The Worcester Greenstar Compact boilers are now coming out of warranty, and one of the most common faults engineers encounter is a gas valve issue.
If you’re a Gas Safe registered engineer troubleshooting fault code EA (234) or low burner pressure, your next step should be to test the gas valve solenoids.
This guide explains how to test them safely and accurately.
Boiler Repair and Maintenance Services
At C4UK, we understand that a faulty boiler can cause major disruption to your home or business. Our Gas Safe registered engineers provide prompt, professional, and affordable boiler repair services across Surrey and London.
We use advanced diagnostic tools to identify and resolve issues quickly — from ignition faults and leaking valves to system pressure problems. Every repair is carried out to the highest safety standards, ensuring your heating system runs smoothly and efficiently.
Whether it’s an emergency boiler repair or a routine inspection, we’re committed to delivering fast, reliable service you can trust.
Tools You’ll Need
- Manometer
- Multimeter (set to Ohms scale)
- Access to plug X4 on the PCB
- Basic ignition resistance specifications
Step 1: Pressure Test
- Attach a manometer to the gas inlet test nipple.
- Check both the standing pressure and the working pressure.
If pressure doesn’t drop when the boiler calls for heat, proceed to the electrical tests.
Step 2: Resistance Checks (Solenoids)
Access the plug X4 on the PCB and test the gas valve coil resistance.
| Solenoid | Wire Colors | Expected Resistance | Acceptable Range |
|---|---|---|---|
| Top Solenoid | Red to Blue | 7.1–7.2kΩ | ±10% (5400–6600Ω) |
| Bottom Solenoid | Blue to Orange | 7.2–7.3Ω | ±10% (792–968Ω) |
If readings fall outside these ranges, the solenoid or harness may be faulty.
Step 3: Voltage and Ignition Tests
- If coil resistance is correct, check that the PCB supplies 240V AC to the valve.
- If voltage is present but the valve doesn’t open, this indicates a mechanical issue such as a blocked inlet or jammed solenoid.
Step 4: Igniter Test
Use Test Menu t1 on the boiler display.
- The igniter should be audible when activated.
- Check ignition lead resistance (expected: 0.10 – 0.20 Ω).
- Inspect the electrodes and replace them if worn or damaged.
Step 5: Replacement Parts
If the gas valve or solenoids are found to be faulty, contact Worcester Bosch Technical Support with the boiler’s serial number to obtain the correct replacement part number.
Safety Notice
Only Gas Safe registered engineers should perform these tests or any gas appliance repairs. Always isolate both the boiler and gas supply before starting work.
Contact Certificates4UK Ltd
Need a reliable Gas Safe engineer for boiler repairs, safety checks, or certification? We’re here to help.
We cover:
Molesey • Walton • Woking • Cobham• Weybridge • Sunbury-on-Thames • Surrey • London
Before replacing any parts or booking costly work, let one of our qualified engineers carry out a professional inspection to save you time and money.
Booking Options:
- 🌐 Book Online – Simple, quick, and available 24/7
- 📞 Call: 07596 076700 or 07869 520044
- 📧 Email: info@certificates4uk.co.uk
📍 Proudly serving Molesey, Surrey, and London, we specialise in:
Boiler repairs, Gas Safety Certificates (CP12), Installation, plumbing, EICR testing, EPC inspections, and full property compliance.
⭐ Established in 2014, C4UK has been providing professional heating and property compliance services across Surrey and London. 160+ five-star reviews, Certificates4UK Ltd is the trusted choice for safe, professional, and cost-effective heating services.
Leave a Reply