Air Pressure Switch Junkers Novastar ZW 20 1 AME 23 Huba Control Ref. 8738709736
When you open the tap or turn on the heating, the Junkers Novastar ZW 20 1 AME 23 Huba Control pressure switch Ref. 8738709736 ensures that the air pressure is correct for the operation of the boiler. This part checks the pressure and authorizes the start, but if it fails, the boiler may not start or may lock out, even if the actual pressure is adequate. It is compatible with models such as ZW20-1AME23, ZW23-1AE23, and ZS23-1AE23, among others. It is recommended to replace the pressure switch if you experience starting issues or if fault codes C1, C4, or C6 are triggered.
VAT included
Consult via WhatsAppJunkers boilers compatible with reference 8738709736
Pressure switch with reference 8738709736. 18 verified compatibilities: ZW23-1AE23 and ZW23-1AE31.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZW23-1AE23 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Junkers ZW23-1AE31 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Junkers ZW23 AE 31 S2805 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Junkers ZW24 AE 23 S2805 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Junkers ZW24 AE 31 S2805 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Junkers ZW24-1LH AE23 | Junkers Euroline (ZW23 / ZW24) | Contrasted |
| Junkers ZS23-1AE23 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Junkers ZS23-1AE31 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Junkers ZS23 AE 23 S2805 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Junkers ZS23 AE 31 S2805 | Junkers ZS23 (AE / Euromaxx) | Contrasted |
| Junkers ZW20-1AME23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers ZW20-1AME31 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers WT11 AM1E 23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers WT11 AM1E 31 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers WT14 AM1E 23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers WT14 AM1E 31 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers WTD14 AM1E 23 S2805 | Junkers WT/WTD water heaters and ZW20 | Contrasted |
| Junkers 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 boiler ignites, tries to operate, and shuts down after a few seconds without producing a flame.
Cause: The air pressure switch does not detect the depression generated by the fan, and the control board cuts off the gas for safety.
Check that the hose connecting to the fan is not disconnected, twisted, or has water inside.
- 02
It mainly gets blocked on windy days or when the flue has not been cleaned for a while.
Cause: The pressure switch toggles at the limit of its range, and any loss of draft prevents it from closing the contact.
Check the flue terminal outside: if it is dirty or if the wind is blowing directly into it, it can cause the same symptom.
- 03
A fault code appears on the screen that the manual associates with the combustion air.
Cause: It is the message given by the control unit when the pressure switch does not change state within the expected safety time.
Note the exact code and confirm it in the manual before assuming that the part is faulty.
- 04
It works normally for a while and then stops by itself, without you having touched anything.
Cause: The pressure switch loses the depression signal with the boiler already running, not just when starting.
Check if the fan changes sound or loses power just before the cut: this indicates a lack of airflow.
Fault codes from Junkers 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.
Junkers 8738709736 pressure switch datasheet
- Catalogue reference
- 8738709736
- Brand
- Junkers
- Type of part
- Pressure switches
- Units in stock
- 7 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Frequently asked questions about the pressure switch 8738709736
Is there a code on the Junkers ZW20-1 AME pressure switch that can be used to identify it?
What type of pressure switch is the Junkers ZW20-1 AME, air or flue gas?
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