BoilerFaultCodesTechnical description
Dry fire - Flow/return temperature sensor change too small
What causes this fault?
This fault occurs when the boiler's internal computer registers that the burners are on, but the temperature sensors fail to detect a significant rise in heat within the water. The most common reason is a lack of water circulating through the system, often caused by a pump failure, a blockage, or even just too much air trapped in the pipework. Because the boiler cannot move the heat away from the burner quickly enough, it shuts down to prevent 'dry firing' and damaging the internal components.
This fault is more frequent in autumn when the heating is turned on for the first time after summer, as circulation pumps are prone to seizing or sticking after long periods of inactivity.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.