Diaphragm for WISY pump controller ZETA 02

The membrane is a central component of the WISY ZETA 02 pump controller. We recommend replacing it after approximately 10 years, as it becomes brittle over time, changes shape, and may lead to unwanted water leakage. The replacement is straightforward:

Replacing the membrane:

• Disconnect the power plug and turn off the water supply.
• Loosen the six screws on the head of the pump controller and remove the cover.
• Remove the old membrane, unscrew the plastic plunger in the centre.
• Screw the plastic plunger onto the new membrane and insert it.
• Replace the cover with spring and tighten it.
• Reopen the water supply and plug in the power.

Important note regarding the appearance of the rubber membrane:
The new membrane may appear visually different (more angular), but it is the correct original replacement part. Additionally, it is factory-treated with a white release agent (e.g., talcum powder) to prevent sticking during storage. This may cause the membrane to look used at first glance or show white residues. This is a normal technical process – it does not affect the function or quality of the membrane.

Is replacing the membrane worthwhile or is a new pump controller recommended?

If your pump controller is already 10 years or older, it is usually not a ZETA 02 model but older pump controllers such as the SA06 or Controlmatic E. These devices often have a high standby power consumption of up to 8 watts. In this case, it may be worthwhile to upgrade to a new, efficient ZETA 02 pump controller. It offers several advantages:

Energy savings:

The ZETA 02 requires only 0.2 watts in standby, which can save up to €350 over the device's lifetime and reduce up to 25 kg of CO2 emissions annually.

Increased safety:

When replacing the membrane, the threads in the plastic may be overstressed. This poses the risk that the housing may give way under pressure and the lid may lift. In this case, the pump would continue to operate uncontrollably until someone pulls the plug. This could lead to the cistern being pumped empty and, if necessary, the drinking water refill being triggered.

Simple replacement:

Customers who only replace the membrane often have questions about fit, sealing, and installation. A new pump controller eliminates this effort and ensures reliable operation without uncertainties.

Our recommendation:

For pump controllers older than 10 years, switching to a new ZETA 02 is usually the better choice – both economically and from a safety perspective.

* compared to an automatic switch with 8 watt standby consumption with a service life of the Zeta 02 of 15 years at 23h standby/day, 37 ct/kWh and 380 g CO2 emissions / kW (German electricity mix 2024)