Worcester Greenstar Cdi: won't come up to heat

1. 1. Check gas supply to the property and boiler.

   Why: No gas supply will prevent the boiler from igniting and producing heat, often indicated by an EA fault code if the boiler attempts to fire.

   How: Verify other gas appliances in the property are working. Check the gas meter isolation valve is open. If no other gas appliances are working, contact the gas supplier.

2. 2. Verify boiler system pressure.

   Why: Low system pressure is a common cause for a boiler to not fire as a safety measure.

   How: Check the pressure gauge on the boiler; it should be between 1 and 1.5 bar when cold. If low, repressurise the system using the filling loop according to manufacturer's instructions. Ensure the filling loop is closed afterwards.

3. 3. Check thermostat and heating controls settings.

   Why: Incorrect settings on the room thermostat or programmer will prevent the boiler from calling for heat.

   How: Ensure the room thermostat is set to a temperature higher than the current room temperature and the programmer is set to 'ON' or a heating period. Check the boiler's central heating temperature control is set to the desired level.

4. 4. Inspect the condensate pipe for blockages.

   Why: A blocked or frozen condensate pipe can prevent the boiler from operating, especially in colder weather, and can lead to lockout.

   How: Visually inspect the condensate pipe, particularly external sections, for any signs of freezing or obstruction. Safely thaw any frozen sections using warm water, if accessible and safe to do so.

5. 5. Bleed radiators for trapped air.

   Why: Trapped air in the heating system can prevent proper circulation and reduce heating efficiency, potentially leading to the boiler not coming up to heat.

   How: Using a radiator key, open the bleed valve on the top of each radiator until water appears, then close the valve. Start with the lowest radiator in the system and work upwards. Recheck system pressure afterwards.

6. 6. Check the overheat thermostat.

   Why: A tripped overheat thermostat will prevent the boiler from firing as a safety measure.

   How: Locate the overheat thermostat (refer to the service manual for exact location) and check if the reset button has popped out. If so, press it to reset. *WARNING: Ensure the boiler is isolated electrically before attempting this check.*

7. 7. Verify fan operation.

   Why: A faulty fan or issues with the air pressure switch can prevent the boiler from igniting.

   How: Listen for the fan operating when there is a demand for heat. If no fan noise is heard, further investigation into the fan, air pressure switch, and associated wiring is required. *WARNING: Electrical isolation is required before inspecting internal components.*

8. 8. Inspect ignition and flame sensing electrodes.

   Why: Worn or dirty electrodes can lead to ignition failure or the boiler not detecting a flame.

   How: Visually inspect the ignition and flame sensing electrodes for signs of wear, damage, or soot build-up. Clean or replace as necessary. *WARNING: This involves working within the combustion chamber and requires gas isolation and electrical isolation. Only proceed if competent and Gas Safe registered.*

Sources

The AI cross-checked the following manufacturer and trade sources while producing this checklist.

• scribd.com
• youtube.com
• justanswer.co.uk
• rapidheat247.co.uk
• justanswer.co.uk
• worcester-bosch.co.uk
• pkc.gov.uk
• justanswer.co.uk
• superwarm.co.uk
• plumbnation.co.uk
• worcester-bosch.co.uk
• petervis.com