- Heat pumps
- Air-to-water heat pump
7H-23
Daikin Altherma 4 H F 7H-23: Main zone pump communication error
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
7H-23 means “Main zone pump communication error” on the scoped Altherma 4 H F family. Daikin records this trigger: Communication abnormality between indoor unit and main zone pump. Effect: Unit will stop operating. The table marks the reset as automatic.
Safety first
Stop and check this first
- Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Safe checks you can perform
- Preserve the diagnostic state
- Let the automatic reset logic decide
- Check only user-visible water-circuit evidence
Leave these tasks to a qualified professional
- Do not attempt this professional task: Measured handoff for 7H-23
What a technician must be able to justify
A technician is coming
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.
Measured handoff for 7H-23
What they doGive the technician 7H-23, both model numbers, the source trigger “Communication abnormality between indoor unit and main zone pump”, the effect “Unit will stop operating”, reset result and recurrence conditions. They should follow Daikin's water flow and pump branch and compare live measurements with the service values before replacing parts.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Checks and evidence, step by step
Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
- 1
Preserve the diagnostic state
No special tools
Procedure
Photograph 7H-23 and the complete display. Record both unit model numbers, operating mode, requested temperatures, weather, system pressure shown to the user and the moment the code appeared.
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
- 2
Let the automatic reset logic decide
No special tools
Procedure
Daikin marks this code as automatic reset. Do not cycle breakers or force repeated acknowledgements. Record whether the controller clears it and the exact operating state in which it returns.
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
- 3
Check only user-visible water-circuit evidence
No special tools
Procedure
If the user manual permits it, read the displayed system pressure, confirm no user-accessible valve was accidentally closed and look for a visible leak. Do not fill, bleed, clean strainers or measure flow unless the exact user manual assigns that task to the user.
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
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
- Altherma 4 H F 7H-23
- code erreur Daikin Altherma 7H-23
- codice 7H-23 pompa di calore Daikin
- código 7H-23 bomba de calor Daikin
- Daikin 7H-23
- Daikin Altherma error 7H-23
- Daikin Altherma Fehler 7H-23
- Daikin heat pump code 7H-23
- Daikin Wärmepumpe Fehlercode 7H-23
- défaut 7H-23 pompe à chaleur Daikin
- error Daikin Altherma 7H-23
- errore Daikin Altherma 7H-23
What it means
In guide 4P773391-1C (2026.02), Daikin assigns 7H-23 to “Main zone pump communication error”. The documented trigger is “Communication abnormality between indoor unit and main zone pump” and the operating effect is “Unit will stop operating”. This is a precise controller decision for Daikin Altherma 4 H F — EPSK(S)04~14A + EPVX07~14S18+23A; it does not by itself prove which component failed.
Warnings and stop conditions
- Highsource verified
Stop and isolate the installation for smoke, burning smell, sparks, unusual heat, water near electrical parts, suspected refrigerant release or repeated protective trips. Do not open the R290 refrigerant circuit or live electrical compartments.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Symptoms and causes
Probable causes · in order
- What the controller establishedConfirmed
Daikin's table defines the condition as “Main zone pump communication error” and gives this exact trigger: Communication abnormality between indoor unit and main zone pump.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
- What the unit does nextConfirmed
Documented effect: Unit will stop operating. Reset classification: Automatic. A cleared display is not proof of repair.
Evidence: Daikin Altherma 4 H F installer reference guide — 4PEN773391-1C
Virtual technician
Does 7H-23 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 Altherma 4 H F installer reference guide — 4PEN773391-1C
Daikin Europe N.V. · 2026 · official_doc
Was this entry useful?