Error S.22

Safety precautions:

1. If you smell gas or suspect a gas leak, leave the property immediately and call the gas emergency number. Do not operate electrical switches or the boiler. 2. Before inspecting the boiler internally switch the boiler off at the mains isolator and, if possible, isolate the water supply. Only remove panels if you are competent; many checks must be done by a Gas Safe registered engineer. 3. Wear eye protection and avoid working on live electrical parts. If you are unsure at any point, stop and call a professional.

Initial homeowner checks (safe/simple actions):

1. Note other display messages: write down S.22 and any F.* codes shown. Multiple codes help the engineer. 2. Try a basic reset: switch the boiler off at the internal switch or mains isolator, wait 30 seconds, switch back on and observe whether S.22 returns. 3. Check system water pressure on the front display. If the boiler also shows a low-pressure fault (F22/F.22) repressurise the system using the filling loop to the pressure recommended in your manual (typically around 1–1.5 bar) — only do this if you know how. 4. Open a hot tap: listen for the DHW pump running (you should hear/feel it). Note whether you get hot water, reduced flow, or no flow. 5. Check for visible leaks or closed isolation valves on the domestic hot water pipework and ensure they are open.

Specific diagnostic and practical steps you can attempt (with caution):

1. Airlock / low flow symptoms: If the pump runs but flow is poor, try opening several hot taps around the property for a short period to see if that clears any air locks. Bleeding radiators is not usually a fix for DHW pump issues but can help if the system has been recently drained. 2. External filters/strainers: Some installations have inlet strainers or a magnetic filter on the domestic side. If accessible and you are competent, isolate the water supply, remove and inspect the strainer for debris, then reassemble. If you are not confident, call an engineer. 3. Valves and pipework: Confirm any external service valves to the boiler/DHW circuit are fully open. A closed valve or blocked inline valve will prevent flow. 4. Listen and observe the pump: If the pump is silent when DHW is requested, look for obvious loose wires on the pump terminals (only with the boiler powered down and isolated). Do not probe live terminals unless qualified. 5. Try the boiler’s pump purge or service mode only if you have the manual and understand the procedure: some Vaillant boilers have P‑codes to run purge programs that can clear air in the pump/heat exchanger. If unsure, leave this to the installer.

When to stop and call a professional (or call immediately):

1. If S.22 stays after the simple checks and reset, or if you find a suspected electrical fault, failed pump, blocked heat exchanger, or wiring issue, call a Gas Safe registered engineer. 2. If you find corrosion, seized valve actuators, or cannot access filters/strainers without dismantling the boiler, stop and arrange professional service. 3. If other fault codes (F.11, F.24, F.25, F.22 etc.) appear in combination, this indicates a broader safety cut-out or flow/temperature problem that needs a qualified technician.

What a professional will check/likely do (for your understanding):

A Gas Safe engineer will verify pump operation (electrical supply and pump current), inspect and test the DHW flow/temperature sensors and their wiring, check the 3‑port diverter valve and actuator, inspect domestic heat exchanger and inlet filters for blockages or scale, run pump purge/service routines, and replace failed components (pump, sensors, wiring, valve actuator) as required. They will also test the boiler after repair and confirm safe operation.

Practical notes before calling an engineer:

Have the model (Vaillant EcoTEC 65kW), serial number if possible, the exact fault code(s) (S.22 and any F codes), a brief history (when it started, any work done recently, whether you bled radiators or drained the system), and whether you hear the pump running. This will speed diagnosis. If the code appeared after work on the system or after draining/refilling, mention that as airlocks and low pressure are common causes.

Final reminder:

S.22 often points at pump/flow issues that can be simple (air, closed valve, blocked filter) but can also be component or wiring failures that require a qualified Gas Safe engineer. Do not attempt gas or complex electrical repairs yourself. If basic safe checks do not clear the code, book a registered engineer to diagnose and repair the boiler. If you want Vaillant support directly, the manufacturer helpline listed in the manual is another route for advice.