Bosch/Junkers Air Pressure Switch ZW24-1LH - Ref. 8 707 406 048
The Bosch/Junkers ZW24-1LH - 707 406 048 air pressure switch controls the pressure in the boiler system, allowing it to operate properly. When it fails, the boiler may not start or may lock out, even if the pressure is correct, which can manifest with fault codes C1, C4, or C6. This part is compatible with several boilers from the Junkers Euroline range, such as the ZW23-1AE23, ZW24-1LH AE23, among others. It is recommended to replace the pressure switch when these symptoms or operational errors are detected.
VAT included
Consult via WhatsAppNeckar boilers compatible with reference 8738709736
Pressure switch with reference 8738709736. 18 verified compatibilities: ZW23-1AE23 and ZW23-1AE31.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Neckar ZW23-1AE23 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Neckar ZW23-1AE31 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Neckar ZW23 AE 31 S2805 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Neckar ZW24 AE 23 S2805 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Neckar ZW24 AE 31 S2805 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Neckar ZW24-1LH AE23 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Neckar ZS23-1AE23 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Neckar ZS23-1AE31 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Neckar ZS23 AE 23 S2805 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Neckar ZS23 AE 31 S2805 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Neckar ZW20-1AME23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar ZW20-1AME31 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar WT11 AM1E 23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar WT11 AM1E 31 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar WT14 AM1E 23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar WT14 AM1E 31 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar WTD14 AM1E 23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Neckar WTD14 AM1E 31 S2805 | Junkers WT/WTD water heaters and ZW20 | 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. 8738709736 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 8738709736. 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 pressure switch 8738709736 resolves.
The pressure switch controls the air or water pressure to authorize operation. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The extractor starts and sounds normal, but the boiler does not ignite the flame.
Cause: The differential pressure switch does not detect enough pressure difference between its terminals and does not send the signal to continue.
Check that the two silicone tubes of the pressure switch are properly connected, without cracks or disconnections.
- 02
A fault code for the fan or pressure switch appears even though the extractor is functioning correctly.
Cause: If the extractor is in good condition, the problem is usually with the pressure take-off, which may be blocked by dust or condensation.
Carefully blow out the pressure tubes and clean the connections before replacing the component.
- 03
The boiler fails more in winter or at low temperatures than in summer.
Cause: The cold causes condensation in the connection pipes, which partially blocks the pressure signal to the pressure switch.
Check for water droplets inside the silicone tubes when disconnecting them.
- 04
The fault is intermittent: some days it starts up properly and others it gets stuck on the first attempt.
Cause: This is a typical symptom of a partial obstruction in the flue duct or in the pressure take-off, which varies with the draft.
Check the condition of the flue gas outlet duct and its external terminal, not just the pressure switch.
Fault codes for Neckar that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| C1 | The differential pressure switch has been activated during operation. | The air pressure switch opens during operation due to a fatigued diaphragm, stuck contacts, or incorrectly connected/blocked pressure ports/hoses. Verify by measuring continuity between C and NO and the Δp with a micromanometer while the fan is running. |
| C4 | The differential pressure indicator does not open with the fan disconnected. | The pressure switch remains closed at rest due to a seized diaphragm, incorrect adjustment/calibration, or improperly mounted Pitot tube/hoses. Check that with the fan stopped, the C–NO contact is open and inspect/clean the pressure switch inlets and hoses. |
| C6 | The differential pressure switch does not close. | The minimum Δp is not reached or the micro does not switch due to a damaged diaphragm/faulty pressure switch or obstructed ports. Check for electrical closure between C and NO when the fan starts and measure the pressure drop at the pressure switch ports; if it does not switch within its threshold, replace it. |
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.
Neckar 8738709736 pressure switch datasheet
- Catalogue reference
- 8738709736
- Brand
- Neckar
- Type of part
- Pressure switches
- Units in stock
- 4 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Data read on the part and in the manufacturer's documentation
What we have not been able to verify does not appear here.
- Type
- Diff.Press switch Type K 132
- Factory code
- 8 707 406 048
- Batch (FAB. NR.)
- 985
- Maximum pressure
- Pa max. 20mbar
- Power supply
- 0.1A 24V=DC
- The boiler model "Neckar NW24" listed today in the catalog does not appear in the verified list of compatible boilers; please check the exact model of your boiler.
Frequently asked questions about the pressure switch 8738709736
Is the Bosch/Junkers air pressure switch Ref. 8 707 406 048 compatible with any boiler from the Junkers Euroline range?
What fault does the air pressure switch of the Bosch/Junkers ZW24-1LH resolve?
What is the maximum pressure that the air pressure switch of the Junkers Euroline range can handle?
How many models are compatible with the Bosch/Junkers air pressure switch Ref. 8 707 406 048?
What fault codes are documented for this pressure switch?
Where can I find more information about the pressure switch reference?
Spare parts related to Neckar Junkers WT/WTD water heaters and ZW20.
