Worcester A7: sealed system pressure fault on a Greenstar
A7 is Worcester's way of saying the sealed system has fallen outside the range the appliance is designed to run within. In most cases that means low pressure specifically, and refilling via the filling loop clears it in minutes.
A Worcester A7 pressure fault explained in plain terms
The refill itself is simple: with the boiler cold, open the loop slowly until the gauge reaches the figure on the boiler's data plate, then shut both valves fully. If A7 returns within days rather than months, attention shifts to why pressure is being lost — the expansion vessel charge, the pressure relief valve seat, and slow weeps at radiator valves are checked in that order before any pipework is disturbed.
Who should undertake the work
- Gas appliance work must be completed by a suitably qualified Gas Safe engineer
- Oil appliance work should be completed by a suitably qualified OFTEC technician
- Jamie Crawford Heating states both Gas Safe and OFTEC registration
A Worcester A7 pressure fault — the facts that change the job
- Refill slowly and cold, watching the gauge rather than the clock
- Both filling loop valves must be shut fully once done
- A7 returning quickly points to a genuine loss, not a one-off
- Vessel charge is the fastest thing to test after a repeat event
- Concealed pipework leaks are investigated last, not first
Questions we get asked
- Can A7 mean the boiler is broken rather than the system?
- Rarely — A7 is almost always about system water content, not a fault with the boiler's own components.
- Is a filling loop always fitted permanently?
- No, some are detachable by design and must be removed after topping up to comply with water regulations.
Related help pages
- Ideal fault codeIdeal Logic L2 lockout: flame loss on a Logic or Vogue
- Ideal fault codeIdeal F1: low pressure lockout on a Logic or Vogue
- Fault isolationBoiler faults on hot water only: isolating the DHW circuit
- Glow-worm fault codeGlow-worm F1: ignition failure and what precedes it
- Ideal rangeIdeal Vogue Max: the flagship Ideal combi
- Pressure lossWhy heating system pressure keeps dropping between top-ups
Services that cover this
Where we deal with this
Sorted quickly: a Worcester A7 pressure fault
Where this leaves you: A7 is a pressure message, not a boiler diagnosis. Refill correctly, and treat repeat events as a leak-finding task.
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