Vaillant F.22: Low Water Pressure / Dry Fire
What the Vaillant F.22 error code means, what causes it, and why it's a job for a licensed BC gas technician — not a DIY reset.
Severity
High — needs prompt professional attention
What the Vaillant F.22 error code means
The boiler has detected too little water in the system (low pressure or no flow) and shut the burner down to avoid firing against a dry or near-dry heat exchanger.
On Vaillant ecoTEC plus and ecoTEC exclusive condensing boilers & combis, F.22 is a system water-pressure fault. It is a protective response — the boiler is telling you something needs attention, and the safe, lasting fix is a proper diagnosis rather than repeated resets.
Symptoms you may notice
- Pressure gauge reading low (or very high)
- No heat; boiler will not fire
- Needing to top up system pressure often
Common causes of Vaillant F.22
Why this is not a DIY fix
Chronic pressure loss almost always means a leak, a water-logged expansion vessel, or a failed pressure-relief valve. Simply re-pressurising hides the real fault and can over-stress the system. A technician must locate the leak and recharge or replace the expansion tank correctly.
In British Columbia, gas work must be performed by a TSBC-licensed gas fitter. GasBoilers.ca — a CanroHeat division — sends Red Seal–certified, gas-licensed technicians who diagnose the true cause, repair it correctly, and verify safe operation before they leave.
How our technicians diagnose & repair it
- 1Locate leaks across the heat exchanger, pump, valves and fittings
- 2Test and recharge or replace the expansion tank to the correct pre-charge
- 3Inspect the pressure-relief valve and auto air vents
- 4Refill, purge air and confirm stable cold/hot pressure
Related Vaillant codes
Vaillant F.22 — FAQ
What does the Vaillant F.22 error code mean?
The boiler has detected too little water in the system (low pressure or no flow) and shut the burner down to avoid firing against a dry or near-dry heat exchanger. On Vaillant ecoTEC plus and ecoTEC exclusive condensing boilers & combis, this is categorised as a system water-pressure fault.
What causes Vaillant F.22?
The most common causes are: System pressure below ~0.5–0.8 bar; A leak on the system or boiler; Failed or air-bound circulating pump; Faulty water pressure sensor. A licensed technician confirms which one applies before any part is replaced.
Can I fix Vaillant F.22 myself?
No. Chronic pressure loss almost always means a leak, a water-logged expansion vessel, or a failed pressure-relief valve. Simply re-pressurising hides the real fault and can over-stress the system. A technician must locate the leak and recharge or replace the expansion tank correctly. Repeatedly resetting the boiler without fixing the root cause can be unsafe and can cause further damage. Call GasBoilers.ca at 604-359-1081 for a licensed diagnosis.
Is the Vaillant F.22 error code dangerous?
This is a protective fault — the boiler has shut down a function to protect itself. It is best diagnosed promptly by a licensed technician so the underlying cause does not lead to a more expensive failure.
How much does it cost to fix Vaillant F.22 in Greater Vancouver?
Cost depends on the root cause and any parts needed. We start with a flat-rate diagnostic, then quote the repair before any work begins — no surprises. Call 604-359-1081 for current pricing and same-day availability.
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