Vaillant F.75 Error: Pump & Pressure Sensor Fault Fix
Independent guide — no official affiliation with the platforms mentioned.
Risposta breve
Vaillant F.75 means the pump starts but the pressure sensor doesn't detect the expected pressure change — usually a blocked pressure sensor, air in the system or a faulty pump. First bring the water pressure to 1.2–1.8 bar, bleed the radiators and reset the boiler. If it persists after 2–3 attempts, the pressure sensor or pump needs service.
Fonte ufficiale
vaillant.com.tr
F.75 birkaç adımdan sonra çözülmezse yetkili servis randevusu buradan alınır.
01 — Risoluzione passo dopo passo
Risoluzione passo dopo passo
STEP 01
Check and refill pressure to 1.2–1.8 bar
If the display shows below 0.8 bar, F.75 triggers. Open the filling loop under the boiler slowly and close it when the display reaches 1.2–1.8 bar. Make sure the filling tap is fully closed afterwards.
STEP 02
Bleed the radiators
Trapped air confuses the pump's pressure detection. Open each radiator's bleed valve slowly; when hissing stops and water appears, close it. Start with the radiators on the highest floor.
Bleeding drops the pressure by 0.3–0.5 bar; top it back to 1.2–1.8 bar once done.
STEP 03
Reset the boiler
Press the reset/power button or switch off the boiler's breaker for 30 seconds. When it restarts, watch whether F.75 returns.
STEP 04
Open the heating valves fully
Half-closed flow/return valves cause pressure swings. Make sure the service valves below the boiler are fully open and any filter/dirt trap isn't clogged.
STEP 05
Check for frozen condensate pipes
In winter, frozen external pipes stop circulation and can raise F.75. Thaw them first, then reset. Don't force the boiler to run against a frozen system.
Running the boiler against a frozen system can damage the pump and heat exchanger. Keep the boiler in standby until thawed.
STEP 06
If it persists: pressure sensor / pump service
After the steps above, a persistent F.75 points to a blocked or failed pressure sensor or a pump problem. These are authorized-service jobs — don't open the boiler yourself while under warranty.
Consigli
- An annual system filter cleaning prevents the most common cause: a blocked sensor.
- Keeping the boiler in summer mode instead of full off prevents pump seizing.
- Pressure keeps dropping? That's a separate fault — see our 'boiler pressure keeps dropping' guide.
02 — Domande frequenti
Domande frequenti
Can F.75 clear by itself?
If caused by air or a temporary pressure dip, it clears after refill, bleeding and reset. Sensor blockage or pump failure won't clear without service.
How much does F.75 repair cost?
Typically a pressure sensor cleaning/replacement or pump repair. Under warranty parts and labour are free; otherwise get a quote from authorized service.
Difference between F.75 and F.28?
F.28 is an ignition/flame fault (gas arrives, no flame detected); F.75 is the pressure change not being detected when the pump starts. Both can relate to pressure and air, but the fixes differ.
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03 — Guide correlate