo.

If you want to add anything relevant related to the topic or your direct experience, feel free to leave a message, we would like to hear from you.

If you need any additional details do not hesitate to contact us at support@i-acs.co.uk