Hydraulic Block Pump Saunier Duval Isofast Condens F 35 E Ref. 0020037988
The Hydraulic Block Pump Saunier Duval Isofast Condens F 35 E, reference 0020037988, is a hydraulic component responsible for directing and distributing water between the circuits of the boiler. When this part fails, you may notice leaks, loss of pressure, or issues with domestic hot water production. It is installed in models such as the Isofast Condens F 35 E, Isofast Condens F 30 E, among others. It is advisable to replace it when fault codes F.75, F.23, F.24, or F.20 appear.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference 0020037988
Hydraulic group with reference 0020037988. 12 verified compatibilities: Isofast Condens F 35 E and Isofast Condens F 30 E.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Isofast Condens F 35 E | Isofast Condens | Contrasted |
| Saunier Duval Isofast Condens F 30 E | Isofast Condens | Contrasted |
| Saunier Duval Isofast 21 Condens F 35-B | Isofast Condens | Contrasted |
| Saunier Duval Isofast 21 Condens F 25 | Isofast Condens | Contrasted |
| Saunier Duval Isofast F 30 E H-MOD | Isofast (non-condensing) | Contrasted |
| Saunier Duval Isofast F 35 EA | Isofast (non-condensing) | Contrasted |
| Saunier Duval Isofast F35E H-MOD | Isofast (non-condensing) | Contrasted |
| Saunier Duval Themafast Condens F 24E | Themafast Condens | Contrasted |
| Saunier Duval Themafast Condens F 30E | Themafast Condens | Contrasted |
| Saunier Duval Themafast Condens F 30 H-MOD | Themafast Condens | Contrasted |
| Saunier Duval Themafast F 30 E H-MOD | Themafast | Contrasted |
| Saunier Duval Themafast F 25 E H-MOD | Themafast | 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. 0020037988 is the part for your boiler
What determines it is not the boiler model, but the reference printed on the part you already have installed.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 0020037988. 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 and faults that the hydraulic group 0020037988 resolves.
The hydraulic group includes the valve, the by-pass, and the water connections. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
There is a water leak right at the fitting or the part with the flow direction arrow.
Cause: The seals of this type of hydraulic body dry out or lose tightness over time, and water seeps through the joint.
Carefully tighten the connection nuts and check the condition of the gasket before declaring the entire part faulty.
- 02
The water circulates with less force than usual in that area of the circuit, although the overall pressure is normal.
Cause: Lime and sediments easily accumulate in the internal constrictions of this type of fitting or valve.
Check for visible limescale deposits in the nearby connections before replacing the part.
- 03
A dry knock or hammering can be heard in the pipes when the boiler starts or stops.
Cause: If this part acts as a valve and does not close properly, the water changes direction abruptly and causes water hammer.
Check if the noise always coincides with the start or stop of the burner; if so, rule out bleeding the circuit first.
- 04
When installing it, the flow direction arrow does not match the actual direction of the water in the pipe.
Cause: This type of part only works correctly when installed in the direction indicated by the arrow molded on the body.
Before declaring the part defective, check that the arrow on the body points in the same direction as the water flows in your installation.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F.75 | The control does not detect an increase in pressure when the pump starts (lack of water/pressure or pump/sensor fault). | If the circulator (block 0020037988) is blocked, does not start, or does not respond, the pressure sensor does not detect the expected increase and the boiler locks out with F.75; check electrical/PWM start-up, consumption, and that the rotor spins after bleeding. |
| F.23 | Safety shutdown due to excessive temperature difference between flow and return. | A blocked pump or one working at minimum power prevents circulation, increases the ΔT, and triggers F.23; check that the circulator is rotating, its consumption and flow rate, and bleed the primary. |
| F.24 | Safety shutdown due to excessively rapid temperature rise. | If the circulator of block 0020037988 is seized or has insufficient power, the water does not dissipate heat and the temperature rises quickly; check the pump's rotation/consumption, PWM signal, and bleed the circuit. |
| F.20 | Safety shutdown of the temperature limiter (overheating). | The lack of circulation due to a blocked pump in block 0020037988 causes overheating in the heat exchanger; check the start and flow of the circulator, free the shaft if it is seized, and bleed. |
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 Saunier Duval hydraulic group 0020037988
- Catalogue reference
- 0020037988
- Brand
- Saunier Duval
- Type of part
- Hydraulic units
- Units in stock
- 7 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval Isofast 21 Condens F 35-B Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the hydraulic group 0020037988
Is this part compatible with the Saunier Duval Isofast Condens F 30 E?
What is the purpose of the molded arrow on the Hydraulic Block body?
Does this data sheet also correspond to the Saunier Duval Themafast Condens F 30 E?
How many models are compatible with the Saunier Duval Isofast Condens F 35 E Hydraulic Block Pump?
What fault codes are documented for this part?
Spare parts related to Saunier Duval Isofast Condens
