Error E270

Safety precautions:

1. If you smell gas, evacuate the property immediately, do not operate any electrical switches or the boiler, and call your gas emergency number or emergency services. 2. If your carbon monoxide alarm sounds or you suspect CO, turn off the boiler at the mains, ventilate the property, evacuate and call a qualified engineer/emergency services. 3. Do not remove the boiler casing or attempt internal repairs — gas and electrical systems inside the boiler are hazardous and must be handled by a Gas Safe engineer.

Initial homeowner checks (safe, simple actions):

1. Note the exact error (E270) and any other codes, and the circumstances when it happened (e.g., when heating came on, after a power cut, during cold weather). 2. Try a single reset: follow the boiler’s reset procedure (usually press and hold the reset button for 3–5 seconds). If the code clears and the boiler stays on, monitor closely. If it returns, stop resetting. 3. Check the boiler pressure gauge: normal pressure when cold is usually around 1.0–1.5 bar (Potterton guidance commonly quotes ~1.2 bar). If pressure is clearly low (well below 1.0 bar), repressurise via the filling loop following the manual. 4. Confirm gas supply: try lighting another gas appliance (hob) to ensure gas is available. If there is no gas, contact your supplier. 5. Check that boiler isolation/service valves are open (inlet/outlet isolation valves) and radiator valves are not fully closed. 6. In cold weather, inspect the external condensate pipe for freezing; if frozen, thaw gently with warm water/room temperature towels — do not use open flame or boiling water.

Specific diagnostic and next steps:

1. If pressure was low and you repressurised the system to ~1.0–1.5 bar, reset the boiler once and observe. If the E270 does not return and the system behaves normally, monitor for recurring pressure loss. Persistent pressure loss indicates a leak or other fault requiring an engineer. 2. With central heating demand on, listen to and feel the pump (do not touch electrical terminals): you may hear or feel the pump running. If the pump is silent or you get loud banging, grinding or humming without water flow, the pump may be seized or power to it may be faulty — stop and call an engineer. 3. Bleed radiators to remove airlocks if radiators are cool at the top — airlocks can prevent circulation and trigger dry-fire conditions. 4. Try a hot tap demand (DHW) and observe whether the boiler attempts to fire and whether any different errors appear. 5. If the condensate pipe or trap was blocked or frozen and thawing/unblocking clears the error, monitor the boiler. 6. If basic checks (pressure, valves, air bleed, condensate) do not clear E270, or if you see additional codes related to ignition (E128/E129/E133) or PCB/fan faults, do not attempt further internal diagnostics.

When to call a professional:

1. Call a Gas Safe registered engineer if E270 returns after the initial safe checks, if you cannot safely repressurise the system, or if you suspect pump failure, blocked heat exchanger, faulty flow switch/sensors, PCB, gas valve or ignition component issues. 2. Tell the engineer the exact model (Potterton Assure combi/system), the error code E270, the boiler pressure reading, what you tried (reset, repressurised, bled radiators, thawed condensate etc.), and any noises, smells or other codes. 3. Do not continue to reset and force the boiler to run repeatedly; repeated dry-fire attempts can damage the heat exchanger and increase repair complexity.

A qualified engineer will safely diagnose and repair circulation components (pump, valves, flow switch), replace faulty sensors or wiring, clear blockages or airlocks, inspect the heat exchanger for damage, and check the ignition/gas supply and PCB if needed. If you are unsure at any stage, stop, isolate the boiler (switch off at mains), and arrange an engineer visit. No internal or gas work should be attempted by an unqualified person.