BoilerFaultCodesWhat the manual says
Manufacturer manualpump overrun
What causes this fault?
This is a normal operational process rather than a breakdown, occurring when the boiler has finished heating and needs to dissipate residual heat from the heat exchanger. The pump continues to circulate water for several minutes to prevent the internal components from overheating and to protect the long-term health of the unit. You may notice this most often immediately after your thermostat has reached its target temperature and clicked off.
DIY fix possible
Check that your radiator valves are open to allow water to circulateWait up to 10 minutes to see if the code clears automaticallyEnsure there is enough water pressure shown on the boiler gauge (typically 1.0 to 1.5 bar)
Avoid the next call-out bill
A cover plan would handle faults like S.27: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Related fault codes
All 41 fault codes on the Ultracom 24cx 30cx
Seeing a different code? Every code this model can display, in one place.