Ventilation · EC retrofit
Replacing a two-speed ventilation motor with an EC motor
In an air handling unit, the two-speed asynchronous motor reaches the end of its life while the panel and the control system are still in good order. An EC motor needs a 400 V supply, an enable signal and a 0–10 V setpoint: the existing low speed / high speed control does not provide them.
Two ways to do it
Rework the control
Add a 0–10 V output, modify the controller program and change the electrical panel: the work affects the control system, often in an occupied building.
Keep the control, add EC-SWAP
The EC-SWAP module, mounted close to the fan, receives the low and high speed commands from the existing contactors and turns them into a 0–10 V setpoint for the EC motor. Both speeds are set at commissioning with the LOW and HIGH potentiometers. No controller reprogramming.
What changes in the panel
Each contactor now switches a single phase: low speed on W1, high speed on U2; U1, V1 and W2 are taken downstream of the circuit breaker, 16 A max. The existing two-speed motor cable connects as is to the module's PV-GV input. As an option, a voltage monitoring relay in the panel provides the “fan fault” contact.
Check before ordering
- 3 × 400 V AC supply, 50 Hz, no neutral, 16 A max., protected by a three-pole circuit breaker of 16 A max.
- EC motor with a 0–10 V setpoint input, an enable input and a 24 V DC output for the module's logic stage; current draw below 16 A.
- One module per airflow: a supply-and-extract unit therefore needs two.
- IP65 enclosure, 130 × 130 × 75 mm, mounted close to the fan; 0 to 45 °C.
Support from electricity suppliers (EffEl)
Swiss energy law requires electricity suppliers to demonstrate electricity savings at their customers in Switzerland every year. This programme is called EffEl. To reach their target, many of them help fund renovations. The Swiss Federal Office of Energy (SFOE) sets which renovations count and how the savings are calculated.
For a ventilation unit, three cases
LU-01a · savings over 15 years
Fan and motor replaced
The fan impeller and its motor are replaced by a more efficient unit whose speed is set according to demand. The motor must be class IE4 and the fan must reach the minimum efficiency set by the SFOE.
LU-01b · savings over 4 years
Motor only replaced, system less than 15 years old
What counts is the change from two fixed speeds to a control that varies the airflow from a sensor. The efficiency of the new motor is not part of the calculation.
No standardised measure
Motor only replaced, system more than 15 years old
The SFOE standardised measures do not allow any savings to be counted.
And with EC-SWAP?
EC-SWAP keeps the fan impeller and the two speeds of the existing control. For EffEl, this is the “motor only” case: as long as the control stays at two speeds, the motor change does not count.
EC-SWAP-PRO, available in 2027, varies the airflow between LOW and HIGH from a sensor. On a system less than 15 years old, this is the case covered by measure LU-01b. Have it confirmed by the electricity supplier before the work.
If the fan impeller is replaced together with the motor, measure LU-01a applies, with its requirements for the motor and the fan.
How to proceed
- Before the work, ask your electricity supplier whether it accepts the measure and what contribution it pays: each supplier chooses the measures it supports.
- Note the year of the system, the rating plate of the old motor and the operating hours.
- Keep the invoices and the data sheet of the new equipment.
- Dispose of the old motor: it must no longer be used in Switzerland, and the supplier may ask for proof.
- A renovation that already receives other public funding (ProKilowatt, canton or municipality) does not count for EffEl.
Summary drawn up on 23 Oct 2026 from the SFOE guideline and the LU-01a and LU-01b savings protocols, valid from 1 Jan 2026. The decision lies with the electricity supplier. SFOE guideline (PDF, in French)
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Frequently asked questions
Does the electrical wiring or the control system have to be modified?
Not the control system: no controller program is touched. In the cabinet, each contactor now switches one phase to the module, as per the wiring diagram.
How is the air volume controlled?
With the LOW and HIGH potentiometers on the board, flow by flow, or with a setpoint from the controller on the logic port. Sensor-based variable airflow is the EC-SWAP-PRO function, available in 2027.
Does the installation require a prolonged ventilation shutdown?
No: motor replacement, module mounting and setting of the two speeds, one airflow at a time.
Does a renovation with EC-SWAP count for EffEl support from electricity suppliers?
Not on its own: as long as the control stays at two speeds, the SFOE does not count the motor change. On a system less than 15 years old, the change to sensor-based control with EC-SWAP-PRO (2027) falls under measure LU-01b. The electricity supplier decides.
Is EC-SWAP patented?
A patent application has been filed in Switzerland (CH000473/2026, 2 Apr 2026). An EU declaration of conformity dated 5 Oct 2026 covers the EMC, low-voltage and RoHS directives; the module also falls under the WEEE directive 2012/19/EU.