BoilerFaultCodesYour main heat pump unit is unable to talk to the secondary unit, meaning the system cannot coordinate properly to heat your home.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No connection Master Heat Pump to Slave Heat Pump
What causes this fault?
This fault occurs when the electrical link between the two main heating units is broken, preventing them from sharing data. The most common reasons are a loose or damaged communication cable, or a failure in the electronic control boards that manage the system's signals.
This fault can sometimes occur after periods of heavy rain or storms if moisture enters the external wiring enclosures and interferes with the communication signal.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like Hd — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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