Wilo Pump Motor ZRS15/4-1 Ku - Isomax C28E - Ref. 4516125
Wilo circulating pump motor, model ZRS15/4-1 Ku, reference 4516125, for the specified Isomax and Isotwin boilers. According to the label, it operates at 230V~50Hz with a 2µF capacitor, IP44 protection, nominal pressure PN6, and thermal class F. It rotates at 2100 min⁻¹ with 0.31A and 71W. Manufactured in week 30 of 2009.
- Type of part
- Pumps
- Status
- Refurbished
- Catalogue reference
- 4516125
- Warranty
- 1 year
Wilo boilers compatible with reference 4516125
Circulating pump with reference 4516125. Four confirmed compatibilities: Isomax C28 E and Isomax F28 E.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Wilo Isomax C28 E | Saunier Duval Isomax | Contrasted |
| Wilo Isomax F28 E | Saunier Duval Isomax | Contrasted |
| Wilo Isotwin C24E | Saunier Duval Isotwin | Contrasted |
| Wilo Isotwin F24 E | Saunier Duval Isotwin | Contrasted |
Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.
How to check if ref. 4516125 is the part for your boiler
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 4516125. If it is not visible, do not identify the part from its shape alone.
- Check the full boiler model on its data plate and look for it in the model associations on this page.
- Compare the connections and physical body with the original part before installation.
- If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.
Symptoms that require diagnosis in the circulation pump 4516125
The circulation pump circulates the water in the heating circuit. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler heats the water but it does not reach the radiators.
Cause: If the pump rotor does not rotate, the heating circuit will be without flow even though the burner is operating.
Check if the pump vibrates or hums without moving: this indicates that it is receiving power but the rotor is not turning.
- 02
Noise or vibration in the motor when starting the heating.
Cause: It usually comes from air in the pump body or from a worn bearing due to use.
Bleed the air using the front screw of the pump before considering that the motor is faulty.
- 03
The pump does not start or has difficulty turning.
Cause: The rotor may be jammed due to accumulated scale, which is common if the pump has been inactive for a long time.
Turn the shaft by hand through the slot of the front screw to try to unlock it before replacing the motor.
- 04
Moisture or water droplets appear next to the rotor shaft.
Cause: The mechanical seal that isolates the water from the winding has worn out and no longer seals properly.
Dry the area and check after a boiler cycle if the drop reappears in the same spot.
- 05
The boiler indicates a circulation fault and locks out.
Cause: The control board shuts off the burner because it does not detect the minimum flow, even though the motor has power.
Check that the installation valves are open and that there is no clogged filter before replacing the pump.
Wilo fault codes that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| 11 | Pump blocked. | The Wilo ZRS15/4-1 KU pump motor can seize or become blocked due to lime/dirt; if the water does not circulate, the electronics detect a blockage and display 11. Verify by powering the pump (230 V) at startup, checking consumption/ohmage and free rotation of the rotor (unblocking via front cap). |
These symptoms can have more than one cause. If your boiler displays a fault code, send it to us via WhatsApp along with a photo of the labeling, and we'll tell you if this is the part.
Data sheet for the Wilo 4516125 circulation pump.
- Catalogue reference
- 4516125
- Uniclima internal SKU
- MBWZRSKU
- Brand
- Wilo
- Type of part
- Pumps
- Units in stock
- 2 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Part data and available documentation
Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.
- Manufacturer
- Wilo
- Type
- ZRS15/4-1 Ku
- Manufacturer code
- 4516125
- Secondary code
- 4520265
- Condenser
- 2uF - 400VDB
- Voltage
- ~230V-50Hz
- Protection
- IP44
- Nominal pressure
- PN6
- Thermal class
- Class F - TF95
- Speed/current/power
- 2100 min-1 / 0.31A / 71W
- Manufacturing date
- 09W30 (week 30 of 2009)
Frequently asked questions about the circulator pump 4516125
What brand is the pump motor of the Isomax C28E?
Is this pump motor suitable for an Isotwin F24E?
What nominal pressure does the Wilo ZRS15/4-1 Ku motor support?
What year is this pump motor Ref. 4516125?
What is the speed of this motor and how much does it consume?
