Boilers 4 min read Updated 7 June 2026 Trade verified

Ferroli: No Hot Water — Diagnose It

When a Ferroli shows no hot water, the diagnostic order matters — a £5 fill loop check clears many callouts. Here is the trade sequence.

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Step-by-step method

1. Free checks first

Pressure 1.0–1.5 bar cold; timer/programmer settings; room stat batteries; all isolators open.

2. Reset properly

Off at fused spur 60 sec, on, hold reset 5 sec. Note if any fault code briefly appears.

3. Test the likely cause

For no hot water, the top cause is a stuck diverter valve, failed thermistor or scaled heat exchanger. Isolate each in turn.

4. Cheap parts before expensive

NTC thermistor £15, diverter cartridge £60, expansion vessel £70 — cheaper than PCB or heat exchanger.

5. Gas Safe callout

Any gas-side work on a Ferroli requires Gas Safe. £90–£150 diagnostic; £200–£450 typical repair.

Frequently asked questions

Is this covered by warranty?+

Yes if in-warranty with annual services logged. Missed services void most cover.

Emergency?+

No hot water is not statutorily an emergency; landlords have 24 hours to respond.

Repair or replace?+

Boilers over 12 years old: get a fixed-price replacement quote to compare against repair.

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