Wilo ZRS15/4-1 ACS pump Ku Saunier Duval Isomax E Isotwin · 4521812 · SD 05738300
Refurbished Saunier Duval Saunier Duval Wilo

Wilo ZRS15/4-1 ACS pump Ku Saunier Duval Isomax E Isotwin · 4521812 · SD 05738300

Las Saunier Duval Isomax e Isotwin llevan dos bombas. Esta es la del circuito de agua caliente sanitaria. Si la calefacción funciona y el agua caliente sale templada o se acaba enseguida, es una de las piezas que debe revisar el técnico.

Type of part
Saunier Duval
Status
Refurbished
Catalogue reference
4521812
Warranty
1 year
VAT included Stock · 3 units
Compatibility

boilers Saunier Duval compatible with reference 4521812

Saunier Duval with reference 4521812. Two confirmed compatibilities: Isomax F35 and Isotwin. There are another 9 models that we are still verifying.

Proven compatibility

Boiler modelFamilyVerification
Saunier Duval Isomax F35Saunier DuvalContrasted
Saunier Duval IsotwinSaunier DuvalContrasted

Models pending verification

These models are associated with this reference, but we have not finished verifying them yet, so we do not consider them compatibleIf your boiler is one of them, send us a photo of the part you are going to replace and we will verify it before you purchase.

Saunier Duval Isomax F 28 ESaunier DuvalUnconfirmed
Saunier Duval Isomax C 28 E and C 28 E2Saunier DuvalUnconfirmed
Saunier Duval Isomax F 28 E2Saunier DuvalUnconfirmed
Saunier Duval Isotwin F 24 ESaunier DuvalUnconfirmed
Saunier Duval Isotwin F 24 E1, C 24 E and C 24 EVSaunier DuvalUnconfirmed
Saunier Duval Isotwin C 24 EA and Isotwin C 24 EV ASaunier DuvalUnconfirmed
Saunier Duval Isotwin F 24 EASaunier DuvalUnconfirmed
Saunier Duval Isomax Condens F 35 E (before 2010)Saunier DuvalUnconfirmed
Saunier Duval Isomax F 35 H-MOD, Isotwin C 30 E, F 30 H-MOD and Condens F 30 ESaunier DuvalUnconfirmed

Can't see your model or have questions? The printed reference takes precedence. How to check it ·

Guide

How to check if reference 4521812 is the part for your boiler

The part reference, model, and equipment revision must be verified against the manufacturer's documentation.

  1. Look at the motor label: it should say Wilo ZRS15/4-1 Ku.
  2. Search for one of these references: 05738300, 0020087506 or 4521812 (Wilo).
  3. Check on the PCB of your boiler that the model is on the list of compatible ones (Isomax F35 and Isotwin, confirmed).
  4. Any questions? Send us a photo of the label and the PCB of the boiler from Contact.
Diagnosis and fault codes

Symptoms that require diagnosis in the Saunier Duval 4521812

Common symptoms and faults

  • 01

    The heating works, but the hot water comes out lukewarm or runs out quickly.

    Cause: Check if the pump starts when opening a hot water tap.

  • 02

    The pump hums but does not rotate.

    Cause: It is usually the rotor seized due to limescale or sediments, especially after periods of inactivity.

  • 03

    Noise or clicking when opening the hot water.

    Cause: There may be air in the circuit or wear; it is advisable to bleed before replacing the spare part.

  • 04

    Water droplet next to the shaft or on the body of the pump.

    Cause: The closure is worn out.

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.

Technical data

Saunier Duval 4521812

Catalogue reference
4521812
Uniclima internal SKU
MBWZRSKU
Brand
Saunier Duval
Type of part
Saunier Duval
Units in stock
3 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.

Electrical characteristics — Power supply
~230 V, 50 Hz
Electrical characteristics — Capacitor
2 μF - 400 VDB
Electrical characteristics — Current
0.31 A
Electrical characteristics — Power
71 W
Electrical characteristics — Speed
2100 min−1
Identification and construction — Application
domestic hot water (DHW)
Identification and construction — Category
Pumps
Identification and construction — Hydraulic body
Composite material
Identification and construction — Additional unit code
0020087506
Identification and construction — Catalog code
4516125
Identification and construction — Manufacturing code
13W29
Identification and construction — Brand
Wilo
Identification and construction — Manufacturing marking
Made in EU
Identification and construction — Model
ZRS15/4-1 Ku
Identification and construction — Motor
Asynchronous
Identification and construction — Reference
4521812
Identification and construction — SKU
MBWZRSKU
Protection and markings — Insulation class
F
Protection and markings — Water temperature class
TF95
Protection and markings — Degree of protection
IP44
Protection and markings — Markings
VDE, GS, EMV, CE
Protection and markings — Nominal pressure
PN6
Verified data — Pump
Wilo ZRS15/4-1 Ku, domestic hot water pump
Verified data — Power
71 W · 0.31 A
Verified data — Speed
2100 min⁻¹
Verified data — Power supply
230 V · 50 Hz
Verified data — Condenser
2 µF · 400 V
Verified data — Nominal pressure
PN6
Verified data — Protection
IP44 · class F
Verified data — Water temperature
Up to 95 °C (TF95)
Verified data — Body
Composite
To confirm — Connections
To be confirmed: 2 × G 1" thread · Wilo catalog
To confirm — Maximum tightening torque
40 Nm in the connections · Wilo Catalog
To be confirmed — G 1 connection gasket
Ø30 × Ø21 × 2.1 mm · Wilo catalog
To confirm — Use
Only drinking water · Wilo Catalog
To be confirmed — Power in the catalog
26 W · 0.12 A at 2100 min⁻¹ (unclear column); the data is valid · Wilo catalog
Pending applications to verify
Citadas por 1 solo origen (no publicar sin confirmar): • Isotwin F 28 E2: solo el catálogo de (y sus copias ) más la ficha propia de Uniclima. • Isotwin C 24 E-AN: y (mismo catálogo). • Isotwin F 28 E-A: . • Isotwin C 28 EA, F 28 EA, C 24 EV y F 24 E1:, en una ficha S1049900 de identidad dudosa. • Isomax Condens F 35 E fabricadas desde 2010: sin confirmar. Cambió la bomba de calefacción (0010034166); comprobar el nº de serie. NO COMPATIBLES (llevan otra bomba de ACS): • Isomax F 35 H-MOD: bomba de ACS 0020111412 (Xylem SDZ-2/DC). • Isomax C 30, Isotwin C 30 E e Isotwin F 30 H-MOD: 0020111412 según las fichas maestras de Uniclima (a confirmar).
Registered equivalents and substitutions
SAME PUMP (Wilo ZRS15/4-1 Ku) with different references depending on the brand and generation of the boiler: • Saunier Duval 05738300 (= 057383): Isomax / Isotwin 28 E and 24 E. Official spare parts list SD ("Sanitary Pump") and breakdown SD Isomax F 28 E ("57383 Pompe sanitaire"). Also. • Saunier Duval S1076000 (= S10760): Isomax Condens F 35 E (before 2010) and Isotwin Condens F 30 E. Breakdown SD ("S10760 Pompe sanitaire"), nomenclature. • AWB S1076000 (brand of the Vaillant group, Netherlands): IT/DE "Pompa AWB S1076000 Wilo ZRS15/4-1 Ku (4521812)". • Glow-worm (United Kingdom): UK catalog "GLOWWORM WILO PUMP 05738300 4516124 ZRS15/4-1 4520265". • 0020087506: reference of the Vaillant / Saunier Duval group printed on this unit (2013). Also published. Wilo numbers by series: 4521812 (the most cited), 4516125 (this unit), 4516124 and 4520265 (other units). OLD REPLACEMENT (to be confirmed): S1049900 → 05738300. and they call S1049900 a Wilo HB 15/7-3 (another pump). CURRENT OFFICIAL SUBSTITUTE: not found in open sources. DO NOT CONFUSE WITH: • 0020111412: ACS pump of the Isomax F 35 H-MOD (Xylem SDZ-2/DC). • 0020048255 / S1024000 (S10240): Wilo HB15/7-3 heating pump. • 05720700: heating pump 30 W of the Isomax 28 E (replaced by 0010030635 ErP). • Wilo ZRS18/4-1 Ku: another variant.
Before purchasing
  • If the radiators are not heating, the part to check is the heating pump, not this one.
  • This pump does not have its own electronics: the fault codes are provided by the boiler. Check the manual for your model.
  • To confirm: Isomax F 28 E — they give the code 05738300; only 1 matches this Wilo: to confirm.
  • To confirm: Isomax C 28 E and C 28 E2 — they are mentioned: to confirm; the E2, only before the serial number 0400197003.
  • To confirm: Isomax F 28 E2 — with 05738300 and 1 with 5738300 without 0, only before the serial number 0400197003: to confirm
  • To confirm: Isotwin F 24 E — they mention it (a parts list): to confirm
  • To confirm: Isotwin F 24 E1, C 24 E and C 24 EV — they are mentioned (only before the serial number 0400190441; with 5738300 without 0): to confirm
  • To confirm: Isotwin C 24 EA and Isotwin C 24 EV A — 1 origin the quote (with 5738300 without 0): to confirm
  • To confirm: Isotwin F 24 EA — they mention it (with 5738300 without 0): to confirm
  • To confirm: Isomax Condens F 35 E (before 2010), with different codes: its breakdown (S10760) and (5738300 without 0): to confirm.
  • To confirm: Isomax F 35 H-MOD, Isotwin C 30 E, F 30 H-MOD and Condens F 30 E — they are mentioned; the list does not include C 30 E or F 30 H-MOD.
  • Not compatible or excluded: Isomax C 30 — not confirmed: no document lists it for this pump.
  • Do not confuse: 05720700 — Heating pump of the same boiler («Pump 30 W») — Another part: this is the one for domestic hot water.
  • Do not confuse: 0020111412 — Domestic hot water pump of the Isomax Condens F 35 (2010-2015), — To be confirmed
  • Do not confuse: 05459200 (to be confirmed) · 54592 — Domestic water pump gasket (05459200 in a breakdown; 54592) — Another part: it is the gasket.
  • Saunier Duval code 05738300 verified, with official list. Its equivalence with Wilo 4521812 is given by a single one (to be confirmed). Registered confirmation: Isomax F35 and Isotwin.
Frequently Asked Questions

Frequently asked questions: Saunier Duval 4521812

Is it the heating pump or the hot water pump?
The domestic hot water (DHW) one. The heating one is a different part (05720700 in the official list).
Is it compatible with my Isomax F35?
Yes: Confirmed: for the Isomax F35. The F 35 H-MOD is not confirmed: without additional confirmation the appointment. The parts list for the Condens F 35 E (before 2010) lists the "S10760"; the 0020111412 for the Condens F 35 (2010-2015). Compare the code of your pump.
Is it compatible with my Isotwin?
Yes: Confirmed: for the Isotwin. By model, a parts list includes "05738300" for the F 24 E, and it is also applicable for the F 24 E1, C 24 E, and C 24 EV, only before the serial number 0400190441. For the C 30 E, F 30 H-MOD, and Condens F 30 E, there is no additional confirmation: compare the code of your pump.
Is it compatible with an Isomax C 28 E, F 28 E, or 28 E2?
It does not confirm them. F 28 E: they give the code 05738300, but that this Wilo is 05738300 is stated 1: to be confirmed. C 28 E and E2 (these, only before the serial number 0400197003): to be confirmed.
What do 05738300, 57383, and S1076000 mean?
05738300 is the Saunier Duval code for the pump; it matches the Wilo 4521812 (to be confirmed). 57383 is the "Pompe sanitaire" from the parts list of the Isomax F 28 E; it matches the 05738300 (to be confirmed). S1076000: it matches the Wilo 4521812 (to be confirmed).
What gasket and what torque does it require?
According to the Wilo catalog (to be confirmed): G 1 thread, gasket of Ø30 × Ø21 × 2.1 mm and maximum torque of 40 Nm. Another part: the gasket, 05459200 in a breakdown of the Isotwin F 24 E (to be confirmed).
Why does it get locked and can I unlock it myself?
Limescale and sediments from the mains water can seize the rotor, especially after periods of inactivity. If it buzzes and does not turn, consult your technician.
Entrega calculada por destino Delivery time shown at checkout
1-year warranty reviewed and tested
14-day return uninstalled parts
Technical support we verify your model
Wilo ZRS15/4-1 ACS pump Ku Saunier Duval Isomax E Isotwin · 4521812 · SD 05738300