Gas Mechanism Saunier Duval Isofast C28 E1
The Gas Mechanism Saunier Duval Isofast C28 E1, with reference 05742800, is a gas valve that regulates the flow of gas to the burner according to the commands from the boiler's PCB. When it fails, the boiler may not ignite, experience flame lockouts, or have modulation issues. Faults such as F.26, F.27, F.28, F.61, or F.62 may be recorded. This valve is compatible with models from the Isofast, Isomax, and Isotwin ranges, such as the Isofast C 28 E1 or the Isomax C 28 E2, among others. It is recommended to replace it when these symptoms or faults are detected.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference 05742800
Gas valve with reference 05742800. 15 confirmed compatibilities: Isofast C 24 E V1 and Isofast C 28 E1.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Isofast C 24 E V1 | Isofast | Contrasted |
| Saunier Duval Isofast C 28 E1 | Isofast | Contrasted |
| Saunier Duval Isofast C 28 E1 NOx | Isofast | Contrasted |
| Saunier Duval Isofast C 35 E1 | Isofast | Contrasted |
| Saunier Duval Isofast F 28 E1 | Isofast | Contrasted |
| Saunier Duval Isofast F 35 E1 | Isofast | Contrasted |
| Saunier Duval Isomax C 28 E2 | Isomax | Contrasted |
| Saunier Duval Isomax F 28 E2 | Isomax | Contrasted |
| Saunier Duval Isotwin C 24 E | Isotwin | Contrasted |
| Saunier Duval Isotwin C 24 EA | Isotwin | Contrasted |
| Saunier Duval Isotwin C 24 EV | Isotwin | Contrasted |
| Saunier Duval Isotwin C 24 EV A | Isotwin | Contrasted |
| Saunier Duval Isotwin F 24 E | Isotwin | Contrasted |
| Saunier Duval Isotwin F 24 E1 | Isotwin | Contrasted |
| Saunier Duval Isotwin F 24 EA | Isotwin | Contrasted |
Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.
How to check if the part number 05742800 is the one for your boiler
What determines it is not the boiler model, but the reference printed on the part you already have installed.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 05742800. If it is not visible, do not identify the part from its shape alone.
- Check the full boiler model on its data plate and look for it in the model associations on this page.
- Compare the connections and physical body with the original part before installation.
- If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.
Symptoms and faults that the gas valve 05742800 resolves.
The gas valve regulates and modulates the gas flow to the burner. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler does not ignite or start the burner.
Cause: If the mechanism does not open the gas flow, there is no fuel for ignition and the boiler cannot ignite.
Make sure that the main gas valve is open and that there is pressure at the inlet of the mechanism before disassembling it.
- 02
A gas smell is detected in the area of the mechanism.
Cause: An internal gasket or seat that does not seal properly can allow gas to escape even when the boiler is turned off.
With the boiler turned off, apply soapy water to the connections of the mechanism; if it bubbles, there is a confirmed leak.
- 03
The display shows a warning or fault code related to the gas valve.
Cause: The control unit does not receive the expected signal from the mechanism and blocks the ignition for safety reasons.
Note the exact code and compare it in the manual: some 'gas failure' warnings may come from the ionization electrode.
- 04
The boiler tries to ignite several times in a row without success.
Cause: If the mechanism does not allow for a constant flow of gas, each ignition attempt fails and the boiler retries until it locks out.
Measure with a multimeter that current is reaching the connectors of the mechanism at the moment of the attempt, to rule out a previous electrical problem.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F.26 | Fault: gas valve not functioning. | The stepper motor of the gas mechanism (valve ref. 05742800) is not operating or is disconnected. Check coil continuity and signal from the PCB; during demand, verify with a manometer that there is no pressure variation at the valve outlet. |
| F.27 | Safety shutdown: incorrect flame detection. | Non-sealed gas solenoid valve or one that does not close properly produces an incoherent flame signal. Check the valve's tightness (leaks) and ensure the flame extinguishes upon closing; replace the valve if it does not seal. |
| F.28 | Start-up fault: ignition failed. | The gas valve does not open or is misadjusted, preventing supply to the burner. Check that it receives command/voltage and coil continuity; measure inlet/outlet pressures during the ignition attempt. |
| F.61 | Gas valve activation fault. | Short circuit to ground in the harness or valve coils, or driver fault in the PCB prevents the valve from activating. Check insulation to ground, coil resistance, and control signal from the electronics. |
| F.62 | Gas valve fault: disconnection delay. | The valve closes late or does not seal (leaks), allowing gas to pass after the stop command. Check for the closing 'click', immediate drop in ionisation, and absence of gas/flame; perform a tightness test and replace if it does not close in time. |
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.
Data sheet for the gas valve Saunier Duval 05742800
- Catalogue reference
- 05742800
- Brand
- Saunier Duval
- Type of part
- Gas valves
- Units in stock
- 5 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Data read on the part and in the manufacturer's documentation
What we have not been able to verify does not appear here.
- Supply voltage
- 24 VDC
- Power
- 6 VA
- Type of gas
- NATURAL GAS
- Reference on label (partial)
- 116.7...
Frequently asked questions about the gas valve 05742800
Does this gas mechanism work for a Saunier Duval Isofast C 35 E1?
What power supply does this gas mechanism mounted on an Isofast C 28 E1 need?
When should this mechanism be replaced in an Isofast F 28 E1?
What fault codes are documented for the gas mechanism VGIC28E1?
Is this gas mechanism compatible with the Isomax range?
How many models are compatible with the Saunier Duval VGIC28E1 gas mechanism?
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