Grant Aerona P13 fault code
Grant Aerona heat pumps
What it means
4-way valve fault
Valve change-over fault. The manual's FIRST check is a wiring trap: flow and return water sensors connected in reverse mimic a bad valve.
UK models this code applies to
From the Grant service literature we hold (Grant Aerona 290 installation manual DOC0204 Rev 1.8, Table 11-1) — not a scraped list.
Aerona HPR2904 (4 kW)Aerona HPR29065 (6.5 kW)Aerona HPR2909 (9 kW)Aerona HPR29012 (12 kW)Aerona HPR290155 (15.5 kW)
Now the harder half: proving what caused it
P13 names a symptom, not a root cause. In the app, the same code opens a guided investigation: what to measure first, the expected values for your exact model, and an honest verdict — including “nothing in this machine is broken” when that's what the readings say.
Chase this code in the app →