Hydraulic Block Pump Saunier Duval Themafast F25E H MOD Ref. 0020037988
Hydraulic Block Pump Saunier Duval Themafast F25E H MOD Ref. 0020037988 is a hydraulic component that directs and distributes water between circuits in the boiler. When it malfunctions, the user may notice leaks, loss of pressure, or issues with domestic hot water production. This part is compatible with several models, such as Themafast F 30 E H-MOD and Themafast F 25 E H-MOD, among others. It should be replaced when fault codes F.75, F.23, F.24, or F.20 are detected, indicating problems with pressure or overheating.
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 constant water leak at the bottom of the boiler, near the hydraulic circuit.
Cause: The body of the valve or fitting loses tightness, almost always due to a worn gasket or o-ring, and water leaks from that joint.
With the boiler cold, dry the area well and locate the exact point of the leak before changing the part; if it comes right from that joint, also check if it is enough to tighten the connection.
- 02
The heating or hot water takes time to arrive even though the burner ignites normally.
Cause: If the fitting or the valve is partially obstructed by limescale, the water does not circulate properly through that section of the hydraulic circuit.
Check the pressure on the manometer and if you notice restriction or flow noise right in that area before assuming that the part is blocked.
- 03
The boiler frequently requests pressure refill, although you don't see any visible leaks.
Cause: An internal leak in the body of the part allows water to escape slowly without being noticeable from the outside.
Monitor the pressure gauge for several hours without manipulating anything: if it gradually decreases and there are no visible leaks elsewhere, point to this part.
- 04
A clicking or vibrating sound is heard in the hydraulic circuit when the hot water tap is opened.
Cause: A poorly seated fitting or a valve with a worn internal mechanism allows water to flow irregularly.
Check that the part is properly aligned and without play in its housing before replacing it.
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
Frequently asked questions about the hydraulic group 0020037988
Is it the same part as the SKU CHICF35E for the Isofast Condens F35E?
Does this part fit the Saunier Duval Isofast F 30 E H-MOD?
Does this part work for the Saunier Duval Themafast F 30 E H-MOD?
How many models are compatible with the Hydraulic Block Pump Saunier Duval Themafast F25E H MOD Ref. 0020037988?
What fault codes are documented for this part?
What is the reference for this hydraulic block?
Spare parts related to Saunier Duval Isofast Condens
