- Heat pumps
- Air-to-water heat pump
E8005
Daikin Altherma E8005 heat pump error: low water pressure
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
E8005 on a Daikin Altherma EHS(X/H) heat pump means the heating system water pressure has dropped below the minimum limit and you should check the reading in the Info rotary switch position. Daikin links this red-backlit fault to low water from a leak or a faulty DS pressure sensor.
Safety first
Stop and check this first
- Daikin warns of lethal electric shock if leaking water contacts live parts during filling: always disconnect the power supply before filling the heating system and verify that all electronic parts and connection points are completely dry before switching power back on.
- To prevent heating water from contaminating the drinking water supply, Daikin requires using a filling hose with a backflow prevention device on the KFE cock and disconnecting the hose as soon as filling is finished.
Safe checks you can perform
- Read the heating water pressure in the Info rotary switch position
- Inspect visible manifolds, radiators and pipe connections for water leaks
- Check whether E8005 clears once pressure is restored or after a 10-second reset
Leave these tasks to a qualified professional
- Do not attempt this professional task: Leak-test, top up via the KFE cock with backflow prevention and vent the heating circuit
- Do not attempt this professional task: Test the DS pressure sensor wiring, plug contacts and voltage-to-pressure curve
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Leak-test, top up via the KFE cock with backflow prevention and vent the heating circuit
What they doAn authorised heating technician must isolate the electrical supply before filling, check the circuit and expansion vessel pre-charge, connect a filler hose with a backflow preventer and external pressure gauge to the KFE cock to fill to target pressure (system height plus 2 m, where 1 m water column equals 0.1 bar), and run the Air Purge procedure.
They must show youthe matching pressure reading on the external pressure gauge and the Info menu after bleeding all air from the circuit.
In writingthe expansion vessel pre-charge pressure, the final cold fill pressure in bar and confirmation that the circuit is leak-free.
Test the DS pressure sensor wiring, plug contacts and voltage-to-pressure curve
What they doIf actual hydraulic pressure is within range on an external gauge but E8005 persists, the technician must inspect the plug contacts and wiring to the control board before testing or replacing the DS pressure sensor (observing the 10 Nm maximum sensor tightening torque).
They must show youthe comparison between the external reference pressure gauge and the DS sensor voltage curve.
In writingthe DS sensor diagnostic readings, any replaced part number and the cleared fault protocol log.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Read the heating water pressure in the Info rotary switch position
- Who:
- you.
- How:
- turn the rotary switch on the main control unit to the Info position and verify whether the displayed water pressure is above the 0.5 bar minimum specified by Daikin.
- Result that matters:
- confirming the exact water pressure read by the controller before any refilling work is attempted.
- If the reading is 0.5 bar or lower:
- inspect the visible pipework for leaks and arrange for the circuit to be topped up.
- If an external pressure gauge shows normal pressure while E8005 stays active:
- the DS pressure sensor or its wiring needs testing.
- Evidence to keep:
- photo of the red-backlit E8005 screen and the water pressure value shown under Info.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
Inspect visible manifolds, radiators and pipe connections for water leaks
- Who:
- you.
- How:
- check around the Daikin Altherma indoor unit, underfloor heating manifolds, radiator valves and the safety pressure relief discharge for any dripping water or damp patches.
- Result that matters:
- spotting any obvious water loss in the building circuit before refilling the system.
- If you find a leak or dripping joint:
- note the location so the heating technician can seal it before topping up.
- If all visible pipework and valves are dry:
- pass this on so the technician checks the expansion vessel and DS sensor.
- Evidence to keep:
- photos of the manifold connections and the floor area around the indoor unit.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
Check whether E8005 clears once pressure is restored or after a 10-second reset
- Who:
- you, only after water pressure is restored and all electrical areas are confirmed dry.
- How:
- Daikin states that fault codes stay on screen while the fault condition exists; if E8005 remains displayed after the cause has been corrected, disconnect the system from the power supply for at least 10 seconds to unlock it and switch it back on.
- Result that matters:
- the red display backlight clearing and the heat pump returning to normal heating and hot water operation.
- If the code clears and stays off:
- the low-pressure lock has been released.
- If E8005 reappears with a red display:
- do not keep cycling the power and contact an authorised Daikin heating technician.
- Evidence to keep:
- record of the pressure reading under Info and the controller display after restarting.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Heat pumps
- Brand
- Daikin
- Product type
- Air-to-water heat pump
Known code variants
- Daikin Altherma E8005
- Daikin E8005
- Daikin EHSH E8005
- Daikin EHSX E8005
- Daikin heat pump error E8005
- Daikin water pressure too low E8005
- E 8005 Daikin
- error E8005 aerotermia Daikin
- presión de agua insuficiente E8005 Daikin
What it means
In the official Daikin Altherma EHS(X/H)(B) integrated solar unit installation and operating instructions (models 04P30B, 08P30B, 08P50B and 16P50B, document 0081434344_00), fault code E8005 lights the controller display background in red with the message Water pressure in the heating system too low, monitored by pressure sensor DS; warning W8006 also flags when the maximum permissible pressure drop is exceeded. Other Daikin Altherma model families may report low water pressure under different fault codes. On its own, E8005 never proves that the DS pressure sensor or any other part has failed.
Warnings and stop conditions
- Higheditorial warning
Daikin warns of lethal electric shock if leaking water contacts live parts during filling: always disconnect the power supply before filling the heating system and verify that all electronic parts and connection points are completely dry before switching power back on.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
- Mediumeditorial warning
To prevent heating water from contaminating the drinking water supply, Daikin requires using a filling hose with a backflow prevention device on the KFE cock and disconnecting the hose as soon as filling is finished.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
Symptoms and causes
Probable causes · in order
- Too little water or leakage in the space heating circuitCommon
Daikin's fault table lists insufficient water in the heating system as the primary cause when system pressure drops below the minimum permissible 0.5 bar threshold.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
- Loss of pre-charge pressure or fault in the membrane expansion vesselPossible
An improperly pressurised or defective expansion vessel, or trapped air in the circuit, allows the hydraulic pressure to fall below the minimum limit as the water cools.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
- Defective DS water pressure sensor or poor plug and cable contactLess common
Daikin notes that a defective DS pressure sensor, loose plug contact or damaged connection cable can report low pressure even when the heating circuit is full.
Evidence: Daikin Altherma EHS(X/H)(B) integrated solar unit, installation and operating instructions 0081434344_00
Virtual technician
Does E8005 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Daikin Europe N.V. · 2016 · official_doc
- 2
Daikin Europe N.V. · 2016 · official_doc
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