Medium
Water temperature low on Grant Vortex 15-20

Your Grant oil boiler is failing to reach the proper temperature because it is either not burning fuel efficiently or having trouble retaining the heat.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Undersize nozzle, low fuel pressure, fouled heat exchanger, or faulty thermostat

From this model's manual
Verified against the Grant/Grant Vortex 15 20 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

LockoutView →Flame failureView →High limit statView →

All 12 fault codes on the Vortex 15-20

Seeing a different code? Every code this model can display, in one place.

26.036.0Boiler operating on overheat thermostatBoiler will not startBurner lock-outBurner pulsatesCombustion fumes smellFlame slow to stabilise during start upFumes and puffing during startingOil odoursVisible smoke from flue or high smoke number

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