D.75 Medium
Your boiler is taking longer than expected to heat up your hot water tank, causing the system to stop as a precaution.
Technical description: Maximum charging time for a storage without own controller
Typical repair cost: £100-250 (including labour)
DIY fix possible
Check that the valves on your hot water cylinder are fully openEnsure your thermostat is calling for hot waterTry resetting the boiler to see if the error clears
Protect yourself from future repair bills
A boiler cover plan would cover faults like D.75 — no call-out fees, no surprises.
*Affiliate links — we may earn a commission at no extra cost to you. Prices shown are starting prices.
Parts commonly replaced
- NTC Temperature Sensor
- Diverter Valve
- External Pump
*Affiliate links — we may earn a commission at no extra cost to you.