Saunier Duval SYMSI7.0 Control Board · PCB 125872-17 for Themafast F 25 E H-MOD

Application for the exact variant pending confirmation. To be confirmed: It is the main electronic board of the boiler. This unit operates with a 230 V network (ALIM 230V on its label) and features an OMRON G5Q-1A relay.

Type of part: Saunier Duval
Status: Refurbished
internal SKU: PLC096
Warranty: 1 year

VAT included Stock · 3 units

Compatibility

Compatible Saunier Duval boilers

Saunier Duval. 0 confirmed compatibilities. There are another 9 models that we are still verifying.

Models pending verification

These models are associated with this reference, but we have not finished verifying them yet, so we do not consider them compatibleIf your boiler is one of them, send us a photo of the part you are going to replace and we will verify it before you purchase.

Saunier Duval Themaclassic F 25 E	Saunier Duval	Unconfirmed
Saunier Duval Themafast F 25 E	Saunier Duval	Unconfirmed
Saunier Duval Themaplus C 23 to C 30 E and F 24 to F 30 E (including F 25 E H MOD and F 30 E H MOD)	Saunier Duval	Unconfirmed
Saunier Duval Themaclassic C 25 E and C 25 EV	Saunier Duval	Unconfirmed
Saunier Duval Thema C 23 to C 25 E, C AS, F 24 E, F 25 E and F AS 25 E	Saunier Duval	Unconfirmed
Saunier Duval Isotwin C 24 and F 24 E	Saunier Duval	Unconfirmed
Saunier Duval Isosplit C 24 EV to F 35 E H MOD	Saunier Duval	Unconfirmed
Saunier Duval Isofast and Thematek (model unspecified)	Saunier Duval	Unconfirmed
Saunier Duval Themafast F25 E H-MOD	Saunier Duval	Unconfirmed

Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.

Guide

How to check if it is the part for your boiler

The part reference, model, and equipment revision must be verified against the manufacturer's documentation.

Look for the name SYMSI7.0 on your PCB, the circuit code 125872-17, and the marking 0020021126; this unit also has version V3 printed on it.
Compare the OMRON G5Q-1A relay (DC24V coil) and the terminals V3V, OU, REMP, P2, P1, H9, μA, EXT, and TA with those on your PCB.
Do not rely solely on the name SYMSI7.0 or the reference S1047000: check the circuit 125872-17.
The Themafast Condens is another boiler: do not assume it is compatible without checking the codes.
if they match, call us at 911 17 77 77 with your boiler model and we will reserve it for you.

Diagnosis and fault codes

Symptoms that require diagnosis in the Saunier Duval.

Common symptoms and faults

01
The boiler does not ignite: the room thermostat flashes with fault code 01 or 04.
Cause: The burner does not ignite or the flame is not detected. There may be a lack of gas.
Press the thermostat button and follow its instructions. If it appears again, have a technician check it.
02
The boiler does not ignite: the fault code F28 appears (ignition fault).
Cause: Failed ignition: it could be gas, ignition, electrode, or PCB.
Have a technician check it.
03
The boiler shuts down during operation and does not restart (fault code F29).
Cause: Gas cut-off, flue gas recirculation, condensates, or faulty grounding.
Have a technician check it.
04
The boiler does not ignite or turns off during operation and does not ignite again (fault codes F28 or F29).
Cause: Ignition fault: it may be due to lack of gas, gas meter, ignition or PCB.
Put the boiler out of service, wait 5 seconds, and then restart it. If the issue persists, have it checked by the official SAT.
05
The boiler does not ignite when starting and fault code F.28 appears.
Cause: Insufficient gas, condensate siphon blocked or failed ignition.
Have a technician check the gas, the siphon, and the electrode. Do not touch the gas valve.
06
The flame goes out during operation and the boiler tries to ignite several times.
Cause: Dirty ionization electrode, flue gas recirculation or gas cut-off.
Have a technician check the electrode, the flue gases, and the gas supply.
07
Fault codes F.00, F.01, F.10 or F.11 appear on the screen.
Cause: Loose sensor connector, interrupted wiring harness, or faulty NTC sensor.
Have a technician check the connectors first and then the sensor.
08
The red pilot light is flashing and a fault code F followed by a number appears on the screen: the boiler stops due to an anomaly.
Cause: The PCB has detected an anomaly. The number indicates which one: ignition, flue, sensors, or circulation.
Reset it: turn off the boiler, wait 5 seconds, and turn it back on. If the fault persists, have it checked by the official technical service.
09
The boiler does not ignite the burner, with the fault code F.28.
Cause: Gas, electrodes, gas pressure or polarity.
Have a technician check it. Do not attempt to touch the gas valve.
10
The boiler detects flame with the burner off: warning F.27.
Cause: Moisture on the electrode, or gas valve that does not close.
It is a security fault. Have a technician check it immediately.
11
The boiler is locking out with the fault code F.61, related to the gas valve.
Cause: Fault in the gas valve control.
Have a technician check it: it may be necessary to replace the PCB.

Fault codes Saunier Duval that require diagnosis

Code	Fault	Technical checks
F.28	Start-up fault: ignition does not complete.	Code with a dot, typical of the Isofast Condens. It may be due to the gas, ignition, or the PCB; have a technician check it.
F00	Return temperature sensor (NTC2) disconnected.	Check if the sensor connector is loose. If it persists, have a technician check it: it could be the sensor, the cable, or the PCB.
F01	Return temperature sensor (NTC5) disconnected.	Just like the F00: check the connector and, if it persists, have a technician check it.
F27	Flame detection fault: the flame control is not reliable.	If it occurs when turning on or off, have a technician check it: it could be moisture in the electronics or the flame control.
F29	Flame loss during operation.	If it repeats, have a technician check it: it could be a gas cut-off, flue gas recirculation, or a faulty ground connection.
F61	Gas valve activation fault.	Have a technician check it: it could be the wiring of the gas valve, its coils, or the electronics.
F62	The gas valve does not close in time after the flame goes out.	Have a technician check it: the gas valve or the PCB are the suspects.
F15	Flame detection fault: there is a flame with the burner off.	If it occurs when turning off or on, have a technician check it: it points to the PCB or the flame control.
F5	Fault of the heating flow sensor (NTC2).	Check if the sensor connector is loose. If it persists, have a technician check it: it could be the sensor, the cable, or the PCB.
F1	Ignition fault, possible gas supply issue (in Themafast C; in NOx it appears as F28 or F29).	Put the boiler out of service, wait 5 seconds, and then restart it. If the issue persists, have a technician check it.
F.10	Short circuit in the supply temperature sensor (inlet).	Have a technician check the sensor and the wiring harness. Only point to the PCB if the sensor and wiring are fine.
F.11	Short circuit in the return temperature sensor.	Have a technician check the sensor and the wiring harness. Only point to the PCB if the sensor and wiring are fine.
F.20	Safety disconnection due to overheating.	Do not reset it over and over again. Have a technician check it. If the warning returns, it may be due to a lack of water circulation, not the PCB.
F.49	Fault in eBUS communication: lack of voltage or short circuit in the line.	Check the wiring of the thermostat or the bus. If the warning returns, have a technician check it. Point to the communication PCB.
F.63	Fault in the memory (EEPROM) of the PCB.	Have a technician check it. The PCB may need to be replaced.
F.65	Temperature of the electronics too high.	Have a technician check it. Review the location and ventilation of the boiler. Point to the PCB.

These symptoms can have more than one cause. If your boiler displays a fault code, send it to us via WhatsApp along with a photo of the labeling, and we'll tell you if this is the part.

Technical data

Saunier Duval

Uniclima internal SKU: PLC096
Brand: Saunier Duval
Type of part: Saunier Duval
Units in stock: 3 units
Status: Refurbished
Warranty: 1 year
Shipping: Delivery time shown at checkout
Return: 14 days

Part data and available documentation

Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.

Relay observed: OMRON G5Q-1A
Relay coil marked: DC24V
Marked connections: ALIM 230V / TA 230V
Inventory — Indicated reference: 0310144400015
Inventory — Subcomponent relays: OMRON G5Q-1A, DC24V coil
Inventory — Visible terminals: V3V, OU, REMP, P2, P1, H9, μA, EXT, TA
Inventory — Screen printed version: V3
Inventory — Application indicated in inventory: SAUNIER DUVAL THEMAFAST F25 E H-MOD
Inventory — Marked code: 0020021126; 06 38; IND4; S007C; 06V0-A
Dimensions of (S1047000) — Measurements: 183 × 53 × 203 mm (width × height × depth) ·
Weight: 0.5 kg
Identification — Marked code: 0020021126
Identification — Marked code: 06 38
Identification — Marked code: IND4
Identification — Marked code: S007C
Identification — Marked code: 06V0-A
Technical sheet: Observed relay: OMRON G5Q-1A
Technical sheet: Relay coil marked: DC24V
Technical sheet: Marked connections: ALIM 230V / TA 230V
Inventory data — Indicated reference: 0310144400015
Inventory data — Subcomponent relays: OMRON G5Q-1A, DC24V coil
Inventory data — Visible terminals: V3V, OU, REMP, P2, P1, H9, μA, EXT, TA
Inventory data — Screen printed version: V3
Inventory data — Application indicated in inventory: SAUNIER DUVAL THEMAFAST F25 E H-MOD
Inventory data — Marked code: 0020021126; 06 38; IND4; S007C; 06V0-A
Pending applications to verify: Saunier Duval Themafast F25 E H-MOD — compatibility cited; pending confirmation. Consultation 24/10/2026 · 1 supplier; pending confirmation: Themaclassic C 25 E; Themaclassic F 25 E; Thematek S C 24 E. Commercial statement for your sheet "PCB Saunier Duval (0310144400015) v5", no certification of the unit. Confirm OEM reference, revision, configuration, and equipment variant before use.

Before purchasing

To confirm: Saunier Duval Themaclassic F 25 E — To confirm, and · it is titled this way but also mentions the Themafast F25E.
To confirm: Saunier Duval Themafast F 25 E — it is mentioned in its technical sheet (it does not specify if it includes H-MOD) · it is provided for the Themafast F family.
To confirm: Saunier Duval Themaplus C 23 to C 30 E and F 24 to F 30 E (including F 25 E H MOD and F 30 E H MOD) — 1 origin: (S1047000)
To confirm: Saunier Duval Themaclassic C 25 E and C 25 EV — 1 origin: (S1047000)
To confirm: Saunier Duval Thema C 23 to C 25 E, C AS, F 24 E, F 25 E and F AS 25 E — 1 origin: (S1047000)
To confirm: Saunier Duval Isotwin C 24 and F 24 E — (F 24 E and F 24 E1) · (Isotwin C24) · (family)
To confirm: Saunier Duval Isosplit C 24 EV to F 35 E H MOD — 1 origin: (S1047000)
To confirm: Saunier Duval Isofast and Thematek (model unspecified) — Families named by,
They sell the SYMSI7.0 with reference S1047000, but without additional confirmation, it is linked to 0020021126 from this label. Compare the circuit 125872-17.
Registered identity:, and connect SYMSI7.0 with the main PCB and with S1047000. The official manual requires 24 V at the thermostat; the label on this unit indicates TA 230V (registered). Registered application: also 125872-17 and 0020021126.
Pending registered applications to confirm by model, variant, or programming: Saunier Duval Themafast F25 E H-MOD.

Frequently Asked Questions

Frequently asked questions: Saunier Duval

How do I identify the SYMSI7.0 125872-17 PCB?

Compare three markings: the name SYMSI7.0, the circuit 125872-17, and the 0020021126 from the label. This unit also has the reference 0310144400015 and the version V3 printed. Publish SYMSI7.0, 0310144400015, and 125872-17 together in its technical sheet.

Is it compatible with my Saunier Duval Themafast F 25 E H-MOD?

The compatibility of this variant is pending confirmation. Registered: for the Themafast F 25 E H-MOD. In addition, it includes the circuit S1047000 among the spare parts for that boiler and lists the SYMSI 7 PCB on its model page.

Is it compatible with the Themaclassic F 25 E?

The compatibility of this variant is pending confirmation. To be confirmed. They provide it for that boiler; they title their sheet this way, but they also mention the Themafast F25E. Registered: for the Themafast F 25 E H-MOD, not for the Themaclassic: compare circuit 125872-17 or send us a photo of your PCB and the boiler's data plate from Contact.

What do SYMSI7.0, S1047000, and 125872-17 mean?

SYMSI7.0 is the name of the PCB; it is provided as the manufacturer's code visible on the part. S1047000 is the spare part reference from Saunier Duval with which it is sold, and (S10470 in short form). 125872-17 is the circuit code for this unit.

Is the 0020021126 on the label the same as the S1047000?

The 0020021126 is a code marked on the label of this unit and it confirms it. Without additional external confirmation, we have linked it with the S1047000, the reference with which they sell the SYMSI7.0. Compare the circuit 125872-17 and the others marked on your PCB.

In which other Saunier Duval boilers is the SYMSI7.0 sold?

The compatibility of this variant is pending confirmation. Registered application for Thema, Themaclassic, Themaplus (including the F 25 E H MOD), Isotwin, and Isosplit. Registered application for Isofast and Themaclass, as well as for Themaclassic, Thematek, Themafast, Isofast, and Isotwin. Only the workshop has confirmed for the Themafast F 25 E H-MOD; for the others, compare the codes.

Who should install it?

A qualified technician. The PCB operates at 230 V and manages a gas boiler. It requires a specialized technician and warns that incorrect installation or a fault in another part can render the spare part unusable.

How to identify this PCB?

Compare the silkscreen, the distribution of the connectors, and the exact variant of the circuit with the photographs.

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Saunier Duval SYMSI7.0 Control Board · PCB 125872-17 for Themafast F 25 E H-MOD