BoilerFaultCodesYour boiler has detected low water pressure in the system, which is preventing it from heating up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: ALTERNATING 'H' '1' GO TO FRAME 90
What causes this fault?
This fault occurs when the water pressure inside your heating system drops below a safe level, causing the boiler to shut down to prevent damage. The most common reasons for this are a leak somewhere in your radiators or pipework, or simply that air has been bled from the system without being topped back up. It can also happen if a component like the expansion vessel has failed, causing water to be discharged through the safety pipe.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time or bleed their radiators to prepare for winter.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the valve(s) until you hear water flowing and watch the pressure gauge.Close the valves once the needle reaches 1.5 bar on the gauge.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like H1 — no call-out fees, no surprises.
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Ideal Esprit HE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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